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#ifndef SplitElementTxn_h__
#define SplitElementTxn_h__

#include "EditTxn.h"
#include "nsIDOMNode.h"
#include "nsCOMPtr.h"
#include "nsIEditor.h"

class nsEditor;

/**
 * A transaction that splits an element E into two identical nodes, E1 and E2
 * with the children of E divided between E1 and E2.
 */
class SplitElementTxn : public EditTxn
{
public:
  /** initialize the transaction.
    * @param aEditor  the provider of core editing operations
    * @param aNode    the node to split
    * @param aOffset  the location within aNode to do the split.
    *                 aOffset may refer to children of aNode, or content of aNode.
    *                 The left node will have child|content 0..aOffset-1.
    */
  NS_IMETHOD Init (nsEditor   *aEditor,
                   nsIDOMNode *aNode,
                   PRInt32     aOffset);

  SplitElementTxn();

  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(SplitElementTxn, EditTxn)
  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr);

  NS_DECL_EDITTXN

  NS_IMETHOD RedoTransaction(void);

  NS_IMETHOD GetNewNode(nsIDOMNode **aNewNode);

protected:
  
  /** the element to operate upon */
  nsCOMPtr<nsIDOMNode> mExistingRightNode;

  /** the offset into mElement where the children of mElement are split.<BR>
    * mOffset is the index of the first child in the right node. 
    * -1 means the new node gets no children.
    */
  PRInt32  mOffset;

  /** the element we create when splitting mElement */
  nsCOMPtr<nsIDOMNode> mNewLeftNode;

  /** the parent shared by mExistingRightNode and mNewLeftNode */
  nsCOMPtr<nsIDOMNode> mParent;
  nsEditor*  mEditor;
};

#endif
