obelisk/src/lexer.cpp

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#include "lexer.h"
#include <iostream>
obelisk::Lexer::Lexer(const std::string& sourceFile)
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{
fileStream_.open(sourceFile, std::ifstream::in);
if (!fileStream_)
{
throw obelisk::LexerException("could not open source file " + sourceFile);
}
}
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obelisk::Lexer::~Lexer()
{
fileStream_.close();
fileStream_.clear();
}
int obelisk::Lexer::getToken()
{
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while (isspace(lastChar))
{
lastChar = fileStream_.get();
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}
if (isalpha(lastChar))
{
eraseIdentifier();
appendIdentifier(lastChar);
while (isalnum((lastChar = fileStream_.get())))
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{
appendIdentifier(lastChar);
}
if (getIdentifier() == "fact")
{
return Token::kTokenFact;
}
if (getIdentifier() == "rule")
{
return Token::kTokenFact;
}
if (getIdentifier() == "action")
{
return Token::kTokenAction;
}
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if (getIdentifier() == "def")
{
return Token::kTokenDef;
}
if (getIdentifier() == "extern")
{
return kTokenExtern;
}
return kTokenIdentifier;
}
if (isdigit(lastChar))
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{
bool firstPeriod = false;
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std::string numberStr;
do
{
if (firstPeriod && lastChar == '.')
{
throw obelisk::LexerException("invalid double value");
}
else if (!firstPeriod && lastChar == '.')
{
firstPeriod = true;
}
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numberStr += lastChar;
lastChar = fileStream_.get();
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}
while (isdigit(lastChar) || lastChar == '.');
setNumberValue(strtod(numberStr.c_str(), nullptr));
return kTokenNumber;
}
if (lastChar == '#')
{
commentLine(&lastChar);
if (lastChar != EOF)
{
return getToken();
}
}
else if (lastChar == '/')
{
lastChar = fileStream_.get();
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if (lastChar == '/')
{
commentLine(&lastChar);
if (lastChar != EOF)
{
return getToken();
}
}
}
if (lastChar == EOF)
{
return kTokenEof;
}
int thisChar = lastChar;
lastChar = fileStream_.get();
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return thisChar;
}
void obelisk::Lexer::commentLine(int* lastChar)
{
do
{
*lastChar = fileStream_.get();
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}
while (*lastChar != EOF && *lastChar != '\n' && *lastChar != '\r');
}
const std::string& obelisk::Lexer::getIdentifier()
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{
return identifier_;
}
void obelisk::Lexer::setIdentifier(const std::string& identifier)
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{
identifier_ = identifier;
}
void obelisk::Lexer::eraseIdentifier()
{
identifier_ = "";
}
void obelisk::Lexer::appendIdentifier(int lastChar)
{
identifier_ += lastChar;
}
double obelisk::Lexer::getNumberValue()
{
return numberValue_;
}
void obelisk::Lexer::setNumberValue(double numberValue)
{
numberValue_ = numberValue;
}