If Else Parser

grammer.pegjs

/*
/*
 * Simple Selection Grammar
 * ==========================
 * Simple IF ELSE Statement
 */
{
var time = 1;

function drawLine(line){
	
   setTimeout(function(){
   	highlightLine(line.lineNumber);
	insertTextAtCursor(line.evaluated, line.lineNumber);
	console.log('line '+line.lineNumber +' is getting processed, result is: '+line.evaluated);
   }, 1000 * time)	

time++;

}

}


start
 = statement*

statement 
  =	if_statement
  / item:block_item {drawLine(item); return item;} 

if_statement
  = "if(" _ exp:expression_statement  _ ")" _ c1:(compound_statement / (nl block_item)) _ nl _ 
  c2: ("else" _ (compound_statement / (nl block_item)))?
  {
  	drawLine(exp);
    
  	if(exp.evaluated){
    	var lines = (c1[0] == null) ? c1[1] : c1;
        if(lines.constructor.name == "Array")
         for(var i=0; i < lines.length; i++)
             drawLine(lines[i])
        else
             drawLine(lines)
		
    	return lines;
    }
    else if(c2){
    	var lines = (c2[2][0] == null) ? c2[2][1] : c2[2];
        if(lines.constructor.name == "Array")
          for(var i=0; i < lines.length; i++)
               drawLine(lines[i])
        else
            drawLine(lines)   
        
    	return lines;
    }
    return 'false returned if statement'; 
}

compound_statement
 = nl _'{' b:block_item_list '}' nl {
		var loc = location(); 
        
       //console.log('block started at line '+loc.start.line);
       return b
   }

block_item_list	
 = bl:(nl block_item nl)* {var bl2 = bl.map(function(value,index) { return value[1]; });
 	return bl2;
 }

block_item
 = print_statement
 / expression_statement

print_statement = "print" _ n:name _ comment? nl
{ return eval(n); }

expression_statement = _ t:term (expression_statement)* _ nl{
	var temp = eval(t) 

	if(temp.toString() == "[object Object]")
		return t;
	else
 	 	return {'evaluated': eval(t), lineNumber: location().start.line}; // evaluate it, then return it       
} 

term = f1:factor f2:(_ ("*" / "+" / "/" / "-" / operator) _ factor)* 
{
	var text = f1+' ';
    if(f2[0])
	    text += f2[0][1] + ' ' + f2[0][3];
	return text;
}
    
factor = "(" expression_statement ")" 
	   / name
       / integer 

///// Name = Variable

name = l:letter i:integer {return l+i}
     / l:letter {return l;} 

letter "letter" 
  = [a-z]+ {return text()} 

integer "integer"
  = [0-9]+ { return parseInt(text(), 10); }

_ "whitespace"
  = [ \t\r]* {return null;}
  
nl "newline"
  = [\n]* {return null;}
  
comment 
  = "//" _ [a-zA-Z0-9 ]* _ nl
  
operator
  = operator_text / operator_symbol
  
operator_text
  = "and"					{ return "&&"; }
	/ "or"					{ return "||"; }
	/ "smaller"				{ return "<="; }
	/ "smaller or equal"			{ return "<="; }
	/ "greater"	 			{ return ">="; }
	/ "greater or equal" 			{ return ">="; }
	/ "equal"				{ return "=="; }
	/ "not equal"				{ return "!="; }  
  
operator_symbol
  = "&&"					{ return text(); }
	/ "||"					{ return text(); }
	/ "<="					{ return text(); }
	/ "<"					{ return text(); }
	/ ">="					{ return text(); }
	/ ">"					{ return text(); }
	/ "=="					{ return text(); }
	/ "!="					{ return text(); }