tuple.h

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
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 *  deleting the provisions above and replace them with the notice and other 
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 *  *** END LICENSE INFORMATION ***
 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_META_TUPLE_H
#define LASS_GUARDIAN_OF_INCLUSION_META_TUPLE_H

#include "meta_common.h"
#include "type_list.h"
#include "empty_type.h"

namespace lass
{
namespace meta
{

template <typename TList> class Tuple;

template <typename H, typename Ts>
class Tuple< TypeList<H, Ts> >: public Tuple<Ts>
{
public:
    typedef H TValue;
    typedef Tuple<Ts> TTail;
    typedef TypeList<H, Ts> TList;
    Tuple(): value_() {}
    const H& value() const { return value_; }
    H& value() { return value_; }
private:
    H value_;
};

template <typename Ts>
class Tuple< TypeList<meta::EmptyType, Ts> >: public Tuple<Ts>
{
public:
    typedef meta::EmptyType TValue;
    typedef Tuple<Ts> TTail;
    typedef TypeList<meta::EmptyType, Ts> TList;
    const meta::EmptyType& value() const { return meta::EmptyType::instance(); }
    meta::EmptyType& value() { return meta::EmptyType::instance(); }
};

template <>
class Tuple<meta::NullType>
{
public:
    typedef meta::NullType TValue;
    typedef meta::NullType TTail;
    typedef meta::NullType TList;
};



namespace tuple
{

template <typename TupleType, size_t index> 
struct Field
{
    typedef typename type_list::At<typename TupleType::TList, index>::Type Type;
};

template <typename TupleType, size_t index> 
struct Field<const TupleType, index>
{
    typedef const typename type_list::At<typename TupleType::TList, index>::Type Type;
};



template <typename TupleType, size_t index> struct SubType;

template <typename H, typename Ts, size_t index> 
struct SubType< Tuple< TypeList<H, Ts> >, index >: public SubType< Tuple<Ts>, index - 1 >
{
};

template <typename H, typename Ts> 
struct SubType< Tuple< TypeList<H, Ts> >, 0 >
{
    typedef Tuple< TypeList<H, Ts> > Type;
};

template <typename H, typename Ts, size_t index> 
struct SubType< const Tuple< TypeList<H, Ts> >, index >: public SubType< const Tuple<Ts>, index - 1 >
{
};

template <typename H, typename Ts> 
struct SubType< const Tuple< TypeList<H, Ts> >, 0 >
{
    typedef const Tuple< TypeList<H, Ts> > Type;
};



template <size_t index, typename TupleType> 
typename Field<TupleType, index>::Type& field(TupleType& tuple)
{
    typedef typename SubType<TupleType, index>::Type TSubType;
    return static_cast<TSubType&>(tuple).value();
}



namespace impl
{
    template <typename TupleType> struct ForEach;
    template <typename H, typename Ts>
    struct ForEach< Tuple< TypeList<H, Ts> > >
    {
        template <typename Functor> static void call(Tuple< TypeList<H, Ts> >& tuple, Functor& fun)
        {
            fun(tuple.value());
            ForEach< Tuple<Ts> >::call(tuple, fun);
        }
    };
    template <typename Ts>
    struct ForEach< Tuple< TypeList<meta::EmptyType, Ts> > >
    {
        template <typename Functor> static void call(Tuple< TypeList<meta::EmptyType, Ts> >& tuple, Functor& fun)
        {
            ForEach< Tuple<Ts> >::call(tuple, fun);
        }
    };
    template <>
    struct ForEach< Tuple< meta::NullType> >
    {
        template <typename Functor> static void call(Tuple<meta::NullType>& tuple, Functor& fun)
        {
        }
    };
}

template <typename TupleType, typename Functor>
void forEach(TupleType& tuple, Functor& fun)
{
    impl::ForEach<TupleType>::call(tuple, fun);
}



}

}
}

#endif

// EOF