154 lines
4.2 KiB
C++
154 lines
4.2 KiB
C++
/*
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Copyright (C) 1996-1997 Id Software, Inc.
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Copyright (C) 1997 Greg Lewis
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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 General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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See file, 'COPYING', for details.
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*/
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#pragma once
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#include <utility>
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#include <vector>
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#include <string_view>
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enum : int32_t
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{
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PARSE_NORMAL = 0,
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PARSE_SAMELINE = 1, /* Expect the next token the current line */
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PARSE_COMMENT = 2, /* If a // comment is next token, return it */
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PARSE_OPTIONAL = 4, /* Return next token on same line, or false if EOL */
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PARSE_PEEK = 8 /* Don't change parser state */
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};
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using parseflags = int32_t;
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template<typename... T>
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constexpr auto untie(const std::tuple<T...> &tuple)
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{
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return std::tuple<typename std::remove_reference<T>::type...>(tuple);
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}
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template<typename T>
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using untied_t = decltype(untie(std::declval<T>()));
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struct parser_base_t
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{
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std::string token;
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bool was_quoted = false; // whether the current token was from a quoted string or not
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virtual bool parse_token(parseflags flags = PARSE_NORMAL) = 0;
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virtual bool at_end() const = 0;
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virtual void push_state() = 0;
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virtual void pop_state() = 0;
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};
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#include <utility>
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// a parser that works on a single, contiguous string
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struct parser_t : parser_base_t
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{
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const char *pos;
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const char *end;
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uint32_t linenum = 1;
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// base constructor; accept raw start & length
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inline parser_t(const void *start, size_t length)
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: pos(reinterpret_cast<const char *>(start)), end(reinterpret_cast<const char *>(start) + length)
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{
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}
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// pull from string_view; note that the string view must live for the entire
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// duration of the parser's life time
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inline parser_t(const std::string_view &view) : parser_t(&view.front(), view.size()) { }
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// pull from C string; made explicit because this is error-prone
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explicit parser_t(const char *str) : parser_t(str, strlen(str)) { }
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bool parse_token(parseflags flags = PARSE_NORMAL) override;
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using state_type = decltype(std::tie(pos, linenum));
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constexpr state_type state() { return state_type(pos, linenum); }
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bool at_end() const override { return pos >= end; }
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private:
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std::vector<untied_t<state_type>> _states;
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public:
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void push_state() override { _states.push_back(state()); }
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void pop_state() override
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{
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state() = _states.back();
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_states.pop_back();
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}
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};
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// a parser that works on a list of tokens
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struct token_parser_t : parser_base_t
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{
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std::vector<std::string_view> tokens;
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size_t cur = 0;
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inline token_parser_t(int argc, const char **args) : tokens(args, args + argc) { }
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using state_type = decltype(std::tie(cur));
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constexpr state_type state() { return state_type(cur); }
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inline bool parse_token(parseflags flags = PARSE_NORMAL) override
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{
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/* for peek, we'll do a backup/restore. */
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if (flags & PARSE_PEEK) {
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auto restore = untie(state());
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bool result = parse_token(flags & ~PARSE_PEEK);
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state() = restore;
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return result;
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}
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token.clear();
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was_quoted = false;
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if (at_end()) {
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return false;
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}
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token = tokens[cur++];
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was_quoted = std::any_of(token.begin(), token.end(), isspace);
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return true;
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}
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bool at_end() const override { return cur >= tokens.size(); }
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private:
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std::vector<untied_t<state_type>> _states;
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public:
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void push_state() override { _states.push_back(state()); }
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void pop_state() override
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{
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state() = _states.back();
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_states.pop_back();
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}
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}; |