Implement Node.treeRoot

third_party/WebKit/Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 432 matching lines @@
             return last;
         last = currentElement->lastChild();
         if (!last)
             last = currentElement->pseudoElement(BEFORE);
         return last;
     }
 
     return lastChild();
 }
 
+Node* Node::treeRoot()
+{
+    Node* node = this;
+    while (!isTreeScopeRoot(node)) {

[kochi, 2016/01/27 09:18:50]

style nit: if the loop body is one-liner, you have to omit enclosing {}.

(probably fixed code doesn't have one-line body though.)

[kochi, 2016/01/27 09:18:50]

You can get its treeroot by treeScope().rootNode() in O(1) time, and
that is why we want this API exposed to JavaScript, otherwise JavaScript
code can do the same but in O(depth) time.

[yuzuchan, 2016/01/28 06:23:56]

Done.

[yuzuchan, 2016/01/28 06:23:56]

Done.

+        node = node->parentNode();

[kochi, 2016/01/27 09:18:50]

This doesn't work for detached tree (i.e. not in document
or shadow root).

If node->parentNode() returns null, you should return the node
as treeRoot, but this code goes to next iteration and exits the
loop in !isTreeScopeRoot() check (which checks !node) with node == nullptr.

[yuzuchan, 2016/01/28 06:23:56]

Done.

+    }
+    return node;
+}
+
 PassRefPtrWillBeRawPtr<Node> Node::insertBefore(PassRefPtrWillBeRawPtr<Node> newChild, Node* refChild, ExceptionState& exceptionState)
 {
     if (isContainerNode())
         return toContainerNode(this)->insertBefore(newChild, refChild, exceptionState);
 
     exceptionState.throwDOMException(HierarchyRequestError, "This node type does not support this method.");
     return nullptr;
 }
 
 PassRefPtrWillBeRawPtr<Node> Node::replaceChild(PassRefPtrWillBeRawPtr<Node> newChild, PassRefPtrWillBeRawPtr<Node> oldChild, ExceptionState& exceptionState)
@@ skipping 1940 matching lines @@
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
     else
         fprintf(stderr, "Cannot showNodePath for (nil)\n");
 }
 
 #endif