Fix setComposingText when newCursorPosition != 1

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

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov.
  *
  * 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
@@ skipping 55 matching lines @@
 EphemeralRange PlainTextRange::createRangeForSelection(const ContainerNode& scope) const
 {
     return createRangeFor(scope, ForSelection);
 }
 
 EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRangeFor getRangeFor) const
 {
     ASSERT(isNotNull());
 
     size_t docTextPosition = 0;
-    bool startRangeFound = false;
+    bool startOutOfBound = true;
 
     Position textRunStartPosition;
     Position textRunEndPosition;
 
     TextIteratorBehaviorFlags behaviorFlags = TextIteratorEmitsObjectReplacementCharacter;
     if (getRangeFor == ForSelection)
         behaviorFlags |= TextIteratorEmitsCharactersBetweenAllVisiblePositions;
     auto range = EphemeralRange::rangeOfContents(scope);
     TextIterator it(range.startPosition(), range.endPosition(), behaviorFlags);
 
@@ skipping 25 matching lines @@
                 if (!it.atEnd()) {
                     textRunEndPosition = it.startPositionInCurrentContainer();
                 } else {
                     Position runEnd = nextPositionOf(createVisiblePosition(textRunStartPosition)).deepEquivalent();
                     if (runEnd.isNotNull())
                         textRunEndPosition = runEnd;
                 }
             }
         }
 
-        if (foundStart) {
-            startRangeFound = true;
+        // resultStart should be assigned the first time foundStart is true.

[Changwan Ryu, 2016/04/07 11:46:19]

I don't feel that this comment is needed here.

+        if (foundStart && startOutOfBound) {

[Changwan Ryu, 2016/04/07 11:46:19]

no need to check startOutOfBound?

[yabinh, 2016/04/08 01:21:30]

In "foundStart = start() >= docTextPosition && start() <= docTextPosition +
len", there is a "=". It means that foundStart can be true for 2 times in the
loop. But resultStart is assigned correctly only in the first time.

For example, if there are 3 nodes:"hello","\n","world!", and we want to move the
cursor to 5, like:
hello*
world!
where * stands for cursor.
 
foundstart will be true both in the first node(because start()==0,
docTextPosition==0, len==5, and 0 <= 0 <=5) and in the second node(because
start()==5, docTextPosition==5, len==1, and 5 <= 5 <=6). If resultStart is
assigned in the second time, the cursor will be like this:
hello
*world!
which is not correct.

[yabinh, 2016/04/11 05:53:25]

I was wrong about it. I thought the selected range was wrong, and I should
change it. But it turned out that although the selected range was wrong, it was
changed in SelectionEditor::setSelectedRange. So there is no need to change it
in advance. 

And also, it shouldn’t be changed twice, because it will cause some problems for
certain boundary cases.

Anyway, no need to change “if(foundStart)”.

+            startOutOfBound = false;
             if (textRunStartPosition.computeContainerNode()->isTextNode()) {
                 int offset = start() - docTextPosition;
                 resultStart = Position(textRunStartPosition.computeContainerNode(), offset + textRunStartPosition.offsetInContainerNode());
             } else {
                 if (start() == docTextPosition)
                     resultStart = textRunStartPosition;
                 else
                     resultStart = textRunEndPosition;
             }
         }
 
         if (foundEnd) {
             if (textRunStartPosition.computeContainerNode()->isTextNode()) {
                 int offset = end() - docTextPosition;
                 resultEnd = Position(textRunStartPosition.computeContainerNode(), offset + textRunStartPosition.offsetInContainerNode());
             } else {
                 if (end() == docTextPosition)
                     resultEnd = textRunStartPosition;
                 else
                     resultEnd = textRunEndPosition;
             }
             docTextPosition += len;
             break;
         }
         docTextPosition += len;
     }
 
-    if (!startRangeFound)
-        return EphemeralRange();
+    if (startOutOfBound) {
+        resultStart = textRunEndPosition;
+        resultEnd = textRunEndPosition;
+    }
 
     if (length() && end() > docTextPosition) { // end() is out of bounds
         resultEnd = textRunEndPosition;
     }
 
     return EphemeralRange(resultStart.toOffsetInAnchor(), resultEnd.toOffsetInAnchor());
 }
 
 PlainTextRange PlainTextRange::create(const ContainerNode& scope, const EphemeralRange& range)
 {
@@ skipping 17 matching lines @@
 
     return PlainTextRange(start, end);
 }
 
 PlainTextRange PlainTextRange::create(const ContainerNode& scope, const Range& range)
 {
     return create(scope, EphemeralRange(&range));
 }
 
 } // namespace blink