text: /*
   * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
   * Copyright (C) 2003, 2004, 2006, 2007, 2009, 2010 Apple Inc. All right 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.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Library General Public License for more details.
   *
   * You should have received a copy of the GNU Library General Public License
   * along with this library; see the file COPYING.LIB.  If not, write to
   * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   * Boston, MA 02110-1301, USA.
   *
   */
  
  #include "sky/engine/platform/text/BidiContext.h"
  
  #include "sky/engine/wtf/StdLibExtras.h"
  #include "sky/engine/wtf/Vector.h"
  
  namespace blink {
  
  using namespace WTF::Unicode;
  
  struct SameSizeAsBidiContext : public RefCounted<SameSizeAsBidiContext> {
      uint32_t bitfields : 16;
      void* parent;
  };
  
  COMPILE_ASSERT(sizeof(BidiContext) == sizeof(SameSizeAsBidiContext), BidiContext_should_stay_small);
  
  inline PassRefPtr<BidiContext> BidiContext::createUncached(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
  {
      return adoptRef(new BidiContext(level, direction, override, source, parent));
  }
  
  PassRefPtr<BidiContext> BidiContext::create(unsigned char level, Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
  {
      ASSERT(direction == (level % 2 ? RightToLeft : LeftToRight));
  
      if (parent)
          return createUncached(level, direction, override, source, parent);
  
      ASSERT(level <= 1);
      if (!level) {
          if (!override) {
              DEFINE_STATIC_REF(BidiContext, ltrContext, (createUncached(0, LeftToRight, false, FromStyleOrDOM, 0)));
              return ltrContext;
          }
  
          DEFINE_STATIC_REF(BidiContext, ltrOverrideContext, (createUncached(0, LeftToRight, true, FromStyleOrDOM, 0)));
          return ltrOverrideContext;
      }
  
      if (!override) {
          DEFINE_STATIC_REF(BidiContext, rtlContext, (createUncached(1, RightToLeft, false, FromStyleOrDOM, 0)));
          return rtlContext;
      }
  
      DEFINE_STATIC_REF(BidiContext, rtlOverrideContext, (createUncached(1, RightToLeft, true, FromStyleOrDOM, 0)));
      return rtlOverrideContext;
  }
  
  static inline PassRefPtr<BidiContext> copyContextAndRebaselineLevel(BidiContext* context, BidiContext* parent)
  {
      ASSERT(context);
      unsigned char newLevel = parent ? parent->level() : 0;
      if (context->dir() == RightToLeft)
          newLevel = nextGreaterOddLevel(newLevel);
      else if (parent)
          newLevel = nextGreaterEvenLevel(newLevel);
  
      return BidiContext::create(newLevel, context->dir(), context->override(), context->source(), parent);
  }
  
  // The BidiContext stack must be immutable -- they're re-used for re-layout after
  // DOM modification/editing -- so we copy all the non-unicode contexts, and
  // recalculate their levels.
  PassRefPtr<BidiContext> BidiContext::copyStackRemovingUnicodeEmbeddingContexts()
  {
      Vector<BidiContext*, 64> contexts;
      for (BidiContext* iter = this; iter; iter = iter->parent()) {
          if (iter->source() != FromUnicode)
              contexts.append(iter);
      }
      ASSERT(contexts.size());
  
      RefPtr<BidiContext> topContext = copyContextAndRebaselineLevel(contexts.last(), 0);
      for (int i = contexts.size() - 1; i > 0; --i)
          topContext = copyContextAndRebaselineLevel(contexts[i - 1], topContext.get());
  
      return topContext.release();
  }
  
  bool operator==(const BidiContext& c1, const BidiContext& c2)
  {
      if (&c1 == &c2)
          return true;
      if (c1.level() != c2.level() || c1.override() != c2.override() || c1.dir() != c2.dir() || c1.source() != c2.source())
          return false;
      if (!c1.parent())
          return !c2.parent();
      return c2.parent() && *c1.parent() == *c2.parent();
  }
  
  } // namespace blink
  