Internal Redesign:

- Combined MPExpression and MPMutableExpression
- Abstracted children of MPExpression into MPExpressionElement protocol
- Abstracted most of MPExpressionLayout and MPFunctionLayout into common superclass MPLayout

MathPad/NSIndexPath+MPAdditions.m

@@ -0,0 +1,37 @@
+//
+//  NSIndexPath+MPRemoveFirstIndex.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 23.04.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "NSIndexPath+MPAdditions.h"
+
+@implementation NSIndexPath (MPAdditions)
+
+- (NSIndexPath *)indexPathByRemovingFirstIndex
+{
+    if (self.length <= 1) {
+        return [[NSIndexPath alloc] init];
+    }
+    NSUInteger indexes[self.length];
+    [self getIndexes:indexes];
+    NSUInteger newIndexes[self.length-1];
+    for (NSUInteger i = 0; i < self.length-1; i++) {
+        newIndexes[i] = indexes[i+1];
+    }
+    return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length-1];
+}
+
+- (NSIndexPath *)indexPathByPreceedingIndex:(NSUInteger)index
+{
+    NSUInteger newIndexes[self.length+1];
+    newIndexes[0] = index;
+    for (NSUInteger i = 0; i < self.length; i++) {
+        newIndexes[i+1] = [self indexAtPosition:i];
+    }
+    return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length+1];
+}
+
+@end