runtime/RopeImpl.h

   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 "UStringImpl.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 UStringImpl 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<UStringImpl*>(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