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#ifndef QPID_MESSAGING_HANDLE_H
#define QPID_MESSAGING_HANDLE_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"
namespace qpid {
namespace messaging {
template <class> class PrivateImplRef;
/** \ingroup messaging
* A handle is like a pointer: refers to an underlying implementation object.
* Copying the handle does not copy the object.
*
* Handles can be null, like a 0 pointer. Use isValid(), isNull() or the
* conversion to bool to test for a null handle.
*/
template <class T> class Handle {
public:
/**@return true if handle is valid, i.e. not null. */
QPID_MESSAGING_INLINE_EXTERN bool isValid() const { return impl; }
/**@return true if handle is null. It is an error to call any function on a null handle. */
QPID_MESSAGING_INLINE_EXTERN bool isNull() const { return !impl; }
/** Conversion to bool supports idiom if (handle) { handle->... } */
QPID_MESSAGING_INLINE_EXTERN operator bool() const { return impl; }
/** Operator ! supports idiom if (!handle) { do_if_handle_is_null(); } */
QPID_MESSAGING_INLINE_EXTERN bool operator !() const { return !impl; }
void swap(Handle<T>& h) { T* t = h.impl; h.impl = impl; impl = t; }
protected:
typedef T Impl;
QPID_MESSAGING_INLINE_EXTERN Handle() :impl() {}
// Not implemented,subclasses must implement.
QPID_MESSAGING_EXTERN Handle(const Handle&);
QPID_MESSAGING_EXTERN Handle& operator=(const Handle&);
Impl* impl;
friend class PrivateImplRef<T>;
};
}} // namespace qpid::messaging
#endif /*!QPID_MESSAGING_HANDLE_H*/
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