#include <stdio.h>
#include <stdlib.h>

#include "lex.h"
#include "stack.h"


void skipLine();
void binop(int op);
int calc();

int main()
{
  return calc();
}

int calc()
{
  int token;
  while( (token = lex()) != EOF){
    switch(token){
    case '\n':
      printStack();
      break;
    case NUMBER:
      push(val);
      break;
    case POP:
      if( !isStackEmpty() ) pop();
      break;
    case POPALL:
      emptyStack();
      break;
    case UNKNOWN:
      printf("lex error skipping till end of the line\n");
      break;
    default:
      binop(token);
    } /* switch */
  }/* while */
  return 0;
}


   
void binop(int op)
{
  long double a,b;
  if( isStackEmpty() ){
    printf("stack underfull\n");
    skipLine();
    return;
  } 

  b = pop();
 
  if( isStackEmpty() ){
    printf("stack underfull\n");
    push(b);
    return;
  }
  a = pop();

  switch(op){
  case '+' : push(a+b); break;
  case '-' : push(a-b); break;
  case '*' : push(a*b); break;
  case '/' : push(a/b); break;
  }
  return;
}



void skipLine()
{
  int token;
  while( (token = lex()) != EOF && token != '\n');
}