ceph/src/boost/libs/proto/include/boost/proto/functional/fusion/reverse.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 /// \file reverse.hpp
   3 /// Proto callables Fusion reverse
   4 //
   5 //  Copyright 2010 Eric Niebler. Distributed under the Boost
   6 //  Software License, Version 1.0. (See accompanying file
   7 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #ifndef BOOST_PROTO_FUNCTIONAL_FUSION_REVERSE_HPP_EAN_11_27_2010
  10 #define BOOST_PROTO_FUNCTIONAL_FUSION_REVERSE_HPP_EAN_11_27_2010
  11
  12 #include <boost/fusion/include/reverse.hpp>
  13 #include <boost/proto/proto_fwd.hpp>
  14
  15 namespace boost { namespace proto { namespace functional
  16 {
  17     /// \brief A PolymorphicFunctionObject type that invokes the
  18     /// \c fusion::reverse() algorithm on its argument.
  19     ///
  20     /// A PolymorphicFunctionObject type that invokes the
  21     /// \c fusion::reverse() algorithm on its argument. This is
  22     /// useful for defining a CallableTransform like \c reverse(_)
  23     /// which reverses the order of the children of a Proto
  24     /// expression node.
  25     struct reverse
  26     {
  27         BOOST_PROTO_CALLABLE()
  28
  29         template<typename Sig>
  30         struct result;
  31
  32         template<typename This, typename Seq>
  33         struct result<This(Seq)>
  34           : result<This(Seq const &)>
  35         {};
  36
  37         template<typename This, typename Seq>
  38         struct result<This(Seq &)>
  39           : fusion::result_of::reverse<Seq>
  40         {};
  41
  42         template<typename Seq>
  43         typename fusion::result_of::reverse<Seq>::type
  44         operator ()(Seq &seq) const
  45         {
  46             // Work around a const-correctness issue in Fusion
  47             typedef typename fusion::result_of::reverse<Seq>::type result_type;
  48             return result_type(seq);
  49         }
  50
  51         template<typename Seq>
  52         typename fusion::result_of::reverse<Seq const>::type
  53         operator ()(Seq const &seq) const
  54         {
  55             return fusion::reverse(seq);
  56         }
  57     };
  58 }}}
  59
  60 #endif