obelisk/src/lexer.h

188 lines
5.1 KiB
C++

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