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- /*=============================================================================
- Copyright (c) 2003 Joel de Guzman
- http://spirit.sourceforge.net/
- Distributed under the Boost Software License, Version 1.0. (See accompanying
- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- =============================================================================*/
- #if !defined(BOOST_SPIRIT_SAFE_BOOL_HPP)
- #define BOOST_SPIRIT_SAFE_BOOL_HPP
- #include <boost/config.hpp>
- #include <boost/detail/workaround.hpp>
- #include <boost/spirit/home/classic/namespace.hpp>
- namespace boost { namespace spirit {
- BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
- namespace impl
- {
- template <typename T>
- struct no_base {};
- template <typename T>
- struct safe_bool_impl
- {
- #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
- void stub(T*) {};
- typedef void (safe_bool_impl::*type)(T*);
- #else
- typedef T* TP; // workaround to make parsing easier
- TP stub;
- typedef TP safe_bool_impl::*type;
- #endif
- };
- }
- template <typename DerivedT, typename BaseT = impl::no_base<DerivedT> >
- struct safe_bool : BaseT
- {
- private:
- typedef impl::safe_bool_impl<DerivedT> impl_t;
- typedef typename impl_t::type bool_type;
- public:
- operator bool_type() const
- {
- return static_cast<const DerivedT*>(this)->operator_bool() ?
- &impl_t::stub : 0;
- }
- operator bool_type()
- {
- return static_cast<DerivedT*>(this)->operator_bool() ?
- &impl_t::stub : 0;
- }
- };
- BOOST_SPIRIT_CLASSIC_NAMESPACE_END
- }}
- #endif
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