#include "mathparser.h"


//** PARSER CONSTRUCTORS **//
MathParser::MathParser() 
  : Parser()
{}

MathParser::MathParser(const string& userInput)
  : Parser(userInput)
{
    StripWhite(myInput); 
}

MathParser::MathParser(const int& index)
  : Parser(index)
{
    //NOTE: must be careful here because if
    //user creates a parser class and then
    //modifies the myInput, StripWhite must be run on it
    //at some point in time to prevent program crashes
    //during runtime
}

MathParser::MathParser(const string& userInput, const int& index)
  : Parser(userInput, index)
{
    StripWhite(myInput); 
}


void MathParser::makeVariable()
{ 
    while (isalpha(myInput[myIndex]) && myInput[myIndex] != '=')
    {
        token += myInput[myIndex];
        myIndex++;    
    }
}


void MathParser::makeNum ()
{
    while (isdigit(myInput[myIndex]))
    {
        token += myInput[myIndex];
        myIndex++;    
    }
}


bool MathParser::isParen()
{
    return (myInput[myIndex]=='(' || myInput[myIndex]==')');
}


bool MathParser::isAssign()
{
    return (myInput[myIndex]=='=');    
}


bool MathParser::isOp()
{
    return (myInput[myIndex]=='-' || myInput[myIndex]=='+' || myInput[myIndex]=='*' || myInput[myIndex]=='/' || myInput[myIndex]=='%');
}


void MathParser::nextToken ()
{
    token = "";
    
 //absolute value
 if(LowerString(myInput.substr(myIndex,3))=="sab")
 {
  token += LowerString(myInput.substr(myIndex,3));
  myIndex+=3;    
  return;
 }
 
 //square root
 else if(LowerString(myInput.substr(myIndex,4))=="sqrt")
 {
  token += LowerString(myInput.substr(myIndex,4));
  myIndex+=4;    
  return;
 }
 
 //sum
  else if(LowerString(myInput.substr(myIndex,3))=="sum")
 {
  token += LowerString(myInput.substr(myIndex,3));
  myIndex+=3;    
  return;
 }
 
 //average
 else if(LowerString(myInput.substr(myIndex,7))=="average")
 {
  token += LowerString(myInput.substr(myIndex,7));
  myIndex+=7;    
  return;
 }
 
 //mean
 else if(LowerString(myInput.substr(myIndex,4))=="mean")
 {
  token += LowerString(myInput.substr(myIndex,4));
  myIndex+=4;    
  return;
 }
  
 //makes a variable    
 if(isalpha(myInput[myIndex]))
 {    
     makeVariable();     
     return; 
 } 
 
 //makes a number out of digit chars      
 else if(isdigit(myInput[myIndex]))
 {    
     makeNum();
     return;
 } 
 
 else if(isAssign())
 {
  token += myInput[myIndex];
  myIndex++;     
 }
 
 else if(isParen())
 {
  token += myInput[myIndex];
  myIndex++;     
 }
 
 else if(isOp())
 {
  token += myInput[myIndex];
  myIndex++;     
 }
}