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#ifndef QPID_MESSAGING_PRIVATEIMPL_H
#define QPID_MESSAGING_PRIVATEIMPL_H
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
#include "qpid/messaging/ImportExport.h"
#include <boost/intrusive_ptr.hpp>
#include "qpid/RefCounted.h"
namespace qpid {
namespace messaging {
/**
* Helper class to implement a class with a private, reference counted
* implementation and reference semantics.
*
* Such classes are used in the public API to hide implementation, they
* should. Example of use:
*
* === Foo.h
*
* template <class T> class PrivateImplRef;
* class FooImpl;
*
* Foo : public Handle<FooImpl> {
* public:
* Foo(FooImpl* = 0);
* Foo(const Foo&);
* ~Foo();
* Foo& operator=(const Foo&);
*
* int fooDo(); // and other Foo functions...
*
* private:
* typedef FooImpl Impl;
* Impl* impl;
* friend class PrivateImplRef<Foo>;
*
* === Foo.cpp
*
* typedef PrivateImplRef<Foo> PI;
* Foo::Foo(FooImpl* p) { PI::ctor(*this, p); }
* Foo::Foo(const Foo& c) : Handle<FooImpl>() { PI::copy(*this, c); }
* Foo::~Foo() { PI::dtor(*this); }
* Foo& Foo::operator=(const Foo& c) { return PI::assign(*this, c); }
*
* int foo::fooDo() { return impl->fooDo(); }
*
*/
template <class T> class PrivateImplRef {
public:
typedef typename T::Impl Impl;
typedef boost::intrusive_ptr<Impl> intrusive_ptr;
/** Get the implementation pointer from a handle */
static intrusive_ptr get(const T& t) { return intrusive_ptr(t.impl); }
/** Set the implementation pointer in a handle */
static void set(T& t, const intrusive_ptr& p) {
if (t.impl == p) return;
if (t.impl) intrusive_ptr_release(t.impl);
t.impl = p.get();
if (t.impl) intrusive_ptr_add_ref(t.impl);
}
// Helper functions to implement the ctor, dtor, copy, assign
static void ctor(T& t, Impl* p) { t.impl = p; if (p) intrusive_ptr_add_ref(p); }
static void copy(T& t, const T& x) { if (&t == &x) return; t.impl = 0; assign(t, x); }
static void dtor(T& t) { if(t.impl) intrusive_ptr_release(t.impl); }
static T& assign(T& t, const T& x) { set(t, get(x)); return t;}
};
}} // namespace qpid::messaging
#endif /*!QPID_MESSAGING_PRIVATEIMPL_H*/
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