Added Documentation

MathPad/MPFunction.m

@@ -12,9 +12,13 @@
 #import "MPRangePath.h"
 #import "NSIndexPath+MPAdditions.h"
 
+
+
 @implementation MPFunction
 
 #pragma mark Creation Methods
+
+
 - (instancetype)init
 {
     self = [super init];
@@ -29,35 +33,49 @@
     return self;
 }
 
+
 #pragma mark Working With the Expression Tree
+
+
 - (MPExpression *)rootExpression
 {
     return [self.parent rootExpression];
 }
 
+
 - (NSIndexPath *)indexPath
 {
+    if (!self.parent) {
+        return nil;
+    }
     NSUInteger selfIndex = [self.parent indexOfElement:self];
     return [[self.parent indexPath] indexPathByAddingIndex:selfIndex];
 }
 
+
 - (NSUInteger)numberOfChildren
 {
     return self.childrenAccessors.count;
 }
 
+
 - (MPExpression *)childAtIndex:(NSUInteger)index
 {
     return [self valueForKey:self.childrenAccessors[index]];
 }
 
+
 - (void)setChild:(MPExpression *)child
          atIndex:(NSUInteger)index
 {
-    [self setValue:child forKey:self.childrenAccessors[index]];
+    [[self valueForKey:self.childrenAccessors[index]] setParent:nil];
+    [self setValue:child
+            forKey:self.childrenAccessors[index]];
+    child.parent = self;
     [self didChangeChildAtIndex:index];
 }
 
+
 - (NSArray *)children
 {
     NSUInteger childCount = [self numberOfChildren];
@@ -68,8 +86,10 @@
     return [children copy];
 }
 
+
 - (NSUInteger)indexOfChild:(MPExpression *)child
 {
+    
     NSUInteger index = 0;
     for (; index < [self numberOfChildren]; index++) {
         if ([self childAtIndex:index] == child) {
@@ -79,6 +99,7 @@
     return NSNotFound;
 }
 
+
 - (id)elementAtIndexPath:(NSIndexPath *)indexPath
 {
     if (indexPath.length == 0) {
@@ -88,7 +109,10 @@
     return [child elementAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
 }
 
+
 #pragma mark Notifications
+
+
 - (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
                    replacementLength:(NSUInteger)replacementLength
 {
@@ -98,6 +122,7 @@
                             replacementLength:replacementLength];
 }
 
+
 - (void)didChangeChildAtIndex:(NSUInteger)index
 {
     MPRangePath *path = [[MPRangePath alloc] initWithRange:NSMakeRange(index, 1)];
@@ -105,39 +130,26 @@
                      replacementLength:1];
 }
 
-#pragma mark Working With Functions
-/*
-- (BOOL)isEqual:(id)object
-{
-    if (self == object) {
-        return YES;
-    }
-    if (object == nil) {
-        return NO;
-    }
-    if (![object isKindOfClass:[MPFunction class]]) {
-        return NO;
-    }
-    return [self isEqualToFunction:(MPFunction *)object];
-}
 
-- (BOOL)isEqualToFunction:(MPFunction *)aFunction
-{
-    return [aFunction isMemberOfClass:[MPFunction class]] && [self isMemberOfClass:[MPFunction class]];
-}*/
+#pragma mark Working With Functions
+
 
 - (NSString *)description
 {
     return @"[]";
 }
 
+
 - (NSUInteger)hash
 {
 #warning Unimplemented Method
     return 0;
 }
 
+
 #pragma mark - NSCopying
+
+
 - (id)copyWithZone:(NSZone *)zone
 {
     id copy = [[self.class allocWithZone:zone] init];
@@ -148,7 +160,10 @@
     return copy;
 }
 
+
 #pragma mark - NSCoding
+
+
 - (id)initWithCoder:(NSCoder *)aDecoder
 {
     self = [super init];
@@ -163,22 +178,28 @@
     return self;
 }
 
+
 - (void)encodeWithCoder:(NSCoder *)aCoder
 {
     [aCoder encodeObject:self.children];
 }
 
+
 #pragma mark - MPExpressionElement
+
+
 - (BOOL)isString
 {
     return NO;
 }
 
+
 - (BOOL)isFunction
 {
     return YES;
 }
 
+
 - (NSUInteger)length
 {
     return 1;