blob: 8e13063385ee33c24d7f39646bd0d7c237253f23 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#ifndef QPID_FRAMING_VARIANT_H
#define QPID_FRAMING_VARIANT_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.
*
*/
/**@file Tools for using boost::variant. */
#include <boost/variant.hpp>
namespace qpid {
namespace framing {
class Buffer;
/** boost::static_visitor that throws an exception if variant contains a blank.
* Subclasses need to have a using() declaration, which can be generated
* with QPID_USING_NOBLANK(R)
*/
template <class R=void>
struct NoBlankVisitor : public boost::static_visitor<R> {
R foundBlank() const {
assert(0);
throw Exception(QPID_MSG("Invalid variant value."));
}
R operator()(const boost::blank&) const { return foundBlank(); }
R operator()(boost::blank&) const { return foundBlank(); }
};
}} // qpid::framing
/** Generate a using statement, needed in visitors inheriting NoBlankVisitor
* @param R return type.
*/
#define QPID_USING_NOBLANK(R) using ::qpid::framing::NoBlankVisitor<R>::operator()
namespace qpid {
namespace framing {
/** Convert the variant value to type R. */
template <class R> struct ConvertVisitor : public NoBlankVisitor<R> {
QPID_USING_NOBLANK(R);
template <class T> R operator()(T& t) const { return t; }
};
/** Convert the address of variant value to type R. */
template <class R> struct AddressVisitor : public NoBlankVisitor<R> {
QPID_USING_NOBLANK(R);
template <class T> R operator()(T& t) const { return &t; }
};
/** Apply a visitor to the nested variant.*/
template<class V>
struct ApplyVisitor : public NoBlankVisitor<typename V::result_type> {
QPID_USING_NOBLANK(typename V::result_type);
const V& visitor;
ApplyVisitor(const V& v) : visitor(v) {}
template <class T> typename V::result_type operator()(T& t) const {
return boost::apply_visitor(visitor, t);
}
};
/** Convenience function to construct and apply an ApplyVisitor */
template <class Visitor, class Visitable>
typename Visitor::result_type applyApplyVisitor(const Visitor& visitor, Visitable& visitable) {
return boost::apply_visitor(ApplyVisitor<Visitor>(visitor), visitable);
}
}} // namespace qpid::framing
#endif /*!QPID_FRAMING_VARIANT_H*/
|
