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#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*/
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