StringFromStringLexer.cpp

/*
 * StringFromStringLexer.cpp
 *
 *  Created on: Nov 23, 2013
 *      Author: Jan Travnicek
 */

#include "StringFromStringLexer.h"

namespace string {

StringFromStringLexer::Token StringFromStringLexer::next(std::istream& in) {
	StringFromStringLexer::Token token;
	token.type = TokenType::ERROR;
	token.value = "";
	token.raw = "";
	char character;

L0:
	character = in.get();
	if ( in.eof ( ) || character == EOF ) {
		token.type = TokenType::TEOF;
		return token;
	} else if(character == ' ' || character == '\n' || character == '\t') {
		token.raw += character;
		goto L0;
	} else if(character == '<') {
		token.type = TokenType::LESS;
		token.value += character;
		token.raw += character;
		return token;
	} else if(character == '>') {
		token.type = TokenType::GREATER;
		token.value += character;
		token.raw += character;
		return token;
	} else if(character == '"') {
		token.type = TokenType::QUOTE;
		token.value += character;
		token.raw += character;
		return token;
	} else if(character == '#') {
		token.value += character;
		token.raw += character;
		goto L1;
	} else {
		in.clear ( );
		in.unget ( );
		putback(in, std::move(token));
		token.type = TokenType::ERROR;
		return token;
	}
L1:
	character = in.get();
	if(in.eof()) {
		token.type = TokenType::TEOF;
		return token;
	} else if(character == 'E') {
		token.type = TokenType::EPSILON;
		token.value += character;
		token.raw += character;
		return token;
	} else if(character == '$') {
		token.type = TokenType::TERM;
		token.value += character;
		token.raw += character;
		return token;
	} else {
		in.clear ( );
		in.unget ( );
		putback(in, std::move(token));
		token.type = TokenType::ERROR;
		return token;
	}
}

void StringFromStringLexer::putback(std::istream& in, StringFromStringLexer::Token token) {
	in.clear();

	while(!token.raw.empty()) {
		in.putback(token.raw.back());
		token.raw.pop_back();
	}
}

} /* namespace string */