CS193p Fall 2011 Assignment 2--Calculator Variables

gistfile1.m

+ (BOOL)isOperation:(NSString *)argument
{
    NSSet *operations = [NSSet setWithObjects:@"+",@"-",@"/",@"*",@"sin",@"cos",@"sqrt",@"pi",nil];
    if ([operations containsObject:argument])
        return YES;
    else
        return NO;
}

//Converts variables in program to their double value
//Then runs popOperandOffStack
+ (double)runProgram:(id)program 
 usingVariableValues:(NSDictionary *)variableValues
{
    NSMutableArray *stack;
    if ([program isKindOfClass:[NSArray class]]) {
        stack = [program mutableCopy]; 
    }
    
    for (int i=0; i<[stack count]; i++) {
        if ([[stack objectAtIndex:i] isKindOfClass:[NSString class]] && ![CalculatorBrain isOperation:[stack objectAtIndex:i]]) { //if YES then it is a variable. 
            NSString *variable = [stack objectAtIndex:i];
            [stack replaceObjectAtIndex:i withObject:[variableValues objectForKey:variable]];
        }
        }
    return [self popOperandOffProgramStack:stack];
}

//Returns set of NSString variables used in program
+ (NSMutableSet *)variablesUsedInProgram:(id)program
{
    NSMutableSet *set = [[NSMutableSet alloc] init];
    for (int i=0; i<[program count]; i++) {
        if ([[program objectAtIndex:i] isKindOfClass:[NSString class]]) {
            if ([CalculatorBrain isOperation:[program objectAtIndex:i]] != YES) {
                [set addObject:[program objectAtIndex:i]];
            } 
        }
    }
    if ([set count] == 0)
        return nil;
    else
        return set;
}