188 lines
5.1 KiB
C++
188 lines
5.1 KiB
C++
#ifndef OBELISK_LEXER_H
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#define OBELISK_LEXER_H
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#include <string>
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namespace obelisk
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{
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/**
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* @brief The Lexer reads and identifies tokens in the obelisk source code.
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*
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*/
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class Lexer
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{
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private:
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/**
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* @brief The last found identifier.
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*
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*/
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std::string identifier_;
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/**
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* @brief The last found number.
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*
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*/
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double numberValue_;
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/**
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* @brief Set the identifier.
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*
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* @param[in] identifier The new identifier.
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*/
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void setIdentifier(const std::string& identifier);
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/**
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* @brief Erase the last identifier.
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*
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*/
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void eraseIdentifier();
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/**
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* @brief Add the last found char to the end of the identifier.
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*
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* @param[in] lastChar The last char that was found.
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*/
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void appendIdentifier(int lastChar);
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/**
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* @brief Set the number value.
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*
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* @param[in] numberValue The new number value.
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*/
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void setNumberValue(double numberValue);
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/**
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* @brief Comment the rest of the line.
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*
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* @param[in] lastChar The char to check to see if it in the end of
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* the line.
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*/
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void commentLine(int* lastChar);
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public:
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/**
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* @brief These token represent recognized language keywords and
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* language functionality.
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*
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*/
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enum Token
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{
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/**
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* @brief End of file is returned when the source code is
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* finished.
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*
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*/
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kTokenEof = -1,
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/**
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* @brief A fact which is a relationship between 2 entities.
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*
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*/
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kTokenFact = -2,
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/**
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* @brief A rule which is a relationship between a new fact a
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* existing fact.
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*
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*/
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kTokenRule = -3,
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/**
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* @brief An action to take if a fact is true.
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*
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*/
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kTokenAction = -4,
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/**
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* @brief A definition of a new function.
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*
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*/
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kTokenDef = -5,
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/**
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* @brief An external function that will be linked to.
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*
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*/
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kTokenExtern = -6,
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/**
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* @brief An identifier which is a alphanumeric value.
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*
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*/
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kTokenIdentifier = -7,
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/**
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* @brief A double floating point value.
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*
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*/
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kTokenNumber = -8,
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/**
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* @brief A string.
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*
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*/
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kTokenString = -9
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};
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/**
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* @brief Gets the next token in the source code.
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*
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* @throws LexerException when an invalid token is found.
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* @return int Returns a Token value or char if no known token was
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* found.
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*/
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int getToken();
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/**
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* @brief Get the last identifier.
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*
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* @return const std::string& Returns a string that contains the
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* last found identifier.
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*/
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const std::string& getIdentifier();
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/**
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* @brief Get the last number value.
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*
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* @return double Return the last number that was found.
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*/
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double getNumberValue();
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};
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/**
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* @brief Lexer exception class.
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*
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*/
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class LexerException : public std::exception
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{
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private:
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/**
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* @brief The error message from the exception.
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*
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*/
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const std::string errorMessage_;
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public:
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/**
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* @brief Construct a new Lexer Exception object.
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*
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*/
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LexerException() :
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errorMessage_("an unknown error ocurred")
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{
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}
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/**
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* @brief Construct a new Lexer Exception object.
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*
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* @param[in] errorMessage Error message to include.
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*/
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LexerException(const std::string& errorMessage) :
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errorMessage_(errorMessage)
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{
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}
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/**
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* @brief Return the exception's error message.
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*
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* @return const char* Returns a string containing the error
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* message.
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*/
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const char* what() const noexcept
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{
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return errorMessage_.c_str();
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}
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};
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} // namespace obelisk
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#endif
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