C:/Documents and Settings/mtauraso/Desktop/proj3/projectX/Parser.cpp

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#include <iostream>
#include <sstream>

#include "Parser.h"

using namespace std;
int Parser::_lineNumber = 0;
char Parser::comment = ';';
char Parser::open = '(';
char Parser::close = ')';

List *Parser::parse(std::string filename)
{
        ifstream in(filename.c_str());
        return parse(in);
}

List *Parser::parse(std::istream& in)
{
        _lineNumber = 0;
        getNext(in);
        return parseOpen(in);
}

List *Parser::parseOpen(std::istream &in)
{
        List *newList = new List(_lineNumber);
        string next = getNext(in);
        while(next[0] != close) {
                if(next[0] == open)
                        newList->snoc(parseOpen(in));
        else
                    newList->snoc(new Atom(string(next),_lineNumber));
                next = getNext(in);
        }
        return newList;
}

std::string Parser::getNext(std::istream& in)
{       
        consumeWhitespaceAndComments(in);

        if(!in)
                return "";

        string next;
        char c;

        in.get(c);
        do {
                if(c == '"')
                        return readString(in);

                next += c;
                if(c == open || c == close) {
                        in.get(c);
                        break;
                }
                in.get(c);
        } while(!isspace(c) && c!= comment && c != open && c != close);
        in.putback(c);

        return next;
}

void Parser::consumeWhitespaceAndComments(std::istream& in)
{
        char c;
        in.get(c);
        while(isspace(c) || c == comment) {
                if(!in)
                        break;
                if(c == '\n')
                        _lineNumber ++;
                if(c == comment) {
                        while(c != '\n') {
                                if(!in)
                                        break;
                                in.get(c);
                        }
                        _lineNumber++;
                }
                in.get(c);
        }

        in.putback(c);
}

std::string Parser::readString(std::istream& in)
{
        string next;
        char c;
        in.get(c);
        while(c != '"') {
                next += c;
                in.get(c);
        }

        return next;
}

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