78 lines
1.7 KiB
C++
78 lines
1.7 KiB
C++
#pragma once
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#ifndef LEXER_InputLexer_H
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#define LEXER_InputLexer_H
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#include <exception>
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#include <istream>
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#include <string>
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class InputLexer {
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public:
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class NoMoreTokens : public std::exception {};
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class NoMatch : public std::exception {};
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enum TokenType {
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nonmatching,
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ARROW,
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COLON,
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GRAMMAR,
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LEFT,
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LEXESIS,
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LEXESISNAME,
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NONASSOC,
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NUM,
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PARSER,
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PARSERTYPE,
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PIPE,
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PRECEDENCE,
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RIGHT,
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SEMICOLON,
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START,
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TERMINAL,
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TERMINALS,
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VARIABLE,
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ignore,
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};
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struct Token {
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TokenType type;
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std::string content;
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};
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InputLexer(std::istream& in);
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~InputLexer();
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/**
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* Get the next token
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*
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* @throws NoMoreTokens if no more tokens are available
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* @throws NoMatch if no match was found
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*/
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Token nextToken();
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/**
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* Skip the following `n` bytes.
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*
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* @param n The number of bytes to skip
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*/
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void skip(std::size_t n);
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/**
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* Peek at the current head of the input stream, useful in error reporting when a character mismatches for example
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*
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* @throws NoMoreTokens if the input stream is at an end
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*/
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char peek();
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/**
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* Get the current byte offset
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*/
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std::size_t getByteOffset();
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private:
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std::size_t m_offset;
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std::istream& m_input;
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};
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#endif //LEXER_InputLexer_H
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