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// Copyright (c) 2019 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "math-server" project.
// For details, see https://github.com/egor-tensin/math-server.
// Distributed under the MIT License.
#pragma once
#include "input.hpp"
#include "token.hpp"
#include "token_type.hpp"
#include <functional>
#include <optional>
#include <string_view>
#include <vector>
namespace math::server {
class Lexer {
public:
explicit Lexer(const std::string_view& input);
explicit Lexer(const lexer::Input& input);
using Token = lexer::Token;
using ParsedToken = lexer::ParsedToken;
using Type = Token::Type;
using TokenProcessor = std::function<bool(const ParsedToken&)>;
bool for_each_token(const TokenProcessor& process);
std::vector<ParsedToken> get_tokens();
bool has_token() const { return peek_token().has_value(); }
std::optional<ParsedToken> peek_token() const { return m_token_buffer; }
void drop_token();
std::optional<ParsedToken> drop_token_of_type(Type type);
private:
std::optional<ParsedToken> parse_whitespace() const;
std::optional<ParsedToken> parse_const_token() const;
std::optional<ParsedToken> parse_number() const;
ParsedToken parse_token() const;
void consume_whitespace();
void consume_token();
lexer::Input m_input;
std::optional<ParsedToken> m_token_buffer;
};
} // namespace math::server
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