[All-In-One] Introduce BackspaceStateMachine

third_party/WebKit/Source/core/editing/EditingUtilities.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 14 matching lines @@
 
 #include "core/editing/EditingUtilities.h"
 
 #include "core/HTMLElementFactory.h"
 #include "core/HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/Range.h"
 #include "core/dom/Text.h"
 #include "core/dom/shadow/ShadowRoot.h"
+#include "core/editing/BackspaceStateMachine.h"
 #include "core/editing/EditingStrategy.h"
 #include "core/editing/Editor.h"
 #include "core/editing/PlainTextRange.h"
 #include "core/editing/PositionIterator.h"
 #include "core/editing/VisiblePosition.h"
 #include "core/editing/VisibleSelection.h"
 #include "core/editing/VisibleUnits.h"
 #include "core/editing/iterators/TextIterator.h"
 #include "core/editing/serializers/HTMLInterchange.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 504 matching lines @@
     const String& text = toText(node)->data();
     if (text.is8Bit())
         return current - 1; // TODO(nona): Good to support CR x LF.
     TextBreakIterator* iterator = cursorMovementIterator(text.characters16(), text.length());
     if (!iterator)
         return current - 1;
     const int result = iterator->preceding(current);
     return result == TextBreakDone ? current - 1 : result;
 }
 
-static int uncheckedPreviousOffsetForBackwardDeletion(const Node* n, int current)
+static int uncheckedPreviousOffsetForBackwardDeletion(const Node* node, int current)
 {

[yosin_UTC9, 2016/03/28 05:05:47]

Could you add DCHECK_GE(current, 0)?

[Seigo Nonaka, 2016/03/28 07:28:12]

Done.

-    return n->layoutObject() ? n->layoutObject()->previousOffsetForBackwardDeletion(current) : current - 1;
+    if (current <= 1)
+        return 0;
+    if (!node->isTextNode())
+        return current - 1;
+
+    const String& text = toText(node)->data();
+    CHECK(static_cast<unsigned>(current - 1) < text.length());
+    BackspaceStateMachine machine;
+    for (int i = current - 1; i >= 0; --i) {
+        if (machine.updateState(text[i]))
+            break;
+    }
+    return current - machine.finalizeAndGetCodeUnitCountToBeDeleted();

[yosin_UTC9, 2016/03/28 05:05:47]

Could you check |current| >= 0?

e.g.
int amount = machine.finalizeAndGetCodeUnitCountToBeDeleted();
DCHECK_GE(amount, 1);
DCHECK_GE(current, amount);
return current - amount;

[Seigo Nonaka, 2016/03/28 07:28:11]

Done.

 }
 
 int uncheckedNextOffset(const Node* node, int current)
 {
     if (!node->isTextNode())
         return current + 1;
     const String& text = toText(node)->data();
     if (text.is8Bit())
         return current + 1; // TODO(nona): Good to support CR x LF.
     TextBreakIterator* iterator = cursorMovementIterator(text.characters16(), text.length());
@@ skipping 1092 matching lines @@
     // instead of possibly at the end of the last node before the selection
     return mostForwardCaretPosition(visiblePosition.deepEquivalent());
 }
 
 bool isTextSecurityNode(const Node* node)
 {
     return node && node->layoutObject() && node->layoutObject()->style()->textSecurity() != TSNONE;
 }
 
 } // namespace blink