Drastic Simplification of MPFunction subclass implementations

MathPad/MPFunction.m

@@ -24,6 +24,12 @@
 {
     self = [super init];
     if (self) {
+        for (NSString *key in self.childrenAccessors) {
+            MPExpression *emptyExpression = [[MPExpression alloc] init];
+            emptyExpression.parent = self;
+            [self setValue:emptyExpression
+                    forKey:key];
+        }
     }
     return self;
 }
@@ -42,17 +48,18 @@
 
 - (NSUInteger)numberOfChildren
 {
-    return 0;
+    return self.childrenAccessors.count;
 }
 
 - (MPExpression *)childAtIndex:(NSUInteger)index
 {
-    return nil;
+    return [self valueForKey:self.childrenAccessors[index]];
 }
 
 - (void)setChild:(MPExpression *)child
          atIndex:(NSUInteger)index
 {
+    [self setValue:child forKey:self.childrenAccessors[index]];
     [self didChangeChildAtIndex:index];
 }
 
@@ -86,12 +93,6 @@
     return [child elementAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
 }
 
-#pragma mark Evaluating Functions
-- (MPTerm *)parseWithError:(MPParseError *__autoreleasing *)error
-{
-    return nil;
-}
-
 #pragma mark Notifications
 - (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
                    replacementLength:(NSUInteger)replacementLength
@@ -102,11 +103,6 @@
                             replacementLength:replacementLength];
 }
 
-- (void)didChangeChild:(MPExpression *)child
-{
-    [self didChangeChildAtIndex:[self indexOfChild:child]];
-}
-
 - (void)didChangeChildAtIndex:(NSUInteger)index
 {
     MPRangePath *path = [[MPRangePath alloc] initWithRange:NSMakeRange(index, 1)];
@@ -142,13 +138,19 @@
 
 - (NSUInteger)hash
 {
+#warning Unimplemented Method
     return 0;
 }
 
 #pragma mark - NSCopying
 - (id)copyWithZone:(NSZone *)zone
 {
-    return [[MPFunction allocWithZone:zone] init];
+    id copy = [[self.class allocWithZone:zone] init];
+    for (NSString *key in self.childrenAccessors) {
+        MPExpression *child = [[self valueForKey:key] copy];
+        [copy setValue:child forKey:key];
+    }
+    return copy;
 }
 
 #pragma mark - NSCoding