Reorganized File Structure

Added Documentation

MathKit/MPVariable.m

@@ -0,0 +1,36 @@
+//
+//  MPVariable.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 09.10.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPVariable.h"
+
+#import "MPParsedExpression.h"
+
+#import "MPToken.h"
+
+#import "MPExpression.h"
+#import "MPEvaluationContext.h"
+
+@implementation MPVariable
+
+- (instancetype)initWithVariableName:(NSString *)variableName
+{
+    self = [super init];
+    if (self) {
+        NSAssert(variableName != nil, @"variableName must not be nil.");
+        _variableName = variableName;
+    }
+    return self;
+}
+
+- (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
+{
+    return [self valueForVariable:self.variableName
+                            error:error];
+}
+
+@end