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119 lines
3.6 KiB
C++
119 lines
3.6 KiB
C++
// sprit-forth: A portable subroutine-threaded Forth.
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// Copyright (C) 2023 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 TYPES_HPP
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#define TYPES_HPP
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#include <array>
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#include <cstddef>
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#include <cstdint>
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using Cell = intptr_t; /** Type of a dictionary's cell. */
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using Addr = uintptr_t; /** Type of a dictionary address. */
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using Func = void (*)(); /** Words are built of these types of functions. */
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using FuncList = Func const *; /** Words are defined as a list of Func. */
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// Cells, Addrs, and Funcs must all be the same size in bytes since the
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// dictionary stores all of these types of values.
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static_assert(sizeof(Cell) == sizeof(Addr));
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static_assert(sizeof(Cell) == sizeof(Func));
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/**
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* @struct Word
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* @brief Structure of a word's definition.
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* A word has a name, a body (list of functions), a link to the next word
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* definition, and an immediate indicator. This structure is matched when
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* words are defined in the dictionary by ":" and ";".
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*/
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struct Word {
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FuncList list; /** The word's body/definition. */
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const char *name; /** Null-terminated string of word's name. */
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Word *link = nullptr; /** Link to next word in definition chain. */
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Cell imm = 0; /** If non-zero, word is "immediate". */
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constexpr Word(const char *n, FuncList l):
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list(l), name(n) {}
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constexpr Word& markImmediate() noexcept {
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imm = -1;
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return *this;
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}
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constexpr bool immediate() const noexcept {
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return imm;
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}
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};
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// Words are built in the dictionary by the user using ":". These assertions
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// ensure that the structures created by ":" match the actual structure of a
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// Word exactly.
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static_assert(offsetof(Word, list) == 0);
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static_assert(offsetof(Word, name) == 1 * sizeof(Cell));
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static_assert(offsetof(Word, link) == 2 * sizeof(Cell));
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static_assert(offsetof(Word, imm) == 3 * sizeof(Cell));
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static_assert(sizeof(Word) == 4 * sizeof(Cell));
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/**
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* @struct WordSet
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* @brief Groups a set of pre-defined words and links them.
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*/
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template<typename... Words>
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struct WordSet
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{
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std::array<Word, sizeof...(Words)> words;
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Word *latest;
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/**
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* Stores the given pre-defined words into the `words` array and links
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* their definitions together. The resulting `latest` value can be used
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* to set the global LATEST.
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*/
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constexpr WordSet(Words... ws):
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words {ws...}
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{
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auto it = words.begin();
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while (++it != words.end())
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it->link = it - 1;
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latest = &*words.rbegin();
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}
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};
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/**
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* Wraps the given functions so that a function pointer list can be created
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* and used for a word's definition.
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*/
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template<auto... funcs>
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constexpr auto WordWrap = []() noexcept {
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constexpr static auto wrapper = +[] { (funcs(), ...); };
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return &wrapper;
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}();
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enum class Error : int {
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none = 1,
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push,
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pop,
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rpush,
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rpop,
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noword
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};
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#endif // TYPES_HPP
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