functional/std/iterator.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 /// \file iterator.hpp
0003 /// Proto callables for std functions found in \<iterator\>
0004 //
0005 //  Copyright 2012 Eric Niebler. Distributed under the Boost
0006 //  Software License, Version 1.0. (See accompanying file
0007 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0008
0009 #ifndef BOOST_PROTO_FUNCTIONAL_STD_ITERATOR_HPP_EAN_27_08_2012
0010 #define BOOST_PROTO_FUNCTIONAL_STD_ITERATOR_HPP_EAN_27_08_2012
0011
0012 #include <iterator>
0013 #include <boost/type_traits/remove_const.hpp>
0014 #include <boost/type_traits/remove_reference.hpp>
0015 #include <boost/proto/proto_fwd.hpp>
0016
0017 namespace boost { namespace proto { namespace functional
0018 {
0019
0020     // A PolymorphicFunctionObject wrapping std::advance
0021     struct advance
0022     {
0023         BOOST_PROTO_CALLABLE()
0024
0025         typedef void result_type;
0026
0027         template<typename InputIterator, typename Distance>
0028         void operator()(InputIterator &x, Distance n) const
0029         {
0030             std::advance(x, n);
0031         }
0032     };
0033
0034     // A PolymorphicFunctionObject wrapping std::distance
0035     struct distance
0036     {
0037         BOOST_PROTO_CALLABLE()
0038
0039         template<typename Sig>
0040         struct result;
0041
0042         template<typename This, typename InputIter1, typename InputIter2>
0043         struct result<This(InputIter1, InputIter2)>
0044         {
0045             typedef
0046                 typename std::iterator_traits<
0047                     typename boost::remove_const<
0048                         typename boost::remove_reference<InputIter1>::type
0049                     >::type
0050                 >::difference_type
0051             type;
0052         };
0053
0054         template<typename InputIterator>
0055         typename std::iterator_traits<InputIterator>::difference_type
0056         operator()(InputIterator first, InputIterator last) const
0057         {
0058             return std::distance(first, last);
0059         }
0060     };
0061
0062     // A PolymorphicFunctionObject wrapping std::next
0063     struct next
0064     {
0065         BOOST_PROTO_CALLABLE()
0066
0067         template<typename Sig>
0068         struct result;
0069
0070         template<typename This, typename ForwardIterator>
0071         struct result<This(ForwardIterator)>
0072         {
0073             typedef
0074                 typename boost::remove_const<
0075                     typename boost::remove_reference<ForwardIterator>::type
0076                 >::type
0077             type;
0078         };
0079
0080         template<typename This, typename ForwardIterator, typename Distance>
0081         struct result<This(ForwardIterator, Distance)>
0082         {
0083             typedef
0084                 typename boost::remove_const<
0085                     typename boost::remove_reference<ForwardIterator>::type
0086                 >::type
0087             type;
0088         };
0089
0090         template<typename ForwardIterator>
0091         ForwardIterator operator()(ForwardIterator x) const
0092         {
0093             return std::advance(
0094                 x
0095               , static_cast<typename std::iterator_traits<ForwardIterator>::difference_type>(1)
0096             );
0097         }
0098
0099         template<typename ForwardIterator>
0100         ForwardIterator operator()(
0101             ForwardIterator x
0102           , typename std::iterator_traits<ForwardIterator>::difference_type n
0103         ) const
0104         {
0105             return std::advance(x, n);
0106         }
0107     };
0108
0109     // A PolymorphicFunctionObject wrapping std::prior
0110     struct prior
0111     {
0112         BOOST_PROTO_CALLABLE()
0113
0114         template<typename Sig>
0115         struct result;
0116
0117         template<typename This, typename BidirectionalIterator>
0118         struct result<This(BidirectionalIterator)>
0119         {
0120             typedef
0121                 typename boost::remove_const<
0122                     typename boost::remove_reference<BidirectionalIterator>::type
0123                 >::type
0124             type;
0125         };
0126
0127         template<typename This, typename BidirectionalIterator, typename Distance>
0128         struct result<This(BidirectionalIterator, Distance)>
0129         {
0130             typedef
0131                 typename boost::remove_const<
0132                     typename boost::remove_reference<BidirectionalIterator>::type
0133                 >::type
0134             type;
0135         };
0136
0137         template<typename BidirectionalIterator>
0138         BidirectionalIterator operator()(BidirectionalIterator x) const
0139         {
0140             return std::advance(
0141                 x
0142               , -static_cast<typename std::iterator_traits<BidirectionalIterator>::difference_type>(1)
0143             );
0144         }
0145
0146         template<typename BidirectionalIterator>
0147         BidirectionalIterator operator()(
0148             BidirectionalIterator x
0149           , typename std::iterator_traits<BidirectionalIterator>::difference_type n
0150         ) const
0151         {
0152             return std::advance(x, -n);
0153         }
0154     };
0155
0156 }}}
0157
0158 #endif