duckstation/dep/reshadefx/include/effect_lexer.hpp

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2023-08-13 04:03:17 +00:00
/*
* Copyright (C) 2014 Patrick Mours
* SPDX-License-Identifier: BSD-3-Clause
*/
#pragma once
#include "effect_token.hpp"
namespace reshadefx
{
/// <summary>
/// A lexical analyzer for C-like languages.
/// </summary>
class lexer
{
public:
explicit lexer(
std::string input,
bool ignore_comments = true,
bool ignore_whitespace = true,
bool ignore_pp_directives = true,
bool ignore_line_directives = false,
bool ignore_keywords = false,
bool escape_string_literals = true,
const location &start_location = location()) :
_input(std::move(input)),
_cur_location(start_location),
_ignore_comments(ignore_comments),
_ignore_whitespace(ignore_whitespace),
_ignore_pp_directives(ignore_pp_directives),
_ignore_line_directives(ignore_line_directives),
_ignore_keywords(ignore_keywords),
_escape_string_literals(escape_string_literals)
{
_cur = _input.data();
_end = _cur + _input.size();
}
lexer(const lexer &lexer) { operator=(lexer); }
lexer &operator=(const lexer &lexer)
{
_input = lexer._input;
_cur_location = lexer._cur_location;
reset_to_offset(lexer._cur - lexer._input.data());
_end = _input.data() + _input.size();
_ignore_comments = lexer._ignore_comments;
_ignore_whitespace = lexer._ignore_whitespace;
_ignore_pp_directives = lexer._ignore_pp_directives;
_ignore_keywords = lexer._ignore_keywords;
_escape_string_literals = lexer._escape_string_literals;
_ignore_line_directives = lexer._ignore_line_directives;
return *this;
}
/// <summary>
/// Gets the current position in the input string.
/// </summary>
size_t input_offset() const { return _cur - _input.data(); }
/// <summary>
/// Gets the input string this lexical analyzer works on.
/// </summary>
/// <returns>Constant reference to the input string.</returns>
const std::string &input_string() const { return _input; }
/// <summary>
/// Performs lexical analysis on the input string and return the next token in sequence.
/// </summary>
/// <returns>Next token from the input string.</returns>
token lex();
/// <summary>
/// Advances to the next token that is not whitespace.
/// </summary>
void skip_space();
/// <summary>
/// Advances to the next new line, ignoring all tokens.
/// </summary>
void skip_to_next_line();
/// <summary>
/// Resets position to the specified <paramref name="offset"/>.
/// </summary>
/// <param name="offset">Offset in characters from the start of the input string.</param>
void reset_to_offset(size_t offset);
private:
/// <summary>
/// Skips an arbitrary amount of characters in the input string.
/// </summary>
/// <param name="length">Number of input characters to skip.</param>
void skip(size_t length);
void parse_identifier(token &tok) const;
bool parse_pp_directive(token &tok);
void parse_string_literal(token &tok, bool escape);
void parse_numeric_literal(token &tok) const;
std::string _input;
location _cur_location;
const std::string::value_type *_cur, *_end;
bool _ignore_comments;
bool _ignore_whitespace;
bool _ignore_pp_directives;
bool _ignore_line_directives;
bool _ignore_keywords;
bool _escape_string_literals;
};
}