editor/libeditor/PlaceholderTransaction.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 PlaceholderTransaction_h
   7 #define PlaceholderTransaction_h
   8
   9 #include "EditAggregateTransaction.h"
  10 #include "EditorForwards.h"
  11 #include "SelectionState.h"
  12
  13 #include "mozilla/Maybe.h"
  14 #include "mozilla/WeakPtr.h"
  15
  16 namespace mozilla {
  17
  18 /**
  19  * An aggregate transaction that knows how to absorb all subsequent
  20  * transactions with the same name.  This transaction does not "Do" anything.
  21  * But it absorbs other transactions via merge, and can undo/redo the
  22  * transactions it has absorbed.
  23  */
  24
  25 class PlaceholderTransaction final : public EditAggregateTransaction,
  26                                      public SupportsWeakPtr {
  27  protected:
  28   PlaceholderTransaction(EditorBase& aEditorBase, nsStaticAtom& aName,
  29                          Maybe<SelectionState>&& aSelState);
  30
  31  public:
  32   /**
  33    * Creates a placeholder transaction.  This never returns nullptr.
  34    *
  35    * @param aEditorBase     The editor.
  36    * @param aName           The name of creating transaction.
  37    * @param aSelState       The selection state of aEditorBase.
  38    */
  39   static already_AddRefed<PlaceholderTransaction> Create(
  40       EditorBase& aEditorBase, nsStaticAtom& aName,
  41       Maybe<SelectionState>&& aSelState) {
  42     // Make sure to move aSelState into a local variable to null out the
  43     // original Maybe<SelectionState> variable.
  44     Maybe<SelectionState> selState(std::move(aSelState));
  45     RefPtr<PlaceholderTransaction> transaction =
  46         new PlaceholderTransaction(aEditorBase, aName, std::move(selState));
  47     return transaction.forget();
  48   }
  49
  50   NS_DECL_ISUPPORTS_INHERITED
  51
  52   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(PlaceholderTransaction,
  53                                            EditAggregateTransaction)
  54
  55   NS_DECL_EDITTRANSACTIONBASE
  56   NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(PlaceholderTransaction)
  57
  58   MOZ_CAN_RUN_SCRIPT NS_IMETHOD RedoTransaction() override;
  59   NS_IMETHOD Merge(nsITransaction* aTransaction, bool* aDidMerge) override;
  60
  61   void AppendChild(EditTransactionBase& aTransaction);
  62
  63   nsresult EndPlaceHolderBatch();
  64
  65   void ForwardEndBatchTo(PlaceholderTransaction& aForwardingTransaction) {
  66     mForwardingTransaction = &aForwardingTransaction;
  67   }
  68
  69   void Commit() { mCommitted = true; }
  70
  71   nsresult RememberEndingSelection();
  72
  73  protected:
  74   virtual ~PlaceholderTransaction() = default;
  75
  76   // The editor for this transaction.
  77   RefPtr<EditorBase> mEditorBase;
  78
  79   WeakPtr<PlaceholderTransaction> mForwardingTransaction;
  80
  81   // First IME txn in this placeholder - used for IME merging.
  82   WeakPtr<CompositionTransaction> mCompositionTransaction;
  83
  84   // These next two members store the state of the selection in a safe way.
  85   // Selection at the start of the transaction is stored, as is the selection
  86   // at the end.  This is so that UndoTransaction() and RedoTransaction() can
  87   // restore the selection properly.
  88
  89   SelectionState mStartSel;
  90   SelectionState mEndSel;
  91
  92   // Do we auto absorb any and all transaction?
  93   bool mAbsorb;
  94   // Do we stop auto absorbing any matching placeholder transactions?
  95   bool mCommitted;
  96 };
  97
  98 }  // namespace mozilla
  99
 100 #endif  // #ifndef PlaceholderTransaction_h