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92 lines
2.2 KiB
C++
92 lines
2.2 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 <cstddef>
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#include <string_view>
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struct Dictionary
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{
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Addr here = 1;
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Addr latest = 0;
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virtual Cell read(Addr) const = 0;
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virtual int write(Addr, Cell) = 0;
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Addr allot(Cell amount) {
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Addr old = here;
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here += amount;
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return old;
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}
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void add(Cell value) {
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write(here++, value);
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}
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void addDefinition(std::string_view str) {
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add(str.size());
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for (char c : str)
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add(c);
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if (here & 1)
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allot(1);
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}
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bool issame(Addr addr, std::string_view str, std::size_t n) {
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if (str.size() != n)
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return false;
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for (char c : str) {
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if (read(addr++) != c)
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return false;
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}
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return true;
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}
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Addr find(std::string_view str) {
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if (latest == 0)
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return 0;
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auto lt = latest;
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do {
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const auto l = read(lt);
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const auto len = l & 0x1F;
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if (issame(lt + 1, str, len))
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return lt;
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else
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lt -= l >> 6;
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} while (lt);
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return 0;
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}
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Addr getexec(Addr addr) {
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const auto len = read(addr) & 0x1F;
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return ((addr + 1 + len) + 1) & ~1;
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}
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};
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#endif // ALEEFORTH_DICTIONARY_HPP
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