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// - lambda_traits.hpp --- Boost Lambda Library ----------------------------
//
// Copyright (C) 1999, 2000 Jaakko Järvi (jaakko.jarvi@cs.utu.fi)
//
// 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)
//
// For more information, see www.boost.org
// -------------------------------------------------------------------------

#ifndef BOOST_LAMBDA_LAMBDA_TRAITS_HPP
#define BOOST_LAMBDA_LAMBDA_TRAITS_HPP

#include "boost/type_traits/transform_traits.hpp"
#include "boost/type_traits/cv_traits.hpp"
#include "boost/type_traits/function_traits.hpp"
#include "boost/type_traits/object_traits.hpp"

namespace boost {
namespace lambda {

// -- if construct ------------------------------------------------
// Proposed by Krzysztof Czarnecki and Ulrich Eisenecker

namespace detail {

template <bool If, class Then, class Else> struct IF { typedef Then RET; };

template <class Then, class Else> struct IF<false, Then, Else> {
  typedef Else RET;
};


// An if construct that doesn't instantiate the non-matching template:

// Called as: 
//  IF_type<condition, A, B>::type 
// The matching template must define the typeded 'type'
// I.e. A::type if condition is true, B::type if condition is false
// Idea from Vesa Karvonen (from C&E as well I guess)
template<class T>
struct IF_type_
{
  typedef typename T::type type;
};


template<bool C, class T, class E>
struct IF_type
{
  typedef typename
    IF_type_<typename IF<C, T, E>::RET >::type type;
};

// helper that can be used to give typedef T to some type
template <class T> struct identity_mapping { typedef T type; };

// An if construct for finding an integral constant 'value'
// Does not instantiate the non-matching branch
// Called as IF_value<condition, A, B>::value
// If condition is true A::value must be defined, otherwise B::value

template<class T>
struct IF_value_
{
  BOOST_STATIC_CONSTANT(int, value = T::value);
};


template<bool C, class T, class E>
struct IF_value
{
  BOOST_STATIC_CONSTANT(int, value = (IF_value_<typename IF<C, T, E>::RET>::value));
};


// --------------------------------------------------------------

// removes reference from other than function types:
template<class T> class remove_reference_if_valid
{

  typedef typename boost::remove_reference<T>::type plainT;
public:
  typedef typename IF<
    boost::is_function<plainT>::value,
    T,
    plainT
  >::RET type;

};


template<class T> struct remove_reference_and_cv {
   typedef typename boost::remove_cv<
     typename boost::remove_reference<T>::type
   >::type type;
};