boost/mpl/lower_bound.hpp

0001
0002 #ifndef BOOST_MPL_LOWER_BOUND_HPP_INCLUDED
0003 #define BOOST_MPL_LOWER_BOUND_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2001-2004
0006 //
0007 // Distributed under the Boost Software License, Version 1.0.
0008 // (See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // See http://www.boost.org/libs/mpl for documentation.
0012
0013 // $Id$
0014 // $Date$
0015 // $Revision$
0016
0017 #include <boost/mpl/less.hpp>
0018 #include <boost/mpl/lambda.hpp>
0019 #include <boost/mpl/aux_/na_spec.hpp>
0020 #include <boost/mpl/aux_/config/workaround.hpp>
0021
0022 #if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x610))
0023 #   define BOOST_MPL_CFG_STRIPPED_DOWN_LOWER_BOUND_IMPL
0024 #endif
0025
0026 #if !defined(BOOST_MPL_CFG_STRIPPED_DOWN_LOWER_BOUND_IMPL)
0027 #   include <boost/mpl/minus.hpp>
0028 #   include <boost/mpl/divides.hpp>
0029 #   include <boost/mpl/size.hpp>
0030 #   include <boost/mpl/advance.hpp>
0031 #   include <boost/mpl/begin_end.hpp>
0032 #   include <boost/mpl/long.hpp>
0033 #   include <boost/mpl/eval_if.hpp>
0034 #   include <boost/mpl/prior.hpp>
0035 #   include <boost/mpl/deref.hpp>
0036 #   include <boost/mpl/apply.hpp>
0037 #   include <boost/mpl/aux_/value_wknd.hpp>
0038 #else
0039 #   include <boost/mpl/not.hpp>
0040 #   include <boost/mpl/find.hpp>
0041 #   include <boost/mpl/bind.hpp>
0042 #endif
0043
0044 #include <boost/config.hpp>
0045
0046 namespace boost { namespace mpl {
0047
0048 #if defined(BOOST_MPL_CFG_STRIPPED_DOWN_LOWER_BOUND_IMPL)
0049
0050 // agurt 23/oct/02: has a wrong complexity etc., but at least it works
0051 // feel free to contribute a better implementation!
0052 template<
0053       typename BOOST_MPL_AUX_NA_PARAM(Sequence)
0054     , typename BOOST_MPL_AUX_NA_PARAM(T)
0055     , typename Predicate = less<>
0056     , typename pred_ = typename lambda<Predicate>::type
0057     >
0058 struct lower_bound
0059     : find_if< Sequence, bind1< not_<>, bind2<pred_,_,T> > >
0060 {
0061 };
0062
0063 #else
0064
0065 namespace aux {
0066
0067 template<
0068       typename Distance
0069     , typename Predicate
0070     , typename T
0071     , typename DeferredIterator
0072     >
0073 struct lower_bound_step_impl;
0074
0075 template<
0076       typename Distance
0077     , typename Predicate
0078     , typename T
0079     , typename DeferredIterator
0080     >
0081 struct lower_bound_step
0082 {
0083     typedef typename eval_if<
0084           Distance
0085         , lower_bound_step_impl<Distance,Predicate,T,DeferredIterator>
0086         , DeferredIterator
0087         >::type type;
0088 };
0089
0090 template<
0091       typename Distance
0092     , typename Predicate
0093     , typename T
0094     , typename DeferredIterator
0095     >
0096 struct lower_bound_step_impl
0097 {
0098     typedef typename divides< Distance, long_<2> >::type offset_;
0099     typedef typename DeferredIterator::type iter_;
0100     typedef typename advance< iter_,offset_ >::type middle_;
0101     typedef typename apply2<
0102               Predicate
0103             , typename deref<middle_>::type
0104             , T
0105             >::type cond_;
0106
0107     typedef typename prior< minus< Distance, offset_> >::type step_;
0108     typedef lower_bound_step< offset_,Predicate,T,DeferredIterator > step_forward_;
0109     typedef lower_bound_step< step_,Predicate,T,next<middle_> > step_backward_;
0110     typedef typename eval_if<
0111           cond_
0112         , step_backward_
0113         , step_forward_
0114         >::type type;
0115 };
0116
0117
0118 } // namespace aux
0119
0120 template<
0121       typename BOOST_MPL_AUX_NA_PARAM(Sequence)
0122     , typename BOOST_MPL_AUX_NA_PARAM(T)
0123     , typename Predicate = less<>
0124     >
0125 struct lower_bound
0126 {
0127  private:
0128     typedef typename lambda<Predicate>::type pred_;
0129     typedef typename size<Sequence>::type size_;
0130
0131  public:
0132     typedef typename aux::lower_bound_step<
0133         size_,pred_,T,begin<Sequence>
0134         >::type type;
0135 };
0136
0137 #endif // BOOST_MPL_CFG_STRIPPED_DOWN_LOWER_BOUND_IMPL
0138
0139 BOOST_MPL_AUX_NA_SPEC(2, lower_bound)
0140
0141 }}
0142
0143 #endif // BOOST_MPL_LOWER_BOUND_HPP_INCLUDED