gecko-dev/layout/generic/nsFrameList.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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 Communicator client code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* 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 ***** */
/* class for maintaining a linked list of child frames */
#ifndef nsFrameList_h___
#define nsFrameList_h___
#include "nscore.h"
#include "nsTraceRefcnt.h"
#include <stdio.h> /* for FILE* */
#include "nsDebug.h"
class nsIFrame;
/**
* A class for managing a list of frames.
*/
class nsFrameList {
public:
nsFrameList() :
mFirstChild(nsnull)
{
MOZ_COUNT_CTOR(nsFrameList);
}
// XXX We should make this explicit when we can!
nsFrameList(nsIFrame* aHead) :
mFirstChild(aHead)
{
MOZ_COUNT_CTOR(nsFrameList);
#ifdef DEBUG
CheckForLoops();
#endif
}
nsFrameList(const nsFrameList& aOther) :
mFirstChild(aOther.mFirstChild)
{
MOZ_COUNT_CTOR(nsFrameList);
}
~nsFrameList() {
MOZ_COUNT_DTOR(nsFrameList);
// Don't destroy our frames here, so that we can have temporary nsFrameLists
}
void DestroyFrames();
// Delete this and destroy all its frames
void Destroy();
void SetFrames(nsIFrame* aFrameList) {
mFirstChild = aFrameList;
#ifdef DEBUG
CheckForLoops();
#endif
}
void Clear() { SetFrames(nsnull); }
void SetFrames(nsFrameList& aFrameList) {
NS_PRECONDITION(!mFirstChild, "Losing frames");
mFirstChild = aFrameList.FirstChild();
aFrameList.Clear();
}
class Slice;
/**
* Appends frames from aFrameList to this list. If aParent
* is not null, reparents the newly-added frames.
*/
void AppendFrames(nsIFrame* aParent, nsIFrame* aFrameList) {
InsertFrames(aParent, LastChild(), aFrameList);
}
/**
* Appends 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) {
NS_PRECONDITION(!aFrameList.IsEmpty(), "Unexpected empty list");
nsIFrame* firstNewFrame = aFrameList.FirstChild();
AppendFrames(aParent, firstNewFrame);
aFrameList.Clear();
return Slice(*this, firstNewFrame, nsnull);
}
/* This is implemented in nsIFrame.h because it needs to know about
nsIFrame. */
inline void AppendFrame(nsIFrame* aParent, nsIFrame* aFrame);
/**
* Take aFrame out of the frame list. This also disconnects aFrame
* from the sibling list. This will return PR_FALSE if aFrame is
* nsnull or if aFrame is not in the list. The second frame is
* a hint for the prev-sibling of aFrame; if the hint is correct,
* then this is O(1) time. If successfully removed, the child's
* NextSibling pointer is cleared.
*/
PRBool RemoveFrame(nsIFrame* aFrame, nsIFrame* aPrevSiblingHint = nsnull);
/**
* Remove the first child from the list. The caller is assumed to be
* holding a reference to the first child. This call is equivalent
* in behavior to calling RemoveFrame(FirstChild()). If successfully
* removed the first child's NextSibling pointer is cleared.
*/
PRBool RemoveFirstChild();
/**
* Take aFrame out of the frame list and then destroy it. This also
* disconnects aFrame from the sibling list. This will return
* PR_FALSE if aFrame is nsnull or if aFrame is not in the list. The
* second frame is a hint for the prev-sibling of aFrame; if the
* hint is correct, then the time this method takes doesn't depend
* on the number of previous siblings of aFrame.
*/
PRBool DestroyFrame(nsIFrame* aFrame, nsIFrame* aPrevSiblingHint = nsnull);
/**
* Inserts aNewFrame right after aPrevSibling, or prepends to
* 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.
* This is implemented in nsIFrame.h because it needs to know about nsIFrame.
*/
inline void InsertFrame(nsIFrame* aParent, nsIFrame* aPrevSibling,
nsIFrame* aNewFrame);
/**
* Inserts aFrameList right after aPrevSibling, or prepends to
* list if aPrevSibling is null. If aParent is not null, also
* reparents newly-added frame.
*/
void InsertFrames(nsIFrame* aParent,
nsIFrame* aPrevSibling,
nsIFrame* aFrameList);
/**
* 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.
*
* This is implemented in nsIFrame.h because it needs to know about nsIFrame.
*/
inline 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);
/**
* Sort the frames according to content order so that the first
* frame in the list is the first in content order. Frames for
* the same content will be ordered so that a prev in flow
* comes before its next in flow.
*/
void SortByContentOrder();
nsIFrame* FirstChild() const {
return mFirstChild;
}
nsIFrame* LastChild() const;
nsIFrame* FrameAt(PRInt32 aIndex) const;
PRInt32 IndexOf(nsIFrame* aFrame) const;
PRBool IsEmpty() const {
return nsnull == mFirstChild;
}
PRBool NotEmpty() const {
return nsnull != mFirstChild;
}
PRBool ContainsFrame(const nsIFrame* aFrame) const;
PRBool ContainsFrameBefore(const nsIFrame* aFrame, const nsIFrame* aEnd) const;
PRInt32 GetLength() const;
nsIFrame* GetPrevSiblingFor(nsIFrame* aFrame) const;
/**
* If this frame list has only one frame, return that frame.
* Otherwise, return null.
*/
nsIFrame* OnlyChild() const {
if (FirstChild() == LastChild()) {
return FirstChild();
}
return nsnull;
}
#ifdef IBMBIDI
/**
* 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;
#endif // IBMBIDI
#ifdef DEBUG
void List(FILE* out) const;
#endif
static nsresult Init();
static void Shutdown() { delete sEmptyList; }
static const nsFrameList& EmptyList() { return *sEmptyList; }
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(nsnull)
{}
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)
{}
PRBool 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, nsnull);
}
#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(nsnull)
{}
FrameLinkEnumerator(const FrameLinkEnumerator& aOther) :
Enumerator(aOther),
mPrev(aOther.mPrev)
{}
void operator=(const FrameLinkEnumerator& aOther) {
NS_PRECONDITION(&List() == &aOther.List(), "Different lists?");
mFrame = aOther.mFrame;
mPrev = aOther.mPrev;
}
void Next() {
mPrev = mFrame;
Enumerator::Next();
}
PRBool AtEnd() const { return Enumerator::AtEnd(); }
nsIFrame* PrevFrame() const { return mPrev; }
nsIFrame* NextFrame() const { return mFrame; }
protected:
nsIFrame* mPrev;
};
private:
#ifdef DEBUG
void CheckForLoops();
#endif
static const nsFrameList* sEmptyList;
protected:
nsIFrame* mFirstChild;
};
#endif /* nsFrameList_h___ */