1/*=============================================================================
2 Copyright (c) 2003 Joel de Guzman
3 http://spirit.sourceforge.net/
4
5 Distributed under the Boost Software License, Version 1.0. (See accompanying
6 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7=============================================================================*/
8#if !defined(BOOST_SPIRIT_SAFE_BOOL_HPP)
9#define BOOST_SPIRIT_SAFE_BOOL_HPP
10
11#include <boost/config.hpp>
12#include <boost/detail/workaround.hpp>
13#include <boost/spirit/home/classic/namespace.hpp>
14
15namespace boost { namespace spirit {
16
17BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
18
19 namespace impl
20 {
21 template <typename T>
22 struct no_base {};
23
24 template <typename T>
25 struct safe_bool_impl
26 {
27#if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
28 void stub(T*) {};
29 typedef void (safe_bool_impl::*type)(T*);
30#else
31 typedef T* TP; // workaround to make parsing easier
32 TP stub;
33 typedef TP safe_bool_impl::*type;
34#endif
35 };
36 }
37
38 template <typename DerivedT, typename BaseT = impl::no_base<DerivedT> >
39 struct safe_bool : BaseT
40 {
41 private:
42 typedef impl::safe_bool_impl<DerivedT> impl_t;
43 typedef typename impl_t::type bool_type;
44
45 public:
46 operator bool_type() const
47 {
48 return static_cast<const DerivedT*>(this)->operator_bool() ?
49 &impl_t::stub : 0;
50 }
51
52 operator bool_type()
53 {
54 return static_cast<DerivedT*>(this)->operator_bool() ?
55 &impl_t::stub : 0;
56 }
57 };
58
59BOOST_SPIRIT_CLASSIC_NAMESPACE_END
60
61}}
62
63#endif
64
65

source code of boost/libs/spirit/include/boost/spirit/home/classic/core/safe_bool.hpp