1 /*
2 * Copyright Andrey Semashev 2007 - 2015.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * http://www.boost.org/LICENSE_1_0.txt)
6 */
7
8 #include <cstddef>
9 #include <string>
10 #include <iostream>
11 #include <boost/mpl/vector.hpp>
12 #include <boost/log/attributes/value_visitation.hpp>
13 #include <boost/log/attributes/attribute_value_impl.hpp>
14 #include <boost/log/utility/functional/save_result.hpp>
15
16 namespace logging = boost::log;
17 namespace attrs = boost::log::attributes;
18
19 //[ example_attr_value_visitation
20 // Our attribute value visitor
21 struct print_visitor
22 {
23 typedef void result_type;
24
operator ()print_visitor25 result_type operator() (int val) const
26 {
27 std::cout << "Visited value is int: " << val << std::endl;
28 }
29
operator ()print_visitor30 result_type operator() (std::string const& val) const
31 {
32 std::cout << "Visited value is string: " << val << std::endl;
33 }
34 };
35
print_value(logging::attribute_value const & attr)36 void print_value(logging::attribute_value const& attr)
37 {
38 // Define the set of expected types of the stored value
39 typedef boost::mpl::vector< int, std::string > types;
40
41 // Apply our visitor
42 logging::visitation_result result = logging::visit< types >(attr, print_visitor());
43
44 // Check the result
45 if (result)
46 std::cout << "Visitation succeeded" << std::endl;
47 else
48 std::cout << "Visitation failed" << std::endl;
49 }
50 //]
51
52 //[ example_attr_value_visitation_with_retval
53 struct hash_visitor
54 {
55 typedef std::size_t result_type;
56
operator ()hash_visitor57 result_type operator() (int val) const
58 {
59 std::size_t h = val;
60 h = (h << 15) + h;
61 h ^= (h >> 6) + (h << 7);
62 return h;
63 }
64
operator ()hash_visitor65 result_type operator() (std::string const& val) const
66 {
67 std::size_t h = 0;
68 for (std::string::const_iterator it = val.begin(), end = val.end(); it != end; ++it)
69 h += *it;
70
71 h = (h << 15) + h;
72 h ^= (h >> 6) + (h << 7);
73 return h;
74 }
75 };
76
hash_value(logging::attribute_value const & attr)77 void hash_value(logging::attribute_value const& attr)
78 {
79 // Define the set of expected types of the stored value
80 typedef boost::mpl::vector< int, std::string > types;
81
82 // Apply our visitor
83 std::size_t h = 0;
84 logging::visitation_result result = logging::visit< types >(attr, logging::save_result(hash_visitor(), h));
85
86 // Check the result
87 if (result)
88 std::cout << "Visitation succeeded, hash value: " << h << std::endl;
89 else
90 std::cout << "Visitation failed" << std::endl;
91 }
92 //]
93
94 #if 0
95 //[ example_attr_value_visitation_with_retval_rec
96 void hash_value(logging::record_view const& rec, logging::attribute_name name)
97 {
98 // Define the set of expected types of the stored value
99 typedef boost::mpl::vector< int, std::string > types;
100
101 // Apply our visitor
102 std::size_t h = 0;
103 logging::visitation_result result = logging::visit< types >(name, rec, logging::save_result(hash_visitor(), h));
104
105 // Check the result
106 if (result)
107 std::cout << "Visitation succeeded, hash value: " << h << std::endl;
108 else
109 std::cout << "Visitation failed" << std::endl;
110 }
111 //]
112 #endif
113
main(int,char * [])114 int main(int, char*[])
115 {
116 print_value(attrs::make_attribute_value(10));
117 print_value(attrs::make_attribute_value(std::string("Hello")));
118
119 hash_value(attrs::make_attribute_value(10));
120 hash_value(attrs::make_attribute_value(std::string("Hello")));
121
122 return 0;
123 }
124