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 * \file has_attr.hpp
9 * \author Andrey Semashev
10 * \date 23.07.2012
11 *
12 * The header contains implementation of a generic attribute presence checker in template expressions.
13 */
14
15 #ifndef BOOST_LOG_EXPRESSIONS_PREDICATES_HAS_ATTR_HPP_INCLUDED_
16 #define BOOST_LOG_EXPRESSIONS_PREDICATES_HAS_ATTR_HPP_INCLUDED_
17
18 #include <boost/phoenix/core/actor.hpp>
19 #include <boost/log/detail/config.hpp>
20 #include <boost/log/core/record_view.hpp>
21 #include <boost/log/attributes/attribute_name.hpp>
22 #include <boost/log/attributes/attribute_value_set.hpp>
23 #include <boost/log/attributes/value_visitation.hpp>
24 #include <boost/log/expressions/keyword_fwd.hpp>
25 #include <boost/log/detail/unary_function_terminal.hpp>
26 #include <boost/log/utility/functional/nop.hpp>
27 #include <boost/log/detail/header.hpp>
28
29 #ifdef BOOST_HAS_PRAGMA_ONCE
30 #pragma once
31 #endif
32
33 namespace boost {
34
35 BOOST_LOG_OPEN_NAMESPACE
36
37 namespace expressions {
38
39 /*!
40 * An attribute value presence checker.
41 */
42 template< typename T >
43 class has_attribute
44 {
45 public:
46 //! Function result_type
47 typedef bool result_type;
48 //! Expected attribute value type
49 typedef T value_type;
50
51 private:
52 //! Attribute value name
53 const attribute_name m_name;
54 //! Visitor invoker
55 value_visitor_invoker< value_type > m_visitor_invoker;
56
57 public:
58 /*!
59 * Initializing constructor
60 *
61 * \param name Attribute name
62 */
has_attribute(attribute_name const & name)63 explicit has_attribute(attribute_name const& name) : m_name(name)
64 {
65 }
66
67 /*!
68 * Checking operator
69 *
70 * \param arg A set of attribute values or a log record
71 * \return \c true if the log record contains the sought attribute value, \c false otherwise
72 */
73 template< typename ArgT >
operator ()(ArgT const & arg) const74 result_type operator() (ArgT const& arg) const
75 {
76 return m_visitor_invoker(m_name, arg, nop()).code() == visitation_result::ok;
77 }
78 };
79
80 /*!
81 * An attribute value presence checker. This specialization does not check the type of the attribute value.
82 */
83 template< >
84 class has_attribute< void >
85 {
86 public:
87 //! Function result_type
88 typedef bool result_type;
89 //! Expected attribute value type
90 typedef void value_type;
91
92 private:
93 //! Attribute name
94 const attribute_name m_name;
95
96 public:
97 /*!
98 * Initializing constructor
99 *
100 * \param name Attribute name
101 */
has_attribute(attribute_name const & name)102 explicit has_attribute(attribute_name const& name) : m_name(name)
103 {
104 }
105
106 /*!
107 * Checking operator
108 *
109 * \param attrs A set of attribute values
110 * \return \c true if the log record contains the sought attribute value, \c false otherwise
111 */
operator ()(attribute_value_set const & attrs) const112 result_type operator() (attribute_value_set const& attrs) const
113 {
114 return attrs.find(m_name) != attrs.end();
115 }
116
117 /*!
118 * Checking operator
119 *
120 * \param rec A log record
121 * \return \c true if the log record contains the sought attribute value, \c false otherwise
122 */
operator ()(boost::log::record_view const & rec) const123 result_type operator() (boost::log::record_view const& rec) const
124 {
125 return operator()(rec.attribute_values());
126 }
127 };
128
129 /*!
130 * The function generates a terminal node in a template expression. The node will check for the attribute value
131 * presence in a log record. The node will also check that the attribute value has the specified type, if present.
132 */
133 template< typename AttributeValueT >
has_attr(attribute_name const & name)134 BOOST_FORCEINLINE phoenix::actor< aux::unary_function_terminal< has_attribute< AttributeValueT > > > has_attr(attribute_name const& name)
135 {
136 typedef aux::unary_function_terminal< has_attribute< AttributeValueT > > terminal_type;
137 phoenix::actor< terminal_type > act = {{ terminal_type(name) }};
138 return act;
139 }
140
141 /*!
142 * The function generates a terminal node in a template expression. The node will check for the attribute value
143 * presence in a log record.
144 */
has_attr(attribute_name const & name)145 BOOST_FORCEINLINE phoenix::actor< aux::unary_function_terminal< has_attribute< void > > > has_attr(attribute_name const& name)
146 {
147 typedef aux::unary_function_terminal< has_attribute< void > > terminal_type;
148 phoenix::actor< terminal_type > act = {{ terminal_type(name) }};
149 return act;
150 }
151
152 /*!
153 * The function generates a terminal node in a template expression. The node will check for the attribute value
154 * presence in a log record. The node will also check that the attribute value has the specified type, if present.
155 */
156 template< typename DescriptorT, template< typename > class ActorT >
has_attr(attribute_keyword<DescriptorT,ActorT> const &)157 BOOST_FORCEINLINE ActorT< aux::unary_function_terminal< has_attribute< typename DescriptorT::value_type > > > has_attr(attribute_keyword< DescriptorT, ActorT > const&)
158 {
159 typedef aux::unary_function_terminal< has_attribute< typename DescriptorT::value_type > > terminal_type;
160 ActorT< terminal_type > act = {{ terminal_type(DescriptorT::get_name()) }};
161 return act;
162 }
163
164 } // namespace expressions
165
166 BOOST_LOG_CLOSE_NAMESPACE // namespace log
167
168 } // namespace boost
169
170 #include <boost/log/detail/footer.hpp>
171
172 #endif // BOOST_LOG_EXPRESSIONS_PREDICATES_HAS_ATTR_HPP_INCLUDED_
173