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/**
* Alee Forth: A portable and concise Forth implementation in modern C++.
* Copyright (C) 2023 Clyne Sullivan <clyne@bitgloo.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef ALEEFORTH_DICTIONARY_HPP
#define ALEEFORTH_DICTIONARY_HPP
#include "types.hpp"
#include <cstddef>
#include <string_view>
struct Dictionary
{
Addr here = 1;
Addr latest = 0;
virtual Cell read(Addr) const = 0;
virtual int write(Addr, Cell) = 0;
Addr allot(Cell amount) {
Addr old = here;
here += amount;
return old;
}
void add(Cell value) {
write(here++, value);
}
void addDefinition(std::string_view str) {
add(str.size());
for (char c : str)
add(c);
if (here & 1)
allot(1);
}
bool issame(Addr addr, std::string_view str, std::size_t n) {
if (str.size() != n)
return false;
for (char c : str) {
if (read(addr++) != c)
return false;
}
return true;
}
Addr find(std::string_view str) {
if (latest == 0)
return 0;
auto lt = latest;
do {
const auto l = read(lt);
const auto len = l & 0x1F;
if (issame(lt + 1, str, len))
return lt;
else
lt -= l >> 6;
} while (lt);
return 0;
}
Addr getexec(Addr addr) {
const auto len = read(addr) & 0x1F;
return ((addr + 1 + len) + 1) & ~1;
}
};
#endif // ALEEFORTH_DICTIONARY_HPP
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