gecko-dev/layout/generic/nsFrameList.h

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/* -*- 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"
#include "mozilla/ReverseIterator.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 nsContainerFrame;
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
};
} // namespace layout
} // namespace mozilla
// 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)
{
}
/**
* Infallibly 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(nsContainerFrame* 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(nsContainerFrame* 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(nsContainerFrame* 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(nsContainerFrame* 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(nsContainerFrame* 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.
MOZ_IMPLICIT 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:
explicit 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;
explicit 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;
};
class Iterator
{
public:
Iterator(const nsFrameList& aList, nsIFrame* aCurrent)
: mList(aList)
, mCurrent(aCurrent)
{}
Iterator(const Iterator& aOther)
: mList(aOther.mList)
, mCurrent(aOther.mCurrent)
{}
nsIFrame* operator*() const { return mCurrent; }
// The operators need to know about nsIFrame, hence the
// implementations are in nsIFrame.h
Iterator& operator++();
Iterator& operator--();
Iterator operator++(int) { auto ret = *this; ++*this; return ret; }
Iterator operator--(int) { auto ret = *this; --*this; return ret; }
friend bool operator==(const Iterator& aIter1, const Iterator& aIter2);
friend bool operator!=(const Iterator& aIter1, const Iterator& aIter2);
private:
const nsFrameList& mList;
nsIFrame* mCurrent;
};
typedef Iterator iterator;
typedef Iterator const_iterator;
typedef mozilla::ReverseIterator<Iterator> reverse_iterator;
typedef mozilla::ReverseIterator<Iterator> const_reverse_iterator;
iterator begin() const { return iterator(*this, mFirstChild); }
const_iterator cbegin() const { return begin(); }
iterator end() const { return iterator(*this, nullptr); }
const_iterator cend() const { return end(); }
reverse_iterator rbegin() const { return reverse_iterator(end()); }
const_reverse_iterator crbegin() const { return rbegin(); }
reverse_iterator rend() const { return reverse_iterator(begin()); }
const_reverse_iterator crend() const { return rend(); }
private:
void operator delete(void*) = 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;
};
inline bool
operator==(const nsFrameList::Iterator& aIter1,
const nsFrameList::Iterator& aIter2)
{
MOZ_ASSERT(&aIter1.mList == &aIter2.mList,
"must not compare iterator from different list");
return aIter1.mCurrent == aIter2.mCurrent;
}
inline bool
operator!=(const nsFrameList::Iterator& aIter1,
const nsFrameList::Iterator& aIter2)
{
MOZ_ASSERT(&aIter1.mList == &aIter2.mList,
"Must not compare iterator from different list");
return aIter1.mCurrent != aIter2.mCurrent;
}
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;
} // namespace detail
} // namespace layout
} // namespace mozilla
/* static */ inline const nsFrameList&
nsFrameList::EmptyList()
{
return *reinterpret_cast<const nsFrameList*>(&mozilla::layout::detail::gEmptyFrameListBytes);
}
#endif /* nsFrameList_h___ */