/*
 * $Id$
 */

/*
 * Copyright (c) 2016 Brook Milligan.
 * Distributed under the Boost Software License, Version 1.0. (See
 * accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 */

#ifndef MATH_EXP_HPP
#define MATH_EXP_HPP 1

#include <cmath>
#include <type_traits>
#include <boost/proto/core.hpp>

namespace math
{

  struct exp_
  {
    template< typename Signature >
    struct result;

    template< typename This, typename Arg >
    struct result< This(Arg) >
      : std::decay<Arg>
    {};

    template < typename Arg >
    Arg operator () (Arg const& arg) const
    {
      using std::exp;
      return exp(arg);
    }
  };

  template < typename A >
  typename boost::proto::result_of::make_expr<
    boost::proto::tag::function
    , typename boost::proto::domain_of<A>::type
    , exp_
    , A const&
    >::type const
  exp (A const& a)
  {
    return boost::proto::make_expr<
      boost::proto::tag::function
      , typename boost::proto::domain_of<A>::type
      >(exp_(),boost::ref(a));
  }

} // namespace math

#endif