editor/libeditor/JoinNodesTransaction.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 JoinNodesTransaction_h
   7 #define JoinNodesTransaction_h
   8
   9 #include "EditTransactionBase.h"  // for EditTransactionBase, etc.
  10
  11 #include "EditorDOMPoint.h"  // for EditorDOMPoint, etc.
  12 #include "EditorForwards.h"
  13
  14 #include "nsCOMPtr.h"  // for nsCOMPtr
  15 #include "nsCycleCollectionParticipant.h"
  16 #include "nsID.h"    // for REFNSIID
  17 #include "nscore.h"  // for NS_IMETHOD
  18
  19 class nsIContent;
  20 class nsINode;
  21
  22 namespace mozilla {
  23
  24 /**
  25  * A transaction that joins two nodes E1 (left node) and E2 (right node) into a
  26  * single node E.  The children of E are the children of E1 followed by the
  27  * children of E2.  After DoTransaction() and RedoTransaction(), E1 is removed
  28  * from the content tree and E2 remains.
  29  */
  30 class JoinNodesTransaction final : public EditTransactionBase {
  31  protected:
  32   JoinNodesTransaction(HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
  33                        nsIContent& aRightContent);
  34
  35  public:
  36   /**
  37    * Creates a join node transaction.  This returns nullptr if cannot join the
  38    * nodes.
  39    *
  40    * @param aHTMLEditor     The provider of core editing operations.
  41    * @param aLeftContent    The first of two nodes to join.
  42    * @param aRightContent   The second of two nodes to join.
  43    */
  44   static already_AddRefed<JoinNodesTransaction> MaybeCreate(
  45       HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
  46       nsIContent& aRightContent);
  47
  48   /**
  49    * CanDoIt() returns true if there are enough members and can join or
  50    * restore the nodes.  Otherwise, false.
  51    */
  52   bool CanDoIt() const;
  53
  54   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(JoinNodesTransaction,
  55                                            EditTransactionBase)
  56   NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;
  57
  58   NS_DECL_EDITTRANSACTIONBASE
  59   NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(JoinNodesTransaction)
  60
  61   MOZ_CAN_RUN_SCRIPT NS_IMETHOD RedoTransaction() override;
  62
  63   /**
  64    * GetExistingContent() and GetRemovedContent() never returns nullptr
  65    * unless the cycle collector clears them out.
  66    */
  67   nsIContent* GetExistingContent() const { return mKeepingContent; }
  68   nsIContent* GetRemovedContent() const { return mRemovedContent; }
  69   nsINode* GetParentNode() const { return mParentNode; }
  70
  71   template <typename EditorDOMPointType>
  72   EditorDOMPointType CreateJoinedPoint() const {
  73     if (MOZ_UNLIKELY(!mKeepingContent)) {
  74       return EditorDOMPointType();
  75     }
  76     return EditorDOMPointType(
  77         mKeepingContent, std::min(mJoinedOffset, mKeepingContent->Length()));
  78   }
  79
  80   friend std::ostream& operator<<(std::ostream& aStream,
  81                                   const JoinNodesTransaction& aTransaction);
  82
  83  protected:
  84   virtual ~JoinNodesTransaction() = default;
  85
  86   enum class RedoingTransaction { No, Yes };
  87   MOZ_CAN_RUN_SCRIPT nsresult DoTransactionInternal(RedoingTransaction);
  88
  89   RefPtr<HTMLEditor> mHTMLEditor;
  90
  91   // The original parent of the left/right nodes.
  92   nsCOMPtr<nsINode> mParentNode;
  93
  94   // Removed content after joined.
  95   nsCOMPtr<nsIContent> mRemovedContent;
  96
  97   // The keeping content node which contains ex-children of mRemovedContent.
  98   nsCOMPtr<nsIContent> mKeepingContent;
  99
 100   // Offset where the original first content is in mKeepingContent after
 101   // doing or redoing.
 102   uint32_t mJoinedOffset = 0u;
 103 };
 104
 105 }  // namespace mozilla
 106
 107 #endif  // #ifndef JoinNodesTransaction_h