editor/libeditor/JoinNodeTransaction.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef JoinNodeTransaction_h
   7 #define JoinNodeTransaction_h
   8
   9 #include "mozilla/EditTransactionBase.h"  // for EditTransactionBase, etc.
  10 #include "nsCOMPtr.h"                     // for nsCOMPtr
  11 #include "nsCycleCollectionParticipant.h"
  12 #include "nsID.h"    // for REFNSIID
  13 #include "nscore.h"  // for NS_IMETHOD
  14
  15 class nsIContent;
  16 class nsINode;
  17
  18 namespace mozilla {
  19
  20 class HTMLEditor;
  21
  22 /**
  23  * A transaction that joins two nodes E1 (left node) and E2 (right node) into a
  24  * single node E.  The children of E are the children of E1 followed by the
  25  * children of E2.  After DoTransaction() and RedoTransaction(), E1 is removed
  26  * from the content tree and E2 remains.
  27  */
  28 class JoinNodeTransaction final : public EditTransactionBase {
  29  protected:
  30   JoinNodeTransaction(HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
  31                       nsIContent& aRightContent);
  32
  33  public:
  34   /**
  35    * Creates a join node transaction.  This returns nullptr if cannot join the
  36    * nodes.
  37    *
  38    * @param aHTMLEditor     The provider of core editing operations.
  39    * @param aLeftContent    The first of two nodes to join.
  40    * @param aRightContent   The second of two nodes to join.
  41    */
  42   static already_AddRefed<JoinNodeTransaction> MaybeCreate(
  43       HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
  44       nsIContent& aRightContent);
  45
  46   /**
  47    * CanDoIt() returns true if there are enough members and can join or
  48    * restore the nodes.  Otherwise, false.
  49    */
  50   bool CanDoIt() const;
  51
  52   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(JoinNodeTransaction,
  53                                            EditTransactionBase)
  54   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;
  55
  56   NS_DECL_EDITTRANSACTIONBASE
  57   NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(JoinNodeTransaction)
  58
  59  protected:
  60   RefPtr<HTMLEditor> mHTMLEditor;
  61
  62   // The nodes to operate upon.  After the merge, mRightContent remains and
  63   // mLeftContent is removed from the content tree.
  64   nsCOMPtr<nsIContent> mLeftContent;
  65   nsCOMPtr<nsIContent> mRightContent;
  66
  67   // The offset into mNode where the children of mElement are split (for
  68   // undo). mOffset is the index of the first child in the right node.  -1
  69   // means the left node had no children.
  70   uint32_t mOffset;
  71
  72   // The parent node containing mLeftContent and mRightContent.
  73   nsCOMPtr<nsINode> mParentNode;
  74 };
  75
  76 }  // namespace mozilla
  77
  78 #endif  // #ifndef JoinNodeTransaction_h