lexer.h

#ifndef QUERY_LEXER_H
#define QUERY_LEXER_H
 
#include <vkdb/token.h>
#include <vector>
#include <unordered_map>
#include <concepts>
 
namespace vkdb {
static const std::unordered_map<Lexeme, TokenType> WORD_TO_TOKEN_TYPE{
  {"SELECT", TokenType::SELECT},
  {"PUT", TokenType::PUT},
  {"DELETE", TokenType::DELETE},
  {"CREATE", TokenType::CREATE},
  {"DROP", TokenType::DROP},
  {"ADD", TokenType::ADD},
  {"REMOVE", TokenType::REMOVE},
  {"TABLES", TokenType::TABLES},
  {"DATA", TokenType::DATA},
  {"AVG", TokenType::AVG},
  {"SUM", TokenType::SUM},
  {"COUNT", TokenType::COUNT},
  {"MIN", TokenType::MIN},
  {"MAX", TokenType::MAX},
  {"TABLE", TokenType::TABLE},
  {"TAGS", TokenType::TAGS},
  {"ALL", TokenType::ALL},
  {"BETWEEN", TokenType::BETWEEN},
  {"AND", TokenType::AND},
  {"AT", TokenType::AT},
  {"WHERE", TokenType::WHERE},
  {"FROM", TokenType::FROM},
  {"INTO", TokenType::INTO},
  {"TO", TokenType::TO}
};
 
class Lexer {
public:
  using size_type = uint64_t;
 
  Lexer() = delete;
 
  explicit Lexer(const std::string& input) noexcept;
 
  Lexer(Lexer&&) noexcept = default;
 
  Lexer& operator=(Lexer&&) noexcept = default;
 
  Lexer(const Lexer&) = delete;
 
  Lexer& operator=(const Lexer&) = delete;
 
  ~Lexer() noexcept = default;
 
  std::vector<Token> tokenize();
 
private:
  [[nodiscard]] bool is_whitespace(char ch) const noexcept;
 
  [[nodiscard]] bool is_alpha(char ch) const noexcept;
 
  [[nodiscard]] bool is_digit(char ch) const noexcept;
 
  [[nodiscard]] bool is_alnum(char ch) const noexcept;
 
  [[nodiscard]] bool chars_remaining() const noexcept;
 
  [[nodiscard]] char peek() const;
 
  [[nodiscard]] char peek_next() const;
 
  char advance();
 
  template <std::predicate<char> Pred>
  void advance_while(const Pred& pred) noexcept;
 
  void lex_whitespace() noexcept;
 
  [[nodiscard]] Token lex_word() noexcept;
 
  [[nodiscard]] Token lex_number() noexcept;
 
  void lex_comment() noexcept;
 
  [[nodiscard]] Token lex_equal() noexcept;
 
  [[nodiscard]] Token lex_comma() noexcept;
 
  [[nodiscard]] Token lex_semicolon() noexcept;
 
  [[nodiscard]] Token lex_unknown() noexcept;
 
  [[nodiscard]] Token lex_end_of_file() noexcept;
 
  [[nodiscard]] Lexeme make_lexeme_from(size_type start) const;
 
  [[nodiscard]] Token make_token(
    TokenType type,
    const Lexeme& lexeme
  ) noexcept;
 
  std::string input_;
 
  size_type position_;
 
  size_type line_;
 
  size_type column_;
};
 
}  // namespace vkdb
 
#endif // QUERY_LEXER_H