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127 lines
3.3 KiB
C++
127 lines
3.3 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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#include "corewords.hpp"
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#include "ctype.hpp"
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#include "parser.hpp"
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#include <cstring>
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Error Parser::parse(State& state, const char *str)
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{
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auto addr = Dictionary::Input;
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state.dict.write(addr, 0);
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state.dict.write(Dictionary::SourceLen, std::strlen(str));
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addr += sizeof(Cell);
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while (*str)
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state.dict.writebyte(addr++, *str++);
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while (addr < Dictionary::Input + Dictionary::InputCells)
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state.dict.writebyte(addr++, '\0');
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return parseSource(state);
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}
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Error Parser::parseSource(State& state)
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{
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auto word = state.dict.input();
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while (word.size() > 0) {
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if (auto ret = parseWord(state, word); ret != Error::none)
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return ret;
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word = state.dict.input();
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}
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return Error::none;
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}
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Error Parser::parseWord(State& state, Word word)
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{
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int ins, imm;
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ins = state.dict.find(word);
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if (ins <= 0) {
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ins = CoreWords::findi(state, word);
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if (ins < 0)
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return parseNumber(state, word);
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else
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imm = ins == CoreWords::Semicolon;
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} else {
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imm = state.dict.read(ins) & CoreWords::Immediate;
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ins = state.dict.getexec(ins);
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}
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if (state.compiling() && !imm)
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state.dict.add(ins);
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else if (auto stat = state.execute(ins); stat != Error::none)
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return stat;
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return Error::none;
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}
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Error Parser::parseNumber(State& state, Word word)
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{
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const auto base = state.dict.read(Dictionary::Base);
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DoubleCell result = 0;
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auto i = word.start;
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bool inv;
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char c;
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c = state.dict.readbyte(i);
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if (inv = c == '-'; inv)
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c = state.dict.readbyte(++i);
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do {
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if (isdigit(c)) {
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result *= base;
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result += c - '0';
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} else if (isalpha(c) && base > 10) {
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result *= base;
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result += 10 + (c > 'a' ? c - 'a' : c - 'A');
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} else {
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return Error::noword;
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}
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if (++i < word.wend)
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c = state.dict.readbyte(i);
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} while (i < word.wend);
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if (inv)
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result *= -1;
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Cell value = static_cast<Cell>(result);
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if (state.compiling()) {
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auto ins = CoreWords::findi("_lit");
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if (value >= 0 && value < static_cast<Cell>(Dictionary::Begin - CoreWords::WordCount)) {
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state.dict.add(value + CoreWords::WordCount);
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} else {
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state.dict.add(ins);
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state.dict.add(value);
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}
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} else {
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state.push(value);
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}
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return Error::none;
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}
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