type_list

// vi:set ft=cpp: -*- Mode: C++ -*-
#pragma once
 
/*
 * (c) 2012 Alexander Warg <warg@os.inf.tu-dresden.de>,
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 *
 * As a special exception, you may use this file as part of a free software
 * library without restriction.  Specifically, if other files instantiate
 * templates or use macros or inline functions from this file, or you compile
 * this file and link it with other files to produce an executable, this
 * file does not by itself cause the resulting executable to be covered by
 * the GNU General Public License.  This exception does not however
 * invalidate any other reasons why the executable file might be covered by
 * the GNU General Public License.
 */
 
 
#include "type_traits"
 
namespace cxx {
 
template< typename ...T >
struct type_list;
 
template<>
struct type_list<>
{
  typedef false_type head;
  typedef false_type tail;
};
 
template<typename HEAD, typename ...TAIL>
struct type_list<HEAD, TAIL...>
{
  typedef HEAD head;
  typedef type_list<TAIL...> tail;
};
 
template<typename TYPELIST, template <typename T> class PREDICATE>
struct find_type;
 
template<template <typename T> class PREDICATE>
struct find_type<type_list<>, PREDICATE>
{
  typedef false_type type;
};
 
template<typename TYPELIST, template <typename T> class PREDICATE>
struct find_type
{
  typedef typename conditional<PREDICATE<typename TYPELIST::head>::value,
                               typename TYPELIST::head,
                               typename find_type<typename TYPELIST::tail, PREDICATE>::type>::type type;
};
 
template<typename TYPELIST, template <typename T> class PREDICATE>
using find_type_t = typename find_type<TYPELIST, PREDICATE>::type;
 
}