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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 mozilla_a11y_TextUpdater_h__
+#define mozilla_a11y_TextUpdater_h__
+
+#include "AccEvent.h"
+#include "HyperTextAccessible.h"
+
+namespace mozilla {
+namespace a11y {
+
+/**
+ * Used to find a difference between old and new text and fire text change
+ * events.
+ */
+class TextUpdater {
+ public:
+ /**
+ * Start text of the text leaf update.
+ */
+ static void Run(DocAccessible* aDocument, TextLeafAccessible* aTextLeaf,
+ const nsAString& aNewText);
+
+ private:
+ TextUpdater(DocAccessible* aDocument, TextLeafAccessible* aTextLeaf)
+ : mDocument(aDocument),
+ mTextLeaf(aTextLeaf),
+ mHyperText(nullptr),
+ mTextOffset(-1) {}
+
+ ~TextUpdater() {
+ mDocument = nullptr;
+ mTextLeaf = nullptr;
+ mHyperText = nullptr;
+ }
+
+ /**
+ * Update text of the text leaf accessible, fire text change and value change
+ * (if applicable) events for its container hypertext accessible.
+ */
+ void DoUpdate(const nsAString& aNewText, const nsAString& aOldText,
+ uint32_t aSkipStart);
+
+ private:
+ TextUpdater();
+ TextUpdater(const TextUpdater&);
+ TextUpdater& operator=(const TextUpdater&);
+
+ /**
+ * Fire text change events based on difference between strings.
+ */
+ void ComputeTextChangeEvents(const nsAString& aStr1, const nsAString& aStr2,
+ uint32_t* aEntries,
+ nsTArray<RefPtr<AccEvent> >& aEvents);
+
+ /**
+ * Helper to create text change events for inserted text.
+ */
+ inline void FireInsertEvent(const nsAString& aText, uint32_t aAddlOffset,
+ nsTArray<RefPtr<AccEvent> >& aEvents) {
+ RefPtr<AccEvent> event = new AccTextChangeEvent(
+ mHyperText, mTextOffset + aAddlOffset, aText, true);
+ aEvents.AppendElement(event);
+ }
+
+ /**
+ * Helper to create text change events for removed text.
+ */
+ inline void FireDeleteEvent(const nsAString& aText, uint32_t aAddlOffset,
+ nsTArray<RefPtr<AccEvent> >& aEvents) {
+ RefPtr<AccEvent> event = new AccTextChangeEvent(
+ mHyperText, mTextOffset + aAddlOffset, aText, false);
+ aEvents.AppendElement(event);
+ }
+
+ /**
+ * The constant used to skip string difference calculation in case of long
+ * strings.
+ */
+ const static uint32_t kMaxStrLen = 1 << 6;
+
+ private:
+ DocAccessible* mDocument;
+ TextLeafAccessible* mTextLeaf;
+ HyperTextAccessible* mHyperText;
+ int32_t mTextOffset;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif