X-Git-Url: https://git.saurik.com/apple/javascriptcore.git/blobdiff_plain/1df5f87f1309a8daa30dabdee855f48ae40d14ab..6fe7ccc865dc7d7541b93c5bcaf6368d2c98a174:/heap/PassWeak.h

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+/*
+ * Copyright (C) 2012 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef PassWeak_h
+#define PassWeak_h
+
+#include "JSCell.h"
+#include "WeakSetInlines.h"
+#include <wtf/Assertions.h>
+#include <wtf/NullPtr.h>
+#include <wtf/TypeTraits.h>
+
+namespace JSC {
+
+template<typename T> class Weak;
+template<typename T> class PassWeak;
+template<typename T> PassWeak<T> adoptWeak(WeakImpl*);
+
+template<typename Base, typename T> class WeakImplAccessor {
+public:
+    typedef T* GetType;
+
+    T* operator->() const;
+    T& operator*() const;
+    GetType get() const;
+
+#if !ASSERT_DISABLED
+    bool was(GetType) const;
+#endif
+};
+
+template<typename T> class PassWeak : public WeakImplAccessor<PassWeak<T>, T> {
+public:
+    friend class WeakImplAccessor<PassWeak<T>, T>;
+    typedef typename WeakImplAccessor<PassWeak<T>, T>::GetType GetType;
+
+    PassWeak();
+    PassWeak(std::nullptr_t);
+    PassWeak(GetType, WeakHandleOwner* = 0, void* context = 0);
+
+    // It somewhat breaks the type system to allow transfer of ownership out of
+    // a const PassWeak. However, it makes it much easier to work with PassWeak
+    // temporaries, and we don't have a need to use real const PassWeaks anyway.
+    PassWeak(const PassWeak&);
+    template<typename U> PassWeak(const PassWeak<U>&);
+
+    ~PassWeak();
+
+    bool operator!() const;
+
+    // This conversion operator allows implicit conversion to bool but not to other integer types.
+    typedef JSValue (PassWeak::*UnspecifiedBoolType);
+    operator UnspecifiedBoolType*() const;
+
+    WeakImpl* leakImpl() const WARN_UNUSED_RETURN;
+
+private:
+    friend PassWeak adoptWeak<T>(WeakImpl*);
+    explicit PassWeak(WeakImpl*);
+
+    WeakImpl* m_impl;
+};
+
+template<typename Base, typename T> inline T* WeakImplAccessor<Base, T>::operator->() const
+{
+    ASSERT(static_cast<const Base*>(this)->m_impl && static_cast<const Base*>(this)->m_impl->state() == WeakImpl::Live);
+    return jsCast<T*>(static_cast<const Base*>(this)->m_impl->jsValue().asCell());
+}
+
+template<typename Base, typename T> inline T& WeakImplAccessor<Base, T>::operator*() const
+{
+    ASSERT(static_cast<const Base*>(this)->m_impl && static_cast<const Base*>(this)->m_impl->state() == WeakImpl::Live);
+    return *jsCast<T*>(static_cast<const Base*>(this)->m_impl->jsValue().asCell());
+}
+
+template<typename Base, typename T> inline typename WeakImplAccessor<Base, T>::GetType WeakImplAccessor<Base, T>::get() const
+{
+    if (!static_cast<const Base*>(this)->m_impl || static_cast<const Base*>(this)->m_impl->state() != WeakImpl::Live)
+        return GetType();
+    return jsCast<T*>(static_cast<const Base*>(this)->m_impl->jsValue().asCell());
+}
+
+#if !ASSERT_DISABLED
+template<typename Base, typename T> inline bool WeakImplAccessor<Base, T>::was(typename WeakImplAccessor<Base, T>::GetType other) const
+{
+    return jsCast<T*>(static_cast<const Base*>(this)->m_impl->jsValue().asCell()) == other;
+}
+#endif
+
+template<typename T> inline PassWeak<T>::PassWeak()
+    : m_impl(0)
+{
+}
+
+template<typename T> inline PassWeak<T>::PassWeak(std::nullptr_t)
+    : m_impl(0)
+{
+}
+
+template<typename T> inline PassWeak<T>::PassWeak(typename PassWeak<T>::GetType getType, WeakHandleOwner* weakOwner, void* context)
+    : m_impl(getType ? WeakSet::allocate(getType, weakOwner, context) : 0)
+{
+}
+
+template<typename T> inline PassWeak<T>::PassWeak(const PassWeak& o)
+    : m_impl(o.leakImpl())
+{
+}
+
+template<typename T> template<typename U> inline PassWeak<T>::PassWeak(const PassWeak<U>& o)
+    : m_impl(o.leakImpl())
+{
+}
+
+template<typename T> inline PassWeak<T>::~PassWeak()
+{
+    if (!m_impl)
+        return;
+    WeakSet::deallocate(m_impl);
+}
+
+template<typename T> inline bool PassWeak<T>::operator!() const
+{
+    return !m_impl || m_impl->state() != WeakImpl::Live || !m_impl->jsValue();
+}
+
+template<typename T> inline PassWeak<T>::operator UnspecifiedBoolType*() const
+{
+    return reinterpret_cast<UnspecifiedBoolType*>(!!*this);
+}
+
+template<typename T> inline PassWeak<T>::PassWeak(WeakImpl* impl)
+: m_impl(impl)
+{
+}
+
+template<typename T> inline WeakImpl* PassWeak<T>::leakImpl() const
+{
+    WeakImpl* tmp = 0;
+    std::swap(tmp, const_cast<WeakImpl*&>(m_impl));
+    return tmp;
+}
+
+template<typename T> PassWeak<T> inline adoptWeak(WeakImpl* impl)
+{
+    return PassWeak<T>(impl);
+}
+
+template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, const PassWeak<U>& b) 
+{
+    return a.get() == b.get(); 
+}
+
+template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, const Weak<U>& b) 
+{
+    return a.get() == b.get(); 
+}
+
+template<typename T, typename U> inline bool operator==(const Weak<T>& a, const PassWeak<U>& b) 
+{
+    return a.get() == b.get(); 
+}
+
+template<typename T, typename U> inline bool operator==(const PassWeak<T>& a, U* b) 
+{
+    return a.get() == b; 
+}
+
+template<typename T, typename U> inline bool operator==(T* a, const PassWeak<U>& b) 
+{
+    return a == b.get(); 
+}
+
+template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, const PassWeak<U>& b) 
+{
+    return a.get() != b.get(); 
+}
+
+template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, const Weak<U>& b) 
+{
+    return a.get() != b.get(); 
+}
+
+template<typename T, typename U> inline bool operator!=(const Weak<T>& a, const PassWeak<U>& b) 
+{
+    return a.get() != b.get(); 
+}
+
+template<typename T, typename U> inline bool operator!=(const PassWeak<T>& a, U* b)
+{
+    return a.get() != b; 
+}
+
+template<typename T, typename U> inline bool operator!=(T* a, const PassWeak<U>& b) 
+{
+    return a != b.get(); 
+}
+
+} // namespace JSC
+
+#endif // PassWeak_h