Bug 344258. Create nsReferencedElement to track which element is associated with a given ID. r+sr=jst

content/base/public/nsReferencedElement.h

@@ -0,0 +1,120 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=78: */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is Mozilla.org.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Robert O'Callahan   <robert@ocallahan.org>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef NSREFERENCEDELEMENT_H_
+#define NSREFERENCEDELEMENT_H_
+
+#include "nsIContent.h"
+#include "nsIAtom.h"
+#include "nsIDocument.h"
+#include "nsThreadUtils.h"
+#include "nsAutoPtr.h"
+
+class nsIURI;
+class nsCycleCollectionCallback;
+
+/**
+ * Class to track what content is referenced by a given ID.
+ * 
+ * By default this is a single-shot tracker --- i.e., when ContentChanged
+ * fires, we will automatically stop tracking. Override IsPersistent
+ * to return PR_TRUE if you want to keep tracking after the content for
+ * an ID has changed.
+ */
+class nsReferencedElement {
+public:
+  nsReferencedElement() {}
+  ~nsReferencedElement() {
+    Unlink();
+    if (mPendingNotification) {
+      mPendingNotification->Clear();
+    }
+  }
+  nsIContent* get() { return mContent; }
+
+  void Reset(nsIContent* aFrom, nsIURI* aURI, PRBool aWatch = PR_TRUE);
+  void Unlink();
+
+  void Traverse(nsCycleCollectionTraversalCallback* aCB);
+  
+protected:
+  /**
+   * Override this to be notified of content changes. Don't forget
+   * to call this method to change mContent.
+   */
+  virtual void ContentChanged(nsIContent* aFrom, nsIContent* aTo) {
+    mContent = aTo;
+  }
+
+  /**
+   * Override this to convert from a single-shot notification to
+   * a persistent notification.
+   */
+  virtual PRBool IsPersistent() { return PR_FALSE; }
+  
+private:
+  static PRBool Observe(nsIContent* aOldContent,
+                        nsIContent* aNewContent, void* aData);
+
+  class Notification : public nsRunnable {
+  public:
+    Notification(nsReferencedElement* aTarget, nsIContent* aFrom, nsIContent* aTo)
+      : mTarget(aTarget), mFrom(aFrom), mTo(aTo) {}
+    virtual nsresult Run() {
+      if (mTarget) {
+        mTarget->mPendingNotification = nsnull;
+        mTarget->ContentChanged(mFrom, mTo);
+      }
+      return NS_OK;
+    }
+    void SetTo(nsIContent* aTo) { mTo = aTo; }
+    void Clear() { mTarget = nsnull; mFrom = nsnull; mTo = nsnull; }
+  private:
+    nsReferencedElement* mTarget;
+    nsCOMPtr<nsIContent> mFrom;
+    nsCOMPtr<nsIContent> mTo;
+  };
+  friend class Notification;
+
+  nsCOMPtr<nsIAtom>      mWatchID;
+  nsCOMPtr<nsIDocument>  mWatchDocument;
+  nsCOMPtr<nsIContent>   mContent;
+  nsRefPtr<Notification> mPendingNotification;
+};
+
+#endif /*NSREFERENCEDELEMENT_H_*/

content/base/src/nsReferencedElement.cpp

@@ -0,0 +1,212 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=78: */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is Mozilla.org.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Robert O'Callahan   <robert@ocallahan.org>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "nsReferencedElement.h"
+#include "nsContentUtils.h"
+#include "nsIURI.h"
+#include "nsBindingManager.h"
+#include "nsIURL.h"
+#include "nsEscape.h"
+#include "nsXBLPrototypeBinding.h"
+#include "nsIDOMNode.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMElement.h"
+#include "nsCycleCollectionParticipant.h"
+
+static PRBool EqualExceptRef(nsIURL* aURL1, nsIURL* aURL2)
+{
+  nsCOMPtr<nsIURI> u1;
+  nsCOMPtr<nsIURI> u2;
+
+  nsresult rv = aURL1->Clone(getter_AddRefs(u1));
+  if (NS_SUCCEEDED(rv)) {
+    rv = aURL2->Clone(getter_AddRefs(u2));
+  }
+  if (NS_FAILED(rv))
+    return PR_FALSE;
+
+  nsCOMPtr<nsIURL> url1 = do_QueryInterface(u1);
+  nsCOMPtr<nsIURL> url2 = do_QueryInterface(u2);
+  if (!url1 || !url2) {
+    NS_WARNING("Cloning a URL produced a non-URL");
+    return PR_FALSE;
+  }
+  url1->SetRef(EmptyCString());
+  url2->SetRef(EmptyCString());
+
+  PRBool equal;
+  rv = url1->Equals(url2, &equal);
+  return NS_SUCCEEDED(rv) && equal;
+}
+
+void
+nsReferencedElement::Reset(nsIContent* aFromContent, nsIURI* aURI, PRBool aWatch)
+{
+  Unlink();
+
+  nsCOMPtr<nsIURL> url = do_QueryInterface(aURI);
+  if (!url)
+    return;
+
+  nsCAutoString refPart;
+  url->GetRef(refPart);
+  // Unescape %-escapes in the reference. The result will be in the
+  // origin charset of the URL, hopefully...
+  NS_UnescapeURL(refPart);
+
+  nsCAutoString charset;
+  url->GetOriginCharset(charset);
+  nsAutoString ref;
+  nsresult rv = nsContentUtils::ConvertStringFromCharset(charset, refPart, ref);
+  if (NS_FAILED(rv)) {
+    CopyUTF8toUTF16(refPart, ref);
+  }
+  if (ref.IsEmpty())
+    return;
+
+  // Get the current document
+  nsIDocument *doc = aFromContent->GetCurrentDoc();
+  if (!doc)
+    return;
+
+  // This will be the URI of the document the content belongs to
+  // (the URI of the XBL document if the content is anonymous
+  // XBL content)
+  nsCOMPtr<nsIURL> documentURL = do_QueryInterface(doc->GetDocumentURI());
+  nsIContent* bindingParent = aFromContent->GetBindingParent();
+  PRBool isXBL = PR_FALSE;
+  if (bindingParent) {
+    nsXBLBinding* binding = doc->BindingManager()->GetBinding(bindingParent);
+    if (binding) {
+      // XXX sXBL/XBL2 issue
+      // If this is an anonymous XBL element then the URI is
+      // relative to the binding document. A full fix requires a
+      // proper XBL2 implementation but for now URIs that are
+      // relative to the binding document should be resolve to the
+      // copy of the target element that has been inserted into the
+      // bound document.
+      documentURL = do_QueryInterface(binding->PrototypeBinding()->DocURI());
+      isXBL = PR_TRUE;
+    }
+  }
+  if (!documentURL)
+    return;
+
+  if (!EqualExceptRef(url, documentURL)) {
+    // Oops -- we don't support off-document references
+    return;
+  }
+
+  // Get the element
+  if (isXBL) {
+    nsCOMPtr<nsIDOMNodeList> anonymousChildren;
+    doc->BindingManager()->
+      GetAnonymousNodesFor(bindingParent, getter_AddRefs(anonymousChildren));
+
+    if (anonymousChildren) {
+      PRUint32 length;
+      anonymousChildren->GetLength(&length);
+      for (PRUint32 i = 0; i < length && !mContent; ++i) {
+        nsCOMPtr<nsIDOMNode> node;
+        anonymousChildren->Item(i, getter_AddRefs(node));
+        nsCOMPtr<nsIContent> c = do_QueryInterface(node);
+        if (c) {
+          mContent = nsContentUtils::MatchElementId(c, ref);
+        }
+      }
+    }
+    return;
+  }
+
+  if (aWatch) {
+    nsCOMPtr<nsIAtom> atom = do_GetAtom(ref);
+    if (!atom)
+      return;
+    atom.swap(mWatchID);
+    mWatchDocument = doc;
+    mContent = mWatchDocument->AddIDTargetObserver(mWatchID, Observe, this);
+    return;
+  }
+  
+  nsCOMPtr<nsIDOMDocument> domDoc = do_QueryInterface(doc);
+  NS_ASSERTION(domDoc, "Content doesn't reference a dom Document");
+
+  nsCOMPtr<nsIDOMElement> element;
+  rv = domDoc->GetElementById(ref, getter_AddRefs(element));
+  if (element) {
+    mContent = do_QueryInterface(element);
+  }
+}
+
+void
+nsReferencedElement::Traverse(nsCycleCollectionTraversalCallback* aCB)
+{
+  aCB->NoteXPCOMChild(mWatchDocument);
+  aCB->NoteXPCOMChild(mContent);
+}
+
+void
+nsReferencedElement::Unlink()
+{
+  if (mWatchDocument && mWatchID) {
+    mWatchDocument->RemoveIDTargetObserver(mWatchID, Observe, this);
+  }
+  mWatchDocument = nsnull;
+  mWatchID = nsnull;
+  mContent = nsnull;
+}
+
+PRBool
+nsReferencedElement::Observe(nsIContent* aOldContent,
+                             nsIContent* aNewContent, void* aData)
+{
+  nsReferencedElement* p = static_cast<nsReferencedElement*>(aData);
+  if (p->mPendingNotification) {
+    p->mPendingNotification->SetTo(aNewContent);
+  } else {
+    NS_ASSERTION(aOldContent == p->mContent, "Failed to track content!");
+    p->mPendingNotification = new Notification(p, aOldContent, aNewContent);
+    nsContentUtils::AddScriptRunner(p->mPendingNotification);
+  }
+  PRBool keepTracking = p->IsPersistent();
+  if (!keepTracking) {
+    p->mWatchDocument = nsnull;
+    p->mWatchID = nsnull;
+  }
+  return keepTracking;
+}