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00001 #ifndef QPID_FRAMING_VARIANT_H 00002 #define QPID_FRAMING_VARIANT_H 00003 00004 /* 00005 * Licensed to the Apache Software Foundation (ASF) under one 00006 * or more contributor license agreements. See the NOTICE file 00007 * distributed with this work for additional information 00008 * regarding copyright ownership. The ASF licenses this file 00009 * to you under the Apache License, Version 2.0 (the 00010 * "License"); you may not use this file except in compliance 00011 * with the License. You may obtain a copy of the License at 00012 * 00013 * http://www.apache.org/licenses/LICENSE-2.0 00014 * 00015 * Unless required by applicable law or agreed to in writing, 00016 * software distributed under the License is distributed on an 00017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 00018 * KIND, either express or implied. See the License for the 00019 * specific language governing permissions and limitations 00020 * under the License. 00021 * 00022 */ 00023 00027 #include <boost/variant.hpp> 00028 00029 namespace qpid { 00030 namespace framing { 00031 class Buffer; 00032 00037 template <class R=void> 00038 struct NoBlankVisitor : public boost::static_visitor<R> { 00039 R foundBlank() const { 00040 assert(0); 00041 throw Exception(QPID_MSG("Invalid variant value.")); 00042 } 00043 R operator()(const boost::blank&) const { return foundBlank(); } 00044 R operator()(boost::blank&) const { return foundBlank(); } 00045 }; 00046 00047 00048 }} // qpid::framing 00049 00050 00054 #define QPID_USING_NOBLANK(R) using ::qpid::framing::NoBlankVisitor<R>::operator() 00055 00056 namespace qpid { 00057 namespace framing { 00058 00060 template <class R> struct ConvertVisitor : public NoBlankVisitor<R> { 00061 QPID_USING_NOBLANK(R); 00062 template <class T> R operator()(T& t) const { return t; } 00063 }; 00064 00066 template <class R> struct AddressVisitor : public NoBlankVisitor<R> { 00067 QPID_USING_NOBLANK(R); 00068 template <class T> R operator()(T& t) const { return &t; } 00069 }; 00070 00072 template<class V> 00073 struct ApplyVisitor : public NoBlankVisitor<typename V::result_type> { 00074 QPID_USING_NOBLANK(typename V::result_type); 00075 const V& visitor; 00076 ApplyVisitor(const V& v) : visitor(v) {} 00077 template <class T> typename V::result_type operator()(T& t) const { 00078 return boost::apply_visitor(visitor, t); 00079 } 00080 }; 00081 00083 template <class Visitor, class Visitable> 00084 typename Visitor::result_type applyApplyVisitor(const Visitor& visitor, Visitable& visitable) { 00085 return boost::apply_visitor(ApplyVisitor<Visitor>(visitor), visitable); 00086 } 00087 00088 }} // namespace qpid::framing 00089 00090 00091 #endif