Quelle  DeleteTextTransaction.h

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef DeleteTextTransaction_h
#define DeleteTextTransaction_h

#include "DeleteContentTransactionBase.h"

#include "EditorForwards.h"

#include "mozilla/dom/Text.h"

#include "nsCOMPtr.h"
#include "nsCycleCollectionParticipant.h"
#include "nsID.h"
#include "nsString.h"
#include "nscore.h"

namespace mozilla {

/**
 * A transaction that removes text from a content node.
 */
class DeleteTextTransaction : public DeleteContentTransactionBase {
 protected:
  DeleteTextTransaction(EditorBase& aEditorBase, dom::Text& aTextNode,
                        uint32_t aOffset, uint32_t aLengthToDelete);

 public:
  /**
   * Creates a delete text transaction to remove given range.  This returns
   * nullptr if it cannot modify the text node.
   *
   * @param aEditorBase         The provider of basic editing operations.
   * @param aTextNode           The content node to remove text from.
   * @param aOffset             The location in aElement to begin the deletion.
   * @param aLengthToDelete     The length to delete.
   */
  static already_AddRefed<DeleteTextTransaction> MaybeCreate(
      EditorBase& aEditorBase, dom::Text& aTextNode, uint32_t aOffset,
      uint32_t aLengthToDelete);

  /**
   * Creates a delete text transaction to remove a previous or next character.
   * Those methods MAY return nullptr.
   *
   * @param aEditorBase         The provider of basic editing operations.
   * @param aTextNode           The content node to remove text from.
   * @param aOffset             The location in aElement to begin the deletion.
   */
  static already_AddRefed<DeleteTextTransaction>
  MaybeCreateForPreviousCharacter(EditorBase& aEditorBase, dom::Text& aTextNode,
                                  uint32_t aOffset);
  static already_AddRefed<DeleteTextTransaction> MaybeCreateForNextCharacter(
      EditorBase& aEditorBase, dom::Text& aTextNode, uint32_t aOffset);

  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(DeleteTextTransaction,
                                           DeleteContentTransactionBase)
  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;

  NS_DECL_EDITTRANSACTIONBASE
  NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(DeleteTextTransaction)

  MOZ_CAN_RUN_SCRIPT NS_IMETHOD RedoTransaction() final;

  EditorDOMPoint SuggestPointToPutCaret() const final;

  dom::Text* GetTextNode() const;
  uint32_t Offset() const { return mOffset; }
  uint32_t LengthToDelete() const { return mLengthToDelete; }

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const DeleteTextTransaction& aTransaction);

 protected:
  // The offset into the text node where the deletion is to take place.
  uint32_t mOffset;

  // The length to delete.
  uint32_t mLengthToDelete;

  // The text that was deleted.
  nsString mDeletedText;
};

/**
 * Private class for DeleteTextTransaction when it needs to handle a transaction
 * of `HTMLEditor`.
 */
class DeleteTextFromTextNodeTransaction final : public DeleteTextTransaction {
 public:
  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(DeleteTextFromTextNodeTransaction,
                                           DeleteTextTransaction)
  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;

  friend std::ostream& operator<<(
      std::ostream& aStream,
      const DeleteTextFromTextNodeTransaction& aTransaction);

 private:
  DeleteTextFromTextNodeTransaction(EditorBase& aEditorBase,
                                    dom::Text& aTextNode, uint32_t aOffset,
                                    uint32_t aLengthToDelete);
  virtual ~DeleteTextFromTextNodeTransaction() = default;

  NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(
      DeleteTextFromTextNodeTransaction)

  // The CharacterData node to operate upon.
  RefPtr<dom::Text> mTextNode;

  friend class DeleteTextTransaction;
};

}  // namespace mozilla

#endif  // #ifndef DeleteTextTransaction_h