From e1cdfd27cad943290a0233119548a8dd8876bd52 Mon Sep 17 00:00:00 2001 From: Andy Belle-Isle Date: Thu, 29 Aug 2019 20:02:35 -0400 Subject: Replaced LuaBridge with sol2 and completely encapsulated scripting within script system --- .../Tests/Lua/Lua.5.2.0/doc/contents.html | 531 - lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/logo.gif | Bin 4232 -> 0 bytes lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.1 | 116 - lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.css | 83 - lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/luac.1 | 118 - lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.css | 24 - lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.html | 10397 ------------------- .../Lua/Lua.5.2.0/doc/osi-certified-72x60.png | Bin 3774 -> 0 bytes lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/readme.html | 419 - 9 files changed, 11688 deletions(-) delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/contents.html delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/logo.gif delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.1 delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.css delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/luac.1 delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.css delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.html delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/osi-certified-72x60.png delete mode 100644 lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/readme.html (limited to 'lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc') diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/contents.html b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/contents.html deleted file mode 100644 index 5342723..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/contents.html +++ /dev/null @@ -1,531 +0,0 @@ - - - -Lua 5.2 Reference Manual - contents - - - - - - - -

- -Lua 5.2 Reference Manual -

- -

-The reference manual is the official definition of the Lua language. -For a complete introduction to Lua programming, see the book -Programming in Lua. - -

-start -· -contents -· -index -

- -

Index

- - - - - - - -

- -

- - - - - diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/logo.gif b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/logo.gif deleted file mode 100644 index 2f5e4ac..0000000 Binary files a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/logo.gif and /dev/null differ diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.1 b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.1 deleted file mode 100644 index 1dbf043..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.1 +++ /dev/null @@ -1,116 +0,0 @@ -.\" $Id: lua.man,v 1.13 2011/11/16 17:16:53 lhf Exp $ -.TH LUA 1 "$Date: 2011/11/16 17:16:53 $" -.SH NAME -lua \- Lua interpreter -.SH SYNOPSIS -.B lua -[ -.I options -] -[ -.I script -[ -.I args -] -] -.SH DESCRIPTION -.B lua -is the standalone Lua interpreter. -It loads and executes Lua programs, -either in textual source form or -in precompiled binary form. -(Precompiled binaries are output by -.BR luac , -the Lua compiler.) -.B lua -can be used as a batch interpreter and also interactively. -.LP -The given -.I options -are handled in order and then -the Lua program in file -.I script -is loaded and executed. -The given -.I args -are available to -.I script -as strings in a global table named -.BR arg . -If no options or arguments are given, -then -.B "\-v \-i" -is assumed when the standard input is a terminal; -otherwise, -.B "\-" -is assumed. -.LP -In interactive mode, -.B lua -prompts the user, -reads lines from the standard input, -and executes them as they are read. -If a line does not contain a complete statement, -then a secondary prompt is displayed and -lines are read until a complete statement is formed or -a syntax error is found. -If a line starts with -.BR '=' , -then -.B lua -evaluates and displays -the values of the expressions in the remainder of the line. -.LP -At the very start, -before even handling the command line, -.B lua -checks the contents of the environment variables -.B LUA_INIT_5_2 -or -.BR LUA_INIT , -in that order. -If the contents is of the form -.RI '@ filename ', -then -.I filename -is executed. -Otherwise, the string is assumed to be a Lua statement and is executed. -.SH OPTIONS -.TP -.BI \-e " stat" -execute statement -.IR stat . -.TP -.B \-i -enter interactive mode after executing -.IR script . -.TP -.BI \-l " name" -execute the equivalent of -.IB name =require(' name ') -before executing -.IR script . -.TP -.B \-v -show version information. -.TP -.B \-E -ignore environment variables. -.TP -.B \-\- -stop handling options. -.TP -.B \- -stop handling options and execute the standard input as a file. -.SH "SEE ALSO" -.BR luac (1) -.br -The documentation at lua.org, -especially section 7 of the reference manual. -.SH DIAGNOSTICS -Error messages should be self explanatory. -.SH AUTHORS -R. Ierusalimschy, -L. H. de Figueiredo, -W. Celes -.\" EOF diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.css b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.css deleted file mode 100644 index 54708f8..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/lua.css +++ /dev/null @@ -1,83 +0,0 @@ -body { - color: #000000 ; - background-color: #FFFFFF ; - font-family: Helvetica, Arial, sans-serif ; - text-align: justify ; - margin-right: 20px ; - margin-left: 20px ; -} - -h1, h2, h3, h4 { - font-family: Verdana, Geneva, sans-serif ; - font-weight: normal ; - font-style: italic ; -} - -h2 { - padding-top: 0.4em ; - padding-bottom: 0.4em ; - padding-left: 20px ; - padding-right: 20px ; - margin-left: -20px ; - background-color: #E0E0FF ; -} - -h3 { - padding-left: 0.5em ; - border-left: solid #E0E0FF 1em ; -} - -table h3 { - padding-left: 0px ; - border-left: none ; -} - -a:link { - color: #000080 ; - background-color: inherit ; - text-decoration: none ; -} - -a:visited { - background-color: inherit ; - text-decoration: none ; -} - -a:link:hover, a:visited:hover { - color: #000080 ; - background-color: #E0E0FF ; -} - -a:link:active, a:visited:active { - color: #FF0000 ; -} - -hr { - border: 0 ; - height: 1px ; - color: #a0a0a0 ; - background-color: #a0a0a0 ; -} - -:target { - background-color: #F8F8F8 ; - padding: 8px ; - border: solid #a0a0a0 2px ; -} - -.footer { - color: gray ; - font-size: small ; -} - -input[type=text] { - border: solid #a0a0a0 2px ; - border-radius: 2em ; - -moz-border-radius: 2em ; - background-image: url('images/search.png') ; - background-repeat: no-repeat; - background-position: 4px center ; - padding-left: 20px ; - height: 2em ; -} - diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/luac.1 b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/luac.1 deleted file mode 100644 index 33a4ed0..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/luac.1 +++ /dev/null @@ -1,118 +0,0 @@ -.\" $Id: luac.man,v 1.29 2011/11/16 13:53:40 lhf Exp $ -.TH LUAC 1 "$Date: 2011/11/16 13:53:40 $" -.SH NAME -luac \- Lua compiler -.SH SYNOPSIS -.B luac -[ -.I options -] [ -.I filenames -] -.SH DESCRIPTION -.B luac -is the Lua compiler. -It translates programs written in the Lua programming language -into binary files containing precompiled chunks -that can be later loaded and executed. -.LP -The main advantages of precompiling chunks are: -faster loading, -protecting source code from accidental user changes, -and -off-line syntax checking. -Precompiling does not imply faster execution -because in Lua chunks are always compiled into bytecodes before being executed. -.B luac -simply allows those bytecodes to be saved in a file for later execution. -Precompiled chunks are not necessarily smaller than the corresponding source. -The main goal in precompiling is faster loading. -.LP -In the command line, -you can mix -text files containing Lua source and -binary files containing precompiled chunks. -.B luac -produces a single output file containing the combined bytecodes -for all files given. -Executing the combined file is equivalent to executing the given files. -By default, -the output file is named -.BR luac.out , -but you can change this with the -.B \-o -option. -.LP -Precompiled chunks are -.I not -portable across different architectures. -Moreover, -the internal format of precompiled chunks -is likely to change when a new version of Lua is released. -Make sure you save the source files of all Lua programs that you precompile. -.LP -.SH OPTIONS -.TP -.B \-l -produce a listing of the compiled bytecode for Lua's virtual machine. -Listing bytecodes is useful to learn about Lua's virtual machine. -If no files are given, then -.B luac -loads -.B luac.out -and lists its contents. -Use -.B \-l \-l -for a full listing. -.TP -.BI \-o " file" -output to -.IR file , -instead of the default -.BR luac.out . -(You can use -.B "'\-'" -for standard output, -but not on platforms that open standard output in text mode.) -The output file may be one of the given files because -all files are loaded before the output file is written. -Be careful not to overwrite precious files. -.TP -.B \-p -load files but do not generate any output file. -Used mainly for syntax checking and for testing precompiled chunks: -corrupted files will probably generate errors when loaded. -If no files are given, then -.B luac -loads -.B luac.out -and tests its contents. -No messages are displayed if the file loads without errors. -.TP -.B \-s -strip debug information before writing the output file. -This saves some space in very large chunks, -but if errors occur when running a stripped chunk, -then the error messages may not contain the full information they usually do. -In particular, -line numbers and names of local variables are lost. -.TP -.B \-v -show version information. -.TP -.B \-\- -stop handling options. -.TP -.B \- -stop handling options and process standard input. -.SH "SEE ALSO" -.BR lua (1) -.br -The documentation at lua.org. -.SH DIAGNOSTICS -Error messages should be self explanatory. -.SH AUTHORS -R. Ierusalimschy, -L. H. de Figueiredo, -W. Celes -.\" EOF diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.css b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.css deleted file mode 100644 index ac357a8..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.css +++ /dev/null @@ -1,24 +0,0 @@ -h3 code { - font-family: inherit ; - font-size: inherit ; -} - -pre, code { - font-size: 12pt ; -} - -span.apii { - float: right ; - font-family: inherit ; - font-style: normal ; - font-size: small ; - color: gray ; -} - -p+h1, ul+h1 { - padding-top: 0.4em ; - padding-bottom: 0.4em ; - padding-left: 20px ; - margin-left: -20px ; - background-color: #E0E0FF ; -} diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.html b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.html deleted file mode 100644 index 360d316..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/manual.html +++ /dev/null @@ -1,10397 +0,0 @@ - - - - -Lua 5.2 Reference Manual - - - - - - - -

- -Lua 5.2 Reference Manual -

- -by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes -

- -contents -· -index - - -

- - - - - - -

1 – Introduction

- -

-Lua is an extension programming language designed to support -general procedural programming with data description -facilities. -It also offers good support for object-oriented programming, -functional programming, and data-driven programming. -Lua is intended to be used as a powerful, lightweight, -embeddable scripting language for any program that needs one. -Lua is implemented as a library, written in clean C, -the common subset of Standard C and C++. - - -

-Being an extension language, Lua has no notion of a "main" program: -it only works embedded in a host client, -called the embedding program or simply the host. -The host program can invoke functions to execute a piece of Lua code, -can write and read Lua variables, -and can register C functions to be called by Lua code. -Through the use of C functions, Lua can be augmented to cope with -a wide range of different domains, -thus creating customized programming languages sharing a syntactical framework. -The Lua distribution includes a sample host program called lua, -which uses the Lua library to offer a complete, standalone Lua interpreter, -for interactive or batch use. - - -

-Lua is free software, -and is provided as usual with no guarantees, -as stated in its license. -The implementation described in this manual is available -at Lua's official web site, www.lua.org. - - -

-Like any other reference manual, -this document is dry in places. -For a discussion of the decisions behind the design of Lua, -see the technical papers available at Lua's web site. -For a detailed introduction to programming in Lua, -see Roberto's book, Programming in Lua. - - - -

2 – Basic Concepts

- -

-This section describes the basic concepts of the language. - - - -

2.1 – Values and Types

- -

-Lua is a dynamically typed language. -This means that -variables do not have types; only values do. -There are no type definitions in the language. -All values carry their own type. - - -

-All values in Lua are first-class values. -This means that all values can be stored in variables, -passed as arguments to other functions, and returned as results. - - -

-There are eight basic types in Lua: -nil, boolean, number, -string, function, userdata, -thread, and table. -Nil is the type of the value nil, -whose main property is to be different from any other value; -it usually represents the absence of a useful value. -Boolean is the type of the values false and true. -Both nil and false make a condition false; -any other value makes it true. -Number represents real (double-precision floating-point) numbers. -Operations on numbers follow the same rules of -the underlying C implementation, -which, in turn, usually follows the IEEE 754 standard. -(It is easy to build Lua interpreters that use other -internal representations for numbers, -such as single-precision floats or long integers; -see file luaconf.h.) -String represents immutable sequences of bytes. - -Lua is 8-bit clean: -strings can contain any 8-bit value, -including embedded zeros ('\0'). - - -

-Lua can call (and manipulate) functions written in Lua and -functions written in C -(see §3.4.9). - - -

-The type userdata is provided to allow arbitrary C data to -be stored in Lua variables. -A userdata value is a pointer to a block of raw memory. -There are two kinds of userdata: -full userdata, where the block of memory is managed by Lua, -and light userdata, where the block of memory is managed by the host. -Userdata has no predefined operations in Lua, -except assignment and identity test. -By using metatables, -the programmer can define operations for full userdata values -(see §2.4). -Userdata values cannot be created or modified in Lua, -only through the C API. -This guarantees the integrity of data owned by the host program. - - -

-The type thread represents independent threads of execution -and it is used to implement coroutines (see §2.6). -Do not confuse Lua threads with operating-system threads. -Lua supports coroutines on all systems, -even those that do not support threads. - - -

-The type table implements associative arrays, -that is, arrays that can be indexed not only with numbers, -but with any Lua value except nil and NaN -(Not a Number, a special numeric value used to represent -undefined or unrepresentable results, such as 0/0). -Tables can be heterogeneous; -that is, they can contain values of all types (except nil). -Any key with value nil is not considered part of the table. -Conversely, any key that is not part of a table has -an associated value nil. - - -

-Tables are the sole data structuring mechanism in Lua; -they can be used to represent ordinary arrays, sequences, -symbol tables, sets, records, graphs, trees, etc. -To represent records, Lua uses the field name as an index. -The language supports this representation by -providing a.name as syntactic sugar for a["name"]. -There are several convenient ways to create tables in Lua -(see §3.4.8). - - -

-We use the term sequence to denote a table where -the set of all positive numeric keys is equal to {1..n} -for some integer n, -which is called the length of the sequence (see §3.4.6). - - -

-Like indices, -the values of table fields can be of any type. -In particular, -because functions are first-class values, -table fields can contain functions. -Thus tables can also carry methods (see §3.4.10). - - -

-The indexing of tables follows -the definition of raw equality in the language. -The expressions a[i] and a[j] -denote the same table element -if and only if i and j are raw equal -(that is, equal without metamethods). - - -

-Tables, functions, threads, and (full) userdata values are objects: -variables do not actually contain these values, -only references to them. -Assignment, parameter passing, and function returns -always manipulate references to such values; -these operations do not imply any kind of copy. - - -

-The library function type returns a string describing the type -of a given value (see §6.1). - - - - - -

2.2 – Environments and the Global Environment

- -

-As will be discussed in §3.2 and §3.3.3, -any reference to a global name var is syntactically translated -to _ENV.var. -Moreover, every chunk is compiled in the scope of -an external local variable called _ENV (see §3.3.2), -so _ENV itself is never a global name in a chunk. - - -

-Despite the existence of this external _ENV variable and -the translation of global names, -_ENV is a completely regular name. -In particular, -you can define new variables and parameters with that name. -Each reference to a global name uses the _ENV that is -visible at that point in the program, -following the usual visibility rules of Lua (see §3.5). - - -

-Any table used as the value of _ENV is called an environment. - - -

-Lua keeps a distinguished environment called the global environment. -This value is kept at a special index in the C registry (see §4.5). -In Lua, the variable _G is initialized with this same value. - - -

-When Lua compiles a chunk, -it initializes the value of its _ENV upvalue -with the global environment (see load). -Therefore, by default, -global variables in Lua code refer to entries in the global environment. -Moreover, all standard libraries are loaded in the global environment -and several functions there operate on that environment. -You can use load (or loadfile) -to load a chunk with a different environment. -(In C, you have to load the chunk and then change the value -of its first upvalue.) - - -

-If you change the global environment in the registry -(through C code or the debug library), -all chunks loaded after the change will get the new environment. -Previously loaded chunks are not affected, however, -as each has its own reference to the environment in its _ENV variable. -Moreover, the variable _G -(which is stored in the original global environment) -is never updated by Lua. - - - - - -

2.3 – Error Handling

- -

-Because Lua is an embedded extension language, -all Lua actions start from C code in the host program -calling a function from the Lua library (see lua_pcall). -Whenever an error occurs during -the compilation or execution of a Lua chunk, -control returns to the host, -which can take appropriate measures -(such as printing an error message). - - -

-Lua code can explicitly generate an error by calling the -error function. -If you need to catch errors in Lua, -you can use pcall or xpcall -to call a given function in protected mode. - - -

-Whenever there is an error, -an error object (also called an error message) -is propagated with information about the error. -Lua itself only generates errors where the error object is a string, -but programs may generate errors with -any value for the error object. - - -

-When you use xpcall or lua_pcall, -you may give a message handler -to be called in case of errors. -This function is called with the original error message -and returns a new error message. -It is called before the error unwinds the stack, -so that it can gather more information about the error, -for instance by inspecting the stack and creating a stack traceback. -This message handler is still protected by the protected call; -so, an error inside the message handler -will call the message handler again. -If this loop goes on, Lua breaks it and returns an appropriate message. - - - - - -

2.4 – Metatables and Metamethods

- -

-Every value in Lua can have a metatable. -This metatable is an ordinary Lua table -that defines the behavior of the original value -under certain special operations. -You can change several aspects of the behavior -of operations over a value by setting specific fields in its metatable. -For instance, when a non-numeric value is the operand of an addition, -Lua checks for a function in the field "__add" of the value's metatable. -If it finds one, -Lua calls this function to perform the addition. - - -

-The keys in a metatable are derived from the event names; -the corresponding values are called metamethods. -In the previous example, the event is "add" -and the metamethod is the function that performs the addition. - - -

-You can query the metatable of any value -using the getmetatable function. - - -

-You can replace the metatable of tables -using the setmetatable function. -You cannot change the metatable of other types from Lua -(except by using the debug library); -you must use the C API for that. - - -

-Tables and full userdata have individual metatables -(although multiple tables and userdata can share their metatables). -Values of all other types share one single metatable per type; -that is, there is one single metatable for all numbers, -one for all strings, etc. -By default, a value has no metatable, -but the string library sets a metatable for the string type (see §6.4). - - -

-A metatable controls how an object behaves in arithmetic operations, -order comparisons, concatenation, length operation, and indexing. -A metatable also can define a function to be called -when a userdata or a table is garbage collected. -When Lua performs one of these operations over a value, -it checks whether this value has a metatable with the corresponding event. -If so, the value associated with that key (the metamethod) -controls how Lua will perform the operation. - - -

-Metatables control the operations listed next. -Each operation is identified by its corresponding name. -The key for each operation is a string with its name prefixed by -two underscores, '__'; -for instance, the key for operation "add" is the -string "__add". - - -

-The semantics of these operations is better explained by a Lua function -describing how the interpreter executes the operation. -The code shown here in Lua is only illustrative; -the real behavior is hard coded in the interpreter -and it is much more efficient than this simulation. -All functions used in these descriptions -(rawget, tonumber, etc.) -are described in §6.1. -In particular, to retrieve the metamethod of a given object, -we use the expression - -

-     metatable(obj)[event]
-

-This should be read as - -

-     rawget(getmetatable(obj) or {}, event)
-

- -This means that the access to a metamethod does not invoke other metamethods, -and access to objects with no metatables does not fail -(it simply results in nil). - - -

-For the unary - and # operators, -the metamethod is called with a dummy second argument. -This extra argument is only to simplify Lua's internals; -it may be removed in future versions and therefore it is not present -in the following code. -(For most uses this extra argument is irrelevant.) - - - -

"add": -the + operation. - - - -

-The function getbinhandler below defines how Lua chooses a handler -for a binary operation. -First, Lua tries the first operand. -If its type does not define a handler for the operation, -then Lua tries the second operand. - -

-     function getbinhandler (op1, op2, event)
-       return metatable(op1)[event] or metatable(op2)[event]
-     end
-

-By using this function, -the behavior of the op1 + op2 is - -

-     function add_event (op1, op2)
-       local o1, o2 = tonumber(op1), tonumber(op2)
-       if o1 and o2 then  -- both operands are numeric?
-         return o1 + o2   -- '+' here is the primitive 'add'
-       else  -- at least one of the operands is not numeric
-         local h = getbinhandler(op1, op2, "__add")
-         if h then
-           -- call the handler with both operands
-           return (h(op1, op2))
-         else  -- no handler available: default behavior
-           error(···)
-         end
-       end
-     end
-

"sub": -the - operation. - -Behavior similar to the "add" operation. -
"mul": -the * operation. - -Behavior similar to the "add" operation. -
"div": -the / operation. - -Behavior similar to the "add" operation. -
"mod": -the % operation. - -Behavior similar to the "add" operation, -with the operation -o1 - floor(o1/o2)*o2 as the primitive operation. -
"pow": -the ^ (exponentiation) operation. - -Behavior similar to the "add" operation, -with the function pow (from the C math library) -as the primitive operation. -

"unm": -the unary - operation. - - -

-     function unm_event (op)
-       local o = tonumber(op)
-       if o then  -- operand is numeric?
-         return -o  -- '-' here is the primitive 'unm'
-       else  -- the operand is not numeric.
-         -- Try to get a handler from the operand
-         local h = metatable(op).__unm
-         if h then
-           -- call the handler with the operand
-           return (h(op))
-         else  -- no handler available: default behavior
-           error(···)
-         end
-       end
-     end
-

"concat": -the .. (concatenation) operation. - - -

-     function concat_event (op1, op2)
-       if (type(op1) == "string" or type(op1) == "number") and
-          (type(op2) == "string" or type(op2) == "number") then
-         return op1 .. op2  -- primitive string concatenation
-       else
-         local h = getbinhandler(op1, op2, "__concat")
-         if h then
-           return (h(op1, op2))
-         else
-           error(···)
-         end
-       end
-     end
-

"len": -the # operation. - - -

-     function len_event (op)
-       if type(op) == "string" then
-         return strlen(op)      -- primitive string length
-       else
-         local h = metatable(op).__len
-         if h then
-           return (h(op))       -- call handler with the operand
-         elseif type(op) == "table" then
-           return #op              -- primitive table length
-         else  -- no handler available: error
-           error(···)
-         end
-       end
-     end
-

-See §3.4.6 for a description of the length of a table. -

"eq": -the == operation. - -The function getequalhandler defines how Lua chooses a metamethod -for equality. -A metamethod is selected only when both values -being compared have the same type -and the same metamethod for the selected operation, -and the values are either tables or full userdata. - -

-     function getequalhandler (op1, op2)
-       if type(op1) ~= type(op2) or
-          (type(op1) ~= "table" and type(op1) ~= "userdata") then
-         return nil     -- different values
-       end
-       local mm1 = metatable(op1).__eq
-       local mm2 = metatable(op2).__eq
-       if mm1 == mm2 then return mm1 else return nil end
-     end
-

-The "eq" event is defined as follows: - -

-     function eq_event (op1, op2)
-       if op1 == op2 then   -- primitive equal?
-         return true   -- values are equal
-       end
-       -- try metamethod
-       local h = getequalhandler(op1, op2)
-       if h then
-         return not not h(op1, op2)
-       else
-         return false
-       end
-     end
-

-Note that the result is always a boolean. -

"lt": -the < operation. - - -

-     function lt_event (op1, op2)
-       if type(op1) == "number" and type(op2) == "number" then
-         return op1 < op2   -- numeric comparison
-       elseif type(op1) == "string" and type(op2) == "string" then
-         return op1 < op2   -- lexicographic comparison
-       else
-         local h = getbinhandler(op1, op2, "__lt")
-         if h then
-           return not not h(op1, op2)
-         else
-           error(···)
-         end
-       end
-     end
-

-Note that the result is always a boolean. -

"le": -the <= operation. - - -

-     function le_event (op1, op2)
-       if type(op1) == "number" and type(op2) == "number" then
-         return op1 <= op2   -- numeric comparison
-       elseif type(op1) == "string" and type(op2) == "string" then
-         return op1 <= op2   -- lexicographic comparison
-       else
-         local h = getbinhandler(op1, op2, "__le")
-         if h then
-           return not not h(op1, op2)
-         else
-           h = getbinhandler(op1, op2, "__lt")
-           if h then
-             return not h(op2, op1)
-           else
-             error(···)
-           end
-         end
-       end
-     end
-

-Note that, in the absence of a "le" metamethod, -Lua tries the "lt", assuming that a <= b is -equivalent to not (b < a). - - -

-As with the other comparison operators, -the result is always a boolean. -

"index": -The indexing access table[key]. -Note that the metamethod is tried only -when key is not present in table. -(When table is not a table, -no key is ever present, -so the metamethod is always tried.) - - -

-     function gettable_event (table, key)
-       local h
-       if type(table) == "table" then
-         local v = rawget(table, key)
-         -- if key is present, return raw value
-         if v ~= nil then return v end
-         h = metatable(table).__index
-         if h == nil then return nil end
-       else
-         h = metatable(table).__index
-         if h == nil then
-           error(···)
-         end
-       end
-       if type(h) == "function" then
-         return (h(table, key))     -- call the handler
-       else return h[key]           -- or repeat operation on it
-       end
-     end
-

"newindex": -The indexing assignment table[key] = value. -Note that the metamethod is tried only -when key is not present in table. - - -

-     function settable_event (table, key, value)
-       local h
-       if type(table) == "table" then
-         local v = rawget(table, key)
-         -- if key is present, do raw assignment
-         if v ~= nil then rawset(table, key, value); return end
-         h = metatable(table).__newindex
-         if h == nil then rawset(table, key, value); return end
-       else
-         h = metatable(table).__newindex
-         if h == nil then
-           error(···)
-         end
-       end
-       if type(h) == "function" then
-         h(table, key,value)           -- call the handler
-       else h[key] = value             -- or repeat operation on it
-       end
-     end
-

"call": -called when Lua calls a value. - - -

-     function function_event (func, ...)
-       if type(func) == "function" then
-         return func(...)   -- primitive call
-       else
-         local h = metatable(func).__call
-         if h then
-           return h(func, ...)
-         else
-           error(···)
-         end
-       end
-     end
-

- - - - -

2.5 – Garbage Collection

- -

-Lua performs automatic memory management. -This means that -you have to worry neither about allocating memory for new objects -nor about freeing it when the objects are no longer needed. -Lua manages memory automatically by running -a garbage collector to collect all dead objects -(that is, objects that are no longer accessible from Lua). -All memory used by Lua is subject to automatic management: -strings, tables, userdata, functions, threads, internal structures, etc. - - -

-Lua implements an incremental mark-and-sweep collector. -It uses two numbers to control its garbage-collection cycles: -the garbage-collector pause and -the garbage-collector step multiplier. -Both use percentage points as units -(e.g., a value of 100 means an internal value of 1). - - -

-The garbage-collector pause -controls how long the collector waits before starting a new cycle. -Larger values make the collector less aggressive. -Values smaller than 100 mean the collector will not wait to -start a new cycle. -A value of 200 means that the collector waits for the total memory in use -to double before starting a new cycle. - - -

-The garbage-collector step multiplier -controls the relative speed of the collector relative to -memory allocation. -Larger values make the collector more aggressive but also increase -the size of each incremental step. -Values smaller than 100 make the collector too slow and -can result in the collector never finishing a cycle. -The default is 200, -which means that the collector runs at "twice" -the speed of memory allocation. - - -

-If you set the step multiplier to a very large number -(larger than 10% of the maximum number of -bytes that the program may use), -the collector behaves like a stop-the-world collector. -If you then set the pause to 200, -the collector behaves as in old Lua versions, -doing a complete collection every time Lua doubles its -memory usage. - - -

-You can change these numbers by calling lua_gc in C -or collectgarbage in Lua. -You can also use these functions to control -the collector directly (e.g., stop and restart it). - - -

-As an experimental feature in Lua 5.2, -you can change the collector's operation mode -from incremental to generational. -A generational collector assumes that most objects die young, -and therefore it traverses only young (recently created) objects. -This behavior can reduce the time used by the collector, -but also increases memory usage (as old dead objects may accumulate). -To mitigate this second problem, -from time to time the generational collector performs a full collection. -Remember that this is an experimental feature; -you are welcome to try it, -but check your gains. - - - -

2.5.1 – Garbage-Collection Metamethods

- -

-You can set garbage-collector metamethods for tables -and, using the C API, -for full userdata (see §2.4). -These metamethods are also called finalizers. -Finalizers allow you to coordinate Lua's garbage collection -with external resource management -(such as closing files, network or database connections, -or freeing your own memory). - - -

-For an object (table or userdata) to be finalized when collected, -you must mark it for finalization. - -You mark an object for finalization when you set its metatable -and the metatable has a field indexed by the string "__gc". -Note that if you set a metatable without a __gc field -and later create that field in the metatable, -the object will not be marked for finalization. -However, after an object is marked, -you can freely change the __gc field of its metatable. - - -

-When a marked object becomes garbage, -it is not collected immediately by the garbage collector. -Instead, Lua puts it in a list. -After the collection, -Lua does the equivalent of the following function -for each object in that list: - -

-     function gc_event (obj)
-       local h = metatable(obj).__gc
-       if type(h) == "function" then
-         h(obj)
-       end
-     end
-

- -

-At the end of each garbage-collection cycle, -the finalizers for objects are called in -the reverse order that they were marked for collection, -among those collected in that cycle; -that is, the first finalizer to be called is the one associated -with the object marked last in the program. -The execution of each finalizer may occur at any point during -the execution of the regular code. - - -

-Because the object being collected must still be used by the finalizer, -it (and other objects accessible only through it) -must be resurrected by Lua. -Usually, this resurrection is transient, -and the object memory is freed in the next garbage-collection cycle. -However, if the finalizer stores the object in some global place -(e.g., a global variable), -then there is a permanent resurrection. -In any case, -the object memory is freed only when it becomes completely inaccessible; -its finalizer will never be called twice. - - - - - -

2.5.2 – Weak Tables

- -

-A weak table is a table whose elements are -weak references. -A weak reference is ignored by the garbage collector. -In other words, -if the only references to an object are weak references, -then the garbage collector will collect that object. - - -

-A weak table can have weak keys, weak values, or both. -A table with weak keys allows the collection of its keys, -but prevents the collection of its values. -A table with both weak keys and weak values allows the collection of -both keys and values. -In any case, if either the key or the value is collected, -the whole pair is removed from the table. -The weakness of a table is controlled by the -__mode field of its metatable. -If the __mode field is a string containing the character 'k', -the keys in the table are weak. -If __mode contains 'v', -the values in the table are weak. - - -

-A table with weak keys and strong values -is also called an ephemeron table. -In an ephemeron table, -a value is considered reachable only if its key is reachable. -In particular, -if the only reference to a key comes through its value, -the pair is removed. - - -

-Any change in the weakness of a table may take effect only -at the next collect cycle. -In particular, if you change the weakness to a stronger mode, -Lua may still collect some items from that table -before the change takes effect. - - -

-Only objects that have an explicit construction -are removed from weak tables. -Values, such as numbers and light C functions, -are not subject to garbage collection, -and therefore are not removed from weak tables -(unless its associated value is collected). -Although strings are subject to garbage collection, -they do not have an explicit construction, -and therefore are not removed from weak tables. - - -

-Resurrected objects -(that is, objects being finalized -and objects accessible only through objects being finalized) -have a special behavior in weak tables. -They are removed from weak values before running their finalizers, -but are removed from weak keys only in the next collection -after running their finalizers, when such objects are actually freed. -This behavior allows the finalizer to access properties -associated with the object through weak tables. - - -

-If a weak table is among the resurrected objects in a collection cycle, -it may not be properly cleared until the next cycle. - - - - - - - -

2.6 – Coroutines

- -

-Lua supports coroutines, -also called collaborative multithreading. -A coroutine in Lua represents an independent thread of execution. -Unlike threads in multithread systems, however, -a coroutine only suspends its execution by explicitly calling -a yield function. - - -

-You create a coroutine by calling coroutine.create. -Its sole argument is a function -that is the main function of the coroutine. -The create function only creates a new coroutine and -returns a handle to it (an object of type thread); -it does not start the coroutine. - - -

-You execute a coroutine by calling coroutine.resume. -When you first call coroutine.resume, -passing as its first argument -a thread returned by coroutine.create, -the coroutine starts its execution, -at the first line of its main function. -Extra arguments passed to coroutine.resume are passed on -to the coroutine main function. -After the coroutine starts running, -it runs until it terminates or yields. - - -

-A coroutine can terminate its execution in two ways: -normally, when its main function returns -(explicitly or implicitly, after the last instruction); -and abnormally, if there is an unprotected error. -In the first case, coroutine.resume returns true, -plus any values returned by the coroutine main function. -In case of errors, coroutine.resume returns false -plus an error message. - - -

-A coroutine yields by calling coroutine.yield. -When a coroutine yields, -the corresponding coroutine.resume returns immediately, -even if the yield happens inside nested function calls -(that is, not in the main function, -but in a function directly or indirectly called by the main function). -In the case of a yield, coroutine.resume also returns true, -plus any values passed to coroutine.yield. -The next time you resume the same coroutine, -it continues its execution from the point where it yielded, -with the call to coroutine.yield returning any extra -arguments passed to coroutine.resume. - - -

-Like coroutine.create, -the coroutine.wrap function also creates a coroutine, -but instead of returning the coroutine itself, -it returns a function that, when called, resumes the coroutine. -Any arguments passed to this function -go as extra arguments to coroutine.resume. -coroutine.wrap returns all the values returned by coroutine.resume, -except the first one (the boolean error code). -Unlike coroutine.resume, -coroutine.wrap does not catch errors; -any error is propagated to the caller. - - -

-As an example of how coroutines work, -consider the following code: - -

-     function foo (a)
-       print("foo", a)
-       return coroutine.yield(2*a)
-     end
-     
-     co = coroutine.create(function (a,b)
-           print("co-body", a, b)
-           local r = foo(a+1)
-           print("co-body", r)
-           local r, s = coroutine.yield(a+b, a-b)
-           print("co-body", r, s)
-           return b, "end"
-     end)
-     
-     print("main", coroutine.resume(co, 1, 10))
-     print("main", coroutine.resume(co, "r"))
-     print("main", coroutine.resume(co, "x", "y"))
-     print("main", coroutine.resume(co, "x", "y"))
-

-When you run it, it produces the following output: - -

-     co-body 1       10
-     foo     2
-     main    true    4
-     co-body r
-     main    true    11      -9
-     co-body x       y
-     main    true    10      end
-     main    false   cannot resume dead coroutine
-

- -

-You can also create and manipulate coroutines through the C API: -see functions lua_newthread, lua_resume, -and lua_yield. - - - - - -

3 – The Language

- -

-This section describes the lexis, the syntax, and the semantics of Lua. -In other words, -this section describes -which tokens are valid, -how they can be combined, -and what their combinations mean. - - -

-Language constructs will be explained using the usual extended BNF notation, -in which -{a} means 0 or more a's, and -[a] means an optional a. -Non-terminals are shown like non-terminal, -keywords are shown like kword, -and other terminal symbols are shown like ‘=’. -The complete syntax of Lua can be found in §9 -at the end of this manual. - - - -

3.1 – Lexical Conventions

- -

-Lua is a free-form language. -It ignores spaces (including new lines) and comments -between lexical elements (tokens), -except as delimiters between names and keywords. - - -

-Names -(also called identifiers) -in Lua can be any string of letters, -digits, and underscores, -not beginning with a digit. -Identifiers are used to name variables, table fields, and labels. - - -

-The following keywords are reserved -and cannot be used as names: - - -

-     and       break     do        else      elseif    end
-     false     for       function  goto      if        in
-     local     nil       not       or        repeat    return
-     then      true      until     while
-

- -

-Lua is a case-sensitive language: -and is a reserved word, but And and AND -are two different, valid names. -As a convention, names starting with an underscore followed by -uppercase letters (such as _VERSION) -are reserved for variables used by Lua. - - -

-The following strings denote other tokens: - -

-     +     -     *     /     %     ^     #
-     ==    ~=    <=    >=    <     >     =
-     (     )     {     }     [     ]     ::
-     ;     :     ,     .     ..    ...
-

- -

-Literal strings -can be delimited by matching single or double quotes, -and can contain the following C-like escape sequences: -'\a' (bell), -'\b' (backspace), -'\f' (form feed), -'\n' (newline), -'\r' (carriage return), -'\t' (horizontal tab), -'\v' (vertical tab), -'\\' (backslash), -'\"' (quotation mark [double quote]), -and '\'' (apostrophe [single quote]). -A backslash followed by a real newline -results in a newline in the string. -The escape sequence '\z' skips the following span -of white-space characters, -including line breaks; -it is particularly useful to break and indent a long string -into multiple lines without adding the newlines and spaces -into the string contents. - - -

-A byte in a literal string can also be specified by its numerical value. -This can be done with the escape sequence \xXX, -where XX is a sequence of exactly two hexadecimal digits, -or with the escape sequence \ddd, -where ddd is a sequence of up to three decimal digits. -(Note that if a decimal escape is to be followed by a digit, -it must be expressed using exactly three digits.) -Strings in Lua can contain any 8-bit value, including embedded zeros, -which can be specified as '\0'. - - -

-Literal strings can also be defined using a long format -enclosed by long brackets. -We define an opening long bracket of level n as an opening -square bracket followed by n equal signs followed by another -opening square bracket. -So, an opening long bracket of level 0 is written as [[, -an opening long bracket of level 1 is written as [=[, -and so on. -A closing long bracket is defined similarly; -for instance, a closing long bracket of level 4 is written as ]====]. -A long string starts with an opening long bracket of any level and -ends at the first closing long bracket of the same level. -It can contain any text except a closing bracket of the proper level. -Literals in this bracketed form can run for several lines, -do not interpret any escape sequences, -and ignore long brackets of any other level. -Any kind of end-of-line sequence -(carriage return, newline, carriage return followed by newline, -or newline followed by carriage return) -is converted to a simple newline. - - -

-When parsing a from a string source, -any byte in a literal string not -explicitly affected by the previous rules represents itself. -However, Lua opens files for parsing in text mode, -and the system file functions may have problems with -some control characters. -So, it is safer to represent -non-text data as a quoted literal with -explicit escape sequences for non-text characters. - - -

-For convenience, -when the opening long bracket is immediately followed by a newline, -the newline is not included in the string. -As an example, in a system using ASCII -(in which 'a' is coded as 97, -newline is coded as 10, and '1' is coded as 49), -the five literal strings below denote the same string: - -

-     a = 'alo\n123"'
-     a = "alo\n123\""
-     a = '\97lo\10\04923"'
-     a = [[alo
-     123"]]
-     a = [==[
-     alo
-     123"]==]
-

- -

-A numerical constant can be written with an optional fractional part -and an optional decimal exponent, -marked by a letter 'e' or 'E'. -Lua also accepts hexadecimal constants, -which start with 0x or 0X. -Hexadecimal constants also accept an optional fractional part -plus an optional binary exponent, -marked by a letter 'p' or 'P'. -Examples of valid numerical constants are - -

-     3     3.0     3.1416     314.16e-2     0.31416E1
-     0xff  0x0.1E  0xA23p-4   0X1.921FB54442D18P+1
-

- -

-A comment starts with a double hyphen (--) -anywhere outside a string. -If the text immediately after -- is not an opening long bracket, -the comment is a short comment, -which runs until the end of the line. -Otherwise, it is a long comment, -which runs until the corresponding closing long bracket. -Long comments are frequently used to disable code temporarily. - - - - - -

3.2 – Variables

- -

-Variables are places that store values. -There are three kinds of variables in Lua: -global variables, local variables, and table fields. - - -

-A single name can denote a global variable or a local variable -(or a function's formal parameter, -which is a particular kind of local variable): - -

-	var ::= Name
-

-Name denotes identifiers, as defined in §3.1. - - -

-Any variable name is assumed to be global unless explicitly declared -as a local (see §3.3.7). -Local variables are lexically scoped: -local variables can be freely accessed by functions -defined inside their scope (see §3.5). - - -

-Before the first assignment to a variable, its value is nil. - - -

-Square brackets are used to index a table: - -

-	var ::= prefixexp ‘[’ exp ‘]’
-

-The meaning of accesses to table fields can be changed via metatables. -An access to an indexed variable t[i] is equivalent to -a call gettable_event(t,i). -(See §2.4 for a complete description of the -gettable_event function. -This function is not defined or callable in Lua. -We use it here only for explanatory purposes.) - - -

-The syntax var.Name is just syntactic sugar for -var["Name"]: - -

-	var ::= prefixexp ‘.’ Name
-

- -

-An access to a global variable x -is equivalent to _ENV.x. -Due to the way that chunks are compiled, -_ENV is never a global name (see §2.2). - - - - - -

3.3 – Statements

- -

-Lua supports an almost conventional set of statements, -similar to those in Pascal or C. -This set includes -assignments, control structures, function calls, -and variable declarations. - - - -

3.3.1 – Blocks

- -

-A block is a list of statements, -which are executed sequentially: - -

-	block ::= {stat}
-

-Lua has empty statements -that allow you to separate statements with semicolons, -start a block with a semicolon -or write two semicolons in sequence: - -

-	stat ::= ‘;’
-

- -

-A block can be explicitly delimited to produce a single statement: - -

-	stat ::= do block end
-

-Explicit blocks are useful -to control the scope of variable declarations. -Explicit blocks are also sometimes used to -add a return statement in the middle -of another block (see §3.3.4). - - - - - -

3.3.2 – Chunks

- -

-The unit of execution of Lua is called a chunk. -Syntactically, -a chunk is simply a block: - -

-	chunk ::= block
-

- -

-Lua handles a chunk as the body of an anonymous function -with a variable number of arguments -(see §3.4.10). -As such, chunks can define local variables, -receive arguments, and return values. -Moreover, such anonymous function is compiled as in the -scope of an external local variable called _ENV (see §2.2). -The resulting function always has _ENV as its only upvalue, -even if it does not use that variable. - - -

-A chunk can be stored in a file or in a string inside the host program. -To execute a chunk, -Lua first precompiles the chunk into instructions for a virtual machine, -and then it executes the compiled code -with an interpreter for the virtual machine. - - -

-Chunks can also be precompiled into binary form; -see program luac for details. -Programs in source and compiled forms are interchangeable; -Lua automatically detects the file type and acts accordingly. - - - - - - -

3.3.3 – Assignment

- -

-Lua allows multiple assignments. -Therefore, the syntax for assignment -defines a list of variables on the left side -and a list of expressions on the right side. -The elements in both lists are separated by commas: - -

-	stat ::= varlist ‘=’ explist
-	varlist ::= var {‘,’ var}
-	explist ::= exp {‘,’ exp}
-

-Expressions are discussed in §3.4. - - -

-Before the assignment, -the list of values is adjusted to the length of -the list of variables. -If there are more values than needed, -the excess values are thrown away. -If there are fewer values than needed, -the list is extended with as many nil's as needed. -If the list of expressions ends with a function call, -then all values returned by that call enter the list of values, -before the adjustment -(except when the call is enclosed in parentheses; see §3.4). - - -

-The assignment statement first evaluates all its expressions -and only then are the assignments performed. -Thus the code - -

-     i = 3
-     i, a[i] = i+1, 20
-

-sets a[3] to 20, without affecting a[4] -because the i in a[i] is evaluated (to 3) -before it is assigned 4. -Similarly, the line - -

-     x, y = y, x
-

-exchanges the values of x and y, -and - -

-     x, y, z = y, z, x
-

-cyclically permutes the values of x, y, and z. - - -

-The meaning of assignments to global variables -and table fields can be changed via metatables. -An assignment to an indexed variable t[i] = val is equivalent to -settable_event(t,i,val). -(See §2.4 for a complete description of the -settable_event function. -This function is not defined or callable in Lua. -We use it here only for explanatory purposes.) - - -

-An assignment to a global variable x = val -is equivalent to the assignment -_ENV.x = val (see §2.2). - - - - - -

3.3.4 – Control Structures

-The control structures -if, while, and repeat have the usual meaning and -familiar syntax: - - - - -

-	stat ::= while exp do block end
-	stat ::= repeat block until exp
-	stat ::= if exp then block {elseif exp then block} [else block] end
-

-Lua also has a for statement, in two flavors (see §3.3.5). - - -

-The condition expression of a -control structure can return any value. -Both false and nil are considered false. -All values different from nil and false are considered true -(in particular, the number 0 and the empty string are also true). - - -

-In the repeat–until loop, -the inner block does not end at the until keyword, -but only after the condition. -So, the condition can refer to local variables -declared inside the loop block. - - -

-The goto statement transfers the program control to a label. -For syntactical reasons, -labels in Lua are considered statements too: - - - -

-	stat ::= goto Name
-	stat ::= label
-	label ::= ‘::’ Name ‘::’
-

- -

-A label is visible in the entire block where it is defined, -except -inside nested blocks where a label with the same name is defined and -inside nested functions. -A goto may jump to any visible label as long as it does not -enter into the scope of a local variable. - - -

-Labels and empty statements are called void statements, -as they perform no actions. - - -

-The break statement terminates the execution of a -while, repeat, or for loop, -skipping to the next statement after the loop: - - -

-	stat ::= break
-

-A break ends the innermost enclosing loop. - - -

-The return statement is used to return values -from a function or a chunk (which is a function in disguise). - -Functions can return more than one value, -so the syntax for the return statement is - -

-	stat ::= return [explist] [‘;’]
-

- -

-The return statement can only be written -as the last statement of a block. -If it is really necessary to return in the middle of a block, -then an explicit inner block can be used, -as in the idiom do return end, -because now return is the last statement in its (inner) block. - - - - - -

3.3.5 – For Statement

- -

- -The for statement has two forms: -one numeric and one generic. - - -

-The numeric for loop repeats a block of code while a -control variable runs through an arithmetic progression. -It has the following syntax: - -

-	stat ::= for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end
-

-The block is repeated for name starting at the value of -the first exp, until it passes the second exp by steps of the -third exp. -More precisely, a for statement like - -

-     for v = e1, e2, e3 do block end
-

-is equivalent to the code: - -

-     do
-       local var, limit, step = tonumber(e1), tonumber(e2), tonumber(e3)
-       if not (var and limit and step) then error() end
-       while (step > 0 and var <= limit) or (step <= 0 and var >= limit) do
-         local v = var
-         block
-         var = var + step
-       end
-     end
-

-Note the following: - -

-All three control expressions are evaluated only once, -before the loop starts. -They must all result in numbers. -
-var, limit, and step are invisible variables. -The names shown here are for explanatory purposes only. -
-If the third expression (the step) is absent, -then a step of 1 is used. -
-You can use break to exit a for loop. -
-The loop variable v is local to the loop; -you cannot use its value after the for ends or is broken. -If you need this value, -assign it to another variable before breaking or exiting the loop. -

- -

-The generic for statement works over functions, -called iterators. -On each iteration, the iterator function is called to produce a new value, -stopping when this new value is nil. -The generic for loop has the following syntax: - -

-	stat ::= for namelist in explist do block end
-	namelist ::= Name {‘,’ Name}
-

-A for statement like - -

-     for var_1, ···, var_n in explist do block end
-

-is equivalent to the code: - -

-     do
-       local f, s, var = explist
-       while true do
-         local var_1, ···, var_n = f(s, var)
-         if var_1 == nil then break end
-         var = var_1
-         block
-       end
-     end
-

-Note the following: - -

-explist is evaluated only once. -Its results are an iterator function, -a state, -and an initial value for the first iterator variable. -
-f, s, and var are invisible variables. -The names are here for explanatory purposes only. -
-You can use break to exit a for loop. -
-The loop variables var_i are local to the loop; -you cannot use their values after the for ends. -If you need these values, -then assign them to other variables before breaking or exiting the loop. -

- - - - -

3.3.6 – Function Calls as Statements

-To allow possible side-effects, -function calls can be executed as statements: - -

-	stat ::= functioncall
-

-In this case, all returned values are thrown away. -Function calls are explained in §3.4.9. - - - - - -

3.3.7 – Local Declarations

-Local variables can be declared anywhere inside a block. -The declaration can include an initial assignment: - -

-	stat ::= local namelist [‘=’ explist]
-

-If present, an initial assignment has the same semantics -of a multiple assignment (see §3.3.3). -Otherwise, all variables are initialized with nil. - - -

-A chunk is also a block (see §3.3.2), -and so local variables can be declared in a chunk outside any explicit block. - - -

-The visibility rules for local variables are explained in §3.5. - - - - - - - -

3.4 – Expressions

- -

-The basic expressions in Lua are the following: - -

-	exp ::= prefixexp
-	exp ::= nil | false | true
-	exp ::= Number
-	exp ::= String
-	exp ::= functiondef
-	exp ::= tableconstructor
-	exp ::= ‘...’
-	exp ::= exp binop exp
-	exp ::= unop exp
-	prefixexp ::= var | functioncall | ‘(’ exp ‘)’
-

- -

-Numbers and literal strings are explained in §3.1; -variables are explained in §3.2; -function definitions are explained in §3.4.10; -function calls are explained in §3.4.9; -table constructors are explained in §3.4.8. -Vararg expressions, -denoted by three dots ('...'), can only be used when -directly inside a vararg function; -they are explained in §3.4.10. - - -

-Binary operators comprise arithmetic operators (see §3.4.1), -relational operators (see §3.4.3), logical operators (see §3.4.4), -and the concatenation operator (see §3.4.5). -Unary operators comprise the unary minus (see §3.4.1), -the unary not (see §3.4.4), -and the unary length operator (see §3.4.6). - - -

-Both function calls and vararg expressions can result in multiple values. -If a function call is used as a statement (see §3.3.6), -then its return list is adjusted to zero elements, -thus discarding all returned values. -If an expression is used as the last (or the only) element -of a list of expressions, -then no adjustment is made -(unless the expression is enclosed in parentheses). -In all other contexts, -Lua adjusts the result list to one element, -discarding all values except the first one. - - -

-Here are some examples: - -

-     f()                -- adjusted to 0 results
-     g(f(), x)          -- f() is adjusted to 1 result
-     g(x, f())          -- g gets x plus all results from f()
-     a,b,c = f(), x     -- f() is adjusted to 1 result (c gets nil)
-     a,b = ...          -- a gets the first vararg parameter, b gets
-                        -- the second (both a and b can get nil if there
-                        -- is no corresponding vararg parameter)
-     
-     a,b,c = x, f()     -- f() is adjusted to 2 results
-     a,b,c = f()        -- f() is adjusted to 3 results
-     return f()         -- returns all results from f()
-     return ...         -- returns all received vararg parameters
-     return x,y,f()     -- returns x, y, and all results from f()
-     {f()}              -- creates a list with all results from f()
-     {...}              -- creates a list with all vararg parameters
-     {f(), nil}         -- f() is adjusted to 1 result
-

- -

-Any expression enclosed in parentheses always results in only one value. -Thus, -(f(x,y,z)) is always a single value, -even if f returns several values. -(The value of (f(x,y,z)) is the first value returned by f -or nil if f does not return any values.) - - - -

3.4.1 – Arithmetic Operators

-Lua supports the usual arithmetic operators: -the binary + (addition), -- (subtraction), * (multiplication), -/ (division), % (modulo), and ^ (exponentiation); -and unary - (mathematical negation). -If the operands are numbers, or strings that can be converted to -numbers (see §3.4.2), -then all operations have the usual meaning. -Exponentiation works for any exponent. -For instance, x^(-0.5) computes the inverse of the square root of x. -Modulo is defined as - -

-     a % b == a - math.floor(a/b)*b
-

-That is, it is the remainder of a division that rounds -the quotient towards minus infinity. - - - - - -

3.4.2 – Coercion

- -

-Lua provides automatic conversion between -string and number values at run time. -Any arithmetic operation applied to a string tries to convert -this string to a number, following the rules of the Lua lexer. -(The string may have leading and trailing spaces and a sign.) -Conversely, whenever a number is used where a string is expected, -the number is converted to a string, in a reasonable format. -For complete control over how numbers are converted to strings, -use the format function from the string library -(see string.format). - - - - - -

3.4.3 – Relational Operators

-The relational operators in Lua are - -

-     ==    ~=    <     >     <=    >=
-

-These operators always result in false or true. - - -

-Equality (==) first compares the type of its operands. -If the types are different, then the result is false. -Otherwise, the values of the operands are compared. -Numbers and strings are compared in the usual way. -Tables, userdata, and threads -are compared by reference: -two objects are considered equal only if they are the same object. -Every time you create a new object -(a table, userdata, or thread), -this new object is different from any previously existing object. -Closures with the same reference are always equal. -Closures with any detectable difference -(different behavior, different definition) are always different. - - -

-You can change the way that Lua compares tables and userdata -by using the "eq" metamethod (see §2.4). - - -

-The conversion rules of §3.4.2 -do not apply to equality comparisons. -Thus, "0"==0 evaluates to false, -and t[0] and t["0"] denote different -entries in a table. - - -

-The operator ~= is exactly the negation of equality (==). - - -

-The order operators work as follows. -If both arguments are numbers, then they are compared as such. -Otherwise, if both arguments are strings, -then their values are compared according to the current locale. -Otherwise, Lua tries to call the "lt" or the "le" -metamethod (see §2.4). -A comparison a > b is translated to b < a -and a >= b is translated to b <= a. - - - - - -

3.4.4 – Logical Operators

-The logical operators in Lua are -and, or, and not. -Like the control structures (see §3.3.4), -all logical operators consider both false and nil as false -and anything else as true. - - -

-The negation operator not always returns false or true. -The conjunction operator and returns its first argument -if this value is false or nil; -otherwise, and returns its second argument. -The disjunction operator or returns its first argument -if this value is different from nil and false; -otherwise, or returns its second argument. -Both and and or use short-cut evaluation; -that is, -the second operand is evaluated only if necessary. -Here are some examples: - -

-     10 or 20            --> 10
-     10 or error()       --> 10
-     nil or "a"          --> "a"
-     nil and 10          --> nil
-     false and error()   --> false
-     false and nil       --> false
-     false or nil        --> nil
-     10 and 20           --> 20
-

-(In this manual, ---> indicates the result of the preceding expression.) - - - - - -

3.4.5 – Concatenation

-The string concatenation operator in Lua is -denoted by two dots ('..'). -If both operands are strings or numbers, then they are converted to -strings according to the rules mentioned in §3.4.2. -Otherwise, the __concat metamethod is called (see §2.4). - - - - - -

3.4.6 – The Length Operator

- -

-The length operator is denoted by the unary prefix operator #. -The length of a string is its number of bytes -(that is, the usual meaning of string length when each -character is one byte). - - -

-A program can modify the behavior of the length operator for -any value but strings through the __len metamethod (see §2.4). - - -

-Unless a __len metamethod is given, -the length of a table t is only defined if the -table is a sequence, -that is, -the set of its positive numeric keys is equal to {1..n} -for some integer n. -In that case, n is its length. -Note that a table like - -

-     {10, 20, nil, 40}
-

-is not a sequence, because it has the key 4 -but does not have the key 3. -(So, there is no n such that the set {1..n} is equal -to the set of positive numeric keys of that table.) -Note, however, that non-numeric keys do not interfere -with whether a table is a sequence. - - - - - -

3.4.7 – Precedence

-Operator precedence in Lua follows the table below, -from lower to higher priority: - -

-     or
-     and
-     <     >     <=    >=    ~=    ==
-     ..
-     +     -
-     *     /     %
-     not   #     - (unary)
-     ^
-

-As usual, -you can use parentheses to change the precedences of an expression. -The concatenation ('..') and exponentiation ('^') -operators are right associative. -All other binary operators are left associative. - - - - - -

3.4.8 – Table Constructors

-Table constructors are expressions that create tables. -Every time a constructor is evaluated, a new table is created. -A constructor can be used to create an empty table -or to create a table and initialize some of its fields. -The general syntax for constructors is - -

-	tableconstructor ::= ‘{’ [fieldlist] ‘}’
-	fieldlist ::= field {fieldsep field} [fieldsep]
-	field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
-	fieldsep ::= ‘,’ | ‘;’
-

- -

-Each field of the form [exp1] = exp2 adds to the new table an entry -with key exp1 and value exp2. -A field of the form name = exp is equivalent to -["name"] = exp. -Finally, fields of the form exp are equivalent to -[i] = exp, where i are consecutive numerical integers, -starting with 1. -Fields in the other formats do not affect this counting. -For example, - -

-     a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 }
-

-is equivalent to - -

-     do
-       local t = {}
-       t[f(1)] = g
-       t[1] = "x"         -- 1st exp
-       t[2] = "y"         -- 2nd exp
-       t.x = 1            -- t["x"] = 1
-       t[3] = f(x)        -- 3rd exp
-       t[30] = 23
-       t[4] = 45          -- 4th exp
-       a = t
-     end
-

- -

-If the last field in the list has the form exp -and the expression is a function call or a vararg expression, -then all values returned by this expression enter the list consecutively -(see §3.4.9). - - -

-The field list can have an optional trailing separator, -as a convenience for machine-generated code. - - - - - -

3.4.9 – Function Calls

-A function call in Lua has the following syntax: - -

-	functioncall ::= prefixexp args
-

-In a function call, -first prefixexp and args are evaluated. -If the value of prefixexp has type function, -then this function is called -with the given arguments. -Otherwise, the prefixexp "call" metamethod is called, -having as first parameter the value of prefixexp, -followed by the original call arguments -(see §2.4). - - -

-The form - -

-	functioncall ::= prefixexp ‘:’ Name args
-

-can be used to call "methods". -A call v:name(args) -is syntactic sugar for v.name(v,args), -except that v is evaluated only once. - - -

-Arguments have the following syntax: - -

-	args ::= ‘(’ [explist] ‘)’
-	args ::= tableconstructor
-	args ::= String
-

-All argument expressions are evaluated before the call. -A call of the form f{fields} is -syntactic sugar for f({fields}); -that is, the argument list is a single new table. -A call of the form f'string' -(or f"string" or f[[string]]) -is syntactic sugar for f('string'); -that is, the argument list is a single literal string. - - -

-A call of the form return functioncall is called -a tail call. -Lua implements proper tail calls -(or proper tail recursion): -in a tail call, -the called function reuses the stack entry of the calling function. -Therefore, there is no limit on the number of nested tail calls that -a program can execute. -However, a tail call erases any debug information about the -calling function. -Note that a tail call only happens with a particular syntax, -where the return has one single function call as argument; -this syntax makes the calling function return exactly -the returns of the called function. -So, none of the following examples are tail calls: - -

-     return (f(x))        -- results adjusted to 1
-     return 2 * f(x)
-     return x, f(x)       -- additional results
-     f(x); return         -- results discarded
-     return x or f(x)     -- results adjusted to 1
-

- - - - -

3.4.10 – Function Definitions

- -

-The syntax for function definition is - -

-	functiondef ::= function funcbody
-	funcbody ::= ‘(’ [parlist] ‘)’ block end
-

- -

-The following syntactic sugar simplifies function definitions: - -

-	stat ::= function funcname funcbody
-	stat ::= local function Name funcbody
-	funcname ::= Name {‘.’ Name} [‘:’ Name]
-

-The statement - -

-     function f () body end
-

-translates to - -

-     f = function () body end
-

-The statement - -

-     function t.a.b.c.f () body end
-

-translates to - -

-     t.a.b.c.f = function () body end
-

-The statement - -

-     local function f () body end
-

-translates to - -

-     local f; f = function () body end
-

-not to - -

-     local f = function () body end
-

-(This only makes a difference when the body of the function -contains references to f.) - - -

-A function definition is an executable expression, -whose value has type function. -When Lua precompiles a chunk, -all its function bodies are precompiled too. -Then, whenever Lua executes the function definition, -the function is instantiated (or closed). -This function instance (or closure) -is the final value of the expression. - - -

-Parameters act as local variables that are -initialized with the argument values: - -

-	parlist ::= namelist [‘,’ ‘...’] | ‘...’
-

-When a function is called, -the list of arguments is adjusted to -the length of the list of parameters, -unless the function is a vararg function, -which is indicated by three dots ('...') -at the end of its parameter list. -A vararg function does not adjust its argument list; -instead, it collects all extra arguments and supplies them -to the function through a vararg expression, -which is also written as three dots. -The value of this expression is a list of all actual extra arguments, -similar to a function with multiple results. -If a vararg expression is used inside another expression -or in the middle of a list of expressions, -then its return list is adjusted to one element. -If the expression is used as the last element of a list of expressions, -then no adjustment is made -(unless that last expression is enclosed in parentheses). - - -

-As an example, consider the following definitions: - -

-     function f(a, b) end
-     function g(a, b, ...) end
-     function r() return 1,2,3 end
-

-Then, we have the following mapping from arguments to parameters and -to the vararg expression: - -

-     CALL            PARAMETERS
-     
-     f(3)             a=3, b=nil
-     f(3, 4)          a=3, b=4
-     f(3, 4, 5)       a=3, b=4
-     f(r(), 10)       a=1, b=10
-     f(r())           a=1, b=2
-     
-     g(3)             a=3, b=nil, ... -->  (nothing)
-     g(3, 4)          a=3, b=4,   ... -->  (nothing)
-     g(3, 4, 5, 8)    a=3, b=4,   ... -->  5  8
-     g(5, r())        a=5, b=1,   ... -->  2  3
-

- -

-Results are returned using the return statement (see §3.3.4). -If control reaches the end of a function -without encountering a return statement, -then the function returns with no results. - - -

- -There is a system-dependent limit on the number of values -that a function may return. -This limit is guaranteed to be larger than 1000. - - -

-The colon syntax -is used for defining methods, -that is, functions that have an implicit extra parameter self. -Thus, the statement - -

-     function t.a.b.c:f (params) body end
-

-is syntactic sugar for - -

-     t.a.b.c.f = function (self, params) body end
-

- - - - - - -

3.5 – Visibility Rules

- -

- -Lua is a lexically scoped language. -The scope of a local variable begins at the first statement after -its declaration and lasts until the last non-void statement -of the innermost block that includes the declaration. -Consider the following example: - -

-     x = 10                -- global variable
-     do                    -- new block
-       local x = x         -- new 'x', with value 10
-       print(x)            --> 10
-       x = x+1
-       do                  -- another block
-         local x = x+1     -- another 'x'
-         print(x)          --> 12
-       end
-       print(x)            --> 11
-     end
-     print(x)              --> 10  (the global one)
-

- -

-Notice that, in a declaration like local x = x, -the new x being declared is not in scope yet, -and so the second x refers to the outside variable. - - -

-Because of the lexical scoping rules, -local variables can be freely accessed by functions -defined inside their scope. -A local variable used by an inner function is called -an upvalue, or external local variable, -inside the inner function. - - -

-Notice that each execution of a local statement -defines new local variables. -Consider the following example: - -

-     a = {}
-     local x = 20
-     for i=1,10 do
-       local y = 0
-       a[i] = function () y=y+1; return x+y end
-     end
-

-The loop creates ten closures -(that is, ten instances of the anonymous function). -Each of these closures uses a different y variable, -while all of them share the same x. - - - - - -

4 – The Application Program Interface

- -

- -This section describes the C API for Lua, that is, -the set of C functions available to the host program to communicate -with Lua. -All API functions and related types and constants -are declared in the header file lua.h. - - -

-Even when we use the term "function", -any facility in the API may be provided as a macro instead. -Except where stated otherwise, -all such macros use each of their arguments exactly once -(except for the first argument, which is always a Lua state), -and so do not generate any hidden side-effects. - - -

-As in most C libraries, -the Lua API functions do not check their arguments for validity or consistency. -However, you can change this behavior by compiling Lua -with the macro LUA_USE_APICHECK defined. - - - -

4.1 – The Stack

- -

-Lua uses a virtual stack to pass values to and from C. -Each element in this stack represents a Lua value -(nil, number, string, etc.). - - -

-Whenever Lua calls C, the called function gets a new stack, -which is independent of previous stacks and of stacks of -C functions that are still active. -This stack initially contains any arguments to the C function -and it is where the C function pushes its results -to be returned to the caller (see lua_CFunction). - - -

-For convenience, -most query operations in the API do not follow a strict stack discipline. -Instead, they can refer to any element in the stack -by using an index: -A positive index represents an absolute stack position -(starting at 1); -a negative index represents an offset relative to the top of the stack. -More specifically, if the stack has n elements, -then index 1 represents the first element -(that is, the element that was pushed onto the stack first) -and -index n represents the last element; -index -1 also represents the last element -(that is, the element at the top) -and index -n represents the first element. - - - - - -

4.2 – Stack Size

- -

-When you interact with the Lua API, -you are responsible for ensuring consistency. -In particular, -you are responsible for controlling stack overflow. -You can use the function lua_checkstack -to ensure that the stack has extra slots when pushing new elements. - - -

-Whenever Lua calls C, -it ensures that the stack has at least LUA_MINSTACK extra slots. -LUA_MINSTACK is defined as 20, -so that usually you do not have to worry about stack space -unless your code has loops pushing elements onto the stack. - - -

-When you call a Lua function -without a fixed number of results (see lua_call), -Lua ensures that the stack has enough size for all results, -but it does not ensure any extra space. -So, before pushing anything in the stack after such a call -you should use lua_checkstack. - - - - - -

4.3 – Valid and Acceptable Indices

- -

-Any function in the API that receives stack indices -works only with valid indices or acceptable indices. - - -

-A valid index is an index that refers to a -valid position within the stack, that is, -it lies between 1 and the stack top -(1 ≤ abs(index) ≤ top). - -Usually, functions that need a specific stack position -(e.g., lua_remove) require valid indices. - - -

-Functions that do not need a specific stack position, -but only a value in the stack (e.g., query functions), -can be called with acceptable indices. -An acceptable index refers to a position within -the space allocated for the stack, -that is, indices up to the stack size. -More formally, we define an acceptable index -as follows: - -

-     (index < 0 && abs(index) <= top) ||
-     (index > 0 && index <= stack size)
-

-(Note that 0 is never an acceptable index.) -When a function is called, -its stack size is top + LUA_MINSTACK. -You can change its stack size through function lua_checkstack. - - -

-Acceptable indices serve to avoid extra tests -against the stack top when querying the stack. -For instance, a C function can query its third argument -without the need to first check whether there is a third argument, -that is, without the need to check whether 3 is a valid index. - - -

-For functions that can be called with acceptable indices, -any non-valid index is treated as if it -contains a value of a virtual type LUA_TNONE. - - -

-Unless otherwise noted, -any function that accepts valid indices also accepts pseudo-indices, -which represent some Lua values that are accessible to C code -but which are not in the stack. -Pseudo-indices are used to access the registry -and the upvalues of a C function (see §4.4). - - - - - -

4.4 – C Closures

- -

-When a C function is created, -it is possible to associate some values with it, -thus creating a C closure -(see lua_pushcclosure); -these values are called upvalues and are -accessible to the function whenever it is called. - - -

-Whenever a C function is called, -its upvalues are located at specific pseudo-indices. -These pseudo-indices are produced by the macro -lua_upvalueindex. -The first value associated with a function is at position -lua_upvalueindex(1), and so on. -Any access to lua_upvalueindex(n), -where n is greater than the number of upvalues of the -current function (but not greater than 256), -produces an acceptable (but invalid) index. - - - - - -

4.5 – Registry

- -

-Lua provides a registry, -a predefined table that can be used by any C code to -store whatever Lua values it needs to store. -The registry table is always located at pseudo-index -LUA_REGISTRYINDEX. -Any C library can store data into this table, -but it should take care to choose keys -that are different from those used -by other libraries, to avoid collisions. -Typically, you should use as key a string containing your library name, -or a light userdata with the address of a C object in your code, -or any Lua object created by your code. -As with global names, -string keys starting with an underscore followed by -uppercase letters are reserved for Lua. - - -

-The integer keys in the registry are used by the reference mechanism, -implemented by the auxiliary library, -and by some predefined values. -Therefore, integer keys should not be used for other purposes. - - -

-When you create a new Lua state, -its registry comes with some predefined values. -These predefined values are indexed with integer keys -defined as constants in lua.h. -The following constants are defined: - -

LUA_RIDX_MAINTHREAD: At this index the registry has -the main thread of the state. -(The main thread is the one created together with the state.) -
LUA_RIDX_GLOBALS: At this index the registry has -the global environment. -

- - - - -

4.6 – Error Handling in C

- -

-Internally, Lua uses the C longjmp facility to handle errors. -(You can also choose to use exceptions if you use C++; -see file luaconf.h.) -When Lua faces any error -(such as a memory allocation error, type errors, syntax errors, -and runtime errors) -it raises an error; -that is, it does a long jump. -A protected environment uses setjmp -to set a recovery point; -any error jumps to the most recent active recovery point. - - -

-If an error happens outside any protected environment, -Lua calls a panic function (see lua_atpanic) -and then calls abort, -thus exiting the host application. -Your panic function can avoid this exit by -never returning -(e.g., doing a long jump to your own recovery point outside Lua). - - -

-The panic function runs as if it were a message handler (see §2.3); -in particular, the error message is at the top of the stack. -However, there is no guarantees about stack space. -To push anything on the stack, -the panic function should first check the available space (see §4.2). - - -

-Most functions in the API can throw an error, -for instance due to a memory allocation error. -The documentation for each function indicates whether -it can throw errors. - - -

-Inside a C function you can throw an error by calling lua_error. - - - - - -

4.7 – Handling Yields in C

- -

-Internally, Lua uses the C longjmp facility to yield a coroutine. -Therefore, if a function foo calls an API function -and this API function yields -(directly or indirectly by calling another function that yields), -Lua cannot return to foo any more, -because the longjmp removes its frame from the C stack. - - -

-To avoid this kind of problem, -Lua raises an error whenever it tries to yield across an API call, -except for three functions: -lua_yieldk, lua_callk, and lua_pcallk. -All those functions receive a continuation function -(as a parameter called k) to continue execution after a yield. - - -

-We need to set some terminology to explain continuations. -We have a C function called from Lua which we will call -the original function. -This original function then calls one of those three functions in the C API, -which we will call the callee function, -that then yields the current thread. -(This can happen when the callee function is lua_yieldk, -or when the callee function is either lua_callk or lua_pcallk -and the function called by them yields.) - - -

-Suppose the running thread yields while executing the callee function. -After the thread resumes, -it eventually will finish running the callee function. -However, -the callee function cannot return to the original function, -because its frame in the C stack was destroyed by the yield. -Instead, Lua calls a continuation function, -which was given as an argument to the callee function. -As the name implies, -the continuation function should continue the task -of the original function. - - -

-Lua treats the continuation function as if it were the original function. -The continuation function receives the same Lua stack -from the original function, -in the same state it would be if the callee function had returned. -(For instance, -after a lua_callk the function and its arguments are -removed from the stack and replaced by the results from the call.) -It also has the same upvalues. -Whatever it returns is handled by Lua as if it were the return -of the original function. - - -

-The only difference in the Lua state between the original function -and its continuation is the result of a call to lua_getctx. - - - - - -

4.8 – Functions and Types

- -

-Here we list all functions and types from the C API in -alphabetical order. -Each function has an indicator like this: -[-o, +p, x] - - -

-The first field, o, -is how many elements the function pops from the stack. -The second field, p, -is how many elements the function pushes onto the stack. -(Any function always pushes its results after popping its arguments.) -A field in the form x|y means the function can push (or pop) -x or y elements, -depending on the situation; -an interrogation mark '?' means that -we cannot know how many elements the function pops/pushes -by looking only at its arguments -(e.g., they may depend on what is on the stack). -The third field, x, -tells whether the function may throw errors: -'-' means the function never throws any error; -'m' means the function may throw only memory allocation errors; -'e' means the function may throw other kinds of errors; -'v' means the function may throw an error on purpose. - - - -

`lua_absindex`

-[-0, +0, –] -

int lua_absindex (lua_State *L, int idx);

- -

-Converts the acceptable index idx into an absolute index -(that is, one that does not depend on the stack top). - - - - - -

`lua_Alloc`

typedef void * (*lua_Alloc) (void *ud,
-                             void *ptr,
-                             size_t osize,
-                             size_t nsize);

- -

-The type of the memory-allocation function used by Lua states. -The allocator function must provide a -functionality similar to realloc, -but not exactly the same. -Its arguments are -ud, an opaque pointer passed to lua_newstate; -ptr, a pointer to the block being allocated/reallocated/freed; -osize, the original size of the block or some code about what -is being allocated; -nsize, the new size of the block. - - -

-When ptr is not NULL, -osize is the size of the block pointed by ptr, -that is, the size given when it was allocated or reallocated. - - -

-When ptr is NULL, -osize encodes the kind of object that Lua is allocating. -osize is any of -LUA_TSTRING, LUA_TTABLE, LUA_TFUNCTION, -LUA_TUSERDATA, or LUA_TTHREAD when (and only when) -Lua is creating a new object of that type. -When osize is some other value, -Lua is allocating memory for something else. - - -

-Lua assumes the following behavior from the allocator function: - - -

-When nsize is zero, -the allocator should behave like free -and return NULL. - - -

-When nsize is not zero, -the allocator should behave like realloc. -The allocator returns NULL -if and only if it cannot fulfill the request. -Lua assumes that the allocator never fails when -osize >= nsize. - - -

-Here is a simple implementation for the allocator function. -It is used in the auxiliary library by luaL_newstate. - -

-     static void *l_alloc (void *ud, void *ptr, size_t osize,
-                                                size_t nsize) {
-       (void)ud;  (void)osize;  /* not used */
-       if (nsize == 0) {
-         free(ptr);
-         return NULL;
-       }
-       else
-         return realloc(ptr, nsize);
-     }
-

-Note that Standard C ensures -that free(NULL) has no effect and that -realloc(NULL, size) is equivalent to malloc(size). -This code assumes that realloc does not fail when shrinking a block. -(Although Standard C does not ensure this behavior, -it seems to be a safe assumption.) - - - - - -

`lua_arith`

-[-(2|1), +1, e] -

int lua_arith (lua_State *L, int op);

- -

-Performs an arithmetic operation over the two values -(or one, in the case of negation) -at the top of the stack, -with the value at the top being the second operand, -pops these values, and pushes the result of the operation. -The function follows the semantics of the corresponding Lua operator -(that is, it may call metamethods). - - -

-The value of op must be one of the following constants: - -

LUA_OPADD: performs addition (+)
LUA_OPSUB: performs subtraction (-)
LUA_OPMUL: performs multiplication (*)
LUA_OPDIV: performs division (/)
LUA_OPMOD: performs modulo (%)
LUA_OPPOW: performs exponentiation (^)
LUA_OPUNM: performs mathematical negation (unary -)

- - - - -

`lua_atpanic`

-[-0, +0, –] -

lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);

- -

-Sets a new panic function and returns the old one (see §4.6). - - - - - -

`lua_call`

-[-(nargs+1), +nresults, e] -

void lua_call (lua_State *L, int nargs, int nresults);

- -

-Calls a function. - - -

-To call a function you must use the following protocol: -first, the function to be called is pushed onto the stack; -then, the arguments to the function are pushed -in direct order; -that is, the first argument is pushed first. -Finally you call lua_call; -nargs is the number of arguments that you pushed onto the stack. -All arguments and the function value are popped from the stack -when the function is called. -The function results are pushed onto the stack when the function returns. -The number of results is adjusted to nresults, -unless nresults is LUA_MULTRET. -In this case, all results from the function are pushed. -Lua takes care that the returned values fit into the stack space. -The function results are pushed onto the stack in direct order -(the first result is pushed first), -so that after the call the last result is on the top of the stack. - - -

-Any error inside the called function is propagated upwards -(with a longjmp). - - -

-The following example shows how the host program can do the -equivalent to this Lua code: - -

-     a = f("how", t.x, 14)
-

-Here it is in C: - -

-     lua_getglobal(L, "f");                  /* function to be called */
-     lua_pushstring(L, "how");                        /* 1st argument */
-     lua_getglobal(L, "t");                    /* table to be indexed */
-     lua_getfield(L, -1, "x");        /* push result of t.x (2nd arg) */
-     lua_remove(L, -2);                  /* remove 't' from the stack */
-     lua_pushinteger(L, 14);                          /* 3rd argument */
-     lua_call(L, 3, 1);     /* call 'f' with 3 arguments and 1 result */
-     lua_setglobal(L, "a");                         /* set global 'a' */
-

-Note that the code above is "balanced": -at its end, the stack is back to its original configuration. -This is considered good programming practice. - - - - - -

`lua_callk`

-[-(nargs + 1), +nresults, e] -

void lua_callk (lua_State *L, int nargs, int nresults, int ctx,
-                lua_CFunction k);

- -

-This function behaves exactly like lua_call, -but allows the called function to yield (see §4.7). - - - - - -

`lua_CFunction`

typedef int (*lua_CFunction) (lua_State *L);

- -

-Type for C functions. - - -

-In order to communicate properly with Lua, -a C function must use the following protocol, -which defines the way parameters and results are passed: -a C function receives its arguments from Lua in its stack -in direct order (the first argument is pushed first). -So, when the function starts, -lua_gettop(L) returns the number of arguments received by the function. -The first argument (if any) is at index 1 -and its last argument is at index lua_gettop(L). -To return values to Lua, a C function just pushes them onto the stack, -in direct order (the first result is pushed first), -and returns the number of results. -Any other value in the stack below the results will be properly -discarded by Lua. -Like a Lua function, a C function called by Lua can also return -many results. - - -

-As an example, the following function receives a variable number -of numerical arguments and returns their average and sum: - -

-     static int foo (lua_State *L) {
-       int n = lua_gettop(L);    /* number of arguments */
-       lua_Number sum = 0;
-       int i;
-       for (i = 1; i <= n; i++) {
-         if (!lua_isnumber(L, i)) {
-           lua_pushstring(L, "incorrect argument");
-           lua_error(L);
-         }
-         sum += lua_tonumber(L, i);
-       }
-       lua_pushnumber(L, sum/n);        /* first result */
-       lua_pushnumber(L, sum);         /* second result */
-       return 2;                   /* number of results */
-     }
-

- - - - -

`lua_checkstack`

-[-0, +0, –] -

int lua_checkstack (lua_State *L, int extra);

- -

-Ensures that there are at least extra free stack slots in the stack. -It returns false if it cannot fulfill the request, -because it would cause the stack to be larger than a fixed maximum size -(typically at least a few thousand elements) or -because it cannot allocate memory for the new stack size. -This function never shrinks the stack; -if the stack is already larger than the new size, -it is left unchanged. - - - - - -

`lua_close`

-[-0, +0, –] -

void lua_close (lua_State *L);

- -

-Destroys all objects in the given Lua state -(calling the corresponding garbage-collection metamethods, if any) -and frees all dynamic memory used by this state. -On several platforms, you may not need to call this function, -because all resources are naturally released when the host program ends. -On the other hand, long-running programs that create multiple states, -such as daemons or web servers, -might need to close states as soon as they are not needed. - - - - - -

`lua_compare`

-[-0, +0, e] -

int lua_compare (lua_State *L, int index1, int index2, int op);

- -

-Compares two Lua values. -Returns 1 if the value at acceptable index index1 satisfies op -when compared with the value at acceptable index index2, -following the semantics of the corresponding Lua operator -(that is, it may call metamethods). -Otherwise returns 0. -Also returns 0 if any of the indices is non valid. - - -

-The value of op must be one of the following constants: - -

LUA_OPEQ: compares for equality (==)
LUA_OPLT: compares for less than (<)
LUA_OPLE: compares for less or equal (<=)

- - - - -

`lua_concat`

-[-n, +1, e] -

void lua_concat (lua_State *L, int n);

- -

-Concatenates the n values at the top of the stack, -pops them, and leaves the result at the top. -If n is 1, the result is the single value on the stack -(that is, the function does nothing); -if n is 0, the result is the empty string. -Concatenation is performed following the usual semantics of Lua -(see §3.4.5). - - - - - -

`lua_copy`

-[-0, +0, –] -

void lua_copy (lua_State *L, int fromidx, int toidx);

- -

-Moves the element at the valid index fromidx -into the valid index toidx -without shifting any element -(therefore replacing the value at that position). - - - - - -

`lua_createtable`

-[-0, +1, m] -

void lua_createtable (lua_State *L, int narr, int nrec);

- -

-Creates a new empty table and pushes it onto the stack. -Parameter narr is a hint for how many elements the table -will have as a sequence; -parameter nrec is a hint for how many other elements -the table will have. -Lua may use these hints to preallocate memory for the new table. -This pre-allocation is useful for performance when you know in advance -how many elements the table will have. -Otherwise you can use the function lua_newtable. - - - - - -

`lua_dump`

-[-0, +0, m] -

int lua_dump (lua_State *L, lua_Writer writer, void *data);

- -

-Dumps a function as a binary chunk. -Receives a Lua function on the top of the stack -and produces a binary chunk that, -if loaded again, -results in a function equivalent to the one dumped. -As it produces parts of the chunk, -lua_dump calls function writer (see lua_Writer) -with the given data -to write them. - - -

-The value returned is the error code returned by the last -call to the writer; -0 means no errors. - - -

-This function does not pop the Lua function from the stack. - - - - - -

`lua_error`

-[-1, +0, v] -

int lua_error (lua_State *L);

- -

-Generates a Lua error. -The error message (which can actually be a Lua value of any type) -must be on the stack top. -This function does a long jump, -and therefore never returns -(see luaL_error). - - - - - -

`lua_gc`

-[-0, +0, e] -

int lua_gc (lua_State *L, int what, int data);

- -

-Controls the garbage collector. - - -

-This function performs several tasks, -according to the value of the parameter what: - -

LUA_GCSTOP: -stops the garbage collector. -
LUA_GCRESTART: -restarts the garbage collector. -
LUA_GCCOLLECT: -performs a full garbage-collection cycle. -
LUA_GCCOUNT: -returns the current amount of memory (in Kbytes) in use by Lua. -
LUA_GCCOUNTB: -returns the remainder of dividing the current amount of bytes of -memory in use by Lua by 1024. -
LUA_GCSTEP: -performs an incremental step of garbage collection. -The step "size" is controlled by data -(larger values mean more steps) in a non-specified way. -If you want to control the step size -you must experimentally tune the value of data. -The function returns 1 if the step finished a -garbage-collection cycle. -
LUA_GCSETPAUSE: -sets data as the new value -for the pause of the collector (see §2.5). -The function returns the previous value of the pause. -
LUA_GCSETSTEPMUL: -sets data as the new value for the step multiplier of -the collector (see §2.5). -The function returns the previous value of the step multiplier. -
LUA_GCISRUNNING: -returns a boolean that tells whether the collector is running -(i.e., not stopped). -
LUA_GCGEN: -changes the collector to generational mode -(see §2.5). -
LUA_GCINC: -changes the collector to incremental mode. -This is the default mode. -

- -

-For more details about these options, -see collectgarbage. - - - - - -

`lua_getallocf`

-[-0, +0, –] -

lua_Alloc lua_getallocf (lua_State *L, void **ud);

- -

-Returns the memory-allocation function of a given state. -If ud is not NULL, Lua stores in *ud the -opaque pointer passed to lua_newstate. - - - - - -

`lua_getctx`

-[-0, +0, –] -

int lua_getctx  (lua_State *L, int *ctx);

- -

-This function is called by a continuation function (see §4.7) -to retrieve the status of the thread and a context information. - - -

-When called in the original function, -lua_getctx always returns LUA_OK -and does not change the value of its argument ctx. -When called inside a continuation function, -lua_getctx returns LUA_YIELD and sets -the value of ctx to be the context information -(the value passed as the ctx argument -to the callee together with the continuation function). - - -

-When the callee is lua_pcallk, -Lua may also call its continuation function -to handle errors during the call. -That is, upon an error in the function called by lua_pcallk, -Lua may not return to the original function -but instead may call the continuation function. -In that case, a call to lua_getctx will return the error code -(the value that would be returned by lua_pcallk); -the value of ctx will be set to the context information, -as in the case of a yield. - - - - - -

`lua_getfield`

-[-0, +1, e] -

void lua_getfield (lua_State *L, int index, const char *k);

- -

-Pushes onto the stack the value t[k], -where t is the value at the given valid index. -As in Lua, this function may trigger a metamethod -for the "index" event (see §2.4). - - - - - -

`lua_getglobal`

-[-0, +1, e] -

void lua_getglobal (lua_State *L, const char *name);

- -

-Pushes onto the stack the value of the global name. - - - - - -

`lua_getmetatable`

-[-0, +(0|1), –] -

int lua_getmetatable (lua_State *L, int index);

- -

-Pushes onto the stack the metatable of the value at the given -acceptable index. -If the value does not have a metatable, -the function returns 0 and pushes nothing on the stack. - - - - - -

`lua_gettable`

-[-1, +1, e] -

void lua_gettable (lua_State *L, int index);

- -

-Pushes onto the stack the value t[k], -where t is the value at the given valid index -and k is the value at the top of the stack. - - -

-This function pops the key from the stack -(putting the resulting value in its place). -As in Lua, this function may trigger a metamethod -for the "index" event (see §2.4). - - - - - -

`lua_gettop`

-[-0, +0, –] -

int lua_gettop (lua_State *L);

- -

-Returns the index of the top element in the stack. -Because indices start at 1, -this result is equal to the number of elements in the stack -(and so 0 means an empty stack). - - - - - -

`lua_getuservalue`

-[-0, +1, –] -

void lua_getuservalue (lua_State *L, int index);

- -

-Pushes onto the stack the Lua value associated with the userdata -at the given index. -This Lua value must be a table or nil. - - - - - -

`lua_insert`

-[-1, +1, –] -

void lua_insert (lua_State *L, int index);

- -

-Moves the top element into the given valid index, -shifting up the elements above this index to open space. -Cannot be called with a pseudo-index, -because a pseudo-index is not an actual stack position. - - - - - -

`lua_Integer`

typedef ptrdiff_t lua_Integer;

- -

-The type used by the Lua API to represent signed integral values. - - -

-By default it is a ptrdiff_t, -which is usually the largest signed integral type the machine handles -"comfortably". - - - - - -

`lua_isboolean`

-[-0, +0, –] -

int lua_isboolean (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a boolean, -and 0 otherwise. - - - - - -

`lua_iscfunction`

-[-0, +0, –] -

int lua_iscfunction (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a C function, -and 0 otherwise. - - - - - -

`lua_isfunction`

-[-0, +0, –] -

int lua_isfunction (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a function -(either C or Lua), and 0 otherwise. - - - - - -

`lua_islightuserdata`

-[-0, +0, –] -

int lua_islightuserdata (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a light userdata, -and 0 otherwise. - - - - - -

`lua_isnil`

-[-0, +0, –] -

int lua_isnil (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is nil, -and 0 otherwise. - - - - - -

`lua_isnone`

-[-0, +0, –] -

int lua_isnone (lua_State *L, int index);

- -

-Returns 1 if the given acceptable index is not valid -(that is, it refers to an element outside the current stack), -and 0 otherwise. - - - - - -

`lua_isnoneornil`

-[-0, +0, –] -

int lua_isnoneornil (lua_State *L, int index);

- -

-Returns 1 if the given acceptable index is not valid -(that is, it refers to an element outside the current stack) -or if the value at this index is nil, -and 0 otherwise. - - - - - -

`lua_isnumber`

-[-0, +0, –] -

int lua_isnumber (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a number -or a string convertible to a number, -and 0 otherwise. - - - - - -

`lua_isstring`

-[-0, +0, –] -

int lua_isstring (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a string -or a number (which is always convertible to a string), -and 0 otherwise. - - - - - -

`lua_istable`

-[-0, +0, –] -

int lua_istable (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a table, -and 0 otherwise. - - - - - -

`lua_isthread`

-[-0, +0, –] -

int lua_isthread (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a thread, -and 0 otherwise. - - - - - -

`lua_isuserdata`

-[-0, +0, –] -

int lua_isuserdata (lua_State *L, int index);

- -

-Returns 1 if the value at the given acceptable index is a userdata -(either full or light), and 0 otherwise. - - - - - -

`lua_len`

-[-0, +1, e] -

void lua_len (lua_State *L, int index);

- -

-Returns the "length" of the value at the given acceptable index; -it is equivalent to the '#' operator in Lua (see §3.4.6). -The result is pushed on the stack. - - - - - -

`lua_load`

-[-0, +1, –] -

int lua_load (lua_State *L,
-              lua_Reader reader,
-              void *data,
-              const char *source,
-              const char *mode);

- -

-Loads a Lua chunk (without running it). -If there are no errors, -lua_load pushes the compiled chunk as a Lua -function on top of the stack. -Otherwise, it pushes an error message. - - -

-The return values of lua_load are: - -

LUA_OK: no errors;
LUA_ERRSYNTAX: -syntax error during precompilation;
LUA_ERRMEM: -memory allocation error;
LUA_ERRGCMM: -error while running a __gc metamethod. -(This error has no relation with the chunk being loaded. -It is generated by the garbage collector.) -

- -

-The lua_load function uses a user-supplied reader function -to read the chunk (see lua_Reader). -The data argument is an opaque value passed to the reader function. - - -

-The source argument gives a name to the chunk, -which is used for error messages and in debug information (see §4.9). - - -

-lua_load automatically detects whether the chunk is text or binary -and loads it accordingly (see program luac). -The string mode works as in function load, -with the addition that -a NULL value is equivalent to the string "bt". - - -

-If the resulting function has one upvalue, -this upvalue is set to the value of the global environment -stored at index LUA_RIDX_GLOBALS in the registry (see §4.5). -When loading main chunks, -this upvalue will be the _ENV variable (see §2.2). - - - - - -

`lua_newstate`

-[-0, +0, –] -

lua_State *lua_newstate (lua_Alloc f, void *ud);

- -

-Creates a new thread running in a new, independent state. -Returns NULL if cannot create the thread or the state -(due to lack of memory). -The argument f is the allocator function; -Lua does all memory allocation for this state through this function. -The second argument, ud, is an opaque pointer that Lua -passes to the allocator in every call. - - - - - -

`lua_newtable`

-[-0, +1, m] -

void lua_newtable (lua_State *L);

- -

-Creates a new empty table and pushes it onto the stack. -It is equivalent to lua_createtable(L, 0, 0). - - - - - -

`lua_newthread`

-[-0, +1, m] -

lua_State *lua_newthread (lua_State *L);

- -

-Creates a new thread, pushes it on the stack, -and returns a pointer to a lua_State that represents this new thread. -The new thread returned by this function shares with the original thread -its global environment, -but has an independent execution stack. - - -

-There is no explicit function to close or to destroy a thread. -Threads are subject to garbage collection, -like any Lua object. - - - - - -

`lua_newuserdata`

-[-0, +1, m] -

void *lua_newuserdata (lua_State *L, size_t size);

- -

-This function allocates a new block of memory with the given size, -pushes onto the stack a new full userdata with the block address, -and returns this address. -The host program can freely use this memory. - - - - - -

`lua_next`

-[-1, +(2|0), e] -

int lua_next (lua_State *L, int index);

- -

-Pops a key from the stack, -and pushes a key–value pair from the table at the given index -(the "next" pair after the given key). -If there are no more elements in the table, -then lua_next returns 0 (and pushes nothing). - - -

-A typical traversal looks like this: - -

-     /* table is in the stack at index 't' */
-     lua_pushnil(L);  /* first key */
-     while (lua_next(L, t) != 0) {
-       /* uses 'key' (at index -2) and 'value' (at index -1) */
-       printf("%s - %s\n",
-              lua_typename(L, lua_type(L, -2)),
-              lua_typename(L, lua_type(L, -1)));
-       /* removes 'value'; keeps 'key' for next iteration */
-       lua_pop(L, 1);
-     }
-

- -

-While traversing a table, -do not call lua_tolstring directly on a key, -unless you know that the key is actually a string. -Recall that lua_tolstring may change -the value at the given index; -this confuses the next call to lua_next. - - -

-See function next for the caveats of modifying -the table during its traversal. - - - - - -

`lua_Number`

typedef double lua_Number;

- -

-The type of numbers in Lua. -By default, it is double, but that can be changed in luaconf.h. -Through this configuration file you can change -Lua to operate with another type for numbers (e.g., float or long). - - - - - -

`lua_pcall`

-[-(nargs + 1), +(nresults|1), –] -

int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);

- -

-Calls a function in protected mode. - - -

-Both nargs and nresults have the same meaning as -in lua_call. -If there are no errors during the call, -lua_pcall behaves exactly like lua_call. -However, if there is any error, -lua_pcall catches it, -pushes a single value on the stack (the error message), -and returns an error code. -Like lua_call, -lua_pcall always removes the function -and its arguments from the stack. - - -

-If msgh is 0, -then the error message returned on the stack -is exactly the original error message. -Otherwise, msgh is the stack index of a -message handler. -(In the current implementation, this index cannot be a pseudo-index.) -In case of runtime errors, -this function will be called with the error message -and its return value will be the message -returned on the stack by lua_pcall. - - -

-Typically, the message handler is used to add more debug -information to the error message, such as a stack traceback. -Such information cannot be gathered after the return of lua_pcall, -since by then the stack has unwound. - - -

-The lua_pcall function returns one of the following codes -(defined in lua.h): - -

LUA_OK (0): -success.
LUA_ERRRUN: -a runtime error. -
LUA_ERRMEM: -memory allocation error. -For such errors, Lua does not call the message handler. -
LUA_ERRERR: -error while running the message handler. -
LUA_ERRGCMM: -error while running a __gc metamethod. -(This error typically has no relation with the function being called. -It is generated by the garbage collector.) -

- - - - -

`lua_pcallk`

-[-(nargs + 1), +(nresults|1), –] -

int lua_pcallk (lua_State *L,
-                int nargs,
-                int nresults,
-                int errfunc,
-                int ctx,
-                lua_CFunction k);

- -

-This function behaves exactly like lua_pcall, -but allows the called function to yield (see §4.7). - - - - - -

`lua_pop`

-[-n, +0, –] -

void lua_pop (lua_State *L, int n);

- -

-Pops n elements from the stack. - - - - - -

`lua_pushboolean`

-[-0, +1, –] -

void lua_pushboolean (lua_State *L, int b);

- -

-Pushes a boolean value with value b onto the stack. - - - - - -

`lua_pushcclosure`

-[-n, +1, m] -

void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);

- -

-Pushes a new C closure onto the stack. - - -

-When a C function is created, -it is possible to associate some values with it, -thus creating a C closure (see §4.4); -these values are then accessible to the function whenever it is called. -To associate values with a C function, -first these values should be pushed onto the stack -(when there are multiple values, the first value is pushed first). -Then lua_pushcclosure -is called to create and push the C function onto the stack, -with the argument n telling how many values should be -associated with the function. -lua_pushcclosure also pops these values from the stack. - - -

-The maximum value for n is 255. - - -

-When n is zero, -this function creates a light C function, -which is just a pointer to the C function. -In that case, it never throws a memory error. - - - - - -

`lua_pushcfunction`

-[-0, +1, –] -

void lua_pushcfunction (lua_State *L, lua_CFunction f);

- -

-Pushes a C function onto the stack. -This function receives a pointer to a C function -and pushes onto the stack a Lua value of type function that, -when called, invokes the corresponding C function. - - -

-Any function to be registered in Lua must -follow the correct protocol to receive its parameters -and return its results (see lua_CFunction). - - -

-lua_pushcfunction is defined as a macro: - -

-     #define lua_pushcfunction(L,f)  lua_pushcclosure(L,f,0)
-

-Note that f is used twice. - - - - - -

`lua_pushfstring`

-[-0, +1, m] -

const char *lua_pushfstring (lua_State *L, const char *fmt, ...);

- -

-Pushes onto the stack a formatted string -and returns a pointer to this string. -It is similar to the C function sprintf, -but has some important differences: - -

-You do not have to allocate space for the result: -the result is a Lua string and Lua takes care of memory allocation -(and deallocation, through garbage collection). -
-The conversion specifiers are quite restricted. -There are no flags, widths, or precisions. -The conversion specifiers can only be -'%%' (inserts a '%' in the string), -'%s' (inserts a zero-terminated string, with no size restrictions), -'%f' (inserts a lua_Number), -'%p' (inserts a pointer as a hexadecimal numeral), -'%d' (inserts an int), and -'%c' (inserts an int as a byte). -

- - - - -

`lua_pushinteger`

-[-0, +1, –] -

void lua_pushinteger (lua_State *L, lua_Integer n);

- -

-Pushes a number with value n onto the stack. - - - - - -

`lua_pushlightuserdata`

-[-0, +1, –] -

void lua_pushlightuserdata (lua_State *L, void *p);

- -

-Pushes a light userdata onto the stack. - - -

-Userdata represent C values in Lua. -A light userdata represents a pointer, a void*. -It is a value (like a number): -you do not create it, it has no individual metatable, -and it is not collected (as it was never created). -A light userdata is equal to "any" -light userdata with the same C address. - - - - - -

`lua_pushliteral`

-[-0, +1, m] -

const char *lua_pushliteral (lua_State *L, const char *s);

- -

-This macro is equivalent to lua_pushlstring, -but can be used only when s is a literal string. -It automatically provides the string length. - - - - - -

`lua_pushlstring`

-[-0, +1, m] -

const char *lua_pushlstring (lua_State *L, const char *s, size_t len);

- -

-Pushes the string pointed to by s with size len -onto the stack. -Lua makes (or reuses) an internal copy of the given string, -so the memory at s can be freed or reused immediately after -the function returns. -The string can contain any binary data, -including embedded zeros. - - -

-Returns a pointer to the internal copy of the string. - - - - - -

`lua_pushnil`

-[-0, +1, –] -

void lua_pushnil (lua_State *L);

- -

-Pushes a nil value onto the stack. - - - - - -

`lua_pushnumber`

-[-0, +1, –] -

void lua_pushnumber (lua_State *L, lua_Number n);

- -

-Pushes a number with value n onto the stack. - - - - - -

`lua_pushstring`

-[-0, +1, m] -

const char *lua_pushstring (lua_State *L, const char *s);

- -

-Pushes the zero-terminated string pointed to by s -onto the stack. -Lua makes (or reuses) an internal copy of the given string, -so the memory at s can be freed or reused immediately after -the function returns. - - -

-Returns a pointer to the internal copy of the string. - - -

-If s is NULL, pushes nil and returns NULL. - - - - - -

`lua_pushthread`

-[-0, +1, –] -

int lua_pushthread (lua_State *L);

- -

-Pushes the thread represented by L onto the stack. -Returns 1 if this thread is the main thread of its state. - - - - - -

`lua_pushvalue`

-[-0, +1, –] -

void lua_pushvalue (lua_State *L, int index);

- -

-Pushes a copy of the element at the given valid index -onto the stack. - - - - - -

`lua_pushvfstring`

-[-0, +1, m] -

const char *lua_pushvfstring (lua_State *L,
-                              const char *fmt,
-                              va_list argp);

- -

-Equivalent to lua_pushfstring, except that it receives a va_list -instead of a variable number of arguments. - - - - - -

`lua_rawequal`

-[-0, +0, –] -

int lua_rawequal (lua_State *L, int index1, int index2);

- -

-Returns 1 if the two values in acceptable indices index1 and -index2 are primitively equal -(that is, without calling metamethods). -Otherwise returns 0. -Also returns 0 if any of the indices are non valid. - - - - - -

`lua_rawget`

-[-1, +1, –] -

void lua_rawget (lua_State *L, int index);

- -

-Similar to lua_gettable, but does a raw access -(i.e., without metamethods). - - - - - -

`lua_rawgeti`

-[-0, +1, –] -

void lua_rawgeti (lua_State *L, int index, int n);

- -

-Pushes onto the stack the value t[n], -where t is the table at the given valid index. -The access is raw; -that is, it does not invoke metamethods. - - - - - -

`lua_rawgetp`

-[-0, +1, –] -

void lua_rawgetp (lua_State *L, int index, const void *p);

- -

-Pushes onto the stack the value t[k], -where t is the table at the given valid index and -k is the pointer p represented as a light userdata. -The access is raw; -that is, it does not invoke metamethods. - - - - - -

`lua_rawlen`

-[-0, +0, –] -

size_t lua_rawlen (lua_State *L, int index);

- -

-Returns the raw "length" of the value at the given acceptable index: -for strings, this is the string length; -for tables, this is the result of the length operator ('#') -with no metamethods; -for userdata, this is the size of the block of memory allocated -for the userdata; -for other values, it is 0. - - - - - -

`lua_rawset`

-[-2, +0, m] -

void lua_rawset (lua_State *L, int index);

- -

-Similar to lua_settable, but does a raw assignment -(i.e., without metamethods). - - - - - -

`lua_rawseti`

-[-1, +0, m] -

void lua_rawseti (lua_State *L, int index, int n);

- -

-Does the equivalent of t[n] = v, -where t is the table at the given valid index -and v is the value at the top of the stack. - - -

-This function pops the value from the stack. -The assignment is raw; -that is, it does not invoke metamethods. - - - - - -

`lua_rawsetp`

-[-1, +0, m] -

void lua_rawsetp (lua_State *L, int index, const void *p);

- -

-Does the equivalent of t[k] = v, -where t is the table at the given valid index, -k is the pointer p represented as a light userdata, -and v is the value at the top of the stack. - - -

-This function pops the value from the stack. -The assignment is raw; -that is, it does not invoke metamethods. - - - - - -

`lua_Reader`

typedef const char * (*lua_Reader) (lua_State *L,
-                                    void *data,
-                                    size_t *size);

- -

-The reader function used by lua_load. -Every time it needs another piece of the chunk, -lua_load calls the reader, -passing along its data parameter. -The reader must return a pointer to a block of memory -with a new piece of the chunk -and set size to the block size. -The block must exist until the reader function is called again. -To signal the end of the chunk, -the reader must return NULL or set size to zero. -The reader function may return pieces of any size greater than zero. - - - - - -

`lua_register`

-[-0, +0, e] -

void lua_register (lua_State *L, const char *name, lua_CFunction f);

- -

-Sets the C function f as the new value of global name. -It is defined as a macro: - -

-     #define lua_register(L,n,f) \
-            (lua_pushcfunction(L, f), lua_setglobal(L, n))
-

- - - - -

`lua_remove`

-[-1, +0, –] -

void lua_remove (lua_State *L, int index);

- -

-Removes the element at the given valid index, -shifting down the elements above this index to fill the gap. -Cannot be called with a pseudo-index, -because a pseudo-index is not an actual stack position. - - - - - -

`lua_replace`

-[-1, +0, –] -

void lua_replace (lua_State *L, int index);

- -

-Moves the top element into the given position -without shifting any element -(therefore replacing the value at the given position), -and then pops the top element. - - - - - -

`lua_resume`

-[-?, +?, –] -

int lua_resume (lua_State *L, lua_State *from, int narg);

- -

-Starts and resumes a coroutine in a given thread. - - -

-To start a coroutine, -you push onto the thread stack the main function plus any arguments; -then you call lua_resume, -with narg being the number of arguments. -This call returns when the coroutine suspends or finishes its execution. -When it returns, the stack contains all values passed to lua_yield, -or all values returned by the body function. -lua_resume returns -LUA_YIELD if the coroutine yields, -LUA_OK if the coroutine finishes its execution -without errors, -or an error code in case of errors (see lua_pcall). - - -

-In case of errors, -the stack is not unwound, -so you can use the debug API over it. -The error message is on the top of the stack. - - -

-To resume a coroutine, you put on its stack only the values to -be passed as results from yield, -and then call lua_resume. - - -

-The parameter from represents the coroutine that is resuming L. -If there is no such coroutine, -this parameter can be NULL. - - - - - -

`lua_setallocf`

-[-0, +0, –] -

void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);

- -

-Changes the allocator function of a given state to f -with user data ud. - - - - - -

`lua_setfield`

-[-1, +0, e] -

void lua_setfield (lua_State *L, int index, const char *k);

- -

-Does the equivalent to t[k] = v, -where t is the value at the given valid index -and v is the value at the top of the stack. - - -

-This function pops the value from the stack. -As in Lua, this function may trigger a metamethod -for the "newindex" event (see §2.4). - - - - - -

`lua_setglobal`

-[-1, +0, e] -

void lua_setglobal (lua_State *L, const char *name);

- -

-Pops a value from the stack and -sets it as the new value of global name. - - - - - -

`lua_setmetatable`

-[-1, +0, –] -

void lua_setmetatable (lua_State *L, int index);

- -

-Pops a table from the stack and -sets it as the new metatable for the value at the given -acceptable index. - - - - - -

`lua_settable`

-[-2, +0, e] -

void lua_settable (lua_State *L, int index);

- -

-Does the equivalent to t[k] = v, -where t is the value at the given valid index, -v is the value at the top of the stack, -and k is the value just below the top. - - -

-This function pops both the key and the value from the stack. -As in Lua, this function may trigger a metamethod -for the "newindex" event (see §2.4). - - - - - -

`lua_settop`

-[-?, +?, –] -

void lua_settop (lua_State *L, int index);

- -

-Accepts any acceptable index, or 0, -and sets the stack top to this index. -If the new top is larger than the old one, -then the new elements are filled with nil. -If index is 0, then all stack elements are removed. - - - - - -

`lua_setuservalue`

-[-1, +0, –] -

void lua_setuservalue (lua_State *L, int index);

- -

-Pops a table or nil from the stack and sets it as -the new value associated to the userdata at the given index. - - - - - -

`lua_State`

typedef struct lua_State lua_State;

- -

-An opaque structure that keeps the whole state of a Lua interpreter. -The Lua library is fully reentrant: -it has no global variables. -All information about a state is kept in this structure. - - -

-A pointer to this state must be passed as the first argument to -every function in the library, except to lua_newstate, -which creates a Lua state from scratch. - - - - - -

`lua_status`

-[-0, +0, –] -

int lua_status (lua_State *L);

- -

-Returns the status of the thread L. - - -

-The status can be 0 (LUA_OK) for a normal thread, -an error code if the thread finished the execution -of a lua_resume with an error, -or LUA_YIELD if the thread is suspended. - - -

-You can only call functions in threads with status LUA_OK. -You can resume threads with status LUA_OK -(to start a new coroutine) or LUA_YIELD -(to resume a coroutine). - - - - - -

`lua_toboolean`

-[-0, +0, –] -

int lua_toboolean (lua_State *L, int index);

- -

-Converts the Lua value at the given acceptable index to a C boolean -value (0 or 1). -Like all tests in Lua, -lua_toboolean returns true for any Lua value -different from false and nil; -otherwise it returns false. -It also returns false when called with a non-valid index. -(If you want to accept only actual boolean values, -use lua_isboolean to test the value's type.) - - - - - -

`lua_tocfunction`

-[-0, +0, –] -

lua_CFunction lua_tocfunction (lua_State *L, int index);

- -

-Converts a value at the given acceptable index to a C function. -That value must be a C function; -otherwise, returns NULL. - - - - - -

`lua_tointeger`

-[-0, +0, –] -

lua_Integer lua_tointeger (lua_State *L, int index);

- -

-Equivalent to lua_tointegerx with isnum equal to NULL. - - - - - -

`lua_tointegerx`

-[-0, +0, –] -

lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);

- -

-Converts the Lua value at the given acceptable index -to the signed integral type lua_Integer. -The Lua value must be a number or a string convertible to a number -(see §3.4.2); -otherwise, lua_tointegerx returns 0. - - -

-If the number is not an integer, -it is truncated in some non-specified way. - - -

-If isnum is not NULL, -its referent is assigned a boolean value that -indicates whether the operation succeeded. - - - - - -

`lua_tolstring`

-[-0, +0, m] -

const char *lua_tolstring (lua_State *L, int index, size_t *len);

- -

-Converts the Lua value at the given acceptable index to a C string. -If len is not NULL, -it also sets *len with the string length. -The Lua value must be a string or a number; -otherwise, the function returns NULL. -If the value is a number, -then lua_tolstring also -changes the actual value in the stack to a string. -(This change confuses lua_next -when lua_tolstring is applied to keys during a table traversal.) - - -

-lua_tolstring returns a fully aligned pointer -to a string inside the Lua state. -This string always has a zero ('\0') -after its last character (as in C), -but can contain other zeros in its body. -Because Lua has garbage collection, -there is no guarantee that the pointer returned by lua_tolstring -will be valid after the corresponding value is removed from the stack. - - - - - -

`lua_tonumber`

-[-0, +0, –] -

lua_Number lua_tonumber (lua_State *L, int index);

- -

-Equivalent to lua_tonumberx with isnum equal to NULL. - - - - - -

`lua_tonumberx`

-[-0, +0, –] -

lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);

- -

-Converts the Lua value at the given acceptable index -to the C type lua_Number (see lua_Number). -The Lua value must be a number or a string convertible to a number -(see §3.4.2); -otherwise, lua_tonumberx returns 0. - - -

-If isnum is not NULL, -its referent is assigned a boolean value that -indicates whether the operation succeeded. - - - - - -

`lua_topointer`

-[-0, +0, –] -

const void *lua_topointer (lua_State *L, int index);

- -

-Converts the value at the given acceptable index to a generic -C pointer (void*). -The value can be a userdata, a table, a thread, or a function; -otherwise, lua_topointer returns NULL. -Different objects will give different pointers. -There is no way to convert the pointer back to its original value. - - -

-Typically this function is used only for debug information. - - - - - -

`lua_tostring`

-[-0, +0, m] -

const char *lua_tostring (lua_State *L, int index);

- -

-Equivalent to lua_tolstring with len equal to NULL. - - - - - -

`lua_tothread`

-[-0, +0, –] -

lua_State *lua_tothread (lua_State *L, int index);

- -

-Converts the value at the given acceptable index to a Lua thread -(represented as lua_State*). -This value must be a thread; -otherwise, the function returns NULL. - - - - - -

`lua_tounsigned`

-[-0, +0, –] -

lua_Unsigned lua_tounsigned (lua_State *L, int index);

- -

-Equivalent to lua_tounsignedx with isnum equal to NULL. - - - - - -

`lua_tounsignedx`

-[-0, +0, –] -

lua_Unsigned lua_tounsignedx (lua_State *L, int index, int *isnum);

- -

-Converts the Lua value at the given acceptable index -to the unsigned integral type lua_Unsigned. -The Lua value must be a number or a string convertible to a number -(see §3.4.2); -otherwise, lua_tounsignedx returns 0. - - -

-If the number is not an integer, -it is truncated in some non-specified way. -If the number is outside the range of representable values, -it is normalized to the remainder of its division by -one more than the maximum representable value. - - -

-If isnum is not NULL, -its referent is assigned a boolean value that -indicates whether the operation succeeded. - - - - - -

`lua_touserdata`

-[-0, +0, –] -

void *lua_touserdata (lua_State *L, int index);

- -

-If the value at the given acceptable index is a full userdata, -returns its block address. -If the value is a light userdata, -returns its pointer. -Otherwise, returns NULL. - - - - - -

`lua_type`

-[-0, +0, –] -

int lua_type (lua_State *L, int index);

- -

-Returns the type of the value in the given acceptable index, -or LUA_TNONE for a non-valid index. -The types returned by lua_type are coded by the following constants -defined in lua.h: -LUA_TNIL, -LUA_TNUMBER, -LUA_TBOOLEAN, -LUA_TSTRING, -LUA_TTABLE, -LUA_TFUNCTION, -LUA_TUSERDATA, -LUA_TTHREAD, -and -LUA_TLIGHTUSERDATA. - - - - - -

`lua_typename`

-[-0, +0, –] -

const char *lua_typename  (lua_State *L, int tp);

- -

-Returns the name of the type encoded by the value tp, -which must be one the values returned by lua_type. - - - - - -

`lua_Unsigned`

typedef unsigned long lua_Unsigned;

- -

-The type used by the Lua API to represent unsigned integral values. -It must have at least 32 bits. - - -

-By default it is an unsigned int or an unsigned long, -whichever can hold 32-bit values. - - - - - -

`lua_version`

-[-0, +0, v] -

const lua_Number *lua_version (lua_State *L);

- -

-Returns the address of the version number stored in the Lua core. -When called with a valid lua_State, -returns the address of the version used to create that state. -When called with NULL, -returns the address of the version running the call. - - - - - -

`lua_Writer`

typedef int (*lua_Writer) (lua_State *L,
-                           const void* p,
-                           size_t sz,
-                           void* ud);

- -

-The type of the writer function used by lua_dump. -Every time it produces another piece of chunk, -lua_dump calls the writer, -passing along the buffer to be written (p), -its size (sz), -and the data parameter supplied to lua_dump. - - -

-The writer returns an error code: -0 means no errors; -any other value means an error and stops lua_dump from -calling the writer again. - - - - - -

`lua_xmove`

-[-?, +?, –] -

void lua_xmove (lua_State *from, lua_State *to, int n);

- -

-Exchange values between different threads of the same state. - - -

-This function pops n values from the stack from, -and pushes them onto the stack to. - - - - - -

`lua_yield`

-[-?, +?, –] -

int lua_yield  (lua_State *L, int nresults);

- -

-This function is equivalent to lua_yieldk, -but it has no continuation (see §4.7). -Therefore, when the thread resumes, -it returns to the function that called -the function calling lua_yield. - - - - - -

`lua_yieldk`

-[-?, +?, –] -

int lua_yieldk  (lua_State *L, int nresults, int ctx, lua_CFunction k);

- -

-Yields a coroutine. - - -

-This function should only be called as the -return expression of a C function, as follows: - -

-     return lua_yieldk (L, n, i, k);
-

-When a C function calls lua_yieldk in that way, -the running coroutine suspends its execution, -and the call to lua_resume that started this coroutine returns. -The parameter nresults is the number of values from the stack -that are passed as results to lua_resume. - - -

-When the coroutine is resumed again, -Lua calls the given continuation function k to continue -the execution of the C function that yielded (see §4.7). -This continuation function receives the same stack -from the previous function, -with the results removed and -replaced by the arguments passed to lua_resume. -Moreover, -the continuation function may access the value ctx -by calling lua_getctx. - - - - - - - -

4.9 – The Debug Interface

- -

-Lua has no built-in debugging facilities. -Instead, it offers a special interface -by means of functions and hooks. -This interface allows the construction of different -kinds of debuggers, profilers, and other tools -that need "inside information" from the interpreter. - - - -

`lua_Debug`

typedef struct lua_Debug {
-  int event;
-  const char *name;           /* (n) */
-  const char *namewhat;       /* (n) */
-  const char *what;           /* (S) */
-  const char *source;         /* (S) */
-  int currentline;            /* (l) */
-  int linedefined;            /* (S) */
-  int lastlinedefined;        /* (S) */
-  unsigned char nups;         /* (u) number of upvalues */
-  unsigned char nparams;      /* (u) number of parameters */
-  char isvararg;              /* (u) */
-  char istailcall;            /* (t) */
-  char short_src[LUA_IDSIZE]; /* (S) */
-  /* private part */
-  other fields
-} lua_Debug;

- -

-A structure used to carry different pieces of -information about a function or an activation record. -lua_getstack fills only the private part -of this structure, for later use. -To fill the other fields of lua_Debug with useful information, -call lua_getinfo. - - -

-The fields of lua_Debug have the following meaning: - -

source: -the source of the chunk that created the function. -If source starts with a '@', -it means that the function was defined in a file where -the file name follows the '@'. -If source starts with a '=', -the remainder of its contents describe the source in a user-dependent manner. -Otherwise, -the function was defined in a string where -source is that string. -
short_src: -a "printable" version of source, to be used in error messages. -
linedefined: -the line number where the definition of the function starts. -
lastlinedefined: -the line number where the definition of the function ends. -
what: -the string "Lua" if the function is a Lua function, -"C" if it is a C function, -"main" if it is the main part of a chunk. -
currentline: -the current line where the given function is executing. -When no line information is available, -currentline is set to -1. -
name: -a reasonable name for the given function. -Because functions in Lua are first-class values, -they do not have a fixed name: -some functions can be the value of multiple global variables, -while others can be stored only in a table field. -The lua_getinfo function checks how the function was -called to find a suitable name. -If it cannot find a name, -then name is set to NULL. -
namewhat: -explains the name field. -The value of namewhat can be -"global", "local", "method", -"field", "upvalue", or "" (the empty string), -according to how the function was called. -(Lua uses the empty string when no other option seems to apply.) -
istailcall: -true if this function invocation was called by a tail call. -In this case, the caller of this level is not in the stack. -
nups: -the number of upvalues of the function. -
nparams: -the number of fixed parameters of the function -(always 0 for C functions). -
isvararg: -true if the function is a vararg function -(always true for C functions). -

- - - - -

`lua_gethook`

-[-0, +0, –] -

lua_Hook lua_gethook (lua_State *L);

- -

-Returns the current hook function. - - - - - -

`lua_gethookcount`

-[-0, +0, –] -

int lua_gethookcount (lua_State *L);

- -

-Returns the current hook count. - - - - - -

`lua_gethookmask`

-[-0, +0, –] -

int lua_gethookmask (lua_State *L);

- -

-Returns the current hook mask. - - - - - -

`lua_getinfo`

-[-(0|1), +(0|1|2), m] -

int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);

- -

-Returns information about a specific function or function invocation. - - -

-To get information about a function invocation, -the parameter ar must be a valid activation record that was -filled by a previous call to lua_getstack or -given as argument to a hook (see lua_Hook). - - -

-To get information about a function you push it onto the stack -and start the what string with the character '>'. -(In that case, -lua_getinfo pops the function from the top of the stack.) -For instance, to know in which line a function f was defined, -you can write the following code: - -

-     lua_Debug ar;
-     lua_getglobal(L, "f");  /* get global 'f' */
-     lua_getinfo(L, ">S", &ar);
-     printf("%d\n", ar.linedefined);
-

- -

-Each character in the string what -selects some fields of the structure ar to be filled or -a value to be pushed on the stack: - -

'n': fills in the field name and namewhat; -
'S': -fills in the fields source, short_src, -linedefined, lastlinedefined, and what; -
'l': fills in the field currentline; -
't': fills in the field istailcall; -
'u': fills in the fields -nups, nparams, and isvararg; -
'f': -pushes onto the stack the function that is -running at the given level; -
'L': -pushes onto the stack a table whose indices are the -numbers of the lines that are valid on the function. -(A valid line is a line with some associated code, -that is, a line where you can put a break point. -Non-valid lines include empty lines and comments.) -

- -

-This function returns 0 on error -(for instance, an invalid option in what). - - - - - -

`lua_getlocal`

-[-0, +(0|1), –] -

const char *lua_getlocal (lua_State *L, lua_Debug *ar, int n);

- -

-Gets information about a local variable of -a given activation record or a given function. - - -

-In the first case, -the parameter ar must be a valid activation record that was -filled by a previous call to lua_getstack or -given as argument to a hook (see lua_Hook). -The index n selects which local variable to inspect; -see debug.getlocal for details about variable indices -and names. - - -

-lua_getlocal pushes the variable's value onto the stack -and returns its name. - - -

-In the second case, ar should be NULL and the function -to be inspected must be at the top of the stack. -In this case, only parameters of Lua functions are visible -(as there is no information about what variables are active) -and no values are pushed onto the stack. - - -

-Returns NULL (and pushes nothing) -when the index is greater than -the number of active local variables. - - - - - -

`lua_getstack`

-[-0, +0, –] -

int lua_getstack (lua_State *L, int level, lua_Debug *ar);

- -

-Get information about the interpreter runtime stack. - - -

-This function fills parts of a lua_Debug structure with -an identification of the activation record -of the function executing at a given level. -Level 0 is the current running function, -whereas level n+1 is the function that has called level n -(except for tail calls, which do not count on the stack). -When there are no errors, lua_getstack returns 1; -when called with a level greater than the stack depth, -it returns 0. - - - - - -

`lua_getupvalue`

-[-0, +(0|1), –] -

const char *lua_getupvalue (lua_State *L, int funcindex, int n);

- -

-Gets information about a closure's upvalue. -(For Lua functions, -upvalues are the external local variables that the function uses, -and that are consequently included in its closure.) -lua_getupvalue gets the index n of an upvalue, -pushes the upvalue's value onto the stack, -and returns its name. -funcindex points to the closure in the stack. -(Upvalues have no particular order, -as they are active through the whole function. -So, they are numbered in an arbitrary order.) - - -

-Returns NULL (and pushes nothing) -when the index is greater than the number of upvalues. -For C functions, this function uses the empty string "" -as a name for all upvalues. - - - - - -

`lua_Hook`

typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);

- -

-Type for debugging hook functions. - - -

-Whenever a hook is called, its ar argument has its field -event set to the specific event that triggered the hook. -Lua identifies these events with the following constants: -LUA_HOOKCALL, LUA_HOOKRET, -LUA_HOOKTAILCALL, LUA_HOOKLINE, -and LUA_HOOKCOUNT. -Moreover, for line events, the field currentline is also set. -To get the value of any other field in ar, -the hook must call lua_getinfo. - - -

-For call events, event can be LUA_HOOKCALL, -the normal value, or LUA_HOOKTAILCALL, for a tail call; -in this case, there will be no corresponding return event. - - -

-While Lua is running a hook, it disables other calls to hooks. -Therefore, if a hook calls back Lua to execute a function or a chunk, -this execution occurs without any calls to hooks. - - - - - -

`lua_sethook`

-[-0, +0, –] -

int lua_sethook (lua_State *L, lua_Hook f, int mask, int count);

- -

-Sets the debugging hook function. - - -

-Argument f is the hook function. -mask specifies on which events the hook will be called: -it is formed by a bitwise or of the constants -LUA_MASKCALL, -LUA_MASKRET, -LUA_MASKLINE, -and LUA_MASKCOUNT. -The count argument is only meaningful when the mask -includes LUA_MASKCOUNT. -For each event, the hook is called as explained below: - -

The call hook: is called when the interpreter calls a function. -The hook is called just after Lua enters the new function, -before the function gets its arguments. -
The return hook: is called when the interpreter returns from a function. -The hook is called just before Lua leaves the function. -There is no standard way to access the values -to be returned by the function. -
The line hook: is called when the interpreter is about to -start the execution of a new line of code, -or when it jumps back in the code (even to the same line). -(This event only happens while Lua is executing a Lua function.) -
The count hook: is called after the interpreter executes every -count instructions. -(This event only happens while Lua is executing a Lua function.) -

- -

-A hook is disabled by setting mask to zero. - - - - - -

`lua_setlocal`

-[-(0|1), +0, –] -

const char *lua_setlocal (lua_State *L, lua_Debug *ar, int n);

- -

-Sets the value of a local variable of a given activation record. -Parameters ar and n are as in lua_getlocal -(see lua_getlocal). -lua_setlocal assigns the value at the top of the stack -to the variable and returns its name. -It also pops the value from the stack. - - -

-Returns NULL (and pops nothing) -when the index is greater than -the number of active local variables. - - - - - -

`lua_setupvalue`

-[-(0|1), +0, –] -

const char *lua_setupvalue (lua_State *L, int funcindex, int n);

- -

-Sets the value of a closure's upvalue. -It assigns the value at the top of the stack -to the upvalue and returns its name. -It also pops the value from the stack. -Parameters funcindex and n are as in the lua_getupvalue -(see lua_getupvalue). - - -

-Returns NULL (and pops nothing) -when the index is greater than the number of upvalues. - - - - - -

`lua_upvalueid`

-[-0, +0, –] -

void *lua_upvalueid (lua_State *L, int funcindex, int n);

- -

-Returns an unique identifier for the upvalue numbered n -from the closure at index fidx. -Parameters funcindex and n are as in the lua_getupvalue -(see lua_getupvalue) -(but n cannot be greater than the number of upvalues). - - -

-These unique identifiers allow a program to check whether different -closures share upvalues. -Lua closures that share an upvalue -(that is, that access a same external local variable) -will return identical ids for those upvalue indices. - - - - - -

`lua_upvaluejoin`

void lua_upvaluejoin (lua_State *L, int fidx1, int n1,
-                                    int fidx2, int n2);

- -

-Make the n1-th upvalue of the Lua closure at index fidx1 -refer to the n2-th upvalue of the Lua closure at index fidx2. - - - - - - - -

5 – The Auxiliary Library

- -

- -The auxiliary library provides several convenient functions -to interface C with Lua. -While the basic API provides the primitive functions for all -interactions between C and Lua, -the auxiliary library provides higher-level functions for some -common tasks. - - -

-All functions and types from the auxiliary library -are defined in header file lauxlib.h and -have a prefix luaL_. - - -

-All functions in the auxiliary library are built on -top of the basic API, -and so they provide nothing that cannot be done with that API. -Nevertheless, the use of the auxiliary library ensures -more consistency to your code. - - -

-Several functions in the auxiliary library use internally some -extra stack slots. -When a function in the auxiliary library uses less than five slots, -it does not check the stack size; -it simply assumes that there are enough slots. - - -

-Several functions in the auxiliary library are used to -check C function arguments. -Because the error message is formatted for arguments -(e.g., "bad argument #1"), -you should not use these functions for other stack values. - - -

-Functions called luaL_check* -always throw an error if the check is not satisfied. - - - -

5.1 – Functions and Types

- -

-Here we list all functions and types from the auxiliary library -in alphabetical order. - - - -

`luaL_addchar`

-[-?, +?, m] -

void luaL_addchar (luaL_Buffer *B, char c);

- -

-Adds the byte c to the buffer B -(see luaL_Buffer). - - - - - -

`luaL_addlstring`

-[-?, +?, m] -

void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);

- -

-Adds the string pointed to by s with length l to -the buffer B -(see luaL_Buffer). -The string can contain embedded zeros. - - - - - -

`luaL_addsize`

-[-?, +?, m] -

void luaL_addsize (luaL_Buffer *B, size_t n);

- -

-Adds to the buffer B (see luaL_Buffer) -a string of length n previously copied to the -buffer area (see luaL_prepbuffer). - - - - - -

`luaL_addstring`

-[-?, +?, m] -

void luaL_addstring (luaL_Buffer *B, const char *s);

- -

-Adds the zero-terminated string pointed to by s -to the buffer B -(see luaL_Buffer). -The string cannot contain embedded zeros. - - - - - -

`luaL_addvalue`

-[-1, +?, m] -

void luaL_addvalue (luaL_Buffer *B);

- -

-Adds the value at the top of the stack -to the buffer B -(see luaL_Buffer). -Pops the value. - - -

-This is the only function on string buffers that can (and must) -be called with an extra element on the stack, -which is the value to be added to the buffer. - - - - - -

`luaL_argcheck`

-[-0, +0, v] -

void luaL_argcheck (lua_State *L,
-                    int cond,
-                    int narg,
-                    const char *extramsg);

- -

-Checks whether cond is true. -If not, raises an error with a standard message. - - - - - -

`luaL_argerror`

-[-0, +0, v] -

int luaL_argerror (lua_State *L, int narg, const char *extramsg);

- -

-Raises an error with a standard message -that includes extramsg as a comment. - - -

-This function never returns, -but it is an idiom to use it in C functions -as return luaL_argerror(args). - - - - - -

`luaL_Buffer`

typedef struct luaL_Buffer luaL_Buffer;

- -

-Type for a string buffer. - - -

-A string buffer allows C code to build Lua strings piecemeal. -Its pattern of use is as follows: - -

First declare a variable b of type luaL_Buffer.
Then initialize it with a call luaL_buffinit(L, &b).
-Then add string pieces to the buffer calling any of -the luaL_add* functions. -
-Finish by calling luaL_pushresult(&b). -This call leaves the final string on the top of the stack. -

- -

-If you know beforehand the total size of the resulting string, -you can use the buffer like this: - -

First declare a variable b of type luaL_Buffer.
Then initialize it and preallocate a space of -size sz with a call luaL_buffinitsize(L, &b, sz).
Then copy the string into that space.
-Finish by calling luaL_pushresult(&b, sz), -where sz is the total size of the resulting string -copied into that space. -

- -

-During its normal operation, -a string buffer uses a variable number of stack slots. -So, while using a buffer, you cannot assume that you know where -the top of the stack is. -You can use the stack between successive calls to buffer operations -as long as that use is balanced; -that is, -when you call a buffer operation, -the stack is at the same level -it was immediately after the previous buffer operation. -(The only exception to this rule is luaL_addvalue.) -After calling luaL_pushresult the stack is back to its -level when the buffer was initialized, -plus the final string on its top. - - - - - -

`luaL_buffinit`

-[-0, +0, –] -

void luaL_buffinit (lua_State *L, luaL_Buffer *B);

- -

-Initializes a buffer B. -This function does not allocate any space; -the buffer must be declared as a variable -(see luaL_Buffer). - - - - - -

`luaL_buffinitsize`

-[-?, +?, m] -

char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);

- -

-Equivalent to the sequence -luaL_buffinit, luaL_prepbuffsize. - - - - - -

`luaL_callmeta`

-[-0, +(0|1), e] -

int luaL_callmeta (lua_State *L, int obj, const char *e);

- -

-Calls a metamethod. - - -

-If the object at index obj has a metatable and this -metatable has a field e, -this function calls this field passing the object as its only argument. -In this case this function returns true and pushes onto the -stack the value returned by the call. -If there is no metatable or no metamethod, -this function returns false (without pushing any value on the stack). - - - - - -

`luaL_checkany`

-[-0, +0, v] -

void luaL_checkany (lua_State *L, int narg);

- -

-Checks whether the function has an argument -of any type (including nil) at position narg. - - - - - -

`luaL_checkint`

-[-0, +0, v] -

int luaL_checkint (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a number -and returns this number cast to an int. - - - - - -

`luaL_checkinteger`

-[-0, +0, v] -

lua_Integer luaL_checkinteger (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a number -and returns this number cast to a lua_Integer. - - - - - -

`luaL_checklong`

-[-0, +0, v] -

long luaL_checklong (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a number -and returns this number cast to a long. - - - - - -

`luaL_checklstring`

-[-0, +0, v] -

const char *luaL_checklstring (lua_State *L, int narg, size_t *l);

- -

-Checks whether the function argument narg is a string -and returns this string; -if l is not NULL fills *l -with the string's length. - - -

-This function uses lua_tolstring to get its result, -so all conversions and caveats of that function apply here. - - - - - -

`luaL_checknumber`

-[-0, +0, v] -

lua_Number luaL_checknumber (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a number -and returns this number. - - - - - -

`luaL_checkoption`

-[-0, +0, v] -

int luaL_checkoption (lua_State *L,
-                      int narg,
-                      const char *def,
-                      const char *const lst[]);

- -

-Checks whether the function argument narg is a string and -searches for this string in the array lst -(which must be NULL-terminated). -Returns the index in the array where the string was found. -Raises an error if the argument is not a string or -if the string cannot be found. - - -

-If def is not NULL, -the function uses def as a default value when -there is no argument narg or when this argument is nil. - - -

-This is a useful function for mapping strings to C enums. -(The usual convention in Lua libraries is -to use strings instead of numbers to select options.) - - - - - -

`luaL_checkstack`

-[-0, +0, v] -

void luaL_checkstack (lua_State *L, int sz, const char *msg);

- -

-Grows the stack size to top + sz elements, -raising an error if the stack cannot grow to that size. -msg is an additional text to go into the error message -(or NULL for no additional text). - - - - - -

`luaL_checkstring`

-[-0, +0, v] -

const char *luaL_checkstring (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a string -and returns this string. - - -

-This function uses lua_tolstring to get its result, -so all conversions and caveats of that function apply here. - - - - - -

`luaL_checktype`

-[-0, +0, v] -

void luaL_checktype (lua_State *L, int narg, int t);

- -

-Checks whether the function argument narg has type t. -See lua_type for the encoding of types for t. - - - - - -

`luaL_checkudata`

-[-0, +0, v] -

void *luaL_checkudata (lua_State *L, int narg, const char *tname);

- -

-Checks whether the function argument narg is a userdata -of the type tname (see luaL_newmetatable) and -returns the userdata address (see lua_touserdata). - - - - - -

`luaL_checkunsigned`

-[-0, +0, v] -

lua_Unsigned luaL_checkunsigned (lua_State *L, int narg);

- -

-Checks whether the function argument narg is a number -and returns this number cast to a lua_Unsigned. - - - - - -

`luaL_checkversion`

-[-0, +0, –] -

void luaL_checkversion (lua_State *L);

- -

-Checks whether the core running the call, -the core that created the Lua state, -and the code making the call are all using the same version of Lua. -Also checks whether the core running the call -and the core that created the Lua state -are using the same address space. - - - - - -

`luaL_dofile`

-[-0, +?, m] -

int luaL_dofile (lua_State *L, const char *filename);

- -

-Loads and runs the given file. -It is defined as the following macro: - -

-     (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0))
-

-It returns false if there are no errors -or true in case of errors. - - - - - -

`luaL_dostring`

-[-0, +?, –] -

int luaL_dostring (lua_State *L, const char *str);

- -

-Loads and runs the given string. -It is defined as the following macro: - -

-     (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0))
-

-It returns false if there are no errors -or true in case of errors. - - - - - -

`luaL_error`

-[-0, +0, v] -

int luaL_error (lua_State *L, const char *fmt, ...);

- -

-Raises an error. -The error message format is given by fmt -plus any extra arguments, -following the same rules of lua_pushfstring. -It also adds at the beginning of the message the file name and -the line number where the error occurred, -if this information is available. - - -

-This function never returns, -but it is an idiom to use it in C functions -as return luaL_error(args). - - - - - -

`luaL_execresult`

-[-0, +3, m] -

int luaL_execresult (lua_State *L, int stat);

- -

-This function produces the return values for -process-related functions in the standard library -(os.execute and io.close). - - - - - -

`luaL_fileresult`

-[-0, +(1|3), m] -

int luaL_fileresult (lua_State *L, int stat, const char *fname);

- -

-This function produces the return values for -file-related functions in the standard library -(io.open, os.rename, file:seek, etc.). - - - - - -

`luaL_getmetafield`

-[-0, +(0|1), m] -

int luaL_getmetafield (lua_State *L, int obj, const char *e);

- -

-Pushes onto the stack the field e from the metatable -of the object at index obj. -If the object does not have a metatable, -or if the metatable does not have this field, -returns false and pushes nothing. - - - - - -

`luaL_getmetatable`

-[-0, +1, –] -

void luaL_getmetatable (lua_State *L, const char *tname);

- -

-Pushes onto the stack the metatable associated with name tname -in the registry (see luaL_newmetatable). - - - - - -

`luaL_getsubtable`

-[-0, +1, m] -

int luaL_getsubtable (lua_State *L, int idx, const char *fname);

- -

-Ensures that the value t[fname], -where t is the value at the valid index idx, -is a table, -and pushes that table onto the stack. -Returns true if it finds a previous table there -and false if it creates a new table. - - - - - -

`luaL_gsub`

-[-0, +1, m] -

const char *luaL_gsub (lua_State *L,
-                       const char *s,
-                       const char *p,
-                       const char *r);

- -

-Creates a copy of string s by replacing -any occurrence of the string p -with the string r. -Pushes the resulting string on the stack and returns it. - - - - - -

`luaL_len`

-[-0, +1, e] -

int luaL_len (lua_State *L, int index);

- -

-Returns the "length" of the value at the given acceptable index -as a number; -it is equivalent to the '#' operator in Lua (see §3.4.6). -Raises an error if the result of the operation is not a number. -(This only can happen through metamethods.) - - - - - -

`luaL_loadbuffer`

-[-0, +1, –] -

int luaL_loadbuffer (lua_State *L,
-                     const char *buff,
-                     size_t sz,
-                     const char *name);

- -

-Equivalent to luaL_loadbufferx with mode equal to NULL. - - - - - -

`luaL_loadbufferx`

-[-0, +1, –] -

int luaL_loadbufferx (lua_State *L,
-                      const char *buff,
-                      size_t sz,
-                      const char *name,
-                      const char *mode);

- -

-Loads a buffer as a Lua chunk. -This function uses lua_load to load the chunk in the -buffer pointed to by buff with size sz. - - -

-This function returns the same results as lua_load. -name is the chunk name, -used for debug information and error messages. -The string mode works as in function lua_load. - - - - - -

`luaL_loadfile`

-[-0, +1, m] -

int luaL_loadfile (lua_State *L, const char *filename);

- -

-Equivalent to luaL_loadfilex with mode equal to NULL. - - - - - -

`luaL_loadfilex`

-[-0, +1, m] -

int luaL_loadfilex (lua_State *L, const char *filename,
-                                            const char *mode);

- -

-Loads a file as a Lua chunk. -This function uses lua_load to load the chunk in the file -named filename. -If filename is NULL, -then it loads from the standard input. -The first line in the file is ignored if it starts with a #. - - -

-The string mode works as in function lua_load. - - -

-This function returns the same results as lua_load, -but it has an extra error code LUA_ERRFILE -if it cannot open/read the file or the file has a wrong mode. - - -

-As lua_load, this function only loads the chunk; -it does not run it. - - - - - -

`luaL_loadstring`

-[-0, +1, –] -

int luaL_loadstring (lua_State *L, const char *s);

- -

-Loads a string as a Lua chunk. -This function uses lua_load to load the chunk in -the zero-terminated string s. - - -

-This function returns the same results as lua_load. - - -

-Also as lua_load, this function only loads the chunk; -it does not run it. - - - - - -

`luaL_newlib`

-[-0, +1, m] -

int luaL_newlib (lua_State *L, const luaL_Reg *l);

- -

-Creates a new table and registers there -the functions in list l. -It is implemented as the following macro: - -

-     (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0))
-

- - - - -

`luaL_newlibtable`

-[-0, +1, m] -

int luaL_newlibtable (lua_State *L, const luaL_Reg l[]);

- -

-Creates a new table with a size optimized -to store all entries in the array l -(but does not actually store them). -It is intended to be used in conjunction with luaL_setfuncs -(see luaL_newlib). - - -

-It is implemented as a macro. -The array l must be the actual array, -not a pointer to it. - - - - - -

`luaL_newmetatable`

-[-0, +1, m] -

int luaL_newmetatable (lua_State *L, const char *tname);

- -

-If the registry already has the key tname, -returns 0. -Otherwise, -creates a new table to be used as a metatable for userdata, -adds it to the registry with key tname, -and returns 1. - - -

-In both cases pushes onto the stack the final value associated -with tname in the registry. - - - - - -

`luaL_newstate`

-[-0, +0, –] -

lua_State *luaL_newstate (void);

- -

-Creates a new Lua state. -It calls lua_newstate with an -allocator based on the standard C realloc function -and then sets a panic function (see §4.6) that prints -an error message to the standard error output in case of fatal -errors. - - -

-Returns the new state, -or NULL if there is a memory allocation error. - - - - - -

`luaL_openlibs`

-[-0, +0, e] -

void luaL_openlibs (lua_State *L);

- -

-Opens all standard Lua libraries into the given state. - - - - - -

`luaL_optint`

-[-0, +0, v] -

int luaL_optint (lua_State *L, int narg, int d);

- -

-If the function argument narg is a number, -returns this number cast to an int. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - - - - -

`luaL_optinteger`

-[-0, +0, v] -

lua_Integer luaL_optinteger (lua_State *L,
-                             int narg,
-                             lua_Integer d);

- -

-If the function argument narg is a number, -returns this number cast to a lua_Integer. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - - - - -

`luaL_optlong`

-[-0, +0, v] -

long luaL_optlong (lua_State *L, int narg, long d);

- -

-If the function argument narg is a number, -returns this number cast to a long. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - - - - -

`luaL_optlstring`

-[-0, +0, v] -

const char *luaL_optlstring (lua_State *L,
-                             int narg,
-                             const char *d,
-                             size_t *l);

- -

-If the function argument narg is a string, -returns this string. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - -

-If l is not NULL, -fills the position *l with the result's length. - - - - - -

`luaL_optnumber`

-[-0, +0, v] -

lua_Number luaL_optnumber (lua_State *L, int narg, lua_Number d);

- -

-If the function argument narg is a number, -returns this number. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - - - - -

`luaL_optstring`

-[-0, +0, v] -

const char *luaL_optstring (lua_State *L,
-                            int narg,
-                            const char *d);

- -

-If the function argument narg is a string, -returns this string. -If this argument is absent or is nil, -returns d. -Otherwise, raises an error. - - - - - -

`luaL_optunsigned`

-[-0, +0, v] -

lua_Unsigned luaL_optunsigned (lua_State *L,
-                               int narg,
-                               lua_Unsigned u);

- -

-If the function argument narg is a number, -returns this number cast to a lua_Unsigned. -If this argument is absent or is nil, -returns u. -Otherwise, raises an error. - - - - - -

`luaL_prepbuffer`

-[-?, +?, m] -

char *luaL_prepbuffer (luaL_Buffer *B);

- -

-Equivalent to luaL_prepbuffsize -with the predefined size LUAL_BUFFERSIZE. - - - - - -

`luaL_prepbuffsize`

-[-?, +?, m] -

char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);

- -

-Returns an address to a space of size sz -where you can copy a string to be added to buffer B -(see luaL_Buffer). -After copying the string into this space you must call -luaL_addsize with the size of the string to actually add -it to the buffer. - - - - - -

`luaL_pushresult`

-[-?, +1, m] -

void luaL_pushresult (luaL_Buffer *B);

- -

-Finishes the use of buffer B leaving the final string on -the top of the stack. - - - - - -

`luaL_pushresultsize`

-[-?, +1, m] -

void luaL_pushresultsize (luaL_Buffer *B, size_t sz);

- -

-Equivalent to the sequence luaL_addsize, luaL_pushresult. - - - - - -

`luaL_ref`

-[-1, +0, m] -

int luaL_ref (lua_State *L, int t);

- -

-Creates and returns a reference, -in the table at index t, -for the object at the top of the stack (and pops the object). - - -

-A reference is a unique integer key. -As long as you do not manually add integer keys into table t, -luaL_ref ensures the uniqueness of the key it returns. -You can retrieve an object referred by reference r -by calling lua_rawgeti(L, t, r). -Function luaL_unref frees a reference and its associated object. - - -

-If the object at the top of the stack is nil, -luaL_ref returns the constant LUA_REFNIL. -The constant LUA_NOREF is guaranteed to be different -from any reference returned by luaL_ref. - - - - - -

`luaL_Reg`

typedef struct luaL_Reg {
-  const char *name;
-  lua_CFunction func;
-} luaL_Reg;

- -

-Type for arrays of functions to be registered by -luaL_setfuncs. -name is the function name and func is a pointer to -the function. -Any array of luaL_Reg must end with an sentinel entry -in which both name and func are NULL. - - - - - -

`luaL_requiref`

-[-0, +1, e] -

void luaL_requiref (lua_State *L, const char *modname,
-                    lua_CFunction openf, int glb);

- -

-Calls function openf with string modname as an argument -and sets the call result in package.loaded[modname], -as if that function has been called through require. - - -

-If glb is true, -also stores the result into global modname. - - -

-Leaves a copy of that result on the stack. - - - - - -

`luaL_setfuncs`

-[-nup, +0, e] -

void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);

- -

-Registers all functions in the array l -(see luaL_Reg) into the table on the top of the stack -(below optional upvalues, see next). - - -

-When nup is not zero, -all functions are created sharing nup upvalues, -which must be previously pushed on the stack -on top of the library table. -These values are popped from the stack after the registration. - - - - - -

`luaL_setmetatable`

-[-0, +0, –] -

void luaL_setmetatable (lua_State *L, const char *tname);

- -

-Sets the metatable of the object at the top of the stack -as the metatable associated with name tname -in the registry (see luaL_newmetatable). - - - - - -

`luaL_testudata`

-[-0, +0, m] -

void *luaL_testudata (lua_State *L, int narg, const char *tname);

- -

-This function works like luaL_checkudata, -except that, when the test fails, -it returns NULL instead of throwing an error. - - - - - -

`luaL_tolstring`

-[-0, +1, e] -

const char *luaL_tolstring (lua_State *L, int idx, size_t *len);

- -

-Converts any Lua value at the given acceptable index to a C string -in a reasonable format. -The resulting string is pushed onto the stack and also -returned by the function. -If len is not NULL, -the function also sets *len with the string length. - - -

-If the value has a metatable with a "__tostring" field, -then luaL_tolstring calls the corresponding metamethod -with the value as argument, -and uses the result of the call as its result. - - - - - -

`luaL_traceback`

-[-0, +1, m] -

void luaL_traceback (lua_State *L, lua_State *L1, const char *msg,
-                     int level);

- -

-Creates and pushes a traceback of the stack L1. -If msg is not NULL it is appended -at the beginning of the traceback. -The level parameter tells at which level -to start the traceback. - - - - - -

`luaL_typename`

-[-0, +0, –] -

const char *luaL_typename (lua_State *L, int index);

- -

-Returns the name of the type of the value at the given index. - - - - - -

`luaL_unref`

-[-0, +0, –] -

void luaL_unref (lua_State *L, int t, int ref);

- -

-Releases reference ref from the table at index t -(see luaL_ref). -The entry is removed from the table, -so that the referred object can be collected. -The reference ref is also freed to be used again. - - -

-If ref is LUA_NOREF or LUA_REFNIL, -luaL_unref does nothing. - - - - - -

`luaL_where`

-[-0, +1, m] -

void luaL_where (lua_State *L, int lvl);

- -

-Pushes onto the stack a string identifying the current position -of the control at level lvl in the call stack. -Typically this string has the following format: - -

-     chunkname:currentline:
-

-Level 0 is the running function, -level 1 is the function that called the running function, -etc. - - -

-This function is used to build a prefix for error messages. - - - - - - - -

6 – Standard Libraries

- -

-The standard Lua libraries provide useful functions -that are implemented directly through the C API. -Some of these functions provide essential services to the language -(e.g., type and getmetatable); -others provide access to "outside" services (e.g., I/O); -and others could be implemented in Lua itself, -but are quite useful or have critical performance requirements that -deserve an implementation in C (e.g., table.sort). - - -

-All libraries are implemented through the official C API -and are provided as separate C modules. -Currently, Lua has the following standard libraries: - -

basic library (§6.1);
coroutine library (§6.2);
package library (§6.3);
string manipulation (§6.4);
table manipulation (§6.5);
mathematical functions (§6.6) (sin, log, etc.);
bitwise operations (§6.7);
input and output (§6.8);
operating system facilities (§6.9);
debug facilities (§6.10).

-Except for the basic and the package libraries, -each library provides all its functions as fields of a global table -or as methods of its objects. - - -

-To have access to these libraries, -the C host program should call the luaL_openlibs function, -which opens all standard libraries. -Alternatively, -the host program can open them individually by using -luaL_requiref to call -luaopen_base (for the basic library), -luaopen_package (for the package library), -luaopen_coroutine (for the coroutine library), -luaopen_string (for the string library), -luaopen_table (for the table library), -luaopen_math (for the mathematical library), -luaopen_bitlib (for the bit library), -luaopen_io (for the I/O library), -luaopen_os (for the Operating System library), -and luaopen_debug (for the debug library). -These functions are declared in lualib.h. - - - -

6.1 – Basic Functions

- -

-The basic library provides core functions to Lua. -If you do not include this library in your application, -you should check carefully whether you need to provide -implementations for some of its facilities. - - -

`assert (v [, message])`

-Issues an error when -the value of its argument v is false (i.e., nil or false); -otherwise, returns all its arguments. -message is an error message; -when absent, it defaults to "assertion failed!" - - - - -

`collectgarbage ([opt [, arg]])`

- - -

-This function is a generic interface to the garbage collector. -It performs different functions according to its first argument, opt: - -

"collect": -performs a full garbage-collection cycle. -This is the default option. -
"stop": -stops automatic execution of the garbage collector. -The collector will run only when explicitly invoked, -until a call to restart it. -
"restart": -restarts automatic execution of the garbage collector. -
"count": -returns the total memory in use by Lua (in Kbytes) and -a second value with the total memory in bytes modulo 1024. -The first value has a fractional part, -so the following equality is always true: - -
```
-     k, b = collectgarbage("count")
-     assert(k*1024 == math.floor(k)*1024 + b)
-
```
-(The second result is useful when Lua is compiled -with a non floating-point type for numbers.) -
"step": -performs a garbage-collection step. -The step "size" is controlled by arg -(larger values mean more steps) in a non-specified way. -If you want to control the step size -you must experimentally tune the value of arg. -Returns true if the step finished a collection cycle. -
"setpause": -sets arg as the new value for the pause of -the collector (see §2.5). -Returns the previous value for pause. -
"setstepmul": -sets arg as the new value for the step multiplier of -the collector (see §2.5). -Returns the previous value for step. -
"isrunning": -returns a boolean that tells whether the collector is running -(i.e., not stopped). -
"generational": -changes the collector to generational mode. -This is an experimental feature (see §2.5). -
"incremental": -changes the collector to incremental mode. -This is the default mode. -

- - - -

`dofile ([filename])`

-Opens the named file and executes its contents as a Lua chunk. -When called without arguments, -dofile executes the contents of the standard input (stdin). -Returns all values returned by the chunk. -In case of errors, dofile propagates the error -to its caller (that is, dofile does not run in protected mode). - - - - -

`error (message [, level])`

-Terminates the last protected function called -and returns message as the error message. -Function error never returns. - - -

-Usually, error adds some information about the error position -at the beginning of the message, if the message is a string. -The level argument specifies how to get the error position. -With level 1 (the default), the error position is where the -error function was called. -Level 2 points the error to where the function -that called error was called; and so on. -Passing a level 0 avoids the addition of error position information -to the message. - - - - -

`_G`

-A global variable (not a function) that -holds the global environment (see §2.2). -Lua itself does not use this variable; -changing its value does not affect any environment, -nor vice-versa. - - - - -

`getmetatable (object)`

- - -

-If object does not have a metatable, returns nil. -Otherwise, -if the object's metatable has a "__metatable" field, -returns the associated value. -Otherwise, returns the metatable of the given object. - - - - -

`ipairs (t)`

- - -

-If t has a metamethod __ipairs, -calls it with t as argument and returns the first three -results from the call. - - -

-Otherwise, -returns three values: an iterator function, the table t, and 0, -so that the construction - -

-     for i,v in ipairs(t) do body end
-

-will iterate over the pairs (1,t[1]), (2,t[2]), ..., -up to the first integer key absent from the table. - - - - -

`load (ld [, source [, mode [, env]]])`

- - -

-Loads a chunk. - - -

-If ld is a string, the chunk is this string. -If ld is a function, -load calls it repeatedly to get the chunk pieces. -Each call to ld must return a string that concatenates -with previous results. -A return of an empty string, nil, or no value signals the end of the chunk. - - -

-If there are no syntactic errors, -returns the compiled chunk as a function; -otherwise, returns nil plus the error message. - - -

-If the resulting function has upvalues, -the first upvalue is set to the value of the -global environment or to env, -if that parameter is given. -When loading main chunks, -the first upvalue will be the _ENV variable (see §2.2). - - -

-source is used as the source of the chunk for error messages -and debug information (see §4.9). -When absent, -it defaults to ld, if ld is a string, -or to "=(load)" otherwise. - - -

-The string mode controls whether the chunk can be text or binary -(that is, a precompiled chunk). -It may be the string "b" (only binary chunks), -"t" (only text chunks), -or "bt" (both binary and text). -The default is "bt". - - - - -

`loadfile ([filename [, mode [, env]]])`

- - -

-Similar to load, -but gets the chunk from file filename -or from the standard input, -if no file name is given. - - - - -

`next (table [, index])`

- - -

-Allows a program to traverse all fields of a table. -Its first argument is a table and its second argument -is an index in this table. -next returns the next index of the table -and its associated value. -When called with nil as its second argument, -next returns an initial index -and its associated value. -When called with the last index, -or with nil in an empty table, -next returns nil. -If the second argument is absent, then it is interpreted as nil. -In particular, -you can use next(t) to check whether a table is empty. - - -

-The order in which the indices are enumerated is not specified, -even for numeric indices. -(To traverse a table in numeric order, -use a numerical for.) - - -

-The behavior of next is undefined if, -during the traversal, -you assign any value to a non-existent field in the table. -You may however modify existing fields. -In particular, you may clear existing fields. - - - - -

`pairs (t)`

- - -

-If t has a metamethod __pairs, -calls it with t as argument and returns the first three -results from the call. - - -

-Otherwise, -returns three values: the next function, the table t, and nil, -so that the construction - -

-     for k,v in pairs(t) do body end
-

-will iterate over all key–value pairs of table t. - - -

-See function next for the caveats of modifying -the table during its traversal. - - - - -

`pcall (f [, arg1, ···])`

- - -

-Calls function f with -the given arguments in protected mode. -This means that any error inside f is not propagated; -instead, pcall catches the error -and returns a status code. -Its first result is the status code (a boolean), -which is true if the call succeeds without errors. -In such case, pcall also returns all results from the call, -after this first result. -In case of any error, pcall returns false plus the error message. - - - - -

`print (···)`

-Receives any number of arguments -and prints their values to stdout, -using the tostring function to convert each argument to a string. -print is not intended for formatted output, -but only as a quick way to show a value, -for instance for debugging. -For complete control over the output, -use string.format and io.write. - - - - -

`rawequal (v1, v2)`

-Checks whether v1 is equal to v2, -without invoking any metamethod. -Returns a boolean. - - - - -

`rawget (table, index)`

-Gets the real value of table[index], -without invoking any metamethod. -table must be a table; -index may be any value. - - - - -

`rawlen (v)`

-Returns the length of the object v, -which must be a table or a string, -without invoking any metamethod. -Returns an integer number. - - - - -

`rawset (table, index, value)`

-Sets the real value of table[index] to value, -without invoking any metamethod. -table must be a table, -index any value different from nil and NaN, -and value any Lua value. - - -

-This function returns table. - - - - -

`select (index, ···)`

- - -

-If index is a number, -returns all arguments after argument number index; -a negative number indexes from the end (-1 is the last argument). -Otherwise, index must be the string "#", -and select returns the total number of extra arguments it received. - - - - -

`setmetatable (table, metatable)`

- - -

-Sets the metatable for the given table. -(You cannot change the metatable of other types from Lua, only from C.) -If metatable is nil, -removes the metatable of the given table. -If the original metatable has a "__metatable" field, -raises an error. - - -

-This function returns table. - - - - -

`tonumber (e [, base])`

- - -

-When called with no base, -tonumber tries to convert its argument to a number. -If the argument is already a number or -a string convertible to a number (see §3.4.2), -then tonumber returns this number; -otherwise, it returns nil. - - -

-When called with base, -then e should be a string to be interpreted as -an integer numeral in that base. -The base may be any integer between 2 and 36, inclusive. -In bases above 10, the letter 'A' (in either upper or lower case) -represents 10, 'B' represents 11, and so forth, -with 'Z' representing 35. -If the string e is not a valid numeral in the given base, -the function returns nil. - - - - -

`tostring (v)`

-Receives a value of any type and -converts it to a string in a reasonable format. -(For complete control of how numbers are converted, -use string.format.) - - -

-If the metatable of v has a "__tostring" field, -then tostring calls the corresponding value -with v as argument, -and uses the result of the call as its result. - - - - -

`type (v)`

-Returns the type of its only argument, coded as a string. -The possible results of this function are -"nil" (a string, not the value nil), -"number", -"string", -"boolean", -"table", -"function", -"thread", -and "userdata". - - - - -

`_VERSION`

-A global variable (not a function) that -holds a string containing the current interpreter version. -The current contents of this variable is "Lua 5.2". - - - - -

`xpcall (f, msgh [, arg1, ···])`

- - -

-This function is similar to pcall, -except that it sets a new message handler msgh. - - - - - - - -

6.2 – Coroutine Manipulation

- -

-The operations related to coroutines comprise a sub-library of -the basic library and come inside the table coroutine. -See §2.6 for a general description of coroutines. - - -

`coroutine.create (f)`

- - -

-Creates a new coroutine, with body f. -f must be a Lua function. -Returns this new coroutine, -an object with type "thread". - - - - -

`coroutine.resume (co [, val1, ···])`

- - -

-Starts or continues the execution of coroutine co. -The first time you resume a coroutine, -it starts running its body. -The values val1, ... are passed -as the arguments to the body function. -If the coroutine has yielded, -resume restarts it; -the values val1, ... are passed -as the results from the yield. - - -

-If the coroutine runs without any errors, -resume returns true plus any values passed to yield -(if the coroutine yields) or any values returned by the body function -(if the coroutine terminates). -If there is any error, -resume returns false plus the error message. - - - - -

`coroutine.running ()`

- - -

-Returns the running coroutine plus a boolean, -true when the running coroutine is the main one. - - - - -

`coroutine.status (co)`

- - -

-Returns the status of coroutine co, as a string: -"running", -if the coroutine is running (that is, it called status); -"suspended", if the coroutine is suspended in a call to yield, -or if it has not started running yet; -"normal" if the coroutine is active but not running -(that is, it has resumed another coroutine); -and "dead" if the coroutine has finished its body function, -or if it has stopped with an error. - - - - -

`coroutine.wrap (f)`

- - -

-Creates a new coroutine, with body f. -f must be a Lua function. -Returns a function that resumes the coroutine each time it is called. -Any arguments passed to the function behave as the -extra arguments to resume. -Returns the same values returned by resume, -except the first boolean. -In case of error, propagates the error. - - - - -

`coroutine.yield (···)`

- - -

-Suspends the execution of the calling coroutine. -Any arguments to yield are passed as extra results to resume. - - - - - - - -

6.3 – Modules

- -

-The package library provides basic -facilities for loading modules in Lua. -It exports one function directly in the global environment: -require. -Everything else is exported in a table package. - - -

`require (modname)`

- - -

-Loads the given module. -The function starts by looking into the package.loaded table -to determine whether modname is already loaded. -If it is, then require returns the value stored -at package.loaded[modname]. -Otherwise, it tries to find a loader for the module. - - -

-To find a loader, -require is guided by the package.searchers sequence. -By changing this sequence, -we can change how require looks for a module. -The following explanation is based on the default configuration -for package.searchers. - - -

-First require queries package.preload[modname]. -If it has a value, -this value (which should be a function) is the loader. -Otherwise require searches for a Lua loader using the -path stored in package.path. -If that also fails, it searches for a C loader using the -path stored in package.cpath. -If that also fails, -it tries an all-in-one loader (see package.searchers). - - -

-Once a loader is found, -require calls the loader with two arguments: -modname and an extra value dependent on how it got the loader. -(If the loader came from a file, -this extra value is the file name.) -If the loader returns any non-nil value, -require assigns the returned value to package.loaded[modname]. -If the loader does not return a non-nil value and -has not assigned any value to package.loaded[modname], -then require assigns true to this entry. -In any case, require returns the -final value of package.loaded[modname]. - - -

-If there is any error loading or running the module, -or if it cannot find any loader for the module, -then require raises an error. - - - - -

`package.config`

- - -

-A string describing some compile-time configurations for packages. -This string is a sequence of lines: - -

The first line is the directory separator string. -Default is '\' for Windows and '/' for all other systems.
The second line is the character that separates templates in a path. -Default is ';'.
The third line is the string that marks the -substitution points in a template. -Default is '?'.
The fourth line is a string that, in a path in Windows, -is replaced by the executable's directory. -Default is '!'.
The fifth line is a mark to ignore all text before it -when building the luaopen_ function name. -Default is '-'.

- - - -

`package.cpath`

- - -

-The path used by require to search for a C loader. - - -

-Lua initializes the C path package.cpath in the same way -it initializes the Lua path package.path, -using the environment variable LUA_CPATH_5_2 -or the environment variable LUA_CPATH -or a default path defined in luaconf.h. - - - - -

- -

`package.loaded`

- - -

-A table used by require to control which -modules are already loaded. -When you require a module modname and -package.loaded[modname] is not false, -require simply returns the value stored there. - - -

-This variable is only a reference to the real table; -assignments to this variable do not change the -table used by require. - - - - -

`package.loadlib (libname, funcname)`

- - -

-Dynamically links the host program with the C library libname. - - -

-If funcname is "*", -then it only links with the library, -making the symbols exported by the library -available to other dynamically linked libraries. -Otherwise, -it looks for a function funcname inside the library -and returns this function as a C function. -(So, funcname must follow the prototype lua_CFunction). - - -

-This is a low-level function. -It completely bypasses the package and module system. -Unlike require, -it does not perform any path searching and -does not automatically adds extensions. -libname must be the complete file name of the C library, -including if necessary a path and an extension. -funcname must be the exact name exported by the C library -(which may depend on the C compiler and linker used). - - -

-This function is not supported by Standard C. -As such, it is only available on some platforms -(Windows, Linux, Mac OS X, Solaris, BSD, -plus other Unix systems that support the dlfcn standard). - - - - -

`package.path`

- - -

-The path used by require to search for a Lua loader. - - -

-At start-up, Lua initializes this variable with -the value of the environment variable LUA_PATH_5_2 or -the environment variable LUA_PATH or -with a default path defined in luaconf.h, -if those environment variables are not defined. -Any ";;" in the value of the environment variable -is replaced by the default path. - - - - -

`package.preload`

- - -

-A table to store loaders for specific modules -(see require). - - -

-This variable is only a reference to the real table; -assignments to this variable do not change the -table used by require. - - - - -

`package.searchers`

- - -

-A table used by require to control how to load modules. - - -

-Each entry in this table is a searcher function. -When looking for a module, -require calls each of these searchers in ascending order, -with the module name (the argument given to require) as its -sole parameter. -The function can return another function (the module loader) -plus an extra value that will be passed to that loader, -or a string explaining why it did not find that module -(or nil if it has nothing to say). - - -

-Lua initializes this table with four searcher functions. - - -

-The first searcher simply looks for a loader in the -package.preload table. - - -

-The second searcher looks for a loader as a Lua library, -using the path stored at package.path. -The search is done as described in function package.searchpath. - - -

-The third searcher looks for a loader as a C library, -using the path given by the variable package.cpath. -Again, -the search is done as described in function package.searchpath. -For instance, -if the C path is the string - -

-     "./?.so;./?.dll;/usr/local/?/init.so"
-

-the searcher for module foo -will try to open the files ./foo.so, ./foo.dll, -and /usr/local/foo/init.so, in that order. -Once it finds a C library, -this searcher first uses a dynamic link facility to link the -application with the library. -Then it tries to find a C function inside the library to -be used as the loader. -The name of this C function is the string "luaopen_" -concatenated with a copy of the module name where each dot -is replaced by an underscore. -Moreover, if the module name has a hyphen, -its prefix up to (and including) the first hyphen is removed. -For instance, if the module name is a.v1-b.c, -the function name will be luaopen_b_c. - - -

-The fourth searcher tries an all-in-one loader. -It searches the C path for a library for -the root name of the given module. -For instance, when requiring a.b.c, -it will search for a C library for a. -If found, it looks into it for an open function for -the submodule; -in our example, that would be luaopen_a_b_c. -With this facility, a package can pack several C submodules -into one single library, -with each submodule keeping its original open function. - - -

-All searchers except the first one (preload) return as the extra value -the file name where the module was found, -as returned by package.searchpath. -The first searcher returns no extra value. - - - - -

`package.searchpath (name, path [, sep [, rep]])`

- - -

-Searches for the given name in the given path. - - -

-A path is a string containing a sequence of -templates separated by semicolons. -For each template, -the function replaces each interrogation mark (if any) -in the template with a copy of name -wherein all occurrences of sep -(a dot, by default) -were replaced by rep -(the system's directory separator, by default), -and then tries to open the resulting file name. - - -

-For instance, if the path is the string - -

-     "./?.lua;./?.lc;/usr/local/?/init.lua"
-

-the search for the name foo.a -will try to open the files -./foo/a.lua, ./foo/a.lc, and -/usr/local/foo/a/init.lua, in that order. - - -

-Returns the resulting name of the first file that it can -open in read mode (after closing the file), -or nil plus an error message if none succeeds. -(This error message lists all file names it tried to open.) - - - - - - - -

6.4 – String Manipulation

- -

-This library provides generic functions for string manipulation, -such as finding and extracting substrings, and pattern matching. -When indexing a string in Lua, the first character is at position 1 -(not at 0, as in C). -Indices are allowed to be negative and are interpreted as indexing backwards, -from the end of the string. -Thus, the last character is at position -1, and so on. - - -

-The string library provides all its functions inside the table -string. -It also sets a metatable for strings -where the __index field points to the string table. -Therefore, you can use the string functions in object-oriented style. -For instance, string.byte(s,i) -can be written as s:byte(i). - - -

-The string library assumes one-byte character encodings. - - -

`string.byte (s [, i [, j]])`

-Returns the internal numerical codes of the characters s[i], -s[i+1], ..., s[j]. -The default value for i is 1; -the default value for j is i. -These indices are corrected -following the same rules of function string.sub. - - -

-Numerical codes are not necessarily portable across platforms. - - - - -

`string.char (···)`

-Receives zero or more integers. -Returns a string with length equal to the number of arguments, -in which each character has the internal numerical code equal -to its corresponding argument. - - -

-Numerical codes are not necessarily portable across platforms. - - - - -

`string.dump (function)`

- - -

-Returns a string containing a binary representation of the given function, -so that a later load on this string returns -a copy of the function (but with new upvalues). - - - - -

`string.find (s, pattern [, init [, plain]])`

- - -

-Looks for the first match of -pattern in the string s. -If it finds a match, then find returns the indices of s -where this occurrence starts and ends; -otherwise, it returns nil. -A third, optional numerical argument init specifies -where to start the search; -its default value is 1 and can be negative. -A value of true as a fourth, optional argument plain -turns off the pattern matching facilities, -so the function does a plain "find substring" operation, -with no characters in pattern being considered magic. -Note that if plain is given, then init must be given as well. - - -

-If the pattern has captures, -then in a successful match -the captured values are also returned, -after the two indices. - - - - -

`string.format (formatstring, ···)`

- - -

-Returns a formatted version of its variable number of arguments -following the description given in its first argument (which must be a string). -The format string follows the same rules as the C function sprintf. -The only differences are that the options/modifiers -*, h, L, l, n, -and p are not supported -and that there is an extra option, q. -The q option formats a string between double quotes, -using escape sequences when necessary to ensure that -it can safely be read back by the Lua interpreter. -For instance, the call - -

-     string.format('%q', 'a string with "quotes" and \n new line')
-

-may produce the string: - -

-     "a string with \"quotes\" and \
-      new line"
-

- -

-Options -A and a (when available), -E, e, f, -G, and g all expect a number as argument. -Options c, d, -i, o, u, X, and x -also expect a number, -but the range of that number may be limited by -the underlying C implementation. -For options o, u, X, and x, -the number cannot be negative. -Option q expects a string; -option s expects a string without embedded zeros. -If the argument to option s is not a string, -it is converted to one following the same rules of tostring. - - - - -

`string.gmatch (s, pattern)`

-Returns an iterator function that, -each time it is called, -returns the next captures from pattern over the string s. -If pattern specifies no captures, -then the whole match is produced in each call. - - -

-As an example, the following loop -will iterate over all the words from string s, -printing one per line: - -

-     s = "hello world from Lua"
-     for w in string.gmatch(s, "%a+") do
-       print(w)
-     end
-

-The next example collects all pairs key=value from the -given string into a table: - -

-     t = {}
-     s = "from=world, to=Lua"
-     for k, v in string.gmatch(s, "(%w+)=(%w+)") do
-       t[k] = v
-     end
-

- -

-For this function, a caret '^' at the start of a pattern does not -work as an anchor, as this would prevent the iteration. - - - - -

`string.gsub (s, pattern, repl [, n])`

-Returns a copy of s -in which all (or the first n, if given) -occurrences of the pattern have been -replaced by a replacement string specified by repl, -which can be a string, a table, or a function. -gsub also returns, as its second value, -the total number of matches that occurred. -The name gsub comes from Global SUBstitution. - - -

-If repl is a string, then its value is used for replacement. -The character % works as an escape character: -any sequence in repl of the form %d, -with d between 1 and 9, -stands for the value of the d-th captured substring (see below). -The sequence %0 stands for the whole match. -The sequence %% stands for a single %. - - -

-If repl is a table, then the table is queried for every match, -using the first capture as the key; -if the pattern specifies no captures, -then the whole match is used as the key. - - -

-If repl is a function, then this function is called every time a -match occurs, with all captured substrings passed as arguments, -in order; -if the pattern specifies no captures, -then the whole match is passed as a sole argument. - - -

-If the value returned by the table query or by the function call -is a string or a number, -then it is used as the replacement string; -otherwise, if it is false or nil, -then there is no replacement -(that is, the original match is kept in the string). - - -

-Here are some examples: - -

-     x = string.gsub("hello world", "(%w+)", "%1 %1")
-     --> x="hello hello world world"
-     
-     x = string.gsub("hello world", "%w+", "%0 %0", 1)
-     --> x="hello hello world"
-     
-     x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1")
-     --> x="world hello Lua from"
-     
-     x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv)
-     --> x="home = /home/roberto, user = roberto"
-     
-     x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s)
-           return load(s)()
-         end)
-     --> x="4+5 = 9"
-     
-     local t = {name="lua", version="5.2"}
-     x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t)
-     --> x="lua-5.2.tar.gz"
-

- - - -

`string.len (s)`

-Receives a string and returns its length. -The empty string "" has length 0. -Embedded zeros are counted, -so "a\000bc\000" has length 5. - - - - -

`string.lower (s)`

-Receives a string and returns a copy of this string with all -uppercase letters changed to lowercase. -All other characters are left unchanged. -The definition of what an uppercase letter is depends on the current locale. - - - - -

`string.match (s, pattern [, init])`

-Looks for the first match of -pattern in the string s. -If it finds one, then match returns -the captures from the pattern; -otherwise it returns nil. -If pattern specifies no captures, -then the whole match is returned. -A third, optional numerical argument init specifies -where to start the search; -its default value is 1 and can be negative. - - - - -

`string.rep (s, n [, sep])`

-Returns a string that is the concatenation of n copies of -the string s separated by the string sep. -The default value for sep is the empty string -(that is, no separator). - - - - -

`string.reverse (s)`

-Returns a string that is the string s reversed. - - - - -

`string.sub (s, i [, j])`

-Returns the substring of s that -starts at i and continues until j; -i and j can be negative. -If j is absent, then it is assumed to be equal to -1 -(which is the same as the string length). -In particular, -the call string.sub(s,1,j) returns a prefix of s -with length j, -and string.sub(s, -i) returns a suffix of s -with length i. - - -

-If, after the translation of negative indices, -i is less than 1, -it is corrected to 1. -If j is greater than the string length, -it is corrected to that length. -If, after these corrections, -i is greater than j, -the function returns the empty string. - - - - -

`string.upper (s)`

-Receives a string and returns a copy of this string with all -lowercase letters changed to uppercase. -All other characters are left unchanged. -The definition of what a lowercase letter is depends on the current locale. - - - -

6.4.1 – Patterns

- - -

Character Class:

-A character class is used to represent a set of characters. -The following combinations are allowed in describing a character class: - -

x: -(where x is not one of the magic characters -^$()%.[]*+-?) -represents the character x itself. -
.: (a dot) represents all characters.
%a: represents all letters.
%c: represents all control characters.
%d: represents all digits.
%g: represents all printable characters except space.
%l: represents all lowercase letters.
%p: represents all punctuation characters.
%s: represents all space characters.
%u: represents all uppercase letters.
%w: represents all alphanumeric characters.
%x: represents all hexadecimal digits.
%x: (where x is any non-alphanumeric character) -represents the character x. -This is the standard way to escape the magic characters. -Any punctuation character (even the non magic) -can be preceded by a '%' -when used to represent itself in a pattern. -
[set]: -represents the class which is the union of all -characters in set. -A range of characters can be specified by -separating the end characters of the range, -in ascending order, with a '-', -All classes %x described above can also be used as -components in set. -All other characters in set represent themselves. -For example, [%w_] (or [_%w]) -represents all alphanumeric characters plus the underscore, -[0-7] represents the octal digits, -and [0-7%l%-] represents the octal digits plus -the lowercase letters plus the '-' character. - - -
-The interaction between ranges and classes is not defined. -Therefore, patterns like [%a-z] or [a-%%] -have no meaning. -
[^set]: -represents the complement of set, -where set is interpreted as above. -

-For all classes represented by single letters (%a, %c, etc.), -the corresponding uppercase letter represents the complement of the class. -For instance, %S represents all non-space characters. - - -

-The definitions of letter, space, and other character groups -depend on the current locale. -In particular, the class [a-z] may not be equivalent to %l. - - - - - -

Pattern Item:

-A pattern item can be - -

-a single character class, -which matches any single character in the class; -
-a single character class followed by '*', -which matches 0 or more repetitions of characters in the class. -These repetition items will always match the longest possible sequence; -
-a single character class followed by '+', -which matches 1 or more repetitions of characters in the class. -These repetition items will always match the longest possible sequence; -
-a single character class followed by '-', -which also matches 0 or more repetitions of characters in the class. -Unlike '*', -these repetition items will always match the shortest possible sequence; -
-a single character class followed by '?', -which matches 0 or 1 occurrence of a character in the class; -
-%n, for n between 1 and 9; -such item matches a substring equal to the n-th captured string -(see below); -
-%bxy, where x and y are two distinct characters; -such item matches strings that start with x, end with y, -and where the x and y are balanced. -This means that, if one reads the string from left to right, -counting +1 for an x and -1 for a y, -the ending y is the first y where the count reaches 0. -For instance, the item %b() matches expressions with -balanced parentheses. -
-%f[set], a frontier pattern; -such item matches an empty string at any position such that -the next character belongs to set -and the previous character does not belong to set. -The set set is interpreted as previously described. -The beginning and the end of the subject are handled as if -they were the character '\0'. -

- - - - -

Pattern:

-A pattern is a sequence of pattern items. -A caret '^' at the beginning of a pattern anchors the match at the -beginning of the subject string. -A '$' at the end of a pattern anchors the match at the -end of the subject string. -At other positions, -'^' and '$' have no special meaning and represent themselves. - - - - - -

Captures:

-A pattern can contain sub-patterns enclosed in parentheses; -they describe captures. -When a match succeeds, the substrings of the subject string -that match captures are stored (captured) for future use. -Captures are numbered according to their left parentheses. -For instance, in the pattern "(a*(.)%w(%s*))", -the part of the string matching "a*(.)%w(%s*)" is -stored as the first capture (and therefore has number 1); -the character matching "." is captured with number 2, -and the part matching "%s*" has number 3. - - -

-As a special case, the empty capture () captures -the current string position (a number). -For instance, if we apply the pattern "()aa()" on the -string "flaaap", there will be two captures: 3 and 5. - - - - - - - - - - - -

6.5 – Table Manipulation

- -

-This library provides generic functions for table manipulation. -It provides all its functions inside the table table. - - -

-Remember that, whenever an operation needs the length of a table, -the table should be a proper sequence -or have a __len metamethod (see §3.4.6). -All functions ignore non-numeric keys -in tables given as arguments. - - -

-For performance reasons, -all table accesses (get/set) performed by these functions are raw. - - -

`table.concat (list [, sep [, i [, j]]])`

- - -

-Given a list where all elements are strings or numbers, -returns list[i]..sep..list[i+1] ··· sep..list[j]. -The default value for sep is the empty string, -the default for i is 1, -and the default for j is #list. -If i is greater than j, returns the empty string. - - - - -

`table.insert (list, [pos,] value)`

- - -

-Inserts element value at position pos in list, -shifting up the elements -list[pos], list[pos+1], ···, list[#list]. -The default value for pos is #list+1, -so that a call table.insert(t,x) inserts x at the end -of list t. - - - - -

`table.pack (···)`

- - -

-Returns a new table with all parameters stored into keys 1, 2, etc. -and with a field "n" with the total number of parameters. -Note that the resulting table may not be a sequence. - - - - -

`table.remove (list [, pos])`

- - -

-Removes from list the element at position pos, -shifting down the elements -list[pos+1], list[pos+2], ···, list[#list] -and erasing element list[#list]. -Returns the value of the removed element. -The default value for pos is #list, -so that a call table.remove(t) removes the last element -of list t. - - - - -

`table.sort (list [, comp])`

- - -

-Sorts list elements in a given order, in-place, -from list[1] to list[#list]. -If comp is given, -then it must be a function that receives two list elements -and returns true when the first element must come -before the second in the final order -(so that not comp(list[i+1],list[i]) will be true after the sort). -If comp is not given, -then the standard Lua operator < is used instead. - - -

-The sort algorithm is not stable; -that is, elements considered equal by the given order -may have their relative positions changed by the sort. - - - - -

`table.unpack (list [, i [, j]])`

- - -

-Returns the elements from the given table. -This function is equivalent to - -

-     return list[i], list[i+1], ···, list[j]
-

-By default, i is 1 and j is #list. - - - - - - - -

6.6 – Mathematical Functions

- -

-This library is an interface to the standard C math library. -It provides all its functions inside the table math. - - -

`math.abs (x)`

- - -

-Returns the absolute value of x. - - - - -

`math.acos (x)`

- - -

-Returns the arc cosine of x (in radians). - - - - -

`math.asin (x)`

- - -

-Returns the arc sine of x (in radians). - - - - -

`math.atan (x)`

- - -

-Returns the arc tangent of x (in radians). - - - - -

`math.atan2 (y, x)`

- - -

-Returns the arc tangent of y/x (in radians), -but uses the signs of both parameters to find the -quadrant of the result. -(It also handles correctly the case of x being zero.) - - - - -

`math.ceil (x)`

- - -

-Returns the smallest integer larger than or equal to x. - - - - -

`math.cos (x)`

- - -

-Returns the cosine of x (assumed to be in radians). - - - - -

`math.cosh (x)`

- - -

-Returns the hyperbolic cosine of x. - - - - -

`math.deg (x)`

- - -

-Returns the angle x (given in radians) in degrees. - - - - -

`math.exp (x)`

- - -

-Returns the value e^x. - - - - -

`math.floor (x)`

- - -

-Returns the largest integer smaller than or equal to x. - - - - -

`math.fmod (x, y)`

- - -

-Returns the remainder of the division of x by y -that rounds the quotient towards zero. - - - - -

`math.frexp (x)`

- - -

-Returns m and e such that x = m2^e, -e is an integer and the absolute value of m is -in the range [0.5, 1) -(or zero when x is zero). - - - - -

`math.huge`

- - -

-The value HUGE_VAL, -a value larger than or equal to any other numerical value. - - - - -

`math.ldexp (m, e)`

- - -

-Returns m2^e (e should be an integer). - - - - -

`math.log (x [, base])`

- - -

-Returns the logarithm of x in the given base. -The default for base is e -(so that the function returns the natural logarithm of x). - - - - -

`math.max (x, ···)`

- - -

-Returns the maximum value among its arguments. - - - - -

`math.min (x, ···)`

- - -

-Returns the minimum value among its arguments. - - - - -

`math.modf (x)`

- - -

-Returns two numbers, -the integral part of x and the fractional part of x. - - - - -

`math.pi`

- - -

-The value of π. - - - - -

`math.pow (x, y)`

- - -

-Returns x^y. -(You can also use the expression x^y to compute this value.) - - - - -

`math.rad (x)`

- - -

-Returns the angle x (given in degrees) in radians. - - - - -

`math.random ([m [, n]])`

- - -

-This function is an interface to the simple -pseudo-random generator function rand provided by Standard C. -(No guarantees can be given for its statistical properties.) - - -

-When called without arguments, -returns a uniform pseudo-random real number -in the range [0,1). -When called with an integer number m, -math.random returns -a uniform pseudo-random integer in the range [1, m]. -When called with two integer numbers m and n, -math.random returns a uniform pseudo-random -integer in the range [m, n]. - - - - -

`math.randomseed (x)`

- - -

-Sets x as the "seed" -for the pseudo-random generator: -equal seeds produce equal sequences of numbers. - - - - -

`math.sin (x)`

- - -

-Returns the sine of x (assumed to be in radians). - - - - -

`math.sinh (x)`

- - -

-Returns the hyperbolic sine of x. - - - - -

`math.sqrt (x)`

- - -

-Returns the square root of x. -(You can also use the expression x^0.5 to compute this value.) - - - - -

`math.tan (x)`

- - -

-Returns the tangent of x (assumed to be in radians). - - - - -

`math.tanh (x)`

- - -

-Returns the hyperbolic tangent of x. - - - - - - - -

6.7 – Bitwise Operations

- -

-This library provides bitwise operations. -It provides all its functions inside the table bit32. - - -

-Unless otherwise stated, -all functions accept numeric arguments in the range -(-2⁵¹,+2⁵¹); -each argument is normalized to -the remainder of its division by 2³² -and truncated to an integer (in some unspecified way), -so that its final value falls in the range [0,2³² - 1]. -Similarly, all results are in the range [0,2³² - 1]. -Note that bit32.bnot(0) is 0xFFFFFFFF, -which is different from -1. - - -

`bit32.arshift (x, disp)`

- - -

-Returns the number x shifted disp bits to the right. -The number disp may be any representable integer. -Negative displacements shift to the left. - - -

-This shift operation is what is called arithmetic shift. -Vacant bits on the left are filled -with copies of the higher bit of x; -vacant bits on the right are filled with zeros. -In particular, -displacements with absolute values higher than 31 -result in zero or 0xFFFFFFFF (all original bits are shifted out). - - - - -

`bit32.band (···)`

- - -

-Returns the bitwise and of its operands. - - - - -

`bit32.bnot (x)`

- - -

-Returns the bitwise negation of x. -For any integer x, -the following identity holds: - -

-     assert(bit32.bnot(x) == (-1 - x) % 2^32)
-

- - - -

`bit32.bor (···)`

- - -

-Returns the bitwise or of its operands. - - - - -

`bit32.btest (···)`

- - -

-Returns a boolean signaling -whether the bitwise and of its operands is different from zero. - - - - -

`bit32.bxor (···)`

- - -

-Returns the bitwise exclusive or of its operands. - - - - -

`bit32.extract (n, field [, width])`

- - -

-Returns the unsigned number formed by the bits -field to field + width - 1 from n. -Bits are numbered from 0 (least significant) to 31 (most significant). -All accessed bits must be in the range [0, 31]. - - -

-The default for width is 1. - - - - -

`bit32.replace (n, v, field [, width])`

- - -

-Returns a copy of n with -the bits field to field + width - 1 -replaced by the value v. -See bit32.extract for details about field and width. - - - - -

`bit32.lrotate (x, disp)`

- - -

-Returns the number x rotated disp bits to the left. -The number disp may be any representable integer. - - -

-For any valid displacement, -the following identity holds: - -

-     assert(bit32.lrotate(x, disp) == bit32.lrotate(x, disp % 32))
-

-In particular, -negative displacements rotate to the right. - - - - -

`bit32.lshift (x, disp)`

- - -

-Returns the number x shifted disp bits to the left. -The number disp may be any representable integer. -Negative displacements shift to the right. -In any direction, vacant bits are filled with zeros. -In particular, -displacements with absolute values higher than 31 -result in zero (all bits are shifted out). - - -

-For positive displacements, -the following equality holds: - -

-     assert(bit32.lshift(b, disp) == (b * 2^disp) % 2^32)
-

- - - -

`bit32.rrotate (x, disp)`

- - -

-Returns the number x rotated disp bits to the right. -The number disp may be any representable integer. - - -

-For any valid displacement, -the following identity holds: - -

-     assert(bit32.rrotate(x, disp) == bit32.rrotate(x, disp % 32))
-

-In particular, -negative displacements rotate to the left. - - - - -

`bit32.rshift (x, disp)`

- - -

-Returns the number x shifted disp bits to the right. -The number disp may be any representable integer. -Negative displacements shift to the left. -In any direction, vacant bits are filled with zeros. -In particular, -displacements with absolute values higher than 31 -result in zero (all bits are shifted out). - - -

-For positive displacements, -the following equality holds: - -

-     assert(bit32.rshift(b, disp) == math.floor(b % 2^32 / 2^disp))
-

- -

-This shift operation is what is called logical shift. - - - - - - - -

6.8 – Input and Output Facilities

- -

-The I/O library provides two different styles for file manipulation. -The first one uses implicit file descriptors; -that is, there are operations to set a default input file and a -default output file, -and all input/output operations are over these default files. -The second style uses explicit file descriptors. - - -

-When using implicit file descriptors, -all operations are supplied by table io. -When using explicit file descriptors, -the operation io.open returns a file descriptor -and then all operations are supplied as methods of the file descriptor. - - -

-The table io also provides -three predefined file descriptors with their usual meanings from C: -io.stdin, io.stdout, and io.stderr. -The I/O library never closes these files. - - -

-Unless otherwise stated, -all I/O functions return nil on failure -(plus an error message as a second result and -a system-dependent error code as a third result) -and some value different from nil on success. - - -

`io.close ([file])`

- - -

-Equivalent to file:close(). -Without a file, closes the default output file. - - - - -

`io.flush ()`

- - -

-Equivalent to io.output():flush(). - - - - -

`io.input ([file])`

- - -

-When called with a file name, it opens the named file (in text mode), -and sets its handle as the default input file. -When called with a file handle, -it simply sets this file handle as the default input file. -When called without parameters, -it returns the current default input file. - - -

-In case of errors this function raises the error, -instead of returning an error code. - - - - -

`io.lines ([filename ···])`

- - -

-Opens the given file name in read mode -and returns an iterator function that -works like file:lines(···) over the opened file. -When the iterator function detects the end of file, -it returns nil (to finish the loop) and automatically closes the file. - - -

-The call io.lines() (with no file name) is equivalent -to io.input():lines(); -that is, it iterates over the lines of the default input file. -In this case it does not close the file when the loop ends. - - -

-In case of errors this function raises the error, -instead of returning an error code. - - - - -

`io.open (filename [, mode])`

- - -

-This function opens a file, -in the mode specified in the string mode. -It returns a new file handle, -or, in case of errors, nil plus an error message. - - -

-The mode string can be any of the following: - -

"r": read mode (the default);
"w": write mode;
"a": append mode;
"r+": update mode, all previous data is preserved;
"w+": update mode, all previous data is erased;
"a+": append update mode, previous data is preserved, - writing is only allowed at the end of file.

-The mode string can also have a 'b' at the end, -which is needed in some systems to open the file in binary mode. - - - - -

`io.output ([file])`

- - -

-Similar to io.input, but operates over the default output file. - - - - -

`io.popen (prog [, mode])`

- - -

-This function is system dependent and is not available -on all platforms. - - -

-Starts program prog in a separated process and returns -a file handle that you can use to read data from this program -(if mode is "r", the default) -or to write data to this program -(if mode is "w"). - - - - -

`io.read (···)`

- - -

-Equivalent to io.input():read(···). - - - - -

`io.tmpfile ()`

- - -

-Returns a handle for a temporary file. -This file is opened in update mode -and it is automatically removed when the program ends. - - - - -

`io.type (obj)`

- - -

-Checks whether obj is a valid file handle. -Returns the string "file" if obj is an open file handle, -"closed file" if obj is a closed file handle, -or nil if obj is not a file handle. - - - - -

`io.write (···)`

- - -

-Equivalent to io.output():write(···). - - - - -

`file:close ()`

- - -

-Closes file. -Note that files are automatically closed when -their handles are garbage collected, -but that takes an unpredictable amount of time to happen. - - -

-When closing a file handle created with io.popen, -file:close returns the same values -returned by os.execute. - - - - -

`file:flush ()`

- - -

-Saves any written data to file. - - - - -

`file:lines (···)`

- - -

-Returns an iterator function that, -each time it is called, -reads the file according to the given formats. -When no format is given, -uses "*l" as a default. -As an example, the construction - -

-     for c in file:lines(1) do body end
-

-will iterate over all characters of the file, -starting at the current position. -Unlike io.lines, this function does not close the file -when the loop ends. - - -

-In case of errors this function raises the error, -instead of returning an error code. - - - - -

`file:read (···)`

- - -

-Reads the file file, -according to the given formats, which specify what to read. -For each format, -the function returns a string (or a number) with the characters read, -or nil if it cannot read data with the specified format. -When called without formats, -it uses a default format that reads the next line -(see below). - - -

-The available formats are - -

"*n": -reads a number; -this is the only format that returns a number instead of a string. -
"*a": -reads the whole file, starting at the current position. -On end of file, it returns the empty string. -
"*l": -reads the next line skipping the end of line, -returning nil on end of file. -This is the default format. -
"*L": -reads the next line keeping the end of line (if present), -returning nil on end of file. -
number: -reads a string with up to this number of bytes, -returning nil on end of file. -If number is zero, -it reads nothing and returns an empty string, -or nil on end of file. -

- - - -

`file:seek ([whence [, offset]])`

- - -

-Sets and gets the file position, -measured from the beginning of the file, -to the position given by offset plus a base -specified by the string whence, as follows: - -

"set": base is position 0 (beginning of the file);
"cur": base is current position;
"end": base is end of file;

-In case of success, seek returns the final file position, -measured in bytes from the beginning of the file. -If seek fails, it returns nil, -plus a string describing the error. - - -

-The default value for whence is "cur", -and for offset is 0. -Therefore, the call file:seek() returns the current -file position, without changing it; -the call file:seek("set") sets the position to the -beginning of the file (and returns 0); -and the call file:seek("end") sets the position to the -end of the file, and returns its size. - - - - -

`file:setvbuf (mode [, size])`

- - -

-Sets the buffering mode for an output file. -There are three available modes: - -

"no": -no buffering; the result of any output operation appears immediately. -
"full": -full buffering; output operation is performed only -when the buffer is full or when -you explicitly flush the file (see io.flush). -
"line": -line buffering; output is buffered until a newline is output -or there is any input from some special files -(such as a terminal device). -

-For the last two cases, size -specifies the size of the buffer, in bytes. -The default is an appropriate size. - - - - -

`file:write (···)`

- - -

-Writes the value of each of its arguments to file. -The arguments must be strings or numbers. - - -

-In case of success, this function returns file. -Otherwise it returns nil plus a string describing the error. - - - - - - - -

6.9 – Operating System Facilities

- -

-This library is implemented through table os. - - -

`os.clock ()`

- - -

-Returns an approximation of the amount in seconds of CPU time -used by the program. - - - - -

`os.date ([format [, time]])`

- - -

-Returns a string or a table containing date and time, -formatted according to the given string format. - - -

-If the time argument is present, -this is the time to be formatted -(see the os.time function for a description of this value). -Otherwise, date formats the current time. - - -

-If format starts with '!', -then the date is formatted in Coordinated Universal Time. -After this optional character, -if format is the string "*t", -then date returns a table with the following fields: -year (four digits), month (1–12), day (1–31), -hour (0–23), min (0–59), sec (0–61), -wday (weekday, Sunday is 1), -yday (day of the year), -and isdst (daylight saving flag, a boolean). -This last field may be absent -if the information is not available. - - -

-If format is not "*t", -then date returns the date as a string, -formatted according to the same rules as the C function strftime. - - -

-When called without arguments, -date returns a reasonable date and time representation that depends on -the host system and on the current locale -(that is, os.date() is equivalent to os.date("%c")). - - -

-On some systems, -this function may be not thread safe. - - - - -

`os.difftime (t2, t1)`

- - -

-Returns the number of seconds from time t1 to time t2. -In POSIX, Windows, and some other systems, -this value is exactly t2-t1. - - - - -

`os.execute ([command])`

- - -

-This function is equivalent to the C function system. -It passes command to be executed by an operating system shell. -Its first result is true -if the command terminated successfully, -or nil otherwise. -After this first result -the function returns a string and a number, -as follows: - -

"exit": -the command terminated normally; -the following number is the exit status of the command. -
"signal": -the command was terminated by a signal; -the following number is the signal that terminated the command. -

- -

-When called without a command, -os.execute returns a boolean that is true if a shell is available. - - - - -

`os.exit ([code [, close])`

- - -

-Calls the C function exit to terminate the host program. -If code is true, -the returned status is EXIT_SUCCESS; -if code is false, -the returned status is EXIT_FAILURE; -if code is a number, -the returned status is this number. -The default value for code is true. - - -

-If the optional second argument close is true, -closes the Lua state before exiting. - - - - -

`os.getenv (varname)`

- - -

-Returns the value of the process environment variable varname, -or nil if the variable is not defined. - - - - -

`os.remove (filename)`

- - -

-Deletes the file (or empty directory, on POSIX systems) -with the given name. -If this function fails, it returns nil, -plus a string describing the error and the error code. - - - - -

`os.rename (oldname, newname)`

- - -

-Renames file or directory named oldname to newname. -If this function fails, it returns nil, -plus a string describing the error and the error code. - - - - -

`os.setlocale (locale [, category])`

- - -

-Sets the current locale of the program. -locale is a system-dependent string specifying a locale; -category is an optional string describing which category to change: -"all", "collate", "ctype", -"monetary", "numeric", or "time"; -the default category is "all". -The function returns the name of the new locale, -or nil if the request cannot be honored. - - -

-If locale is the empty string, -the current locale is set to an implementation-defined native locale. -If locale is the string "C", -the current locale is set to the standard C locale. - - -

-When called with nil as the first argument, -this function only returns the name of the current locale -for the given category. - - - - -

`os.time ([table])`

- - -

-Returns the current time when called without arguments, -or a time representing the date and time specified by the given table. -This table must have fields year, month, and day, -and may have fields -hour (default is 12), -min (default is 0), -sec (default is 0), -and isdst (default is nil). -For a description of these fields, see the os.date function. - - -

-The returned value is a number, whose meaning depends on your system. -In POSIX, Windows, and some other systems, -this number counts the number -of seconds since some given start time (the "epoch"). -In other systems, the meaning is not specified, -and the number returned by time can be used only as an argument to -os.date and os.difftime. - - - - -

`os.tmpname ()`

- - -

-Returns a string with a file name that can -be used for a temporary file. -The file must be explicitly opened before its use -and explicitly removed when no longer needed. - - -

-On POSIX systems, -this function also creates a file with that name, -to avoid security risks. -(Someone else might create the file with wrong permissions -in the time between getting the name and creating the file.) -You still have to open the file to use it -and to remove it (even if you do not use it). - - -

-When possible, -you may prefer to use io.tmpfile, -which automatically removes the file when the program ends. - - - - - - - -

6.10 – The Debug Library

- -

-This library provides -the functionality of the debug interface (§4.9) to Lua programs. -You should exert care when using this library. -Several of its functions -violate basic assumptions about Lua code -(e.g., that variables local to a function -cannot be accessed from outside; -that userdata metatables cannot be changed by Lua code; -that Lua programs do not crash) -and therefore can compromise otherwise secure code. -Moreover, some functions in this library may be slow. - - -

-All functions in this library are provided -inside the debug table. -All functions that operate over a thread -have an optional first argument which is the -thread to operate over. -The default is always the current thread. - - -

`debug.debug ()`

- - -

-Enters an interactive mode with the user, -running each string that the user enters. -Using simple commands and other debug facilities, -the user can inspect global and local variables, -change their values, evaluate expressions, and so on. -A line containing only the word cont finishes this function, -so that the caller continues its execution. - - -

-Note that commands for debug.debug are not lexically nested -within any function and so have no direct access to local variables. - - - - -

`debug.gethook ([thread])`

- - -

-Returns the current hook settings of the thread, as three values: -the current hook function, the current hook mask, -and the current hook count -(as set by the debug.sethook function). - - - - -

`debug.getinfo ([thread,] f [, what])`

- - -

-Returns a table with information about a function. -You can give the function directly -or you can give a number as the value of f, -which means the function running at level f of the call stack -of the given thread: -level 0 is the current function (getinfo itself); -level 1 is the function that called getinfo -(except for tail calls, which do not count on the stack); -and so on. -If f is a number larger than the number of active functions, -then getinfo returns nil. - - -

-The returned table can contain all the fields returned by lua_getinfo, -with the string what describing which fields to fill in. -The default for what is to get all information available, -except the table of valid lines. -If present, -the option 'f' -adds a field named func with the function itself. -If present, -the option 'L' -adds a field named activelines with the table of -valid lines. - - -

-For instance, the expression debug.getinfo(1,"n").name returns -a table with a name for the current function, -if a reasonable name can be found, -and the expression debug.getinfo(print) -returns a table with all available information -about the print function. - - - - -

`debug.getlocal ([thread,] f, local)`

- - -

-This function returns the name and the value of the local variable -with index local of the function at level f of the stack. -This function accesses not only explicit local variables, -but also parameters, temporaries, etc. - - -

-The first parameter or local variable has index 1, and so on, -until the last active variable. -Negative indices refer to vararg parameters; --1 is the first vararg parameter. -The function returns nil if there is no variable with the given index, -and raises an error when called with a level out of range. -(You can call debug.getinfo to check whether the level is valid.) - - -

-Variable names starting with '(' (open parentheses) -represent internal variables -(loop control variables, temporaries, varargs, and C function locals). - - -

-The parameter f may also be a function. -In that case, getlocal returns only the name of function parameters. - - - - -

`debug.getmetatable (value)`

- - -

-Returns the metatable of the given value -or nil if it does not have a metatable. - - - - -

`debug.getregistry ()`

- - -

-Returns the registry table (see §4.5). - - - - -

`debug.getupvalue (f, up)`

- - -

-This function returns the name and the value of the upvalue -with index up of the function f. -The function returns nil if there is no upvalue with the given index. - - - - -

`debug.getuservalue (u)`

- - -

-Returns the Lua value associated to u. -If u is not a userdata, -returns nil. - - - - -

`debug.sethook ([thread,] hook, mask [, count])`

- - -

-Sets the given function as a hook. -The string mask and the number count describe -when the hook will be called. -The string mask may have the following characters, -with the given meaning: - -

'c': the hook is called every time Lua calls a function;
'r': the hook is called every time Lua returns from a function;
'l': the hook is called every time Lua enters a new line of code.

-With a count different from zero, -the hook is called after every count instructions. - - -

-When called without arguments, -debug.sethook turns off the hook. - - -

-When the hook is called, its first parameter is a string -describing the event that has triggered its call: -"call" (or "tail call"), -"return", -"line", and "count". -For line events, -the hook also gets the new line number as its second parameter. -Inside a hook, -you can call getinfo with level 2 to get more information about -the running function -(level 0 is the getinfo function, -and level 1 is the hook function). - - - - -

`debug.setlocal ([thread,] level, local, value)`

- - -

-This function assigns the value value to the local variable -with index local of the function at level level of the stack. -The function returns nil if there is no local -variable with the given index, -and raises an error when called with a level out of range. -(You can call getinfo to check whether the level is valid.) -Otherwise, it returns the name of the local variable. - - -

-See debug.getlocal for more information about -variable indices and names. - - - - -

`debug.setmetatable (value, table)`

- - -

-Sets the metatable for the given value to the given table -(which can be nil). -Returns value. - - - - -

`debug.setupvalue (f, up, value)`

- - -

-This function assigns the value value to the upvalue -with index up of the function f. -The function returns nil if there is no upvalue -with the given index. -Otherwise, it returns the name of the upvalue. - - - - -

`debug.setuservalue (udata, value)`

- - -

-Sets the given value as -the Lua value associated to the given udata. -value must be a table or nil; -udata must be a full userdata. - - -

-Returns udata. - - - - -

`debug.traceback ([thread,] [message [, level]])`

- - -

-If message is present but is neither a string nor nil, -this function returns message without further processing. -Otherwise, -it returns a string with a traceback of the call stack. -An optional message string is appended -at the beginning of the traceback. -An optional level number tells at which level -to start the traceback -(default is 1, the function calling traceback). - - - - -

`debug.upvalueid (f, n)`

- - -

-Returns an unique identifier (as a light userdata) -for the upvalue numbered n -from the given function. - - -

`debug.upvaluejoin (f1, n1, f2, n2)`

- - -

-Make the n1-th upvalue of the Lua closure f1 -refer to the n2-th upvalue of the Lua closure f2. - - - - - - - -

7 – Lua Standalone

- -

-Although Lua has been designed as an extension language, -to be embedded in a host C program, -it is also frequently used as a standalone language. -An interpreter for Lua as a standalone language, -called simply lua, -is provided with the standard distribution. -The standalone interpreter includes -all standard libraries, including the debug library. -Its usage is: - -

-     lua [options] [script [args]]
-

-The options are: - -

-e stat: executes string stat;
-l mod: "requires" mod;
-i: enters interactive mode after running script;
-v: prints version information;
-E: ignores environment variables;
--: stops handling options;
-: executes stdin as a file and stops handling options.

-After handling its options, lua runs the given script, -passing to it the given args as string arguments. -When called without arguments, -lua behaves as lua -v -i -when the standard input (stdin) is a terminal, -and as lua - otherwise. - - -

-When called without option -E, -the interpreter checks for an environment variable LUA_INIT_5_2 -(or LUA_INIT if it is not defined) -before running any argument. -If the variable content has the format @filename, -then lua executes the file. -Otherwise, lua executes the string itself. - - -

-When called with option -E, -besides ignoring LUA_INIT, -Lua also ignores -the values of LUA_PATH and LUA_CPATH, -setting the values of -package.path and package.cpath -with the default paths defined in luaconf.h. - - -

-All options are handled in order, except -i and -E. -For instance, an invocation like - -

-     $ lua -e'a=1' -e 'print(a)' script.lua
-

-will first set a to 1, then print the value of a, -and finally run the file script.lua with no arguments. -(Here $ is the shell prompt. Your prompt may be different.) - - -

-Before starting to run the script, -lua collects all arguments in the command line -in a global table called arg. -The script name is stored at index 0, -the first argument after the script name goes to index 1, -and so on. -Any arguments before the script name -(that is, the interpreter name plus the options) -go to negative indices. -For instance, in the call - -

-     $ lua -la b.lua t1 t2
-

-the interpreter first runs the file a.lua, -then creates a table - -

-     arg = { [-2] = "lua", [-1] = "-la",
-             [0] = "b.lua",
-             [1] = "t1", [2] = "t2" }
-

-and finally runs the file b.lua. -The script is called with arg[1], arg[2], ... -as arguments; -it can also access these arguments with the vararg expression '...'. - - -

-In interactive mode, -if you write an incomplete statement, -the interpreter waits for its completion -by issuing a different prompt. - - -

-In case of unprotected errors in the script, -the interpreter reports the error to the standard error stream. -If the error object is a string, -the interpreter adds a stack traceback to it. -Otherwise, if the error object has a metamethod __tostring, -the interpreter calls this metamethod to produce the final message. -Finally, if the error object is nil, -the interpreter does not report the error. - - -

-When finishing normally, -the interpreter closes its main Lua state -(see lua_close). -The script can avoid this step by -calling os.exit to terminate. - - -

-To allow the use of Lua as a -script interpreter in Unix systems, -the standalone interpreter skips -the first line of a chunk if it starts with #. -Therefore, Lua scripts can be made into executable programs -by using chmod +x and the #! form, -as in - -

-     #!/usr/local/bin/lua
-

-(Of course, -the location of the Lua interpreter may be different in your machine. -If lua is in your PATH, -then - -

-     #!/usr/bin/env lua
-

-is a more portable solution.) - - - -

8 – Incompatibilities with the Previous Version

- -

-Here we list the incompatibilities that you may find when moving a program -from Lua 5.1 to Lua 5.2. -You can avoid some incompatibilities by compiling Lua with -appropriate options (see file luaconf.h). -However, -all these compatibility options will be removed in the next version of Lua. - - - -

8.1 – Changes in the Language

-The concept of environment changed. -Only Lua functions have environments. -To set the environment of a Lua function, -use the variable _ENV or the function load. - - -
-C functions no longer have environments. -Use an upvalue with a shared table if you need to keep -shared state among several C functions. -(You may use luaL_setfuncs to open a C library -with all functions sharing a common upvalue.) - - -
-To manipulate the "environment" of a userdata -(which is now called user value), -use the new functions -lua_getuservalue and lua_setuservalue. -
-Lua identifiers cannot use locale-dependent letters. -
-Doing a step or a full collection in the garbage collector -does not restart the collector if it has been stopped. -
-Weak tables with weak keys now perform like ephemeron tables. -
-The event tail return in debug hooks was removed. -Instead, tail calls generate a special new event, -tail call, so that the debugger can know that -there will not be a corresponding return event. -
-Equality between function values has changed. -Now, a function definition may not create a new value; -it may reuse some previous value if there is no -observable difference to the new function. -

- - - - -

8.2 – Changes in the Libraries

-Function module is deprecated. -It is easy to set up a module with regular Lua code. -Modules are not expected to set global variables. -
-Functions setfenv and getfenv were removed, -because of the changes in environments. -
-Function math.log10 is deprecated. -Use math.log with 10 as its second argument, instead. -
-Function loadstring is deprecated. -Use load instead; it now accepts string arguments -and are exactly equivalent to loadstring. -
-Function table.maxn is deprecated. -Write it in Lua if you really need it. -
-Function os.execute now returns true when command -terminates successfully and nil plus error information -otherwise. -
-Function unpack was moved into the table library -and therefore must be called as table.unpack. -
-Character class %z in patterns is deprecated, -as now patterns may contain '\0' as a regular character. -
-The table package.loaders was renamed package.searchers. -
-Lua does not have bytecode verification anymore. -So, all functions that load code -(load and loadfile) -are potentially insecure when loading untrusted binary data. -(Actually, those functions were already insecure because -of flaws in the verification algorithm.) -When in doubt, -use the mode argument of those functions -to restrict them to loading textual chunks. -
-The standard paths in the official distribution may -change between versions. -

- - - - -

8.3 – Changes in the API

-Pseudoindex LUA_GLOBALSINDEX was removed. -You must get the global environment from the registry -(see §4.5). -
-Pseudoindex LUA_ENVIRONINDEX -and functions lua_getfenv/lua_setfenv -were removed, -as C functions no longer have environments. -
-Function luaL_register is deprecated. -Use luaL_setfuncs so that your module does not create globals. -(Modules are not expected to set global variables anymore.) -
-The osize argument to the allocation function -may not be zero when creating a new block, -that is, when ptr is NULL -(see lua_Alloc). -Use only the test ptr == NULL to check whether -the block is new. -
-Finalizers (__gc metamethods) for userdata are called in the -reverse order that they were marked for finalization, -not that they were created (see §2.5.1). -(Most userdata are marked immediately after they are created.) -Moreover, -if the metatable does not have a __gc field when set, -the finalizer will not be called, -even if it is set later. -
-luaL_typerror was removed. -Write your own version if you need it. -
-Function lua_cpcall is deprecated. -You can simply push the function with lua_pushcfunction -and call it with lua_pcall. -
-Functions lua_equal and lua_lessthan are deprecated. -Use the new lua_compare with appropriate options instead. -
-Function lua_objlen was renamed lua_rawlen. -
-Function lua_load has an extra parameter, mode. -Pass NULL to simulate the old behavior. -
-Function lua_resume has an extra parameter, from. -Pass NULL or the thread doing the call. -

- - - - -

9 – The Complete Syntax of Lua

- -

-Here is the complete syntax of Lua in extended BNF. -(It does not describe operator precedences.) - - - - -

-
-	chunk ::= block
-
-	block ::= {stat} [retstat]
-
-	stat ::=  ‘;’ | 
-		 varlist ‘=’ explist | 
-		 functioncall | 
-		 label | 
-		 break | 
-		 goto Name | 
-		 do block end | 
-		 while exp do block end | 
-		 repeat block until exp | 
-		 if exp then block {elseif exp then block} [else block] end | 
-		 for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end | 
-		 for namelist in explist do block end | 
-		 function funcname funcbody | 
-		 local function Name funcbody | 
-		 local namelist [‘=’ explist] 
-
-	retstat ::= return [explist] [‘;’]
-
-	label ::= ‘::’ Name ‘::’
-
-	funcname ::= Name {‘.’ Name} [‘:’ Name]
-
-	varlist ::= var {‘,’ var}
-
-	var ::=  Name | prefixexp ‘[’ exp ‘]’ | prefixexp ‘.’ Name 
-
-	namelist ::= Name {‘,’ Name}
-
-	explist ::= exp {‘,’ exp}
-
-	exp ::=  nil | false | true | Number | String | ‘...’ | functiondef | 
-		 prefixexp | tableconstructor | exp binop exp | unop exp 
-
-	prefixexp ::= var | functioncall | ‘(’ exp ‘)’
-
-	functioncall ::=  prefixexp args | prefixexp ‘:’ Name args 
-
-	args ::=  ‘(’ [explist] ‘)’ | tableconstructor | String 
-
-	functiondef ::= function funcbody
-
-	funcbody ::= ‘(’ [parlist] ‘)’ block end
-
-	parlist ::= namelist [‘,’ ‘...’] | ‘...’
-
-	tableconstructor ::= ‘{’ [fieldlist] ‘}’
-
-	fieldlist ::= field {fieldsep field} [fieldsep]
-
-	field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
-
-	fieldsep ::= ‘,’ | ‘;’
-
-	binop ::= ‘+’ | ‘-’ | ‘*’ | ‘/’ | ‘^’ | ‘%’ | ‘..’ | 
-		 ‘<’ | ‘<=’ | ‘>’ | ‘>=’ | ‘==’ | ‘~=’ | 
-		 and | or
-
-	unop ::= ‘-’ | not | ‘#’
-
-

- -

- - - - - - - -

- - - - - diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/osi-certified-72x60.png b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/osi-certified-72x60.png deleted file mode 100644 index 07df5f6..0000000 Binary files a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/osi-certified-72x60.png and /dev/null differ diff --git a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/readme.html b/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/readme.html deleted file mode 100644 index f0c77a1..0000000 --- a/lib/LuaBridge/Tests/Lua/Lua.5.2.0/doc/readme.html +++ /dev/null @@ -1,419 +0,0 @@ - - - -Lua 5.2 readme - - - - - - - -

- -Welcome to Lua 5.2 -

- -

-about -· -installation -· -changes -· -license -· -reference manual -

- -

About Lua

- -

-Lua is a powerful, fast, lightweight, embeddable scripting language -developed by a -team -at -PUC-Rio, -the Pontifical Catholic University of Rio de Janeiro in Brazil. -Lua is -free software -used in many products and projects around the world. - -

-Lua's -official web site -provides complete information -about Lua, -including -an -executive summary -and -updated -documentation, -especially the -reference manual, -which may differ slightly from the -local copy -distributed in this package. - -

Installing Lua

- -

-Lua is distributed in -source -form. -You need to build it before using it. -Building Lua should be straightforward -because -Lua is implemented in pure ANSI C and compiles unmodified in all known -platforms that have an ANSI C compiler. -Lua also compiles unmodified as C++. -The instructions given below for building Lua are for Unix-like platforms. -See also -instructions for other systems -and -customization options. - -

-If you don't have the time or the inclination to compile Lua yourself, -get a binary from -LuaBinaries. -Try also -Lua for Windows, -an easy-to-use distribution of Lua that includes many useful libraries. - - - -

Building Lua

- -

-In most Unix-like platforms, simply do "make" with a suitable target. -Here are the details. - -

-Open a terminal window and move to -the top-level directory, which is named lua-5.2.0. -The Makefile there controls both the build process and the installation process. -
-
- Do "make" and see if your platform is listed. - The platforms currently supported are: -
-
- aix ansi bsd freebsd generic linux macosx mingw posix solaris -
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- If your platform is listed, just do "make xxx", where xxx - is your platform name. -
- If your platform is not listed, try the closest one or posix, generic, - ansi, in this order. -
-
-The compilation takes only a few moments -and produces three files in the src directory: -lua (the interpreter), -luac (the compiler), -and liblua.a (the library). -
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- To check that Lua has been built correctly, do "make test" - after building Lua. This will run the interpreter and print its version string. -

-If you're running Linux and get compilation errors, -make sure you have installed the readline development package. - -

Installing Lua

- Once you have built Lua, you may want to install it in an official - place in your system. In this case, do "make install". The official - place and the way to install files are defined in the Makefile. You'll - probably need the right permissions to install files. - -

- To build and install Lua in one step, do "make xxx install", - where xxx is your platform name. - -

- To install Lua locally, do "make local". - This will create a directory install with subdirectories - bin, include, lib, man, - and install Lua as listed below. - - To install Lua locally, but in some other directory, do - "make install INSTALL_TOP=xxx", where xxx is your chosen directory. - -

- bin: -: - lua luac -
- include: -: - lua.h luaconf.h lualib.h lauxlib.h lua.hpp -
- lib: -: - liblua.a -
- man/man1: -: - lua.1 luac.1 -

- -

- These are the only directories you need for development. - If you only want to run Lua programs, - you only need the files in bin and man. - The files in include and lib are needed for - embedding Lua in C or C++ programs. - -

Customization

- Three kinds of things can be customized by editing a file: -

Where and how to install Lua — edit Makefile. -
How to build Lua — edit src/Makefile. -
Lua features — edit src/luaconf.h. -

- -

- You don't actually need to edit the Makefiles because you may set the - relevant variables in the command line when invoking make. - Nevertheless, it's probably best to edit and save the Makefiles to - record the changes you need. - -

- On the other hand, if you need to customize some Lua features, you'll need - to edit src/luaconf.h before building and installing Lua. - The edited file will be the one installed, and - it will be used by any Lua clients that you build, to ensure consistency. - Further customization is available to experts by editing the Lua sources. - -

- We strongly recommend that you enable dynamic loading in src/luaconf.h. - This is done automatically for all platforms listed above that have - this feature and also for Windows. - -

Building Lua on other systems

- -

- If you're not using the usual Unix tools, then the instructions for - building Lua depend on the compiler you use. You'll need to create - projects (or whatever your compiler uses) for building the library, - the interpreter, and the compiler, as follows: - -

-library: -: -lapi.c lcode.c lctype.c ldebug.c ldo.c ldump.c lfunc.c lgc.c llex.c -lmem.c lobject.c lopcodes.c lparser.c lstate.c lstring.c ltable.c -ltm.c lundump.c lvm.c lzio.c -lauxlib.c lbaselib.c lbitlib.c lcorolib.c ldblib.c liolib.c -lmathlib.c loslib.c lstrlib.c ltablib.c loadlib.c linit.c -
-interpreter: -: - library, lua.c -
-compiler: -: - library, luac.c -

- -

- To use Lua as a library in your own programs you'll need to know how to - create and use libraries with your compiler. Moreover, to dynamically load - C libraries for Lua you'll need to know how to create dynamic libraries - and you'll need to make sure that the Lua API functions are accessible to - those dynamic libraries — but don't link the Lua library - into each dynamic library. For Unix, we recommend that the Lua library - be linked statically into the host program and its symbols exported for - dynamic linking; src/Makefile does this for the Lua interpreter. - For Windows, we recommend that the Lua library be a DLL. - -

- As mentioned above, you may edit src/luaconf.h to customize - some features before building Lua. - -

Changes since Lua 5.1

- -

-Here are the main changes introduced in Lua 5.2. -The -reference manual -lists the -incompatibilities that had to be introduced. - -

Main changes

yieldable pcall and metamethods -
new lexical scheme for globals -
ephemeron tables -
new library for bitwise operations -
light C functions -
emergency garbage collector -
goto statement -
finalizers for tables -

- -Here are the other changes introduced in Lua 5.2: -

Language

no more fenv for threads or functions -
tables honor the __len metamethod -
hex and \z escapes in strings -
support for hexadecimal floats -
order metamethods work for different types -
no more verification of opcode consistency -
hook event "tail return" replaced by "tail call" -
empty statement -
break statement may appear in the middle of a block -

- -

Libraries

arguments for function called through xpcall -
optional 'mode' argument to load and loadfile (to control binary x text) -
optional 'env' argument to load and loadfile (environment for loaded chunk) -
loadlib may load libraries with global names (RTLD_GLOBAL) -
new function package.searchpath -
modules receive their paths when loaded -
optional base in math.log -
optional separator in string.rep -
file:write returns file -
closing a pipe returns exit status -
os.exit may close state -
new metamethods __pairs and __ipairs -
new option 'isrunning' for collectgarbage and lua_gc -
frontier patterns -
\0 in patterns -
new option *L for io.read -
options for io.lines -
debug.getlocal can access function varargs -

- -

C API

main thread predefined in the registry -
new functions -lua_absindex, -lua_arith, -lua_compare, -lua_copy, -lua_len, -lua_rawgetp, -lua_rawsetp, -lua_upvalueid, -lua_upvaluejoin, -lua_version. -
new functions -luaL_checkversion, -luaL_setmetatable, -luaL_testudata, -luaL_tolstring. -
lua_pushstring and pushlstring return string -
nparams and isvararg available in debug API -
new lua_Unsigned -

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Implementation

max constants per function raised to 2²⁶ -
generational mode for garbage collection (experimental) -
NaN trick (experimental) -
internal (immutable) version of ctypes -
simpler implementation for string buffers -
parser uses much less C-stack space (no more auto arrays) -

- -

Lua standalone interpreter

new -E option to avoid environment variables -
handling of non-string error messages -

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License

- -

- - -

-Lua is free software distributed under the terms of the -MIT license -reproduced below; -it may be used for any purpose, including commercial purposes, -at absolutely no cost without having to ask us. - -The only requirement is that if you do use Lua, -then you should give us credit by including the appropriate copyright notice somewhere in your product or its documentation. - -For details, see -this. - -

-Copyright © 1994–2011 Lua.org, PUC-Rio. - -
-Permission is hereby granted, free of charge, to any person obtaining a copy -of this software and associated documentation files (the "Software"), to deal -in the Software without restriction, including without limitation the rights -to use, copy, modify, merge, publish, distribute, sublicense, and/or sell -copies of the Software, and to permit persons to whom the Software is -furnished to do so, subject to the following conditions: - -
-The above copyright notice and this permission notice shall be included in -all copies or substantial portions of the Software. - -
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR -IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, -FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE -AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER -LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, -OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN -THE SOFTWARE. -

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