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Diffstat (limited to 'qpid/cpp/src/qpid/framing/Invoker.h')
-rw-r--r-- | qpid/cpp/src/qpid/framing/Invoker.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/framing/Invoker.h b/qpid/cpp/src/qpid/framing/Invoker.h new file mode 100644 index 0000000000..4f1cf7c331 --- /dev/null +++ b/qpid/cpp/src/qpid/framing/Invoker.h @@ -0,0 +1,86 @@ +#ifndef QPID_FRAMING_INVOKER_H +#define QPID_FRAMING_INVOKER_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/framing/AMQMethodBody.h" +#include "qpid/framing/MethodBodyDefaultVisitor.h" +#include "qpid/framing/StructHelper.h" + +#include <boost/optional.hpp> + +namespace qpid { +namespace framing { + +class AMQMethodBody; + +/** + * Base class for invoker visitors. + */ +class Invoker: public MethodBodyDefaultVisitor, protected StructHelper +{ + public: + struct Result { + public: + Result() : handled(false) {} + const std::string& getResult() const { return result; } + bool hasResult() const { return !result.empty(); } + bool wasHandled() const { return handled; } + operator bool() const { return handled; } + + std::string result; + bool handled; + }; + + void defaultVisit(const AMQMethodBody&) {} + Result getResult() const { return result; } + + protected: + Result result; +}; + +/** + * Invoke an invocable object. + * Invocable classes must provide a nested type Invoker. + */ +template <class Invocable> +Invoker::Result invoke(Invocable& target, const AMQMethodBody& body) { + typename Invocable::Invoker invoker(target); + body.accept(invoker); + return invoker.getResult(); +} + +/** + * Invoke an invocable object. + * Invocable classes must provide a nested type Invoker. + */ +template <class Invocable> +Invoker::Result invoke(Invocable& target, const AMQBody& body) { + typename Invocable::Invoker invoker(target); + const AMQMethodBody* method = body.getMethod(); + if (method) + method->accept(invoker); + return invoker.getResult(); +} + +}} // namespace qpid::framing + +#endif /*!QPID_FRAMING_INVOKER_H*/ |