337 lines
7.7 KiB
C++
337 lines
7.7 KiB
C++
// vim: set sts=8 ts=4 sw=4 tw=99 et:
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//
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// Copyright (C) 2013, David Anderson and AlliedModders LLC
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of AlliedModders LLC nor the names of its contributors
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// may be used to endorse or promote products derived from this software
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// without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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#ifndef _include_amtl_refcounting_h_
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#define _include_amtl_refcounting_h_
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#include <am-utility.h>
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#include <am-moveable.h>
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namespace ke {
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template <typename T> class Ref;
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// Objects in AMTL inheriting from Refcounted will have an initial refcount
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// of 0. However, in some systems (such as COM), the initial refcount is 1,
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// or functions may return raw pointers that have been AddRef'd. In these
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// cases it would be a mistake to use Ref<> or PassRef<>, since the object
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// would leak an extra reference.
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//
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// This container holds a refcounted object without addrefing it. This is
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// intended only for interacting with functions which return an object that
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// has been manually AddRef'd. Note that this will perform a Release(), so
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// so it is necessary to assign it to retain the object.
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template <typename T>
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class AlreadyRefed
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{
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public:
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AlreadyRefed(T *t)
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: thing_(t)
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{
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}
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AlreadyRefed(const AlreadyRefed<T> &other)
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: thing_(other.thing_)
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{
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// If copy elision for some reason doesn't happen (for example, when
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// returning from AdoptRef), just null out the source ref.
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other.thing_ = NULL;
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}
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~AlreadyRefed() {
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if (thing_)
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thing_->Release();
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}
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T *release() const {
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return ReturnAndVoid(thing_);
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}
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private:
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mutable T *thing_;
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};
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template <typename T>
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static inline AlreadyRefed<T>
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AdoptRef(T *t)
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{
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return AlreadyRefed<T>(t);
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}
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// When returning a value, we'd rather not be needlessly changing the refcount,
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// so we have a special type to use for returns.
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template <typename T>
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class PassRef
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{
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public:
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PassRef(T *thing)
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: thing_(thing)
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{
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AddRef();
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}
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PassRef()
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: thing_(NULL)
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{
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}
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PassRef(const AlreadyRefed<T *> &other)
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: thing_(other.release())
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{
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// Don't addref, newborn means already addref'd.
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}
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template <typename S>
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PassRef(const AlreadyRefed<S *> &other)
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: thing_(other.release())
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{
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// Don't addref, newborn means already addref'd.
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}
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template <typename S>
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inline PassRef(const Ref<S> &other);
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PassRef(const PassRef &other)
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: thing_(other.release())
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{
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}
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template <typename S>
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PassRef(const PassRef<S> &other)
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: thing_(other.release())
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{
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}
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~PassRef()
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{
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Release();
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}
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operator T &() {
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return *thing_;
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}
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operator T *() const {
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return thing_;
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}
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T *operator ->() const {
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return operator *();
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}
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T *operator *() const {
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return thing_;
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}
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bool operator !() const {
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return !thing_;
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}
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T *release() const {
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return ReturnAndVoid(thing_);
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}
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template <typename S>
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PassRef &operator =(const PassRef<S> &other) {
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Release();
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thing_ = other.release();
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return *this;
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}
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private:
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// Disallowed operators.
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PassRef &operator =(T *other);
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PassRef &operator =(AlreadyRefed<T> &other);
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void AddRef() {
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if (thing_)
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thing_->AddRef();
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}
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void Release() {
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if (thing_)
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thing_->Release();
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}
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private:
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mutable T *thing_;
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};
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// Classes which are refcounted should inherit from this. Note that reference
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// counts start at 0 in AMTL, rather than 1. This avoids the complexity of
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// having to adopt the initial ref upon allocation. However, this also means
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// invoking Release() on a newly allocated object is illegal. Newborn objects
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// must either be assigned to a Ref or PassRef (NOT an AdoptRef/AlreadyRefed),
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// or must be deleted using |delete|.
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template <typename T>
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class Refcounted
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{
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public:
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Refcounted()
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: refcount_(0)
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{
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}
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void AddRef() {
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refcount_++;
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}
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void Release() {
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assert(refcount_ > 0);
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if (--refcount_ == 0)
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delete static_cast<T *>(this);
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}
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protected:
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~Refcounted() {
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}
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private:
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uintptr_t refcount_;
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};
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// Simple class for automatic refcounting.
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template <typename T>
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class Ref
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{
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public:
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Ref(T *thing)
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: thing_(thing)
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{
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AddRef();
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}
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Ref()
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: thing_(NULL)
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{
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}
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Ref(const Ref &other)
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: thing_(other.thing_)
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{
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AddRef();
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}
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Ref(Moveable<Ref> other)
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: thing_(other->thing_)
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{
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other->thing_ = NULL;
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}
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template <typename S>
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Ref(const Ref<S> &other)
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: thing_(*other)
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{
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AddRef();
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}
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Ref(const PassRef<T> &other)
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: thing_(other.release())
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{
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}
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template <typename S>
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Ref(const PassRef<S> &other)
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: thing_(other.release())
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{
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}
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Ref(const AlreadyRefed<T> &other)
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: thing_(other.release())
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{
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}
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template <typename S>
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Ref(const AlreadyRefed<S> &other)
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: thing_(other.release())
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{
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}
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~Ref()
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{
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Release();
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}
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T *operator ->() const {
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return operator *();
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}
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T *operator *() const {
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return thing_;
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}
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operator T *() {
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return thing_;
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}
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bool operator !() const {
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return !thing_;
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}
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template <typename S>
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Ref &operator =(S *thing) {
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Release();
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thing_ = thing;
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AddRef();
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return *this;
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}
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template <typename S>
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Ref &operator =(const PassRef<S> &other) {
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Release();
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thing_ = other.release();
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return *this;
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}
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template <typename S>
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Ref &operator =(const AlreadyRefed<S> &other) {
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Release();
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thing_ = other.release();
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return *this;
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}
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Ref &operator =(const Ref &other) {
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Release();
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thing_ = other.thing_;
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AddRef();
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return *this;
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}
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Ref &operator =(Moveable<Ref> other) {
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Release();
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thing_ = other->thing_;
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other->thing_ = NULL;
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return *this;
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}
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private:
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void AddRef() {
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if (thing_)
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thing_->AddRef();
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}
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void Release() {
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if (thing_)
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thing_->Release();
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}
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protected:
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T *thing_;
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};
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template <typename T> template <typename S>
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PassRef<T>::PassRef(const Ref<S> &other)
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: thing_(*other)
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{
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AddRef();
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}
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} // namespace ke
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#endif // _include_amtl_refcounting_h_
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