1/*
2 * Copyright Andrey Semashev 2007 - 2013.
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/*!
9 * \file explicit_operator_bool.hpp
10 * \author Andrey Semashev
11 * \date 08.03.2009
12 *
13 * This header defines a compatibility macro that implements an unspecified
14 * \c bool operator idiom, which is superseded with explicit conversion operators in
15 * C++11.
16 */
17
18#ifndef BOOST_CORE_EXPLICIT_OPERATOR_BOOL_HPP
19#define BOOST_CORE_EXPLICIT_OPERATOR_BOOL_HPP
20
21#include <boost/config.hpp>
22#include <boost/config/workaround.hpp>
23
24#ifdef BOOST_HAS_PRAGMA_ONCE
25#pragma once
26#endif
27
28#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
29
30/*!
31 * \brief The macro defines an explicit operator of conversion to \c bool
32 *
33 * The macro should be used inside the definition of a class that has to
34 * support the conversion. The class should also implement <tt>operator!</tt>,
35 * in terms of which the conversion operator will be implemented.
36 */
37#define BOOST_EXPLICIT_OPERATOR_BOOL()\
38 BOOST_FORCEINLINE explicit operator bool () const\
39 {\
40 return !this->operator! ();\
41 }
42
43/*!
44 * \brief The macro defines a noexcept explicit operator of conversion to \c bool
45 *
46 * The macro should be used inside the definition of a class that has to
47 * support the conversion. The class should also implement <tt>operator!</tt>,
48 * in terms of which the conversion operator will be implemented.
49 */
50#define BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()\
51 BOOST_FORCEINLINE explicit operator bool () const BOOST_NOEXCEPT\
52 {\
53 return !this->operator! ();\
54 }
55
56#if !BOOST_WORKAROUND(BOOST_GCC, < 40700)
57
58/*!
59 * \brief The macro defines a constexpr explicit operator of conversion to \c bool
60 *
61 * The macro should be used inside the definition of a class that has to
62 * support the conversion. The class should also implement <tt>operator!</tt>,
63 * in terms of which the conversion operator will be implemented.
64 */
65#define BOOST_CONSTEXPR_EXPLICIT_OPERATOR_BOOL()\
66 BOOST_FORCEINLINE BOOST_CONSTEXPR explicit operator bool () const BOOST_NOEXCEPT\
67 {\
68 return !this->operator! ();\
69 }
70
71#else
72
73#define BOOST_CONSTEXPR_EXPLICIT_OPERATOR_BOOL() BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()
74
75#endif
76
77#else // !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
78
79#if (defined(__SUNPRO_CC) && (__SUNPRO_CC <= 0x530)) && !defined(BOOST_NO_COMPILER_CONFIG)
80// Sun C++ 5.3 can't handle the safe_bool idiom, so don't use it
81#define BOOST_NO_UNSPECIFIED_BOOL
82#endif // (defined(__SUNPRO_CC) && (__SUNPRO_CC <= 0x530)) && !defined(BOOST_NO_COMPILER_CONFIG)
83
84#if !defined(BOOST_NO_UNSPECIFIED_BOOL)
85
86namespace boost {
87
88namespace detail {
89
90#if !defined(_MSC_VER) && !defined(__IBMCPP__)
91
92 struct unspecified_bool
93 {
94 // NOTE TO THE USER: If you see this in error messages then you tried
95 // to apply an unsupported operator on the object that supports
96 // explicit conversion to bool.
97 struct OPERATORS_NOT_ALLOWED;
98 static void true_value(OPERATORS_NOT_ALLOWED*) {}
99 };
100 typedef void (*unspecified_bool_type)(unspecified_bool::OPERATORS_NOT_ALLOWED*);
101
102#else
103
104 // MSVC and VACPP are too eager to convert pointer to function to void* even though they shouldn't
105 struct unspecified_bool
106 {
107 // NOTE TO THE USER: If you see this in error messages then you tried
108 // to apply an unsupported operator on the object that supports
109 // explicit conversion to bool.
110 struct OPERATORS_NOT_ALLOWED;
111 void true_value(OPERATORS_NOT_ALLOWED*) {}
112 };
113 typedef void (unspecified_bool::*unspecified_bool_type)(unspecified_bool::OPERATORS_NOT_ALLOWED*);
114
115#endif
116
117} // namespace detail
118
119} // namespace boost
120
121#define BOOST_EXPLICIT_OPERATOR_BOOL()\
122 BOOST_FORCEINLINE operator boost::detail::unspecified_bool_type () const\
123 {\
124 return (!this->operator! () ? &boost::detail::unspecified_bool::true_value : (boost::detail::unspecified_bool_type)0);\
125 }
126
127#define BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()\
128 BOOST_FORCEINLINE operator boost::detail::unspecified_bool_type () const BOOST_NOEXCEPT\
129 {\
130 return (!this->operator! () ? &boost::detail::unspecified_bool::true_value : (boost::detail::unspecified_bool_type)0);\
131 }
132
133#define BOOST_CONSTEXPR_EXPLICIT_OPERATOR_BOOL()\
134 BOOST_FORCEINLINE BOOST_CONSTEXPR operator boost::detail::unspecified_bool_type () const BOOST_NOEXCEPT\
135 {\
136 return (!this->operator! () ? &boost::detail::unspecified_bool::true_value : (boost::detail::unspecified_bool_type)0);\
137 }
138
139#else // !defined(BOOST_NO_UNSPECIFIED_BOOL)
140
141#define BOOST_EXPLICIT_OPERATOR_BOOL()\
142 BOOST_FORCEINLINE operator bool () const\
143 {\
144 return !this->operator! ();\
145 }
146
147#define BOOST_EXPLICIT_OPERATOR_BOOL_NOEXCEPT()\
148 BOOST_FORCEINLINE operator bool () const BOOST_NOEXCEPT\
149 {\
150 return !this->operator! ();\
151 }
152
153#define BOOST_CONSTEXPR_EXPLICIT_OPERATOR_BOOL()\
154 BOOST_FORCEINLINE BOOST_CONSTEXPR operator bool () const BOOST_NOEXCEPT\
155 {\
156 return !this->operator! ();\
157 }
158
159#endif // !defined(BOOST_NO_UNSPECIFIED_BOOL)
160
161#endif // !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
162
163#endif // BOOST_CORE_EXPLICIT_OPERATOR_BOOL_HPP
164

source code of include/boost/core/explicit_operator_bool.hpp