1 files changed, 96 insertions, 0 deletions
diff --git a/accessible/base/TextUpdater.h b/accessible/base/TextUpdater.h
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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