Improved Model

Added Keyboard Selection Support
Added Mouse Selection Support
Added Keyboard Editing Support
Corrected Some Bugs
Abstracted the Layout System further
Added Functions Button (test)

MathPad/MPExpressionStorage.m

@@ -20,53 +20,20 @@
 
 @implementation MPExpressionStorage
 
-- (instancetype)initWithExpressionView:(MPExpressionView *)expressionView elements:(NSArray *)elements
-{
-    self = [self initWithElements:elements];
-    if (self) {
-        _expressionView = expressionView;
-    }
-    return self;
-}
-
 - (instancetype)initWithElements:(NSArray *)elements
 {
     self = [super initWithElements:elements];
     if (self) {
-        _rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpressionStorage:self];
+        _rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpression:self];
     }
     return self;
 }
 
-- (NSLayoutManager *)layoutManager
+- (void)setExpressionView:(MPExpressionView *)expressionView
 {
-    [self ensureTextSystemObjects];
-    return _layoutManager;
-}
-
-- (NSTextContainer *)textContainer
-{
-    [self ensureTextSystemObjects];
-    return _textContainer;
-}
-
-- (NSTextStorage *)textStorage
-{
-    [self ensureTextSystemObjects];
-    return _textStorage;
-}
-
-- (void)ensureTextSystemObjects
-{
-    if (_layoutManager == nil || _textContainer == nil || _textStorage == nil) {
-        _textStorage = [[NSTextStorage alloc] init];
-        NSTextContainer *textContainer = [[NSTextContainer alloc] initWithContainerSize:NSMakeSize(CGFLOAT_MAX, CGFLOAT_MAX)];
-        NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
-        [layoutManager addTextContainer:textContainer];
-        [_textStorage addLayoutManager:layoutManager];
-        _textContainer = textContainer;
-        _layoutManager = layoutManager;
-    }
+    _expressionView = expressionView;
+    self.rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpression:self];
+    self.rootLayout.flipped = expressionView.isFlipped;
 }
 
 - (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
@@ -76,11 +43,13 @@
         return;
     }
     MPLayout *current = self.rootLayout;
-    for (NSUInteger index = 1; index < rangePath.location.length-1; index++) {
+    for (NSUInteger position = 0; position < rangePath.location.length-1; position++) {
+        NSUInteger index = [rangePath.location indexAtPosition:position];
         current = [current childLayoutAtIndex:index];
     }
     [current clearCacheInRange:rangePath.rangeAtLastIndex
              replacementLength:replacementLength];
+    [self.expressionView invalidateIntrinsicContentSize];
     self.expressionView.needsDisplay = YES;
 }