The Tor Browser: layout/generic/nsFrameList.h@b8a032363ba2 (annotated)

layout/generic/nsFrameList.h@b8a032363ba2 (annotated)

layout/generic/nsFrameList.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
 #ifndef nsFrameList_h___
 #define nsFrameList_h___
 #include <stdio.h> /* for FILE* */
 #include "nsDebug.h"
 #include "nsTArrayForwardDeclare.h"
 #if defined(DEBUG) || defined(MOZ_DUMP_PAINTING)
 // DEBUG_FRAME_DUMP enables nsIFrame::List and related methods.
 // You can also define this in a non-DEBUG build if you need frame dumps.
 #define DEBUG_FRAME_DUMP 1
 #endif
 class nsIFrame;
 class nsIPresShell;
 class nsPresContext;
 namespace mozilla {
 namespace layout {
   class FrameChildList;
   enum FrameChildListID {
       // The individual concrete child lists.
       kPrincipalList                = 0x1,
       kPopupList                    = 0x2,
       kCaptionList                  = 0x4,
       kColGroupList                 = 0x8,
       kSelectPopupList              = 0x10,
       kAbsoluteList                 = 0x20,
       kFixedList                    = 0x40,
       kOverflowList                 = 0x80,
       kOverflowContainersList       = 0x100,
       kExcessOverflowContainersList = 0x200,
       kOverflowOutOfFlowList        = 0x400,
       kFloatList                    = 0x800,
       kBulletList                   = 0x1000,
       kPushedFloatsList             = 0x2000,
       // A special alias for kPrincipalList that suppress the reflow request that
       // is normally done when manipulating child lists.
       kNoReflowPrincipalList        = 0x4000
   };
 }
 }
 // Uncomment this to enable expensive frame-list integrity checking
 // #define DEBUG_FRAME_LIST
 /**
  * A class for managing a list of frames.
  */
 class nsFrameList {
 public:
   nsFrameList() :
     mFirstChild(nullptr), mLastChild(nullptr)
   {
   }
   nsFrameList(nsIFrame* aFirstFrame, nsIFrame* aLastFrame) :
     mFirstChild(aFirstFrame), mLastChild(aLastFrame)
   {
     VerifyList();
   }
   nsFrameList(const nsFrameList& aOther) :
     mFirstChild(aOther.mFirstChild), mLastChild(aOther.mLastChild)
   {
   }
   /**
    * Allocate a nsFrameList from the shell arena.
    */
   void* operator new(size_t sz, nsIPresShell* aPresShell) CPP_THROW_NEW;
   /**
    * Deallocate this list that was allocated from the shell arena.
    * The list is required to be empty.
    */
   void Delete(nsIPresShell* aPresShell);
   /**
    * For each frame in this list: remove it from the list then call
    * Destroy() on it.
    */
   void DestroyFrames();
   /**
    * For each frame in this list: remove it from the list then call
    * DestroyFrom(aDestructRoot) on it.
    */
   void DestroyFramesFrom(nsIFrame* aDestructRoot);
   void Clear() { mFirstChild = mLastChild = nullptr; }
   void SetFrames(nsIFrame* aFrameList);
   void SetFrames(nsFrameList& aFrameList) {
     NS_PRECONDITION(!mFirstChild, "Losing frames");
     mFirstChild = aFrameList.FirstChild();
     mLastChild = aFrameList.LastChild();
     aFrameList.Clear();
   }
   class Slice;
   /**
    * Append aFrameList to this list.  If aParent is not null,
    * reparents the newly added frames.  Clears out aFrameList and
    * returns a list slice represening the newly-appended frames.
    */
   Slice AppendFrames(nsIFrame* aParent, nsFrameList& aFrameList) {
     return InsertFrames(aParent, LastChild(), aFrameList);
   }
   /**
    * Append aFrame to this list.  If aParent is not null,
    * reparents the newly added frame.
    */
   void AppendFrame(nsIFrame* aParent, nsIFrame* aFrame) {
     nsFrameList temp(aFrame, aFrame);
     AppendFrames(aParent, temp);
   }
   /**
    * Take aFrame out of the frame list. This also disconnects aFrame
    * from the sibling list. The frame must be non-null and present on
    * this list.
    */
   void RemoveFrame(nsIFrame* aFrame);
   /**
    * Take the frames after aAfterFrame out of the frame list.  If
    * aAfterFrame is null, removes the entire list.
    * @param aAfterFrame a frame in this list, or null
    * @return the removed frames, if any
    */
   nsFrameList RemoveFramesAfter(nsIFrame* aAfterFrame);
   /**
    * Take the first frame (if any) out of the frame list.
    * @return the first child, or nullptr if the list is empty
    */
   nsIFrame* RemoveFirstChild();
   /**
    * The following two functions are intended to be used in concert for
    * removing a frame from its frame list when the set of possible frame
    * lists is known in advance, but the exact frame list is unknown.
    * aFrame must be non-null.
    * Example use:
    *   bool removed = frameList1.StartRemoveFrame(aFrame) ||
    *                  frameList2.ContinueRemoveFrame(aFrame) ||
    *                  frameList3.ContinueRemoveFrame(aFrame);
    *   MOZ_ASSERT(removed);
    *
    * @note One of the frame lists MUST contain aFrame, if it's on some other
    *       frame list then the example above will likely lead to crashes.
    * This function is O(1).
    * @return true iff aFrame was removed from /some/ list, not necessarily
    *         this one.  If it was removed from a different list then it is
    *         guaranteed that that list is still non-empty.
    * (this method is implemented in nsIFrame.h to be able to inline)
    */
   inline bool StartRemoveFrame(nsIFrame* aFrame);
   /**
    * Precondition: StartRemoveFrame MUST be called before this.
    * This function is O(1).
    * @see StartRemoveFrame
    * @return true iff aFrame was removed from this list
    * (this method is implemented in nsIFrame.h to be able to inline)
    */
   inline bool ContinueRemoveFrame(nsIFrame* aFrame);
   /**
    * Take aFrame out of the frame list and then destroy it.
    * The frame must be non-null and present on this list.
    */
   void DestroyFrame(nsIFrame* aFrame);
   /**
    * Insert aFrame right after aPrevSibling, or prepend it to this
    * list if aPrevSibling is null. If aParent is not null, also
    * reparents newly-added frame. Note that this method always
    * sets the frame's nextSibling pointer.
    */
   void InsertFrame(nsIFrame* aParent, nsIFrame* aPrevSibling,
                    nsIFrame* aFrame) {
     nsFrameList temp(aFrame, aFrame);
     InsertFrames(aParent, aPrevSibling, temp);
   }
   /**
    * Inserts aFrameList into this list after aPrevSibling (at the beginning if
    * aPrevSibling is null).  If aParent is not null, reparents the newly added
    * frames.  Clears out aFrameList and returns a list slice representing the
    * newly-inserted frames.
    */
   Slice InsertFrames(nsIFrame* aParent, nsIFrame* aPrevSibling,
                      nsFrameList& aFrameList);
   class FrameLinkEnumerator;
   /**
    * Split this frame list such that all the frames before the link pointed to
    * by aLink end up in the returned list, while the remaining frames stay in
    * this list.  After this call, aLink points to the beginning of this list.
    */
   nsFrameList ExtractHead(FrameLinkEnumerator& aLink);
   /**
    * Split this frame list such that all the frames coming after the link
    * pointed to by aLink end up in the returned list, while the frames before
    * that link stay in this list.  After this call, aLink is at end.
    */
   nsFrameList ExtractTail(FrameLinkEnumerator& aLink);
   nsIFrame* FirstChild() const {
     return mFirstChild;
   }
   nsIFrame* LastChild() const {
     return mLastChild;
   }
   nsIFrame* FrameAt(int32_t aIndex) const;
   int32_t IndexOf(nsIFrame* aFrame) const;
   bool IsEmpty() const {
     return nullptr == mFirstChild;
   }
   bool NotEmpty() const {
     return nullptr != mFirstChild;
   }
   bool ContainsFrame(const nsIFrame* aFrame) const;
   int32_t GetLength() const;
   /**
    * If this frame list has only one frame, return that frame.
    * Otherwise, return null.
    */
   nsIFrame* OnlyChild() const {
     if (FirstChild() == LastChild()) {
       return FirstChild();
     }
     return nullptr;
   }
   /**
    * Call SetParent(aParent) for each frame in this list.
    * @param aParent the new parent frame, must be non-null
    */
   void ApplySetParent(nsIFrame* aParent) const;
   /**
    * If this frame list is non-empty then append it to aLists as the
    * aListID child list.
    * (this method is implemented in FrameChildList.h for dependency reasons)
    */
   inline void AppendIfNonempty(nsTArray<mozilla::layout::FrameChildList>* aLists,
                                mozilla::layout::FrameChildListID aListID) const;
   /**
    * Return the frame before this frame in visual order (after Bidi reordering).
    * If aFrame is null, return the last frame in visual order.
    */
   nsIFrame* GetPrevVisualFor(nsIFrame* aFrame) const;
   /**
    * Return the frame after this frame in visual order (after Bidi reordering).
    * If aFrame is null, return the first frame in visual order.
    */
   nsIFrame* GetNextVisualFor(nsIFrame* aFrame) const;
 #ifdef DEBUG_FRAME_DUMP
   void List(FILE* out) const;
 #endif
   static inline const nsFrameList& EmptyList();
   class Enumerator;
   /**
    * A class representing a slice of a frame list.
    */
   class Slice {
     friend class Enumerator;
   public:
     // Implicit on purpose, so that we can easily create enumerators from
     // nsFrameList via this impicit constructor.
     Slice(const nsFrameList& aList) :
 #ifdef DEBUG
       mList(aList),
 #endif
       mStart(aList.FirstChild()),
       mEnd(nullptr)
     {}
     Slice(const nsFrameList& aList, nsIFrame* aStart, nsIFrame* aEnd) :
 #ifdef DEBUG
       mList(aList),
 #endif
       mStart(aStart),
       mEnd(aEnd)
     {}
     Slice(const Slice& aOther) :
 #ifdef DEBUG
       mList(aOther.mList),
 #endif
       mStart(aOther.mStart),
       mEnd(aOther.mEnd)
     {}
   private:
 #ifdef DEBUG
     const nsFrameList& mList;
 #endif
     nsIFrame* const mStart; // our starting frame
     const nsIFrame* const mEnd; // The first frame that is NOT in the slice.
                                 // May be null.
   };
   class Enumerator {
   public:
     Enumerator(const Slice& aSlice) :
 #ifdef DEBUG
       mSlice(aSlice),
 #endif
       mFrame(aSlice.mStart),
       mEnd(aSlice.mEnd)
     {}
     Enumerator(const Enumerator& aOther) :
 #ifdef DEBUG
       mSlice(aOther.mSlice),
 #endif
       mFrame(aOther.mFrame),
       mEnd(aOther.mEnd)
     {}
     bool AtEnd() const {
       // Can't just check mEnd, because some table code goes and destroys the
       // tail of the frame list (including mEnd!) while iterating over the
       // frame list.
       return !mFrame || mFrame == mEnd;
     }
     /* Next() needs to know about nsIFrame, and nsIFrame will need to
        know about nsFrameList methods, so in order to inline this put
        the implementation in nsIFrame.h */
     inline void Next();
     /**
      * Get the current frame we're pointing to.  Do not call this on an
      * iterator that is at end!
      */
     nsIFrame* get() const {
       NS_PRECONDITION(!AtEnd(), "Enumerator is at end");
       return mFrame;
     }
     /**
      * Get an enumerator that is just like this one, but not limited in terms of
      * the part of the list it will traverse.
      */
     Enumerator GetUnlimitedEnumerator() const {
       return Enumerator(*this, nullptr);
     }
 #ifdef DEBUG
     const nsFrameList& List() const { return mSlice.mList; }
 #endif
   protected:
     Enumerator(const Enumerator& aOther, const nsIFrame* const aNewEnd):
 #ifdef DEBUG
       mSlice(aOther.mSlice),
 #endif
       mFrame(aOther.mFrame),
       mEnd(aNewEnd)
     {}
 #ifdef DEBUG
     /* Has to be an object, not a reference, since the slice could
        well be a temporary constructed from an nsFrameList */
     const Slice mSlice;
 #endif
     nsIFrame* mFrame; // our current frame.
     const nsIFrame* const mEnd; // The first frame we should NOT enumerate.
                                 // May be null.
   };
   /**
    * A class that can be used to enumerate links between frames.  When created
    * from an nsFrameList, it points to the "link" immediately before the first
    * frame.  It can then be advanced until it points to the "link" immediately
    * after the last frame.  At any position, PrevFrame() and NextFrame() are
    * the frames before and after the given link.  This means PrevFrame() is
    * null when the enumerator is at the beginning of the list and NextFrame()
    * is null when it's AtEnd().
    */
   class FrameLinkEnumerator : private Enumerator {
   public:
     friend class nsFrameList;
     FrameLinkEnumerator(const nsFrameList& aList) :
       Enumerator(aList),
       mPrev(nullptr)
     {}
     FrameLinkEnumerator(const FrameLinkEnumerator& aOther) :
       Enumerator(aOther),
       mPrev(aOther.mPrev)
     {}
     /* This constructor needs to know about nsIFrame, and nsIFrame will need to
        know about nsFrameList methods, so in order to inline this put
        the implementation in nsIFrame.h */
     inline FrameLinkEnumerator(const nsFrameList& aList, nsIFrame* aPrevFrame);
     void operator=(const FrameLinkEnumerator& aOther) {
       NS_PRECONDITION(&List() == &aOther.List(), "Different lists?");
       mFrame = aOther.mFrame;
       mPrev = aOther.mPrev;
     }
     inline void Next();
     bool AtEnd() const { return Enumerator::AtEnd(); }
     nsIFrame* PrevFrame() const { return mPrev; }
     nsIFrame* NextFrame() const { return mFrame; }
   protected:
     nsIFrame* mPrev;
   };
 private:
   void operator delete(void*) MOZ_DELETE;
 #ifdef DEBUG_FRAME_LIST
   void VerifyList() const;
 #else
   void VerifyList() const {}
 #endif
 protected:
   /**
    * Disconnect aFrame from its siblings.  This must only be called if aFrame
    * is NOT the first or last sibling, because otherwise its nsFrameList will
    * have a stale mFirst/LastChild pointer.  This precondition is asserted.
    * This function is O(1).
    */
   static void UnhookFrameFromSiblings(nsIFrame* aFrame);
   nsIFrame* mFirstChild;
   nsIFrame* mLastChild;
 };
 namespace mozilla {
 namespace layout {
 /**
  * Simple "auto_ptr" for nsFrameLists allocated from the shell arena.
  * The frame list given to the constructor will be deallocated (if non-null)
  * in the destructor.  The frame list must then be empty.
  */
 class AutoFrameListPtr {
 public:
   AutoFrameListPtr(nsPresContext* aPresContext, nsFrameList* aFrameList)
     : mPresContext(aPresContext), mFrameList(aFrameList) {}
   ~AutoFrameListPtr();
   operator nsFrameList*() const { return mFrameList; }
   nsFrameList* operator->() const { return mFrameList; }
 private:
   nsPresContext* mPresContext;
   nsFrameList* mFrameList;
 };
 namespace detail {
 union AlignedFrameListBytes {
   void* ptr;
   char bytes[sizeof(nsFrameList)];
 };
 extern const AlignedFrameListBytes gEmptyFrameListBytes;
 }
 }
 }
 /* static */ inline const nsFrameList&
 nsFrameList::EmptyList()
 {
   return *reinterpret_cast<const nsFrameList*>(&mozilla::layout::detail::gEmptyFrameListBytes);
 }
 #endif /* nsFrameList_h___ */

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layout/generic/nsFrameList.h@b8a032363ba2 (annotated)

layout/generic/nsFrameList.h