typelist_filter.hpp

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// -*- C++ -*-

// Copyright (C) 2005 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// USA.

// 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.

// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.

// Permission to use, copy, modify, sell, and distribute this software
// is hereby granted without fee, provided that the above copyright
// notice appears in all copies, and that both that copyright notice and
// this permission notice appear in supporting documentation. None of
// the above authors, nor IBM Haifa Research Laboratories, make any
// representation about the suitability of this software for any
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#ifndef TYPELIST_FILTER_HPP
#define TYPELIST_FILTER_HPP

#ifdef _MSC_VER
#pragma warning(disable: 4503)
#endif // #ifdef _MSC_VER

#include <ext/pb_assoc/detail/type_utils.hpp>

namespace detail
{

  template<class Typelist_Chain, template<typename T>
  class Pred>
  struct typelist_chain_filter_;

  template<template<typename T>
  class Pred>
  struct typelist_chain_filter_<
    null_type,
    Pred>
  {
    typedef null_type type;
  };

  template<class Hd, class Tl, template<typename T>
  class Pred>
  struct typelist_chain_filter_<
    typelist_chain<Hd, Tl>,
    Pred>
  {
    typedef typename typelist_chain_filter_< Tl, Pred>::type rest;

    enum
      {
    include_hd = Pred<Hd>::value
      };

    typedef
    typename cond_type<
      include_hd,
      typelist_chain<
      Hd,
      rest>,
      rest>::type
    type;
  };

} // namespace detail

#endif // #ifndef TYPELIST_FILTER_HPP

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