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 * License.
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 * The Original Code is Mozilla Communicator client code.
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 *
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/* class for maintaining a linked list of child frames */

#ifndef nsFrameList_h___
#define nsFrameList_h___

#include "nsIFrame.h"

/**
 * A class for managing a singly linked list of frames. Frames are
 * linked together through their next-sibling pointer.
 */

class nsFrameList {
public:
  nsFrameList() {
    mFirstChild = nsnull;
  }

  nsFrameList(nsIFrame* aHead) {
    mFirstChild = aHead;
#ifdef DEBUG
    CheckForLoops();
#endif
  }

  ~nsFrameList() {
  }

  void DestroyFrames();

  // Delete this and destroy all its frames
  void Destroy();

  void SetFrames(nsIFrame* aFrameList) {
    mFirstChild = aFrameList;
#ifdef DEBUG
    CheckForLoops();
#endif
  }

  // Appends frames from aFrameList to this list. If aParent
  // is not null, reparents the newly-added frames.
  void AppendFrames(nsIFrame* aParent, nsIFrame* aFrameList);

  void AppendFrames(nsIFrame* aParent, nsFrameList& aFrameList) {
    AppendFrames(aParent, aFrameList.mFirstChild);
    aFrameList.mFirstChild = nsnull;
  }

  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.
  PRBool DestroyFrame(nsIFrame* aFrame);

  // 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.
  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);

  void InsertFrames(nsIFrame* aParent, nsIFrame* aPrevSibling,
                    nsFrameList& aFrameList) {
    InsertFrames(aParent, aPrevSibling, aFrameList.FirstChild());
    aFrameList.mFirstChild = nsnull;
  }

  PRBool Split(nsIFrame* aAfterFrame, nsIFrame** aNextFrameResult);

  /**
   * 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;

  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;

#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

  void VerifyParent(nsIFrame* aParent) const;

#ifdef NS_DEBUG
  void List(FILE* out) const;
#endif

private:
#ifdef DEBUG
  void CheckForLoops();
#endif
  
protected:
  nsIFrame* mFirstChild;
};

#endif /* nsFrameList_h___ */
