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Parser.cpp
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Parser.cpp
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//
// Created by Kalyan Khandrika on 3/8/17.
//
#include "Parser.h"
#include "Token.h"
#include "Evaluator.h"
using namespace std;
#include <iostream>
Parser::Parser() {
cout<<"<Program Started>"<<endl;
lexer.loadNextToken();
SExpression::InitializeDefaultSymbolizAtoms();
Evaluator evaluator;
SExpression * Alist = SExpression::symbolicAtom("NIL");
SExpression * pDList = SExpression::symbolicAtom("NIL");
SExpression ** Dlist = &pDList;
while (lexer.checkNextToken().getType() != ENDOFINPUT){
try{
// cout<<"Here";
SExpression * outputExp = NULL;
if(lexer.checkNextToken().getType() != ENDOFLINE ){
if(lexer.checkNextToken().getType() == ENDOFINPUT) break;
outputExp = inputRoutine1();
}
if(lexer.checkNextToken().getType() == ENDOFLINE|| lexer.checkNextToken().getType() == ENDOFINPUT) {
string outString = stringifySExpression(outputExp);
cout << "Dot notation>" << outString << endl;
outputExp = evaluator.eval(outputExp,Alist,Dlist);
outString = stringifySExpression(outputExp);
cout << ">" << outString << endl;
if(lexer.checkNextToken().getType() == ENDOFINPUT)
break;
//cout <<"Input:";
lexer.skipNextToken();
}
else
throw std::runtime_error(">Error:: Invalid token after valid s-expression:"+lexer.checkNextToken().getToken());
}
catch (const runtime_error& error) {
//cout<<"In catch, token:"<<checkNextToken().getToken()<<endl;
std::cout << error.what() << endl;
bool bIgnoredChars = false;
if(lexer.checkNextToken().getType() != ENDOFLINE && lexer.checkNextToken().getType() != ENDOFINPUT){
cout<<"Ignoring characters:";
bIgnoredChars = true;
}
while(lexer.checkNextToken().getType() != ENDOFLINE){
if(lexer.checkNextToken().getType() == ENDOFINPUT) break;
cout<<lexer.checkNextToken().getToken()<<",";
lexer.skipNextToken(true);
}
if(bIgnoredChars)
cout<<endl;
if(lexer.checkNextToken().getType() == ENDOFLINE)
lexer.skipNextToken(true);
//cout<<"end of catch"<<endl;
}
}
cout<<"<End of program>"<<endl;
}
Parser::~Parser() {
SExpression::DeleteSymbolicAtoms();
}
/***
* Grammar:
* <ls> :== <IR1>
* <IR1> :== INT | ID | ( <IR1> . <IR1> ) | ( <IR1><IR2> | ()
* <IR2> :== ) | [SPACE]<IR1><IR2>
* @return
*/
// Corresponding to grammar: <ls> :== <IR1>
SExpression* Parser::inputRoutine1() {
Token token = lexer.checkNextToken();
//<IR1> :== ( <IR1> . <IR1> ) | ( <IR1><IR2> | ()
if (token.getType() == OPENBRACE){
Token token = lexer.checkNextToken();
lexer.skipNextToken();
////<IR1> :== ()
if(lexer.checkNextToken().getType() == CLOSEBRACE)
return inputRoutine2();
SExpression * newExpression = new SExpression(NONATOM);
SExpression * leftExpression = inputRoutine1();
newExpression->setLeft(leftExpression);
SExpression * rightExpression;
Token nexttoken = lexer.checkNextToken();
//<IR1> :== ( <IR1> .
if(nexttoken.getType() == DOT){
lexer.skipNextToken();
//<IR1> :== ( <IR1> . <IR1>
rightExpression = inputRoutine1();
nexttoken = lexer.checkNextToken();
//<IR1> :== ( <IR1> . <IR1> )
if(nexttoken.getType() != CLOSEBRACE){
throw std::runtime_error(">Error::Expected ')' ,found "+nexttoken.getToken() );
return NULL;
}
else
{
lexer.skipNextToken();
}
}
//<IR1> :== ( <IR1><IR2>
else {
rightExpression = inputRoutine2();
}
newExpression->setRight(rightExpression);
return newExpression;
}
// <IR1> :== ID
else if(token.getType() == IDENTIFIER){
lexer.skipNextToken();
return SExpression::symbolicAtom(token.getToken());
}
// <IR1> :== INT
else if(token.getType() == INTEGER){
//cout<<"INT"<<token.getToken()<<endl;
SExpression * newIntegerExpression = new SExpression(INTEGERATOM);
newIntegerExpression->setVal(stoi(token.getToken()));
lexer.skipNextToken();
return newIntegerExpression;
}
else{
throw std::runtime_error(">Error:: Invalid token in s-expression:"+token.getToken());
//ERROR
}
}
//<IR2> :== ) | [SPACE]<IR1><IR2>
SExpression* Parser::inputRoutine2() {
Token token = lexer.checkNextToken();
//<IR2> :== )
if(token.getType() == CLOSEBRACE){
lexer.skipNextToken();
return SExpression::symbolicAtom("NIL");
}
//<IR2> :== [SPACE]<IR1><IR2>
else if(token.getType() == SPACE){
lexer.skipNextToken();
SExpression * newExpression = new SExpression(NONATOM);
newExpression->setLeft(inputRoutine1());
newExpression->setRight(inputRoutine2());
return newExpression;
}
else{
throw std::runtime_error(">Error:: Invalid token in s-expression:"+token.getToken());
return NULL;
}
}
string Parser::stringifySExpression(SExpression * exp){
string outString;
switch(exp->getType()){
case NONATOM:
outString+= '(';
outString += stringifySExpression(exp->getLeft());
outString += '.';
outString += stringifySExpression(exp->getRight());
outString += ')';
break;
case INTEGERATOM:
outString += to_string(exp->getVal());
break;
case SYMBOLICATOM:
outString += exp->getName();
break;
default:
break;
}
return outString;
}