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[857] | 1 | /*=============================================================================
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| 2 | Copyright (c) 2003 Joel de Guzman
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| 3 | http://spirit.sourceforge.net/
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| 4 |
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| 5 | Use, modification and distribution is subject to the Boost Software
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| 6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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| 7 | http://www.boost.org/LICENSE_1_0.txt)
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| 8 | =============================================================================*/
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| 9 | #if !defined(BOOST_SPIRIT_SAFE_BOOL_HPP)
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| 10 | #define BOOST_SPIRIT_SAFE_BOOL_HPP
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| 11 |
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| 12 | #include <boost/config.hpp>
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| 13 | #include <boost/detail/workaround.hpp>
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| 14 |
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| 15 | namespace boost { namespace spirit
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| 16 | {
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| 17 | namespace impl
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| 18 | {
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| 19 | template <typename T>
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| 20 | struct no_base {};
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| 21 |
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| 22 | template <typename T>
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| 23 | struct safe_bool_impl
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| 24 | {
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| 25 | #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
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| 26 | void stub(T*) {};
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| 27 | typedef void (safe_bool_impl::*type)(T*);
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| 28 | #else
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| 29 | typedef T* TP; // workaround to make parsing easier
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| 30 | TP stub;
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| 31 | typedef TP safe_bool_impl::*type;
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| 32 | #endif
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| 33 | };
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| 34 | }
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| 35 |
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| 36 | template <typename DerivedT, typename BaseT = impl::no_base<DerivedT> >
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| 37 | struct safe_bool : BaseT
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| 38 | {
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| 39 | private:
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| 40 | typedef impl::safe_bool_impl<DerivedT> impl_t;
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| 41 | typedef typename impl_t::type bool_type;
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| 42 |
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| 43 | public:
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| 44 | operator bool_type() const
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| 45 | {
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| 46 | return static_cast<const DerivedT*>(this)->operator_bool() ?
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| 47 | &impl_t::stub : 0;
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| 48 | }
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| 49 |
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| 50 | operator bool_type()
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| 51 | {
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| 52 | return static_cast<DerivedT*>(this)->operator_bool() ?
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| 53 | &impl_t::stub : 0;
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| 54 | }
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| 55 | };
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| 56 | }}
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| 57 |
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| 58 | #endif
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| 59 |
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