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113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/*
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* Copyright (C) 2014 Patrick Mours
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#pragma once
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#include "effect_token.hpp"
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namespace reshadefx
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{
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/// <summary>
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/// A lexical analyzer for C-like languages.
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/// </summary>
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class lexer
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{
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public:
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explicit lexer(
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std::string input,
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bool ignore_comments = true,
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bool ignore_whitespace = true,
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bool ignore_pp_directives = true,
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bool ignore_line_directives = false,
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bool ignore_keywords = false,
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bool escape_string_literals = true,
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const location &start_location = location()) :
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_input(std::move(input)),
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_cur_location(start_location),
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_ignore_comments(ignore_comments),
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_ignore_whitespace(ignore_whitespace),
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_ignore_pp_directives(ignore_pp_directives),
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_ignore_line_directives(ignore_line_directives),
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_ignore_keywords(ignore_keywords),
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_escape_string_literals(escape_string_literals)
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{
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_cur = _input.data();
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_end = _cur + _input.size();
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}
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lexer(const lexer &lexer) { operator=(lexer); }
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lexer &operator=(const lexer &lexer)
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{
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_input = lexer._input;
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_cur_location = lexer._cur_location;
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reset_to_offset(lexer._cur - lexer._input.data());
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_end = _input.data() + _input.size();
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_ignore_comments = lexer._ignore_comments;
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_ignore_whitespace = lexer._ignore_whitespace;
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_ignore_pp_directives = lexer._ignore_pp_directives;
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_ignore_keywords = lexer._ignore_keywords;
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_escape_string_literals = lexer._escape_string_literals;
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_ignore_line_directives = lexer._ignore_line_directives;
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return *this;
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}
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/// <summary>
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/// Gets the current position in the input string.
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/// </summary>
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size_t input_offset() const { return _cur - _input.data(); }
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/// <summary>
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/// Gets the input string this lexical analyzer works on.
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/// </summary>
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/// <returns>Constant reference to the input string.</returns>
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const std::string &input_string() const { return _input; }
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/// <summary>
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/// Performs lexical analysis on the input string and return the next token in sequence.
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/// </summary>
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/// <returns>Next token from the input string.</returns>
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token lex();
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/// <summary>
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/// Advances to the next token that is not whitespace.
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/// </summary>
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void skip_space();
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/// <summary>
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/// Advances to the next new line, ignoring all tokens.
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/// </summary>
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void skip_to_next_line();
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/// <summary>
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/// Resets position to the specified <paramref name="offset"/>.
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/// </summary>
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/// <param name="offset">Offset in characters from the start of the input string.</param>
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void reset_to_offset(size_t offset);
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private:
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/// <summary>
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/// Skips an arbitrary amount of characters in the input string.
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/// </summary>
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/// <param name="length">Number of input characters to skip.</param>
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void skip(size_t length);
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void parse_identifier(token &tok) const;
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bool parse_pp_directive(token &tok);
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void parse_string_literal(token &tok, bool escape);
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void parse_numeric_literal(token &tok) const;
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std::string _input;
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location _cur_location;
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const std::string::value_type *_cur, *_end;
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bool _ignore_comments;
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bool _ignore_whitespace;
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bool _ignore_pp_directives;
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bool _ignore_line_directives;
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bool _ignore_keywords;
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bool _escape_string_literals;
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};
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}
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