Reorganized File Structure

Added Documentation

MathKit/MPProductTerm.m

@@ -0,0 +1,49 @@
+//
+//  MPProductTerm.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 15.11.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPProductTerm.h"
+
+#import "MPParsedExpression.h"
+#import "MPPowerFunction.h"
+
+#import "MPFunctionTerm.h"
+#import "MPElementaryFunctionTerm.h"
+#import "MPNumber.h"
+#import "MPFactorialTerm.h"
+#import "MPPowerTerm.h"
+#import "MPVariable.h"
+
+#import "MPToken.h"
+
+@implementation MPProductTerm
+
+- (instancetype)initWithFactors:(NSArray *)factors
+{
+    self = [super init];
+    if (self) {
+        NSAssert(factors != nil, @"factors must not be nil.");
+        NSAssert(factors.count > 0, @"factors must not be empty.");
+        _factors = factors;
+    }
+    return self;
+}
+
+- (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
+{
+    NSDecimalNumber *value = [NSDecimalNumber one];
+    for (MPTerm *factor in self.factors) {
+        NSDecimalNumber *currentValue = [factor evaluate:error];
+        if (!currentValue) {
+            return nil;
+        }
+        value = [value decimalNumberByMultiplyingBy:currentValue];
+    }
+    return value;
+}
+
+@end