Internal Redesign:

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

MathPad/MPLayout.h

@@ -0,0 +1,56 @@
+//
+//  MPDrawable.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 07.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+@import Cocoa;
+#import "MPExpressionStorage.h"
+
+#define MPNull [NSNull null]
+
+@interface MPLayout : NSObject
+
+#pragma mark Creation Methods
+- (instancetype)init;
+- (instancetype)initWithPath:(NSIndexPath *)path
+                      parent:(MPLayout *)parent;
+
+#pragma mark Text System Objects
+@property (readonly, nonatomic, weak) MPExpressionStorage *expressionStorage;
+@property (readonly, nonatomic, weak) NSLayoutManager *layoutManager;
+@property (readonly, nonatomic, weak) NSTextContainer *textContainer;
+@property (readonly, nonatomic, weak) NSTextStorage *textStorage;
+
+#pragma mark Cache Tree
+@property (readonly, nonatomic, weak) MPLayout *parent;
+@property (readonly, nonatomic, strong) NSIndexPath *path;
+
+#pragma mark Cache Methods
+// Querying Caches
+- (id)cachableObjectForIndex:(NSUInteger)index
+                   generator:(id(^)())generator;
+
+// Clearing Caches
+- (void)clearCacheInRange:(NSRange)range
+        replacementLength:(NSUInteger)replacementLength;
+- (void)invalidate;
+
+#pragma mark Calculation and Drawing Methods
+// @property (nonatomic) BOOL usesSmallSize;
+- (NSSize)size;
+
+- (NSBezierPath *)bezierPath;
+- (NSBezierPath *)bezierPathAtOrigin:(NSPoint)point;
+
+- (void)drawAtPoint:(NSPoint)point;
+
+@end
+
+@interface MPLayout (MPSubclassImplement)
+- (MPLayout *)childLayoutAtIndex:(NSUInteger)index; // To be implemented
+- (NSSize)sizeForChildAtIndex:(NSUInteger)index; // To be implemented
+- (NSBezierPath *)generateBezierPath; // To be implemented
+@end