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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 JoinNodesTransaction_h
+#define JoinNodesTransaction_h
+
+#include "EditTransactionBase.h" // for EditTransactionBase, etc.
+
+#include "EditorDOMPoint.h" // for EditorDOMPoint, etc.
+#include "EditorForwards.h"
+
+#include "nsCOMPtr.h" // for nsCOMPtr
+#include "nsCycleCollectionParticipant.h"
+#include "nsID.h" // for REFNSIID
+#include "nscore.h" // for NS_IMETHOD
+
+class nsIContent;
+class nsINode;
+
+namespace mozilla {
+
+/**
+ * A transaction that joins two nodes E1 (left node) and E2 (right node) into a
+ * single node E. The children of E are the children of E1 followed by the
+ * children of E2. After DoTransaction() and RedoTransaction(), E1 is removed
+ * from the content tree and E2 remains.
+ */
+class JoinNodesTransaction final : public EditTransactionBase {
+ protected:
+ JoinNodesTransaction(HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
+ nsIContent& aRightContent);
+
+ public:
+ /**
+ * Creates a join node transaction. This returns nullptr if cannot join the
+ * nodes.
+ *
+ * @param aHTMLEditor The provider of core editing operations.
+ * @param aLeftContent The first of two nodes to join.
+ * @param aRightContent The second of two nodes to join.
+ */
+ static already_AddRefed<JoinNodesTransaction> MaybeCreate(
+ HTMLEditor& aHTMLEditor, nsIContent& aLeftContent,
+ nsIContent& aRightContent);
+
+ /**
+ * CanDoIt() returns true if there are enough members and can join or
+ * restore the nodes. Otherwise, false.
+ */
+ bool CanDoIt() const;
+
+ NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(JoinNodesTransaction,
+ EditTransactionBase)
+ NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr) override;
+
+ NS_DECL_EDITTRANSACTIONBASE
+ NS_DECL_EDITTRANSACTIONBASE_GETASMETHODS_OVERRIDE(JoinNodesTransaction)
+
+ MOZ_CAN_RUN_SCRIPT NS_IMETHOD RedoTransaction() override;
+
+ // Note that we don't support join/split node direction switching per
+ // transaction.
+ [[nodiscard]] SplitNodeDirection GetSplitNodeDirection() const;
+ [[nodiscard]] JoinNodesDirection GetJoinNodesDirection() const;
+
+ /**
+ * GetExistingContent() and GetRemovedContent() never returns nullptr
+ * unless the cycle collector clears them out.
+ */
+ nsIContent* GetExistingContent() const { return mKeepingContent; }
+ nsIContent* GetRemovedContent() const { return mRemovedContent; }
+ nsINode* GetParentNode() const { return mParentNode; }
+
+ template <typename EditorDOMPointType>
+ EditorDOMPointType CreateJoinedPoint() const {
+ if (MOZ_UNLIKELY(!mKeepingContent)) {
+ return EditorDOMPointType();
+ }
+ return EditorDOMPointType(
+ mKeepingContent, std::min(mJoinedOffset, mKeepingContent->Length()));
+ }
+
+ friend std::ostream& operator<<(std::ostream& aStream,
+ const JoinNodesTransaction& aTransaction);
+
+ protected:
+ virtual ~JoinNodesTransaction() = default;
+
+ enum class RedoingTransaction { No, Yes };
+ MOZ_CAN_RUN_SCRIPT nsresult DoTransactionInternal(RedoingTransaction);
+
+ RefPtr<HTMLEditor> mHTMLEditor;
+
+ // The original parent of the left/right nodes.
+ nsCOMPtr<nsINode> mParentNode;
+
+ // Removed content after joined.
+ nsCOMPtr<nsIContent> mRemovedContent;
+
+ // The keeping content node which contains ex-children of mRemovedContent.
+ nsCOMPtr<nsIContent> mKeepingContent;
+
+ // Offset where the original first content is in mKeepingContent after
+ // doing or redoing.
+ uint32_t mJoinedOffset = 0u;
+};
+
+} // namespace mozilla
+
+#endif // #ifndef JoinNodesTransaction_h