LCOV - code coverage report
Current view: directory - objdir/dist/include - nsReferencedElement.h (source / functions) Found Hit Coverage
Test: app.info Lines: 35 0 0.0 %
Date: 2012-06-02 Functions: 19 0 0.0 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2                 : /* vim: set ts=2 sw=2 et tw=78: */
       3                 : /* ***** BEGIN LICENSE BLOCK *****
       4                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       5                 :  *
       6                 :  * The contents of this file are subject to the Mozilla Public License Version
       7                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       8                 :  * the License. You may obtain a copy of the License at
       9                 :  * http://www.mozilla.org/MPL/
      10                 :  *
      11                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      12                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      13                 :  * for the specific language governing rights and limitations under the
      14                 :  * License.
      15                 :  *
      16                 :  * The Original Code is mozilla.org code.
      17                 :  *
      18                 :  * The Initial Developer of the Original Code is Mozilla.org.
      19                 :  * Portions created by the Initial Developer are Copyright (C) 2008
      20                 :  * the Initial Developer. All Rights Reserved.
      21                 :  *
      22                 :  * Contributor(s):
      23                 :  *   Robert O'Callahan   <robert@ocallahan.org>
      24                 :  *
      25                 :  * Alternatively, the contents of this file may be used under the terms of
      26                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
      27                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      28                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      29                 :  * of those above. If you wish to allow use of your version of this file only
      30                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      31                 :  * use your version of this file under the terms of the MPL, indicate your
      32                 :  * decision by deleting the provisions above and replace them with the notice
      33                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      34                 :  * the provisions above, a recipient may use your version of this file under
      35                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      36                 :  *
      37                 :  * ***** END LICENSE BLOCK ***** */
      38                 : 
      39                 : #ifndef NSREFERENCEDELEMENT_H_
      40                 : #define NSREFERENCEDELEMENT_H_
      41                 : 
      42                 : #include "mozilla/dom/Element.h"
      43                 : #include "nsIAtom.h"
      44                 : #include "nsIDocument.h"
      45                 : #include "nsThreadUtils.h"
      46                 : #include "nsAutoPtr.h"
      47                 : 
      48                 : class nsIURI;
      49                 : class nsCycleCollectionCallback;
      50                 : 
      51                 : /**
      52                 :  * Class to track what element is referenced by a given ID.
      53                 :  * 
      54                 :  * To use it, call Reset() to set it up to watch a given URI. Call get()
      55                 :  * anytime to determine the referenced element (which may be null if
      56                 :  * the element isn't found). When the element changes, ElementChanged
      57                 :  * will be called, so subclass this class if you want to receive that
      58                 :  * notification. ElementChanged runs at safe-for-script time, i.e. outside
      59                 :  * of the content update. Call Unlink() if you want to stop watching
      60                 :  * for changes (get() will then return null).
      61                 :  *
      62                 :  * By default this is a single-shot tracker --- i.e., when ElementChanged
      63                 :  * fires, we will automatically stop tracking. get() will continue to return
      64                 :  * the changed-to element.
      65                 :  * Override IsPersistent to return true if you want to keep tracking after
      66                 :  * the first change.
      67                 :  */
      68                 : class nsReferencedElement {
      69                 : public:
      70                 :   typedef mozilla::dom::Element Element;
      71                 : 
      72               0 :   nsReferencedElement() {}
      73               0 :   ~nsReferencedElement() {
      74               0 :     Unlink();
      75               0 :   }
      76                 : 
      77                 :   /**
      78                 :    * Find which element, if any, is referenced.
      79                 :    */
      80               0 :   Element* get() { return mElement; }
      81                 : 
      82                 :   /**
      83                 :    * Set up the reference. This can be called multiple times to
      84                 :    * change which reference is being tracked, but these changes
      85                 :    * do not trigger ElementChanged.
      86                 :    * @param aFrom the source element for context
      87                 :    * @param aURI the URI containing a hash-reference to the element
      88                 :    * @param aWatch if false, then we do not set up the notifications to track
      89                 :    * changes, so ElementChanged won't fire and get() will always return the same
      90                 :    * value, the current element for the ID.
      91                 :    * @param aReferenceImage whether the ID references image elements which are
      92                 :    * subject to the document's mozSetImageElement overriding mechanism.
      93                 :    */
      94                 :   void Reset(nsIContent* aFrom, nsIURI* aURI, bool aWatch = true,
      95                 :              bool aReferenceImage = false);
      96                 : 
      97                 :   /**
      98                 :    * A variation on Reset() to set up a reference that consists of the ID of
      99                 :    * an element in the same document as aFrom.
     100                 :    * @param aFrom the source element for context
     101                 :    * @param aID the ID of the element
     102                 :    * @param aWatch if false, then we do not set up the notifications to track
     103                 :    * changes, so ElementChanged won't fire and get() will always return the same
     104                 :    * value, the current element for the ID.
     105                 :    */
     106                 :   void ResetWithID(nsIContent* aFrom, const nsString& aID,
     107                 :                    bool aWatch = true);
     108                 : 
     109                 :   /**
     110                 :    * Clears the reference. ElementChanged is not triggered. get() will return
     111                 :    * null.
     112                 :    */
     113                 :   void Unlink();
     114                 : 
     115                 :   void Traverse(nsCycleCollectionTraversalCallback* aCB);
     116                 :   
     117                 : protected:
     118                 :   /**
     119                 :    * Override this to be notified of element changes. Don't forget
     120                 :    * to call this superclass method to change mElement. This is called
     121                 :    * at script-runnable time.
     122                 :    */
     123               0 :   virtual void ElementChanged(Element* aFrom, Element* aTo) {
     124               0 :     mElement = aTo;
     125               0 :   }
     126                 : 
     127                 :   /**
     128                 :    * Override this to convert from a single-shot notification to
     129                 :    * a persistent notification.
     130                 :    */
     131               0 :   virtual bool IsPersistent() { return false; }
     132                 : 
     133                 :   /**
     134                 :    * Set ourselves up with our new document.  Note that aDocument might be
     135                 :    * null.  Either aWatch must be false or aRef must be empty.
     136                 :    */
     137                 :   void HaveNewDocument(nsIDocument* aDocument, bool aWatch,
     138                 :                        const nsString& aRef);
     139                 :   
     140                 : private:
     141                 :   static bool Observe(Element* aOldElement,
     142                 :                         Element* aNewElement, void* aData);
     143                 : 
     144                 :   class Notification : public nsISupports {
     145                 :   public:
     146                 :     virtual void SetTo(Element* aTo) = 0;
     147               0 :     virtual void Clear() { mTarget = nsnull; }
     148               0 :     virtual ~Notification() {}
     149                 :   protected:
     150               0 :     Notification(nsReferencedElement* aTarget)
     151               0 :       : mTarget(aTarget)
     152                 :     {
     153               0 :       NS_PRECONDITION(aTarget, "Must have a target");
     154               0 :     }
     155                 :     nsReferencedElement* mTarget;
     156                 :   };
     157                 : 
     158                 :   class ChangeNotification : public nsRunnable,
     159                 :                              public Notification
     160                 :   {
     161                 :   public:
     162               0 :     ChangeNotification(nsReferencedElement* aTarget,
     163                 :                        Element* aFrom, Element* aTo)
     164               0 :       : Notification(aTarget), mFrom(aFrom), mTo(aTo)
     165               0 :     {}
     166               0 :     virtual ~ChangeNotification() {}
     167                 : 
     168                 :     NS_DECL_ISUPPORTS_INHERITED
     169               0 :     NS_IMETHOD Run() {
     170               0 :       if (mTarget) {
     171               0 :         mTarget->mPendingNotification = nsnull;
     172               0 :         mTarget->ElementChanged(mFrom, mTo);
     173                 :       }
     174               0 :       return NS_OK;
     175                 :     }
     176               0 :     virtual void SetTo(Element* aTo) { mTo = aTo; }
     177               0 :     virtual void Clear()
     178                 :     {
     179               0 :       Notification::Clear(); mFrom = nsnull; mTo = nsnull;
     180               0 :     }
     181                 :   protected:
     182                 :     nsRefPtr<Element> mFrom;
     183                 :     nsRefPtr<Element> mTo;
     184                 :   };
     185                 :   friend class ChangeNotification;
     186                 : 
     187                 :   class DocumentLoadNotification : public Notification,
     188                 :                                    public nsIObserver
     189                 :   {
     190                 :   public:
     191               0 :     DocumentLoadNotification(nsReferencedElement* aTarget,
     192                 :                              const nsString& aRef) :
     193               0 :       Notification(aTarget)
     194                 :     {
     195               0 :       if (!mTarget->IsPersistent()) {
     196               0 :         mRef = aRef;
     197                 :       }
     198               0 :     }
     199               0 :     virtual ~DocumentLoadNotification() {}
     200                 : 
     201                 :     NS_DECL_ISUPPORTS
     202                 :     NS_DECL_NSIOBSERVER
     203                 :   private:
     204               0 :     virtual void SetTo(Element* aTo) { }
     205                 : 
     206                 :     nsString mRef;
     207                 :   };
     208                 :   friend class DocumentLoadNotification;
     209                 :   
     210                 :   nsCOMPtr<nsIAtom>      mWatchID;
     211                 :   nsCOMPtr<nsIDocument>  mWatchDocument;
     212                 :   nsRefPtr<Element> mElement;
     213                 :   nsRefPtr<Notification> mPendingNotification;
     214                 :   bool                   mReferencingImage;
     215                 : };
     216                 : 
     217                 : #endif /*NSREFERENCEDELEMENT_H_*/

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