heap/WeakInlines.h

   1 /*
   2  * Copyright (C) 2009, 2012, 2013 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 WeakInlines_h
  27 #define WeakInlines_h
  28
  29 #include "PassWeak.h"
  30 #include "WeakSetInlines.h"
  31 #include <wtf/Assertions.h>
  32 #include <wtf/HashTraits.h>
  33
  34 namespace JSC {
  35
  36 template<typename T> inline Weak<T>::Weak(T* cell, WeakHandleOwner* weakOwner, void* context)
  37     : m_impl(cell ? WeakSet::allocate(cell, weakOwner, context) : 0)
  38 {
  39 }
  40
  41 template<typename T> inline bool Weak<T>::isHashTableDeletedValue() const
  42 {
  43     return m_impl == hashTableDeletedValue();
  44 }
  45
  46 template<typename T> inline Weak<T>::Weak(typename Weak<T>::HashTableDeletedValueTag)
  47     : m_impl(hashTableDeletedValue())
  48 {
  49 }
  50
  51 template<typename T> template<typename U>  inline Weak<T>::Weak(const PassWeak<U>& other)
  52     : m_impl(other.leakImpl())
  53 {
  54 }
  55
  56 template<class T> inline void swap(Weak<T>& a, Weak<T>& b)
  57 {
  58     a.swap(b);
  59 }
  60
  61 template<typename T> inline void Weak<T>::swap(Weak& other)
  62 {
  63     std::swap(m_impl, other.m_impl);
  64 }
  65
  66 template<typename T> inline Weak<T>& Weak<T>::operator=(const PassWeak<T>& o)
  67 {
  68     clear();
  69     m_impl = o.leakImpl();
  70     return *this;
  71 }
  72
  73 template<typename T> inline T* Weak<T>::operator->() const
  74 {
  75     ASSERT(m_impl && m_impl->state() == WeakImpl::Live);
  76     return jsCast<T*>(m_impl->jsValue().asCell());
  77 }
  78
  79 template<typename T> inline T& Weak<T>::operator*() const
  80 {
  81     ASSERT(m_impl && m_impl->state() == WeakImpl::Live);
  82     return *jsCast<T*>(m_impl->jsValue().asCell());
  83 }
  84
  85 template<typename T> inline T* Weak<T>::get() const
  86 {
  87     if (!m_impl || m_impl->state() != WeakImpl::Live)
  88         return 0;
  89     return jsCast<T*>(m_impl->jsValue().asCell());
  90 }
  91
  92 template<typename T> inline bool Weak<T>::was(T* other) const
  93 {
  94     return jsCast<T*>(m_impl->jsValue().asCell()) == other;
  95 }
  96
  97 template<typename T> inline bool Weak<T>::operator!() const
  98 {
  99     return !m_impl || !m_impl->jsValue() || m_impl->state() != WeakImpl::Live;
 100 }
 101
 102 template<typename T> inline Weak<T>::operator UnspecifiedBoolType*() const
 103 {
 104     return reinterpret_cast<UnspecifiedBoolType*>(!!*this);
 105 }
 106
 107 template<typename T> inline PassWeak<T> Weak<T>::release()
 108 {
 109     PassWeak<T> tmp = adoptWeak<T>(m_impl);
 110     m_impl = 0;
 111     return tmp;
 112 }
 113
 114 template<typename T> inline WeakImpl* Weak<T>::hashTableDeletedValue()
 115 {
 116     return reinterpret_cast<WeakImpl*>(-1);
 117 }
 118
 119 template <typename T> inline bool operator==(const Weak<T>& lhs, const Weak<T>& rhs)
 120 {
 121     return lhs.get() == rhs.get();
 122 }
 123
 124 // This function helps avoid modifying a weak table while holding an iterator into it. (Object allocation
 125 // can run a finalizer that modifies the table. We avoid that by requiring a pre-constructed object as our value.)
 126 template<typename Map, typename Key, typename Value> inline void weakAdd(Map& map, const Key& key, Value value)
 127 {
 128     ASSERT(!map.get(key));
 129     map.set(key, value); // The table may still have a zombie for value.
 130 }
 131
 132 template<typename Map, typename Key, typename Value> inline void weakRemove(Map& map, const Key& key, Value value)
 133 {
 134     typename Map::iterator it = map.find(key);
 135     ASSERT_UNUSED(value, value);
 136     ASSERT(it != map.end());
 137     ASSERT(it->value.was(value));
 138     ASSERT(!it->value);
 139     map.remove(it);
 140 }
 141
 142 template<typename T> inline void weakClear(Weak<T>& weak, T* cell)
 143 {
 144     ASSERT_UNUSED(cell, cell);
 145     ASSERT(weak.was(cell));
 146     ASSERT(!weak);
 147     weak.clear();
 148 }
 149
 150 } // namespace JSC
 151
 152 namespace WTF {
 153
 154 template<typename T> struct VectorTraits<JSC::Weak<T> > : SimpleClassVectorTraits {
 155     static const bool canCompareWithMemcmp = false;
 156 };
 157
 158 template<typename T> struct HashTraits<JSC::Weak<T> > : SimpleClassHashTraits<JSC::Weak<T> > {
 159     typedef JSC::Weak<T> StorageType;
 160
 161     typedef std::nullptr_t EmptyValueType;
 162     static EmptyValueType emptyValue() { return nullptr; }
 163
 164     typedef JSC::PassWeak<T> PassInType;
 165     static void store(PassInType value, StorageType& storage) { storage = value; }
 166
 167     typedef JSC::PassWeak<T> PassOutType;
 168     static PassOutType passOut(StorageType& value) { return value.release(); }
 169     static PassOutType passOut(EmptyValueType) { return PassOutType(); }
 170
 171     typedef T* PeekType;
 172     static PeekType peek(const StorageType& value) { return value.get(); }
 173     static PeekType peek(EmptyValueType) { return PeekType(); }
 174 };
 175
 176 } // namespace WTF
 177
 178 #endif // WeakInlines_h