Render string sequences of more than 64k characters.

Source/core/rendering/InlineIterator.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 606 matching lines @@
 
 private:
     unsigned m_nestedIsolateCount;
     bool m_haveAddedFakeRunForRootIsolate;
     LineMidpointState m_midpointStateForRootIsolate;
     BidiRunList<BidiRun>& m_runs;
 };
 
 static void inline appendRunObjectIfNecessary(RenderObject* obj, unsigned start, unsigned end, InlineBidiResolver& resolver, AppendRunBehavior behavior, IsolateTracker& tracker)
 {
-    if (behavior == AppendingFakeRun)
-        tracker.addFakeRunIfNecessary(obj, start, end, resolver);
-    else
-        resolver.runs().addRun(createRun(start, end, obj, resolver));
+    bool addEmptyRun = (end == start);

[eae, 2015/01/15 20:07:07]

The general approach seems fine, I have a hard time wrapping my head around the
concept of addEmptyRun though. Could you either try to reorganize the code to
not need it or add a comment explaining what it is used for.

[Daniel Bratell, 2015/01/16 13:47:32]

There is code that calls this with start == end and expects a BidiRun to be
created. If I just had the loop there would be no BidiRun anymore for that case.
Those that do that create an empty BidiRun and then modify the positions. I
think it was used for trailing whitespace.

I will add some kind of comment.

+    while (end > start || addEmptyRun) {
+        const int limit = USHRT_MAX; // Use a small number in Debug to keep the code well tested?
+        unsigned limitedEnd = end;
+        if (end - start > limit)
+            limitedEnd = start + limit;
+        if (behavior == AppendingFakeRun)
+            tracker.addFakeRunIfNecessary(obj, start, limitedEnd, resolver);
+        else
+            resolver.runs().addRun(createRun(start, limitedEnd, obj, resolver));
+        if (addEmptyRun)
+            break;
+        start = limitedEnd;
+    }
 }
 
 static void adjustMidpointsAndAppendRunsForObjectIfNeeded(RenderObject* obj, unsigned start, unsigned end, InlineBidiResolver& resolver, AppendRunBehavior behavior, IsolateTracker& tracker)
 {
     if (start > end || RenderBlockFlow::shouldSkipCreatingRunsForObject(obj))
         return;
 
     LineMidpointState& lineMidpointState = resolver.midpointState();
     bool haveNextMidpoint = (lineMidpointState.currentMidpoint() < lineMidpointState.numMidpoints());
     InlineIterator nextMidpoint;
@@ skipping 81 matching lines @@
         m_sor = m_eor;
     }
 
     m_direction = WTF::Unicode::OtherNeutral;
     m_status.eor = WTF::Unicode::OtherNeutral;
 }
 
 }
 
 #endif // InlineIterator_h