// Copyright Daniel Wallin 2006. Use, modification and distribution is

// subject to 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 BOOST_PARAMETER_VALUE_TYPE_060921_HPP

# define BOOST_PARAMETER_VALUE_TYPE_060921_HPP

# include <boost/mpl/apply.hpp>

# include <boost/mpl/assert.hpp>

# include <boost/mpl/and.hpp>

# include <boost/parameter/aux_/result_of0.hpp>

# include <boost/parameter/aux_/void.hpp>

# include <boost/type_traits/is_same.hpp>

# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)

#  include <boost/mpl/eval_if.hpp>

# endif

namespace boost { namespace parameter { 

// A metafunction that, given an argument pack, returns the type of

// the parameter identified by the given keyword.  If no such

// parameter has been specified, returns Default

# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \

  || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))

template <class Parameters, class Keyword, class Default>

struct value_type0

{

    typedef typename mpl::apply_wrap3<

        typename Parameters::binding,Keyword,Default,mpl::false_

    >::type type;

    BOOST_MPL_ASSERT_NOT((

        mpl::and_<

            is_same<Default, void_>

          , is_same<type, void_>

        >

    ));

};

# endif

template <class Parameters, class Keyword, class Default = void_>

# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)

struct value_type

# else

struct value_type_eti

# endif

{

# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \

  || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))

    typedef typename mpl::eval_if<

        mpl::is_placeholder<Parameters>

      , mpl::identity<int>

      , value_type0<Parameters,Keyword,Default>

    >::type type;

# else

    typedef typename mpl::apply_wrap3<

        typename Parameters::binding,Keyword,Default,mpl::false_

    >::type type;

    BOOST_MPL_ASSERT_NOT((

        mpl::and_<

            is_same<Default, void_>

          , is_same<type, void_>

        >

    ));

# endif

# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)

    BOOST_MPL_AUX_LAMBDA_SUPPORT(3,value_type,(Parameters,Keyword,Default))

# endif

};

# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)

template <class Parameters, class Keyword, class Default = void_>

struct value_type

{

    typedef typename mpl::eval_if<

        is_same<Parameters, int>

      , mpl::identity<int>

      , value_type_eti<Parameters, Keyword, Default>

    >::type type;

    BOOST_MPL_AUX_LAMBDA_SUPPORT(3,value_type,(Parameters,Keyword,Default))

};

# endif

// A metafunction that, given an argument pack, returns the type of

// the parameter identified by the given keyword.  If no such

// parameter has been specified, returns the type returned by invoking

// DefaultFn

template <class Parameters, class Keyword, class DefaultFn>

struct lazy_value_type

{

  typedef typename mpl::apply_wrap3<

      typename Parameters::binding

    , Keyword

    , typename aux::result_of0<DefaultFn>::type

    , mpl::false_

  >::type type;

};

}} // namespace boost::parameter

#endif // BOOST_PARAMETER_VALUE_TYPE_060921_HPP