refactor, encapsulate
parent
b82f1c1f7e
commit
a79eaf8e16
GPG Key ID:
1B74EE6C49C96795
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// sprit-forth: A portable subroutine-threaded Forth.
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// Copyright (C) 2024 Clyne Sullivan <clyne@bitgloo.com>
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Library General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or (at your
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// option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for
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// more details.
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//
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// You should have received a copy of the GNU Library General Public License
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// along with this library; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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#include "executor.hpp"
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Executor Exec;
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Error Executor::executor(FuncList *list) noexcept
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{
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auto result = static_cast<Error>(setjmp(jmpbuf));
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FuncList body;
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if (static_cast<int>(result) == 0) {
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result = Error::none;
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// We are given the pointer to a list of function pointers.
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// Dereference once to retrieve the function pointer list.
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// We do not work with IP initially since it needs to be set to zero if
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// this is a top-level call/execution.
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body = *list;
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// Enter the execution loop.
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goto entry;
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// Execution continues so long as IP is not zero.
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// If this is a top-level execution of a pre-defined word, then IP will
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// remain zero'd and the loop will immediately exit.
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// If this is a defined word's execution, then its "call" will overwrite
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// IP (and push the initial zero-IP to the return stack); execution will
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// continue until we return to the zero-IP.
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while (ip) {
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// Retrieve next function pointer list.
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body = (FuncList)*++ip;
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entry:
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// Dereference `body` to get the first function in the list.
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// This is casted to take a FuncList as an argument since defined
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// words need to know their addresses so that they can perform
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// their "calls".
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// If the word is pre-defined then the argument will simply be
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// ignored.
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auto func = (void (*)(FuncList))*body;
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func(body);
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}
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}
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return result;
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}
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Error Executor::execute1(Word *word) noexcept
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{
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// IP must initially be zero if executing a word at the top level.
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ip = nullptr;
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return executor(&word->list);
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}
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[[noreturn]]
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void Executor::terminate(Error error) noexcept
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{
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std::longjmp(jmpbuf, static_cast<int>(error));
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}
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@ -0,0 +1,53 @@
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// sprit-forth: A portable subroutine-threaded Forth.
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// Copyright (C) 2024 Clyne Sullivan <clyne@bitgloo.com>
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Library General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or (at your
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// option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for
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// more details.
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//
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// You should have received a copy of the GNU Library General Public License
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// along with this library; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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#ifndef EXECUTOR_HPP
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#define EXECUTOR_HPP
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#include "types.hpp"
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#include <csetjmp>
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class Executor
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{
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std::jmp_buf jmpbuf;
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public:
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FuncList ip = nullptr;
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/**
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* Begins execution with the given function pointer list.
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* @param list Function pointer list to execute
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*/
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[[nodiscard]]
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Error executor(FuncList *list) noexcept;
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/**
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* Executes the given word by calling executor on its definition.
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* @param word The word to execute
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*/
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[[nodiscard]]
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Error execute1(Word *word) noexcept;
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[[noreturn]]
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void terminate(Error error) noexcept;
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};
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extern Executor Exec;
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#endif // EXECUTOR_HPP
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