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// Copyright 2020 The Tint Authors.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <string>
#include <vector>
#include "src/tint/reader/wgsl/token.h"
namespace tint::reader::wgsl {
/// Converts the input stream into a series of Tokens
class Lexer {
/// Creates a new Lexer
/// @param file the source file
explicit Lexer(const Source::File* file);
/// @return the token list.
std::vector<Token> Lex();
/// Returns the next token in the input stream.
/// @return Token
Token next();
/// Advances past blankspace and comments, if present at the current position.
/// @returns error token, EOF, or uninitialized
Token skip_blankspace_and_comments();
/// Advances past a comment at the current position, if one exists.
/// Returns an error if there was an unterminated block comment,
/// or a null character was present.
/// @returns uninitialized token on success, or error
Token skip_comment();
Token build_token_from_int_if_possible(Source source, size_t start, int32_t base);
Token check_keyword(const Source&, std::string_view);
/// The try_* methods have the following in common:
/// - They assume there is at least one character to be consumed,
/// i.e. the input has not yet reached end of file.
/// - They return an initialized token when they match and consume
/// a token of the specified kind.
/// - Some can return an error token.
/// - Otherwise they return an uninitialized token when they did not
/// match a token of the specfied kind.
Token try_float();
Token try_hex_float();
Token try_hex_integer();
Token try_ident();
Token try_integer();
Token try_punctuation();
Source begin_source() const;
void end_source(Source&) const;
/// @returns view of current line
const std::string_view line() const;
/// @returns position in current line
size_t pos() const;
/// @returns length of current line
size_t length() const;
/// @returns reference to character at `pos` within current line
const char& at(size_t pos) const;
/// @returns substring view at `offset` within current line of length `count`
std::string_view substr(size_t offset, size_t count);
/// advances current position by `offset` within current line
void advance(size_t offset = 1);
/// sets current position to `pos` within current line
void set_pos(size_t pos);
/// advances current position to next line
void advance_line();
/// @returns true if the end of the input has been reached.
bool is_eof() const;
/// @returns true if the end of the current line has been reached.
bool is_eol() const;
/// @returns true if there is another character on the input and
/// it is not null.
bool is_null() const;
/// @param ch a character
/// @returns true if 'ch' is a decimal digit
bool is_digit(char ch) const;
/// @param ch a character
/// @returns true if 'ch' is a hexadecimal digit
bool is_hex(char ch) const;
/// @returns true if string at `pos` matches `substr`
bool matches(size_t pos, std::string_view substr);
/// @returns true if char at `pos` matches `ch`
bool matches(size_t pos, char ch);
/// The source file content
Source::File const* const file_;
/// The current location within the input
Source::Location location_;
} // namespace tint::reader::wgsl