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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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