projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | /*============================================================================= |
| 2 | Copyright (c) 2002-2003 Martin Wille | |
| 3 | http://spirit.sourceforge.net/ | |
| 4 | ||
| 5 | Use, modification and distribution is subject to the Boost Software | |
| 6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
| 7 | http://www.boost.org/LICENSE_1_0.txt) | |
| 8 | =============================================================================*/ | |
| 9 | #ifndef BOOST_SPIRIT_CONDITIONS_IPP | |
| 10 | #define BOOST_SPIRIT_CONDITIONS_IPP | |
| 11 | ||
| 12 | /////////////////////////////////////////////////////////////////////////////// | |
| 13 | #include <boost/spirit/home/classic/meta/parser_traits.hpp> | |
| 14 | #include <boost/spirit/home/classic/core/composite/epsilon.hpp> | |
| 15 | ||
| 16 | /////////////////////////////////////////////////////////////////////////////// | |
| 17 | namespace boost { namespace spirit { | |
| 18 | ||
| 19 | BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN | |
| 20 | ||
| 21 | namespace impl { | |
| 22 | ||
| 23 | /////////////////////////////////////////////////////////////////////////////// | |
| 24 | // | |
| 25 | // condition evaluation | |
| 26 | // | |
| 27 | /////////////////////////////////////////////////////////////////////////////// | |
| 28 | ////////////////////////////////// | |
| 29 | // condition_parser_selector, decides which parser to use for a condition | |
| 30 | // If the template argument is a parser then that parser is used. | |
| 31 | // If the template argument is a functor then a condition parser using | |
| 32 | // the functor is chosen | |
| 33 | ||
| 34 | template <typename T> struct embed_t_accessor | |
| 35 | { | |
| 36 | typedef typename T::embed_t type; | |
| 37 | }; | |
| 38 | ||
| 39 | template <typename ConditionT> | |
| 40 | struct condition_parser_selector | |
| 41 | { | |
| 42 | typedef | |
| 43 | typename mpl::if_< | |
| 44 | is_parser<ConditionT>, | |
| 45 | ConditionT, | |
| 46 | condition_parser<ConditionT> | |
| 47 | >::type | |
| 48 | type; | |
| 49 | ||
| 50 | typedef typename embed_t_accessor<type>::type embed_t; | |
| 51 | }; | |
| 52 | ||
| 53 | ////////////////////////////////// | |
| 54 | // condition_evaluator, uses a parser to check wether a condition is met | |
| 55 | // takes a parser or a functor that can be evaluated in boolean context | |
| 56 | // as template parameter. | |
| 57 | ||
| 58 | // JDG 4-15-03 refactored | |
| 59 | template <typename ConditionT> | |
| 60 | struct condition_evaluator | |
| 61 | { | |
| 62 | typedef condition_parser_selector<ConditionT> selector_t; | |
| 63 | typedef typename selector_t::type selected_t; | |
| 64 | typedef typename selector_t::embed_t cond_embed_t; | |
| 65 | ||
| 66 | typedef typename boost::call_traits<cond_embed_t>::param_type | |
| 67 | param_t; | |
| 68 | ||
| 69 | condition_evaluator(param_t s) : cond(s) {} | |
| 70 | ||
| 71 | ///////////////////////////// | |
| 72 | // evaluate, checks wether condition is met | |
| 73 | // returns length of a match or a negative number for no-match | |
| 74 | template <typename ScannerT> | |
| 75 | std::ptrdiff_t | |
| 76 | evaluate(ScannerT const &scan) const | |
| 77 | { | |
| 78 | typedef typename ScannerT::iterator_t iterator_t; | |
| 79 | typedef typename parser_result<selected_t, ScannerT>::type cres_t; | |
| 80 | iterator_t save(scan.first); | |
| 81 | cres_t result = cond.parse(scan); | |
| 82 | if (!result) // reset the position if evaluation | |
| 83 | scan.first = save; // fails. | |
| 84 | return result.length(); | |
| 85 | } | |
| 86 | ||
| 87 | cond_embed_t cond; | |
| 88 | }; | |
| 89 | ||
| 90 | /////////////////////////////////////////////////////////////////////////////// | |
| 91 | } // namespace impl | |
| 92 | ||
| 93 | BOOST_SPIRIT_CLASSIC_NAMESPACE_END | |
| 94 | ||
| 95 | }} // namespace boost::spirit | |
| 96 | ||
| 97 | #endif |