tor-browser

TreeWalker.cpp (8347B)

---

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=4 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
* Implementation of DOM Traversal's TreeWalker
*/

#include "mozilla/dom/TreeWalker.h"

#include "mozilla/dom/NodeFilterBinding.h"
#include "mozilla/dom/TreeWalkerBinding.h"
#include "nsContentUtils.h"
#include "nsError.h"
#include "nsIContent.h"
#include "nsINode.h"

namespace mozilla::dom {

/*
* Factories, constructors and destructors
*/

TreeWalker::TreeWalker(nsINode* aRoot, uint32_t aWhatToShow,
                      NodeFilter* aFilter)
   : nsTraversal(aRoot, aWhatToShow, aFilter), mCurrentNode(aRoot) {}

TreeWalker::~TreeWalker() { /* destructor code */ }

/*
* nsISupports and cycle collection stuff
*/

NS_IMPL_CYCLE_COLLECTION(TreeWalker, mFilter, mCurrentNode, mRoot)

// QueryInterface implementation for TreeWalker
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TreeWalker)
 NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

// Have to pass in dom::TreeWalker because a11y has an a11y::TreeWalker that
// passes TreeWalker so refcount logging would get confused on the name
// collision.
NS_IMPL_CYCLE_COLLECTING_ADDREF(dom::TreeWalker)
NS_IMPL_CYCLE_COLLECTING_RELEASE(dom::TreeWalker)

void TreeWalker::SetCurrentNode(nsINode& aNode, ErrorResult& aResult) {
 aResult = nsContentUtils::CheckSameOrigin(mRoot, &aNode);
 if (aResult.Failed()) {
   return;
 }

 mCurrentNode = &aNode;
}

already_AddRefed<nsINode> TreeWalker::ParentNode(ErrorResult& aResult) {
 nsCOMPtr<nsINode> node = mCurrentNode;

 while (node && node != mRoot) {
   node = node->GetParentNode();

   if (node) {
     int16_t filtered = TestNode(node, aResult);
     if (aResult.Failed()) {
       return nullptr;
     }
     if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
       mCurrentNode = node;
       return node.forget();
     }
   }
 }

 return nullptr;
}

already_AddRefed<nsINode> TreeWalker::FirstChild(ErrorResult& aResult) {
 return FirstChildInternal(false, aResult);
}

already_AddRefed<nsINode> TreeWalker::LastChild(ErrorResult& aResult) {
 return FirstChildInternal(true, aResult);
}

already_AddRefed<nsINode> TreeWalker::PreviousSibling(ErrorResult& aResult) {
 return NextSiblingInternal(true, aResult);
}

already_AddRefed<nsINode> TreeWalker::NextSibling(ErrorResult& aResult) {
 return NextSiblingInternal(false, aResult);
}

already_AddRefed<nsINode> TreeWalker::PreviousNode(ErrorResult& aResult) {
 nsCOMPtr<nsINode> node = mCurrentNode;

 while (node != mRoot) {
   while (nsINode* previousSibling = node->GetPreviousSibling()) {
     node = previousSibling;

     int16_t filtered = TestNode(node, aResult);
     if (aResult.Failed()) {
       return nullptr;
     }

     nsINode* lastChild;
     while (filtered != NodeFilter_Binding::FILTER_REJECT &&
            (lastChild = node->GetLastChild())) {
       node = lastChild;
       filtered = TestNode(node, aResult);
       if (aResult.Failed()) {
         return nullptr;
       }
     }

     if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
       mCurrentNode = node;
       return node.forget();
     }
   }

   if (node == mRoot) {
     break;
   }

   node = node->GetParentNode();
   if (!node) {
     break;
   }

   int16_t filtered = TestNode(node, aResult);
   if (aResult.Failed()) {
     return nullptr;
   }

   if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
     mCurrentNode = node;
     return node.forget();
   }
 }

 return nullptr;
}

already_AddRefed<nsINode> TreeWalker::NextNode(ErrorResult& aResult) {
 int16_t filtered =
     NodeFilter_Binding::FILTER_ACCEPT;  // pre-init for inner loop

 nsCOMPtr<nsINode> node = mCurrentNode;

 while (1) {
   nsINode* firstChild;
   while (filtered != NodeFilter_Binding::FILTER_REJECT &&
          (firstChild = node->GetFirstChild())) {
     node = firstChild;

     filtered = TestNode(node, aResult);
     if (aResult.Failed()) {
       return nullptr;
     }

     if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
       // Node found
       mCurrentNode = node;
       return node.forget();
     }
   }

   nsINode* sibling = nullptr;
   nsINode* temp = node;
   do {
     if (temp == mRoot) break;

     sibling = temp->GetNextSibling();
     if (sibling) break;

     temp = temp->GetParentNode();
   } while (temp);

   if (!sibling) break;

   node = sibling;

   // Found a sibling. Either ours or ancestor's
   filtered = TestNode(node, aResult);
   if (aResult.Failed()) {
     return nullptr;
   }

   if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
     // Node found
     mCurrentNode = node;
     return node.forget();
   }
 }

 return nullptr;
}

/*
* TreeWalker helper functions
*/

/*
* Implements FirstChild and LastChild which only vary in which direction
* they search.
* @param aReversed Controls whether we search forwards or backwards
* @param aResult   Whether we threw or not.
* @returns         The desired node. Null if no child is found
*/
already_AddRefed<nsINode> TreeWalker::FirstChildInternal(bool aReversed,
                                                        ErrorResult& aResult) {
 nsCOMPtr<nsINode> node =
     aReversed ? mCurrentNode->GetLastChild() : mCurrentNode->GetFirstChild();

 while (node) {
   int16_t filtered = TestNode(node, aResult);
   if (aResult.Failed()) {
     return nullptr;
   }

   switch (filtered) {
     case NodeFilter_Binding::FILTER_ACCEPT:
       // Node found
       mCurrentNode = node;
       return node.forget();
     case NodeFilter_Binding::FILTER_SKIP: {
       nsINode* child =
           aReversed ? node->GetLastChild() : node->GetFirstChild();
       if (child) {
         node = child;
         continue;
       }
       break;
     }
     case NodeFilter_Binding::FILTER_REJECT:
       // Keep searching
       break;
   }

   do {
     nsINode* sibling =
         aReversed ? node->GetPreviousSibling() : node->GetNextSibling();
     if (sibling) {
       node = sibling;
       break;
     }

     nsINode* parent = node->GetParentNode();

     if (!parent || parent == mRoot || parent == mCurrentNode) {
       return nullptr;
     }

     node = parent;

   } while (node);
 }

 return nullptr;
}

/*
* Implements NextSibling and PreviousSibling which only vary in which
* direction they search.
* @param aReversed Controls whether we search forwards or backwards
* @param aResult   Whether we threw or not.
* @returns         The desired node. Null if no child is found
*/
already_AddRefed<nsINode> TreeWalker::NextSiblingInternal(
   bool aReversed, ErrorResult& aResult) {
 nsCOMPtr<nsINode> node = mCurrentNode;

 if (node == mRoot) {
   return nullptr;
 }

 while (1) {
   nsINode* sibling =
       aReversed ? node->GetPreviousSibling() : node->GetNextSibling();

   while (sibling) {
     node = sibling;

     int16_t filtered = TestNode(node, aResult);
     if (aResult.Failed()) {
       return nullptr;
     }

     if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
       // Node found
       mCurrentNode = node;
       return node.forget();
     }

     // If rejected or no children, try a sibling
     if (filtered == NodeFilter_Binding::FILTER_REJECT ||
         !(sibling =
               aReversed ? node->GetLastChild() : node->GetFirstChild())) {
       sibling =
           aReversed ? node->GetPreviousSibling() : node->GetNextSibling();
     }
   }

   node = node->GetParentNode();

   if (!node || node == mRoot) {
     return nullptr;
   }

   // Is parent transparent in filtered view?
   int16_t filtered = TestNode(node, aResult);
   if (aResult.Failed()) {
     return nullptr;
   }
   if (filtered == NodeFilter_Binding::FILTER_ACCEPT) {
     return nullptr;
   }
 }
}

bool TreeWalker::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
                           JS::MutableHandle<JSObject*> aReflector) {
 return TreeWalker_Binding::Wrap(aCx, this, aGivenProto, aReflector);
}

}  // namespace mozilla::dom