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Diffstat (limited to 'cpp/src/qpid/client/Handle.h')
-rw-r--r-- | cpp/src/qpid/client/Handle.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/cpp/src/qpid/client/Handle.h b/cpp/src/qpid/client/Handle.h new file mode 100644 index 0000000000..b8315481a9 --- /dev/null +++ b/cpp/src/qpid/client/Handle.h @@ -0,0 +1,71 @@ +#ifndef QPID_CLIENT_HANDLE_H +#define QPID_CLIENT_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/client/ClientImportExport.h" + +namespace qpid { +namespace client { + +template <class> class PrivateImplRef; + +/** + * 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_CLIENT_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_CLIENT_INLINE_EXTERN bool isNull() const { return !impl; } + + /** Conversion to bool supports idiom if (handle) { handle->... } */ + QPID_CLIENT_INLINE_EXTERN operator bool() const { return impl; } + + /** Operator ! supports idiom if (!handle) { do_if_handle_is_null(); } */ + QPID_CLIENT_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_CLIENT_INLINE_EXTERN Handle() :impl() {} + + // Not implemented,subclasses must implement. + QPID_CLIENT_EXTERN Handle(const Handle&); + QPID_CLIENT_EXTERN Handle& operator=(const Handle&); + + Impl* impl; + + friend class PrivateImplRef<T>; // FIXME aconway 2009-04-30: Specify +}; + +}} // namespace qpid::client + +#endif /*!QPID_CLIENT_HANDLE_H*/ |