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139 lines
4.3 KiB
C++
139 lines
4.3 KiB
C++
/**
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* Alee Forth: A portable and concise Forth implementation in modern C++.
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* Copyright (C) 2023 Clyne Sullivan <clyne@bitgloo.com>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef ALEEFORTH_DICTIONARY_HPP
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#define ALEEFORTH_DICTIONARY_HPP
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#include "types.hpp"
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#include <algorithm>
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#include <cstddef>
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#include <cstdint>
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/**
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* Dictionary entry format:
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* - 1 information byte
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* bits 0..4: Length of name (L)
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* bit 5: Immediate?
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* bits 6..15: Distance to next entry (negative)
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* - L bytes of name
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* - 0+ bytes for address alignment
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* - 0+ bytes of entry's data...
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*/
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class Dictionary
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{
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public:
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/**
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* The beginning of the dictionary is used for "internal" variables.
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*/
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constexpr static Addr Base = 0;
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constexpr static Addr Here = sizeof(Cell);
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constexpr static Addr Latest = sizeof(Cell) * 2;
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constexpr static Addr Compiling = sizeof(Cell) * 3;
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constexpr static Addr Source = sizeof(Cell) * 4;
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constexpr static Addr SourceLen = sizeof(Cell) * 5;
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constexpr static Addr Input = sizeof(Cell) * 6; // len data...
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constexpr static Addr InputCells = 80; // bytes!
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constexpr static Addr Begin = sizeof(Cell) * 7 + InputCells;
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constexpr static Cell Immediate = (1 << 5);
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/**
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* Dictionary data can be stored on any read-write interface.
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* You must create a dictionary class that inherits Dictionary and
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* implement these functions. See `memdict.hpp` for a simple block-of-
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* memory implementation.
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*/
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virtual Cell read(Addr) const noexcept = 0;
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virtual void write(Addr, Cell) noexcept = 0;
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virtual uint8_t readbyte(Addr) const noexcept = 0;
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virtual void writebyte(Addr, uint8_t) noexcept = 0;
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virtual unsigned long int capacity() const noexcept = 0;
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/**
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* Does initial dictionary setup, required before use for execution.
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*/
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void initialize();
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Addr here() const noexcept { return read(Here); }
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void here(Addr l) noexcept { write(Here, l); }
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Addr latest() const noexcept { return read(Latest); }
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void latest(Addr l) noexcept { write(Latest, l); }
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// Aligns the given address.
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Addr aligned(Addr) const noexcept;
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// Aligns `here`.
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Addr alignhere() noexcept;
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// Advances `here` by the given number of bytes.
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Addr allot(Cell) noexcept;
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// Stores value to `here`, then adds sizeof(Cell) to `here`.
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void add(Cell) noexcept;
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/**
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* Uses add() to store a new definition entry starting at `here`.
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* The entry does not become active until a semicolon is executed.
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*/
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void addDefinition(Word) noexcept;
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/**
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* Searches the dictionary for an entry for the given word.
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* Returns zero if not found.
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*/
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Addr find(Word) noexcept;
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/**
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* Given the address of a dictionary entry, produces the execution token
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* for that entry.
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*/
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Addr getexec(Addr) noexcept;
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/**
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* Reads the next word from the input buffer.
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* Returns an empty word if the buffer is empty or entirely read.
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*/
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Word input() noexcept;
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bool hasInput() const noexcept;
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/**
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* Checks if this dictionary's word is equivalent to the given string/size.
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*/
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bool equal(Word, const char *, unsigned) const noexcept;
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/**
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* Checks if two words in this dictionary's word are equivalent.
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*/
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bool equal(Word, Word) const noexcept;
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// Used for case-insensitive comparison between two iterators.
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template<typename Iter1, typename Iter2>
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static bool equal(Iter1 b1, Iter1 e1, Iter2 b2) {
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return std::equal(b1, e1, b2, eqchars);
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}
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virtual ~Dictionary() = default;
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private:
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// Case-insensitive comparison.
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static bool eqchars(char c1, char c2);
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};
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#endif // ALEEFORTH_DICTIONARY_HPP
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