Move LayoutObject::previousOffsetForBackwardDeletion() to editing.

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 37 matching lines @@
 #include "core/html/HTMLLIElement.h"
 #include "core/html/HTMLParagraphElement.h"
 #include "core/html/HTMLSpanElement.h"
 #include "core/html/HTMLTableCellElement.h"
 #include "core/html/HTMLUListElement.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTableCell.h"
 #include "wtf/Assertions.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
+#include "wtf/text/Unicode.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 // Atomic means that the node has no children, or has children which are ignored for the
 // purposes of editing.
 bool isAtomicNode(const Node *node)
 {
     return node && (!node->hasChildren() || editingIgnoresContent(node));
@@ skipping 481 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)
 {
-    return n->layoutObject() ? n->layoutObject()->previousOffsetForBackwardDeletion(current) : current - 1;
+    DCHECK_GE(current, 0);
+    if (current <= 1)
+        return 0;
+    if (!node->isTextNode())
+        return current - 1;
+
+    const String& text = toText(node)->data();
+    DCHECK(static_cast<unsigned>(current - 1) < text.length());
+    if (U16_IS_TRAIL(text[--current]))
+        --current;
+    if (current < 0)
+        current = 0;
+    return current;
 }
 
 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