core/matcher/alternate_matcher.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // alternate_matcher.hpp
0003 //
0004 //  Copyright 2008 Eric Niebler. Distributed under the Boost
0005 //  Software License, Version 1.0. (See accompanying file
0006 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007
0008 #ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_ALTERNATE_MATCHER_HPP_EAN_10_04_2005
0009 #define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_ALTERNATE_MATCHER_HPP_EAN_10_04_2005
0010
0011 // MS compatible compilers support #pragma once
0012 #if defined(_MSC_VER)
0013 # pragma once
0014 #endif
0015
0016 #include <boost/version.hpp>
0017 #if BOOST_VERSION <= 103200
0018 // WORKAROUND for Fusion bug in Boost 1.32
0019 namespace boost { namespace fusion
0020 {
0021     namespace detail { struct iterator_root; }
0022     using detail::iterator_root;
0023 }}
0024 #endif
0025
0026 #include <boost/xpressive/detail/detail_fwd.hpp>
0027 #include <boost/xpressive/detail/core/quant_style.hpp>
0028 #include <boost/xpressive/detail/core/state.hpp>
0029 #include <boost/xpressive/detail/dynamic/matchable.hpp>
0030 #include <boost/xpressive/detail/utility/hash_peek_bitset.hpp>
0031 #include <boost/xpressive/detail/utility/algorithm.hpp>
0032 #include <boost/xpressive/detail/utility/any.hpp>
0033
0034 namespace boost { namespace xpressive { namespace detail
0035 {
0036
0037     ///////////////////////////////////////////////////////////////////////////////
0038     // alt_match_pred
0039     //
0040     template<typename BidiIter, typename Next>
0041     struct alt_match_pred
0042     {
0043         alt_match_pred(match_state<BidiIter> &state)
0044           : state_(&state)
0045         {
0046         }
0047
0048         template<typename Xpr>
0049         bool operator ()(Xpr const &xpr) const
0050         {
0051             return xpr.BOOST_NESTED_TEMPLATE push_match<Next>(*this->state_);
0052         }
0053
0054     private:
0055         match_state<BidiIter> *state_;
0056     };
0057
0058     ///////////////////////////////////////////////////////////////////////////////
0059     // alt_match
0060     //
0061     template<typename BidiIter, typename Next>
0062     inline bool alt_match
0063     (
0064         alternates_vector<BidiIter> const &alts, match_state<BidiIter> &state, Next const &
0065     )
0066     {
0067         return detail::any(alts.begin(), alts.end(), alt_match_pred<BidiIter, Next>(state));
0068     }
0069
0070     template<typename Head, typename Tail, typename BidiIter, typename Next>
0071     inline bool alt_match
0072     (
0073         alternates_list<Head, Tail> const &alts, match_state<BidiIter> &state, Next const &
0074     )
0075     {
0076         return fusion::any(alts, alt_match_pred<BidiIter, Next>(state));
0077     }
0078
0079     ///////////////////////////////////////////////////////////////////////////////
0080     // alternate_matcher
0081     template<typename Alternates, typename Traits>
0082     struct alternate_matcher
0083       : quant_style<
0084             Alternates::width != unknown_width::value && Alternates::pure ? quant_fixed_width : quant_variable_width
0085           , Alternates::width
0086           , Alternates::pure
0087         >
0088     {
0089         typedef Alternates alternates_type;
0090         typedef typename Traits::char_type char_type;
0091
0092         Alternates alternates_;
0093         mutable hash_peek_bitset<char_type> bset_;
0094
0095         explicit alternate_matcher(Alternates const &alternates = Alternates())
0096           : alternates_(alternates)
0097           , bset_()
0098         {
0099         }
0100
0101         template<typename BidiIter, typename Next>
0102         bool match(match_state<BidiIter> &state, Next const &next) const
0103         {
0104             if(!state.eos() && !this->can_match_(*state.cur_, traits_cast<Traits>(state)))
0105             {
0106                 return false;
0107             }
0108
0109             return detail::alt_match(this->alternates_, state, next);
0110         }
0111
0112         detail::width get_width() const
0113         {
0114             // Only called when constructing static regexes, and this is a
0115             // set of same-width alternates where the widths are known at compile
0116             // time, as in: sregex rx = +(_ | 'a' | _n);
0117             BOOST_MPL_ASSERT_RELATION(unknown_width::value, !=, Alternates::width);
0118             return Alternates::width;
0119         }
0120
0121     private:
0122         alternate_matcher &operator =(alternate_matcher const &);
0123
0124         bool can_match_(char_type ch, Traits const &tr) const
0125         {
0126             return this->bset_.test(ch, tr);
0127         }
0128     };
0129
0130 }}}
0131
0132 #endif