Add methods to attach Node Iterators to the owner document node of the iterator's root

This is a prerequisite to implement the iterator's removing steps.
https://dom.spec.whatwg.org/#interface-nodeiterator

HTMLKit/HTMLDocument.m

@@ -18,6 +18,7 @@
 @interface HTMLDocument ()
 {
 	HTMLDocument *_inertTemplateDocument;
+	NSMutableArray *_nodeIterators;
 }
 @property (nonatomic, assign) HTMLDocumentReadyState readyState;
 @end
@@ -37,6 +38,7 @@
 	self = [super initWithName:@"#document" type:HTMLNodeDocument];
 	if (self) {
 		_readyState = HTMLDocumentLoading;
+		_nodeIterators = [NSMutableArray new];
 	}
 	return self;
 }
@@ -64,6 +66,18 @@
 	}
 }
 
+#pragma mark - Node Iterators
+
+- (void)attachNodeIterator:(HTMLNodeIterator *)iterator
+{
+	[_nodeIterators addObject:iterator];
+}
+
+- (void)detachNodeIterator:(HTMLNodeIterator *)iterator
+{
+	[_nodeIterators removeObject:iterator];
+}
+
 #pragma mark - Mutation Algorithms
 
 - (HTMLNode *)adoptNode:(HTMLNode *)node

HTMLKit/HTMLNodeIterator.m

@@ -7,6 +7,7 @@
 //
 
 #import "HTMLNodeIterator.h"
+#import "HTMLDocument.h"
 #import "HTMLNode.h"
 
 typedef NS_ENUM(short, TraverseDirection)
@@ -15,6 +16,11 @@ typedef NS_ENUM(short, TraverseDirection)
 	TraverseDirectionPrevious
 };
 
+@interface HTMLDocument (Private)
+- (void)attachNodeIterator:(HTMLNodeIterator *)iterator;
+- (void)detachNodeIterator:(HTMLNodeIterator *)iterator;
+@end
+
 @interface HTMLNodeIterator ()
 {
 	HTMLNode *_root;
@@ -23,6 +29,8 @@ typedef NS_ENUM(short, TraverseDirection)
 
 @implementation HTMLNodeIterator
 
+#pragma mark - Lifecycle
+
 - (instancetype)initWithNode:(HTMLNode *)node
 {
 	return [self initWithNode:node filter:nil];
@@ -45,10 +53,18 @@ typedef NS_ENUM(short, TraverseDirection)
 		_whatToShow = showOptions;
 		_referenceNode = _root;
 		_pointerBeforeReferenceNode	= YES;
+		[_root.ownerDocument attachNodeIterator:self];
 	}
 	return self;
 }
 
+- (void)dealloc
+{
+	[_root.ownerDocument detachNodeIterator:self];
+}
+
+#pragma mark - Traversal
+
 - (HTMLNode *)traverseInDirection:(TraverseDirection)direction
 {
 	HTMLNode *node = self.referenceNode;
@@ -129,11 +145,6 @@ NS_INLINE HTMLNodeFilterValue FilterNode(HTMLNodeIterator *iterator, HTMLNode *n
 	return [iterator.filter acceptNode:node];
 }
 
-- (id)nextObject
-{
-	return self.nextNode;
-}
-
 - (HTMLNode *)nextNode
 {
 	return [self traverseInDirection:TraverseDirectionNext];
@@ -144,4 +155,11 @@ NS_INLINE HTMLNodeFilterValue FilterNode(HTMLNodeIterator *iterator, HTMLNode *n
 	return [self traverseInDirection:TraverseDirectionPrevious];
 }
 
+#pragma mark - NSEnumerator
+
+- (id)nextObject
+{
+	return self.nextNode;
+}
+
 @end