runtime/WeakGCMap.h

   1 /*
   2  * Copyright (C) 2009, 2015 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 WeakGCMap_h
  27 #define WeakGCMap_h
  28
  29 #include "Weak.h"
  30 #include "WeakInlines.h"
  31 #include <wtf/HashMap.h>
  32
  33 namespace JSC {
  34
  35 // A HashMap with Weak<JSCell> values, which automatically removes values once they're garbage collected.
  36
  37 template<typename KeyArg, typename ValueArg, typename HashArg = typename DefaultHash<KeyArg>::Hash,
  38     typename KeyTraitsArg = HashTraits<KeyArg>>
  39 class WeakGCMap {
  40     WTF_MAKE_FAST_ALLOCATED;
  41     typedef Weak<ValueArg> ValueType;
  42     typedef HashMap<KeyArg, ValueType, HashArg, KeyTraitsArg> HashMapType;
  43
  44 public:
  45     typedef typename HashMapType::KeyType KeyType;
  46     typedef typename HashMapType::AddResult AddResult;
  47     typedef typename HashMapType::iterator iterator;
  48     typedef typename HashMapType::const_iterator const_iterator;
  49
  50     explicit WeakGCMap(VM&);
  51     ~WeakGCMap();
  52
  53     ValueArg* get(const KeyType& key) const
  54     {
  55         return m_map.get(key);
  56     }
  57
  58     AddResult set(const KeyType& key, ValueType value)
  59     {
  60         return m_map.set(key, WTF::move(value));
  61     }
  62
  63     bool remove(const KeyType& key)
  64     {
  65         return m_map.remove(key);
  66     }
  67
  68     void clear()
  69     {
  70         m_map.clear();
  71     }
  72
  73     bool isEmpty() const
  74     {
  75         const_iterator it = m_map.begin();
  76         const_iterator end = m_map.end();
  77         while (it != end) {
  78             if (it->value)
  79                 return true;
  80         }
  81         return false;
  82     }
  83
  84     iterator find(const KeyType& key)
  85     {
  86         iterator it = m_map.find(key);
  87         iterator end = m_map.end();
  88         if (it != end && !it->value) // Found a zombie value.
  89             return end;
  90         return it;
  91     }
  92
  93     const_iterator find(const KeyType& key) const
  94     {
  95         return const_cast<WeakGCMap*>(this)->find(key);
  96     }
  97
  98     template<typename Functor>
  99     void forEach(Functor functor)
 100     {
 101         for (auto& pair : m_map) {
 102             if (pair.value)
 103                 functor(pair.key, pair.value.get());
 104         }
 105     }
 106
 107     bool contains(const KeyType& key) const
 108     {
 109         return find(key) != m_map.end();
 110     }
 111
 112     void pruneStaleEntries();
 113
 114 private:
 115     HashMapType m_map;
 116     VM& m_vm;
 117 };
 118
 119 } // namespace JSC
 120
 121 #endif // WeakGCMap_h