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      1 /*
      2  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef RopeImpl_h
     27 #define RopeImpl_h
     28 
     29 #include <wtf/text/StringImpl.h>
     30 
     31 namespace JSC {
     32 
     33 class RopeImpl : public StringImplBase {
     34 public:
     35     // A RopeImpl is composed from a set of smaller strings called Fibers.
     36     // Each Fiber in a rope is either StringImpl or another RopeImpl.
     37     typedef StringImplBase* Fiber;
     38 
     39     // Creates a RopeImpl comprising of 'fiberCount' Fibers.
     40     // The RopeImpl is constructed in an uninitialized state - initialize must be called for each Fiber in the RopeImpl.
     41     static PassRefPtr<RopeImpl> tryCreateUninitialized(unsigned fiberCount)
     42     {
     43         void* allocation;
     44         if (tryFastMalloc(sizeof(RopeImpl) + (fiberCount - 1) * sizeof(Fiber)).getValue(allocation))
     45             return adoptRef(new (allocation) RopeImpl(fiberCount));
     46         return 0;
     47     }
     48 
     49     static bool isRope(Fiber fiber)
     50     {
     51         return !fiber->isStringImpl();
     52     }
     53 
     54     static void deref(Fiber fiber)
     55     {
     56         if (isRope(fiber))
     57             static_cast<RopeImpl*>(fiber)->deref();
     58         else
     59             static_cast<StringImpl*>(fiber)->deref();
     60     }
     61 
     62     void initializeFiber(unsigned &index, Fiber fiber)
     63     {
     64         m_fibers[index++] = fiber;
     65         fiber->ref();
     66         m_length += fiber->length();
     67     }
     68 
     69     unsigned fiberCount() { return m_size; }
     70     Fiber* fibers() { return m_fibers; }
     71 
     72     ALWAYS_INLINE void deref()
     73     {
     74         m_refCountAndFlags -= s_refCountIncrement;
     75         if (!(m_refCountAndFlags & s_refCountMask))
     76             destructNonRecursive();
     77     }
     78 
     79 private:
     80     RopeImpl(unsigned fiberCount)
     81         : StringImplBase(ConstructNonStringImpl)
     82         , m_size(fiberCount)
     83     {
     84     }
     85 
     86     void destructNonRecursive();
     87     void derefFibersNonRecursive(Vector<RopeImpl*, 32>& workQueue);
     88 
     89     bool hasOneRef() { return (m_refCountAndFlags & s_refCountMask) == s_refCountIncrement; }
     90 
     91     unsigned m_size;
     92     Fiber m_fibers[1];
     93 };
     94 
     95 }
     96 
     97 #endif
     98