choose.h

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/***************************************************************************
 * include/stxxl/bits/stream/choose.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2003-2005 Roman Dementiev <[email protected]>
 * Copyright (C) 2010 Andreas Beckmann <[email protected]>
 *
 * 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)
 **************************************************************************/

#ifndef STXXL_STREAM_CHOOSE_HEADER
#define STXXL_STREAM_CHOOSE_HEADER

#include <stxxl/bits/namespace.h>

STXXL_BEGIN_NAMESPACE

//! Stream package subnamespace.
namespace stream {

////////////////////////////////////////////////////////////////////////
// CHOOSE //
////////////////////////////////////////////////////////////////////////

template <class Input, int Which>
class choose
{ };

//! Creates stream from a tuple stream taking the first component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 1>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::first_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).first;
 }

 const value_type* operator -> () const
 {
 return &(*in).first;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! Creates stream from a tuple stream taking the second component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 2>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::second_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).second;
 }

 const value_type* operator -> () const
 {
 return &(*in).second;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! Creates stream from a tuple stream taking the third component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 3>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::third_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).third;
 }

 const value_type* operator -> () const
 {
 return &(*in).third;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! Creates stream from a tuple stream taking the fourth component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 4>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::fourth_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).fourth;
 }

 const value_type* operator -> () const
 {
 return &(*in).fourth;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! Creates stream from a tuple stream taking the fifth component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 5>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::fifth_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).fifth;
 }

 const value_type* operator -> () const
 {
 return &(*in).fifth;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! Creates stream from a tuple stream taking the sixth component of each tuple.
//!
//! \tparam Input type of the input tuple stream
//!
//! \remark Tuple stream is a stream which \c value_type is \c stxxl::tuple .
template <class Input>
class choose<Input, 6>
{
 Input& in;

 typedef typename Input::value_type tuple_type;

public:
 //! Standard stream typedef.
 typedef typename tuple_type::sixth_type value_type;

 //! Construction.
 choose(Input& in_) : in(in_)
 { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 return (*in).sixth;
 }

 const value_type* operator -> () const
 {
 return &(*in).sixth;
 }

 //! Standard stream method.
 choose& operator ++ ()
 {
 ++in;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return in.empty();
 }
};

//! \}

} // namespace stream

STXXL_END_NAMESPACE

#include <stxxl/bits/stream/unique.h>

#endif // !STXXL_STREAM_CHOOSE_HEADER
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