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/////////////////////////////////////////////////////////////////////////////
// Copyright (c) Electronic Arts Inc. All rights reserved.
/////////////////////////////////////////////////////////////////////////////
#ifndef EASTL_INTERNAL_ENABLE_SHARED_H
#define EASTL_INTERNAL_ENABLE_SHARED_H
#include <EABase/eabase.h>
#if defined(EA_PRAGMA_ONCE_SUPPORTED)
#pragma once
#endif
namespace eastl
{
/// enable_shared_from_this
///
/// This is a helper mixin class that allows you to make any class
/// export a shared_ptr instance that is associated with the class
/// instance. Any class that inherits from this class gets two functions:
/// shared_ptr<T> shared_from_this();
/// shared_ptr<T> shared_from_this() const;
/// If you call shared_from_this, you get back a shared_ptr that
/// refers to the class. A second call to shared_from_this returns
/// another shared_ptr that is shared with the first one.
///
/// The trick that happens which is not so obvious here (and which is
/// not mentioned at all in the Boost documentation of their version
/// of this) is that the shared_ptr constructor detects that the
/// class has an enable_shared_from_this mixin and sets up this system
/// automatically for the user. This is done with template tricks.
///
/// For some additional explanation, see the Boost documentation for
/// their description of their version of enable_shared_from_this.
///
template <typename T>
class enable_shared_from_this
{
public:
shared_ptr<T> shared_from_this()
{ return shared_ptr<T>(mWeakPtr); }
shared_ptr<const T> shared_from_this() const
{ return shared_ptr<const T>(mWeakPtr); }
weak_ptr<T> weak_from_this()
{ return mWeakPtr; }
weak_ptr<const T> weak_from_this() const
{ return mWeakPtr; }
public: // This is public because the alternative fails on some compilers that we need to support.
mutable weak_ptr<T> mWeakPtr;
protected:
template <typename U> friend class shared_ptr;
EA_CONSTEXPR enable_shared_from_this() EA_NOEXCEPT
{ }
enable_shared_from_this(const enable_shared_from_this&) EA_NOEXCEPT
{ }
enable_shared_from_this& operator=(const enable_shared_from_this&) EA_NOEXCEPT
{ return *this; }
~enable_shared_from_this()
{ }
}; // enable_shared_from_this
} // namespace eastl
#endif // Header include guard
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