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Diffstat (limited to 'qpid/cpp/src/qpid/framing/TemplateVisitor.h')
-rw-r--r-- | qpid/cpp/src/qpid/framing/TemplateVisitor.h | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/framing/TemplateVisitor.h b/qpid/cpp/src/qpid/framing/TemplateVisitor.h new file mode 100644 index 0000000000..8c719e5110 --- /dev/null +++ b/qpid/cpp/src/qpid/framing/TemplateVisitor.h @@ -0,0 +1,89 @@ +#ifndef QPID_FRAMING_TEMPLATEVISITOR_H +#define QPID_FRAMING_TEMPLATEVISITOR_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 <boost/mpl/fold.hpp> +#include <boost/utility/value_init.hpp> + +namespace qpid { +namespace framing { + +/** + * Metafunction to generate a visitor class derived from Base with a + * visit for each type in TypeList calling functor F. TypeList may be + * any boost::mpl type collection e.g. mpl::list. + * + * Generated class is: TemplateVisitor<Base, F, TypeList>::type + * + * @see make_visitor + */ +template <class VisitTemplate, class TypeList, class F> +class TemplateVisitor +{ + struct Base : public VisitorBase { + F action; + Base(F f) : action(f) {} + using VisitorBase::visit; + }; + + template <class B, class T> struct Visit : public B { + Visit(F action) : B(action) {} + using B::visit; + void visit(const T& body) { action(body); } + }; + + typedef typename boost::mpl::fold< + TypeList, Base, Visit<boost::mpl::placeholders::_1, + boost::mpl::placeholders::_2> + >::type type; +}; + +/** + * Construct a TemplateVisitor to perform the given action, + * for example: + * @code + */ +template <class VisitorBase, class TypeList, class F> +TemplateVisitor<VisitorBase,TypeList,F>::type make_visitor(F action) { + return TemplateVisitor<VisitorBase,TypeList,F>::type(action); +}; + +/** + * For method body classes in TypeList, invoke the corresponding function + * on Target and return true. For other body types return false. + */ +template <class TypeList, class Target> +bool invoke(const AMQBody& body, Target& target) { + typename InvokeVisitor<TypeList, Target>::type v(target); + body.accept(v); + return v.target; +} + +}} // namespace qpid::framing + + +#endif /*!QPID_FRAMING_INVOKEVISITOR_H*/ + +}} // namespace qpid::framing + + + +#endif /*!QPID_FRAMING_TEMPLATEVISITOR_H*/ |