heap/OpaqueRootSet.h

   1 /*
   2  * Copyright (C) 2014 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. AND ITS CONTRIBUTORS ``AS IS''
  14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  23  * THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef OpaqueRootSet_h
  27 #define OpaqueRootSet_h
  28
  29 #include <wtf/HashSet.h>
  30
  31 namespace JSC {
  32
  33 class OpaqueRootSet {
  34     WTF_MAKE_NONCOPYABLE(OpaqueRootSet);
  35 public:
  36     OpaqueRootSet()
  37         : m_lastQueriedRoot(nullptr)
  38         , m_containsLastQueriedRoot(false)
  39     {
  40     }
  41
  42     bool contains(void* root) const
  43     {
  44         if (root != m_lastQueriedRoot) {
  45             m_lastQueriedRoot = root;
  46             m_containsLastQueriedRoot = m_roots.contains(root);
  47         }
  48         return m_containsLastQueriedRoot;
  49     }
  50
  51     bool isEmpty() const
  52     {
  53         return m_roots.isEmpty();
  54     }
  55
  56     void clear()
  57     {
  58         m_roots.clear();
  59         m_lastQueriedRoot = nullptr;
  60         m_containsLastQueriedRoot = false;
  61     }
  62
  63     void add(void* root)
  64     {
  65         if (root == m_lastQueriedRoot)
  66             m_containsLastQueriedRoot = true;
  67         m_roots.add(root);
  68     }
  69
  70     int size() const
  71     {
  72         return m_roots.size();
  73     }
  74
  75     HashSet<void*>::const_iterator begin() const
  76     {
  77         return m_roots.begin();
  78     }
  79
  80     HashSet<void*>::const_iterator end() const
  81     {
  82         return m_roots.end();
  83     }
  84
  85
  86 private:
  87     HashSet<void*> m_roots;
  88     mutable void* m_lastQueriedRoot;
  89     mutable bool m_containsLastQueriedRoot;
  90 };
  91
  92 } // namespace JSC
  93
  94 #endif // OpaqueRootSet_h