stream.h

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/***************************************************************************
 * include/stxxl/bits/stream/stream.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2003-2005 Roman Dementiev <[email protected]>
 * Copyright (C) 2009, 2010 Andreas Beckmann <[email protected]>
 * Copyright (C) 2010 Johannes Singler <[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_STREAM_HEADER
#define STXXL_STREAM_STREAM_HEADER

#include <stxxl/bits/namespace.h>
#include <stxxl/bits/mng/buf_istream.h>
#include <stxxl/bits/mng/buf_ostream.h>
#include <stxxl/bits/common/tuple.h>
#include <stxxl/bits/common/error_handling.h>
#include <stxxl/vector>
#include <stxxl/bits/compat/unique_ptr.h>


#ifndef STXXL_VERBOSE_MATERIALIZE
#define STXXL_VERBOSE_MATERIALIZE STXXL_VERBOSE3
#endif


STXXL_BEGIN_NAMESPACE

//! Stream package subnamespace.
namespace stream {

//! \defgroup streampack Stream Package
//! Package that enables pipelining of consequent sorts
//! and scans of the external data avoiding the saving the intermediate
//! results on the disk, e.g. the output of a sort can be directly
//! fed into a scan procedure without the need to save it on a disk.
//! All components of the package are contained in the \c stxxl::stream
//! namespace.
//!
//! STREAM ALGORITHM CONCEPT (Do not confuse with C++ input/output streams)
//!
//! \verbatim
//!
//! struct stream_algorithm // stream, pipe, whatever
//! {
//! typedef some_type value_type;
//!
//! const value_type & operator * () const; // return current element of the stream
//! stream_algorithm & operator ++ (); // go to next element. precondition: empty() == false
//! bool empty() const; // return true if end of stream is reached
//!
//! };
//! \endverbatim
//!
//! \{


////////////////////////////////////////////////////////////////////////
// STREAMIFY //
////////////////////////////////////////////////////////////////////////

//! A model of stream that retrieves the data from an input iterator.
//! For convenience use \c streamify function instead of direct instantiation
//! of \c iterator2stream .
template <class InputIterator_>
class iterator2stream
{
 InputIterator_ current_, end_;

public:
 //! Standard stream typedef.
 typedef typename std::iterator_traits<InputIterator_>::value_type value_type;

 iterator2stream(InputIterator_ begin, InputIterator_ end) :
 current_(begin), end_(end) { }

 iterator2stream(const iterator2stream& a) : current_(a.current_), end_(a.end_) { }

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

 const value_type* operator -> () const
 {
 return &(*current_);
 }

 //! Standard stream method.
 iterator2stream& operator ++ ()
 {
 assert(end_ != current_);
 ++current_;
 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return (current_ == end_);
 }
};


//! Input iterator range to stream converter.
//! \param begin iterator, pointing to the first value
//! \param end iterator, pointing to the last + 1 position, i.e. beyond the range
//! \return an instance of a stream object
template <class InputIterator_>
iterator2stream<InputIterator_> streamify(InputIterator_ begin, InputIterator_ end)
{
 return iterator2stream<InputIterator_>(begin, end);
}

//! Traits class of \c streamify function.
template <class InputIterator_>
struct streamify_traits
{
 //! return type (stream type) of \c streamify for \c InputIterator_.
 typedef iterator2stream<InputIterator_> stream_type;
};

//! A model of stream that retrieves data from an external \c stxxl::vector iterator.
//! It is more efficient than generic \c iterator2stream thanks to use of overlapping
//! For convenience use \c streamify function instead of direct instantiation
//! of \c vector_iterator2stream .
template <class InputIterator_>
class vector_iterator2stream
{
 InputIterator_ current_, end_;
 typedef buf_istream<typename InputIterator_::block_type,
 typename InputIterator_::bids_container_iterator> buf_istream_type;

 typedef typename stxxl::compat_unique_ptr<buf_istream_type>::result buf_istream_unique_ptr_type;
 mutable buf_istream_unique_ptr_type in;

 void delete_stream()
 {
 in.reset(); // delete object
 }

public:
 typedef vector_iterator2stream<InputIterator_> Self_;

 //! Standard stream typedef.
 typedef typename std::iterator_traits<InputIterator_>::value_type value_type;

 vector_iterator2stream(InputIterator_ begin, InputIterator_ end, unsigned_type nbuffers = 0) :
 current_(begin), end_(end), in(static_cast<buf_istream_type*>(NULL))
 {
 if (empty())
 return;

 begin.flush(); // flush container
 typename InputIterator_::bids_container_iterator end_iter = end.bid() + ((end.block_offset()) ? 1 : 0);

 if (end_iter - begin.bid() > 0)
 {
 in.reset(new buf_istream_type(begin.bid(), end_iter, nbuffers ? nbuffers :
 (2 * config::get_instance()->disks_number())));

 InputIterator_ cur = begin - begin.block_offset();

 // skip the beginning of the block
 for ( ; cur != begin; ++cur)
 ++(*in);
 }
 }

 vector_iterator2stream(const Self_& a) :
 current_(a.current_), end_(a.end_), in(a.in.release()) { }

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

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

 //! Standard stream method.
 Self_& operator ++ ()
 {
 assert(end_ != current_);
 ++current_;
 ++(*in);
 if (UNLIKELY(empty()))
 delete_stream();

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return (current_ == end_);
 }
 virtual ~vector_iterator2stream()
 {
 delete_stream(); // not needed actually
 }
};

//! Input external \c stxxl::vector iterator range to stream converter.
//! It is more efficient than generic input iterator \c streamify thanks to use of overlapping
//! \param begin iterator, pointing to the first value
//! \param end iterator, pointing to the last + 1 position, i.e. beyond the range
//! \param nbuffers number of blocks used for overlapped reading (0 is default,
//! which equals to (2 * number_of_disks)
//! \return an instance of a stream object

template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
vector_iterator2stream<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
streamify(
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> begin,
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> end,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE1("streamify for vector_iterator range is called");
 return vector_iterator2stream<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
 (begin, end, nbuffers);
}

template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
struct streamify_traits<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
{
 typedef vector_iterator2stream<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> > stream_type;
};

//! Input external \c stxxl::vector const iterator range to stream converter.
//! It is more efficient than generic input iterator \c streamify thanks to use of overlapping
//! \param begin const iterator, pointing to the first value
//! \param end const iterator, pointing to the last + 1 position, i.e. beyond the range
//! \param nbuffers number of blocks used for overlapped reading (0 is default,
//! which equals to (2 * number_of_disks)
//! \return an instance of a stream object

template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
vector_iterator2stream<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
streamify(
 stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> begin,
 stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> end,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE1("streamify for const_vector_iterator range is called");
 return vector_iterator2stream<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
 (begin, end, nbuffers);
}

template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
struct streamify_traits<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
{
 typedef vector_iterator2stream<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> > stream_type;
};


//! Version of \c iterator2stream. Switches between \c vector_iterator2stream and \c iterator2stream .
//!
//! small range switches between
//! \c vector_iterator2stream and \c iterator2stream .
//! iterator2stream is chosen if the input iterator range
//! is small ( < B )
template <class InputIterator_>
class vector_iterator2stream_sr
{
 vector_iterator2stream<InputIterator_>* vec_it_stream;
 iterator2stream<InputIterator_>* it_stream;

 typedef typename InputIterator_::block_type block_type;

public:
 typedef vector_iterator2stream_sr<InputIterator_> Self_;

 //! Standard stream typedef.
 typedef typename std::iterator_traits<InputIterator_>::value_type value_type;

 vector_iterator2stream_sr(InputIterator_ begin, InputIterator_ end, unsigned_type nbuffers = 0)
 {
 if (end - begin < block_type::size)
 {
 STXXL_VERBOSE1("vector_iterator2stream_sr::vector_iterator2stream_sr: Choosing iterator2stream<InputIterator_>");
 it_stream = new iterator2stream<InputIterator_>(begin, end);
 vec_it_stream = NULL;
 }
 else
 {
 STXXL_VERBOSE1("vector_iterator2stream_sr::vector_iterator2stream_sr: Choosing vector_iterator2stream<InputIterator_>");
 it_stream = NULL;
 vec_it_stream = new vector_iterator2stream<InputIterator_>(begin, end, nbuffers);
 }
 }

 vector_iterator2stream_sr(const Self_& a) : vec_it_stream(a.vec_it_stream), it_stream(a.it_stream) { }

 //! Standard stream method.
 const value_type& operator * () const
 {
 if (it_stream)
 return **it_stream;

 return **vec_it_stream;
 }

 const value_type* operator -> () const
 {
 if (it_stream)
 return &(**it_stream);

 return &(**vec_it_stream);
 }

 //! Standard stream method.
 Self_& operator ++ ()
 {
 if (it_stream)
 ++(*it_stream);

 else
 ++(*vec_it_stream);


 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 if (it_stream)
 return it_stream->empty();

 return vec_it_stream->empty();
 }
 virtual ~vector_iterator2stream_sr()
 {
 if (it_stream)
 delete it_stream;

 else
 delete vec_it_stream;
 }
};

//! Version of \c streamify. Switches from \c vector_iterator2stream to \c iterator2stream for small ranges.
template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
vector_iterator2stream_sr<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
streamify_sr(
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> begin,
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> end,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE1("streamify_sr for vector_iterator range is called");
 return vector_iterator2stream_sr<stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
 (begin, end, nbuffers);
}

//! Version of \c streamify. Switches from \c vector_iterator2stream to \c iterator2stream for small ranges.
template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_>
vector_iterator2stream_sr<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
streamify_sr(
 stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> begin,
 stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> end,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE1("streamify_sr for const_vector_iterator range is called");
 return vector_iterator2stream_sr<stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> >
 (begin, end, nbuffers);
}


////////////////////////////////////////////////////////////////////////
// MATERIALIZE //
////////////////////////////////////////////////////////////////////////

//! Stores consecutively stream content to an output iterator.
//! \param in stream to be stored used as source
//! \param out output iterator used as destination
//! \return value of the output iterator after all increments,
//! i.e. points to the first unwritten value
//! \pre Output (range) is large enough to hold the all elements in the input stream
template <class OutputIterator_, class StreamAlgorithm_>
OutputIterator_ materialize(StreamAlgorithm_& in, OutputIterator_ out)
{
 STXXL_VERBOSE_MATERIALIZE(STXXL_PRETTY_FUNCTION_NAME);
 while (!in.empty())
 {
 *out = *in;
 ++out;
 ++in;
 }
 return out;
}


//! Stores consecutively stream content to an output iterator range \b until end of the stream or end of the iterator range is reached.
//! \param in stream to be stored used as source
//! \param outbegin output iterator used as destination
//! \param outend output end iterator, pointing beyond the output range
//! \return value of the output iterator after all increments,
//! i.e. points to the first unwritten value
//! \pre Output range is large enough to hold the all elements in the input stream
//!
//! This function is useful when you do not know the length of the stream beforehand.
template <class OutputIterator_, class StreamAlgorithm_>
OutputIterator_ materialize(StreamAlgorithm_& in, OutputIterator_ outbegin, OutputIterator_ outend)
{
 STXXL_VERBOSE_MATERIALIZE(STXXL_PRETTY_FUNCTION_NAME);
 while ((!in.empty()) && outend != outbegin)
 {
 *outbegin = *in;
 ++outbegin;
 ++in;
 }
 return outbegin;
}


//! Stores consecutively stream content to an output \c stxxl::vector iterator \b until end of the stream or end of the iterator range is reached.
//! \param in stream to be stored used as source
//! \param outbegin output \c stxxl::vector iterator used as destination
//! \param outend output end iterator, pointing beyond the output range
//! \param nbuffers number of blocks used for overlapped writing (0 is default,
//! which equals to (2 * number_of_disks)
//! \return value of the output iterator after all increments,
//! i.e. points to the first unwritten value
//! \pre Output range is large enough to hold the all elements in the input stream
//!
//! This function is useful when you do not know the length of the stream beforehand.
template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_, class StreamAlgorithm_>
stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_>
materialize(StreamAlgorithm_& in,
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> outbegin,
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> outend,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE_MATERIALIZE(STXXL_PRETTY_FUNCTION_NAME);
 typedef stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> ExtIterator;
 typedef stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> ConstExtIterator;
 typedef buf_ostream<typename ExtIterator::block_type, typename ExtIterator::bids_container_iterator> buf_ostream_type;


 while (outbegin.block_offset()) // go to the beginning of the block
 // of the external vector
 {
 if (in.empty() || outbegin == outend)
 return outbegin;

 *outbegin = *in;
 ++outbegin;
 ++in;
 }

 if (nbuffers == 0)
 nbuffers = 2 * config::get_instance()->disks_number();

 outbegin.flush(); // flush container

 // create buffered write stream for blocks
 buf_ostream_type outstream(outbegin.bid(), nbuffers);

 assert(outbegin.block_offset() == 0);

 // delay calling block_externally_updated() until the block is
 // completely filled (and written out) in outstream
 ConstExtIterator prev_block = outbegin;

 while (!in.empty() && outend != outbegin)
 {
 if (outbegin.block_offset() == 0) {
 if (prev_block != outbegin) {
 prev_block.block_externally_updated();
 prev_block = outbegin;
 }
 }

 *outstream = *in;
 ++outbegin;
 ++outstream;
 ++in;
 }

 ConstExtIterator const_out = outbegin;

 while (const_out.block_offset()) // filling the rest of the block
 {
 *outstream = *const_out;
 ++const_out;
 ++outstream;
 }

 if (prev_block != outbegin)
 prev_block.block_externally_updated();

 outbegin.flush();

 return outbegin;
}


//! Stores consecutively stream content to an output \c stxxl::vector iterator.
//! \param in stream to be stored used as source
//! \param out output \c stxxl::vector iterator used as destination
//! \param nbuffers number of blocks used for overlapped writing (0 is default,
//! which equals to (2 * number_of_disks)
//! \return value of the output iterator after all increments,
//! i.e. points to the first unwritten value
//! \pre Output (range) is large enough to hold the all elements in the input stream
template <typename Tp_, typename AllocStr_, typename SzTp_, typename DiffTp_,
 unsigned BlkSize_, typename PgTp_, unsigned PgSz_, class StreamAlgorithm_>
stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_>
materialize(StreamAlgorithm_& in,
 stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> out,
 unsigned_type nbuffers = 0)
{
 STXXL_VERBOSE_MATERIALIZE(STXXL_PRETTY_FUNCTION_NAME);
 typedef stxxl::vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> ExtIterator;
 typedef stxxl::const_vector_iterator<Tp_, AllocStr_, SzTp_, DiffTp_, BlkSize_, PgTp_, PgSz_> ConstExtIterator;
 typedef buf_ostream<typename ExtIterator::block_type, typename ExtIterator::bids_container_iterator> buf_ostream_type;

 // on the I/O complexity of "materialize":
 // crossing block boundary causes O(1) I/Os
 // if you stay in a block, then materialize function accesses only the cache of the
 // vector (only one block indeed), amortized complexity should apply here

 while (out.block_offset()) // go to the beginning of the block
 // of the external vector
 {
 if (in.empty())
 return out;

 *out = *in;
 ++out;
 ++in;
 }

 if (nbuffers == 0)
 nbuffers = 2 * config::get_instance()->disks_number();


 out.flush(); // flush container

 // create buffered write stream for blocks
 buf_ostream_type outstream(out.bid(), nbuffers);

 assert(out.block_offset() == 0);

 // delay calling block_externally_updated() until the block is
 // completely filled (and written out) in outstream
 ConstExtIterator prev_block = out;

 while (!in.empty())
 {
 if (out.block_offset() == 0) {
 if (prev_block != out) {
 prev_block.block_externally_updated();
 prev_block = out;
 }
 }

 // tells the vector that the block was modified
 *outstream = *in;
 ++out;
 ++outstream;
 ++in;
 }

 ConstExtIterator const_out = out;

 // copy over items remaining in block from vector.
 while (const_out.block_offset())
 {
 *outstream = *const_out; // might cause I/Os for loading the page that
 ++const_out; // contains data beyond out
 ++outstream;
 }

 if (prev_block != out)
 prev_block.block_externally_updated();

 out.flush();

 return out;
}


//! Reads stream content and discards it.
//! Useful where you do not need the processed stream anymore,
//! but are just interested in side effects, or just for debugging.
//! \param in input stream
template <class StreamAlgorithm_>
void discard(StreamAlgorithm_& in)
{
 while (!in.empty())
 {
 *in;
 ++in;
 }
}


////////////////////////////////////////////////////////////////////////
// GENERATE //
////////////////////////////////////////////////////////////////////////

//! A model of stream that outputs data from an adaptable generator functor.
//! For convenience use \c streamify function instead of direct instantiation
//! of \c generator2stream .
template <class Generator_, typename T = typename Generator_::value_type>
class generator2stream
{
public:
 //! Standard stream typedef.
 typedef T value_type;

private:
 Generator_ gen_;
 value_type current_;

public:
 generator2stream(Generator_ g) :
 gen_(g), current_(gen_()) { }

 generator2stream(const generator2stream& a) : gen_(a.gen_), current_(a.current_) { }

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

 const value_type* operator -> () const
 {
 return &current_;
 }

 //! Standard stream method.
 generator2stream& operator ++ ()
 {
 current_ = gen_();
 return *this;
 }

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

//! Adaptable generator to stream converter.
//! \param gen_ generator object
//! \return an instance of a stream object
template <class Generator_>
generator2stream<Generator_> streamify(Generator_ gen_)
{
 return generator2stream<Generator_>(gen_);
}


////////////////////////////////////////////////////////////////////////
// TRANSFORM //
////////////////////////////////////////////////////////////////////////

struct Stopper { };

//! Processes (up to) 6 input streams using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 6 parameters)
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \tparam Input5_ type of the 5th input
//! \tparam Input6_ type of the 6th input
template <class Operation_,
 class Input1_,
 class Input2_ = Stopper,
 class Input3_ = Stopper,
 class Input4_ = Stopper,
 class Input5_ = Stopper,
 class Input6_ = Stopper
 >
class transform
{
 Operation_& op;
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;
 Input5_& i5;
 Input6_& i6;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_, Input2_& i2_, Input3_& i3_, Input4_& i4_,
 Input5_& i5_, Input5_& i6_) :
 op(o), i1(i1_), i2(i2_), i3(i3_), i4(i4_), i5(i5_), i6(i6_)
 {
 if (!empty())
 current = op(*i1, *i2, *i3, *i4, *i5, *i6);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;
 ++i5;
 ++i6;
 if (!empty())
 current = op(*i1, *i2, *i3, *i4, *i5, *i6);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() ||
 i4.empty() || i5.empty() || i6.empty();
 }
};

// Specializations

////////////////////////////////////////////////////////////////////////
// TRANSFORM (1 input stream) //
////////////////////////////////////////////////////////////////////////

//! Processes an input stream using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 1 parameter)
//! \tparam Input1_ type of the input
//! \remark This is a specialization of \c transform .
template <class Operation_,
 class Input1_
 >
class transform<Operation_, Input1_, Stopper, Stopper, Stopper, Stopper, Stopper>
{
 Operation_& op;
 Input1_& i1;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_) : op(o), i1(i1_)
 {
 if (!empty())
 current = op(*i1);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 if (!empty())
 current = op(*i1);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty();
 }
};


////////////////////////////////////////////////////////////////////////
// TRANSFORM (2 input streams) //
////////////////////////////////////////////////////////////////////////

//! Processes 2 input streams using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 2 parameters)
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \remark This is a specialization of \c transform .
template <class Operation_,
 class Input1_,
 class Input2_
 >
class transform<Operation_, Input1_, Input2_, Stopper, Stopper, Stopper, Stopper>
{
 Operation_& op;
 Input1_& i1;
 Input2_& i2;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_, Input2_& i2_) : op(o), i1(i1_), i2(i2_)
 {
 if (!empty())
 current = op(*i1, *i2);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 ++i2;
 if (!empty())
 current = op(*i1, *i2);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty();
 }
};


////////////////////////////////////////////////////////////////////////
// TRANSFORM (3 input streams) //
////////////////////////////////////////////////////////////////////////

//! Processes 3 input streams using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 3 parameters)
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \remark This is a specialization of \c transform .
template <class Operation_,
 class Input1_,
 class Input2_,
 class Input3_
 >
class transform<Operation_, Input1_, Input2_, Input3_, Stopper, Stopper, Stopper>
{
 Operation_& op;
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_, Input2_& i2_, Input3_& i3_) :
 op(o), i1(i1_), i2(i2_), i3(i3_)
 {
 if (!empty())
 current = op(*i1, *i2, *i3);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 if (!empty())
 current = op(*i1, *i2, *i3);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty();
 }
};


////////////////////////////////////////////////////////////////////////
// TRANSFORM (4 input streams) //
////////////////////////////////////////////////////////////////////////

//! Processes 4 input streams using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 4 parameters)
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \remark This is a specialization of \c transform .
template <class Operation_,
 class Input1_,
 class Input2_,
 class Input3_,
 class Input4_
 >
class transform<Operation_, Input1_, Input2_, Input3_, Input4_, Stopper, Stopper>
{
 Operation_& op;
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_, Input2_& i2_, Input3_& i3_, Input4_& i4_) :
 op(o), i1(i1_), i2(i2_), i3(i3_), i4(i4_)
 {
 if (!empty())
 current = op(*i1, *i2, *i3, *i4);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;
 if (!empty())
 current = op(*i1, *i2, *i3, *i4);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() || i4.empty();
 }
};


////////////////////////////////////////////////////////////////////////
// TRANSFORM (5 input streams) //
////////////////////////////////////////////////////////////////////////

//! Processes 5 input streams using given operation functor.
//!
//! \tparam Operation_ type of the operation (type of an
//! adaptable functor that takes 5 parameters)
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \tparam Input5_ type of the 5th input
//! \remark This is a specialization of \c transform .
template <class Operation_,
 class Input1_,
 class Input2_,
 class Input3_,
 class Input4_,
 class Input5_
 >
class transform<Operation_, Input1_, Input2_, Input3_, Input4_, Input5_, Stopper>
{
 Operation_& op;
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;
 Input5_& i5;

public:
 //! Standard stream typedef.
 typedef typename Operation_::value_type value_type;

private:
 value_type current;

public:
 //! Construction.
 transform(Operation_& o, Input1_& i1_, Input2_& i2_, Input3_& i3_, Input4_& i4_,
 Input5_& i5_) :
 op(o), i1(i1_), i2(i2_), i3(i3_), i4(i4_), i5(i5_)
 {
 if (!empty())
 current = op(*i1, *i2, *i3, *i4, *i5);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 transform& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;
 ++i5;
 if (!empty())
 current = op(*i1, *i2, *i3, *i4, *i5);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() || i4.empty() || i5.empty();
 }
};


////////////////////////////////////////////////////////////////////////
// MAKE TUPLE //
////////////////////////////////////////////////////////////////////////

//! Creates stream of 6-tuples from 6 input streams.
//!
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \tparam Input5_ type of the 5th input
//! \tparam Input6_ type of the 6th input
template <class Input1_,
 class Input2_,
 class Input3_ = Stopper,
 class Input4_ = Stopper,
 class Input5_ = Stopper,
 class Input6_ = Stopper
 >
class make_tuple
{
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;
 Input5_& i5;
 Input6_& i6;

public:
 //! Standard stream typedef.
 typedef typename stxxl::tuple<
 typename Input1_::value_type,
 typename Input2_::value_type,
 typename Input3_::value_type,
 typename Input4_::value_type,
 typename Input5_::value_type,
 typename Input6_::value_type
 > value_type;

private:
 value_type current;

public:
 //! Construction.
 make_tuple(
 Input1_& i1_,
 Input2_& i2_,
 Input3_& i3_,
 Input4_& i4_,
 Input5_& i5_,
 Input6_& i6_
 ) :
 i1(i1_), i2(i2_), i3(i3_), i4(i4_), i5(i5_), i6(i6_)
 {
 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4, *i5, *i6);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 make_tuple& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;
 ++i5;
 ++i6;

 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4, *i5, *i6);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() ||
 i4.empty() || i5.empty() || i6.empty();
 }
};


//! Creates stream of 2-tuples (pairs) from 2 input streams.
//!
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \remark A specialization of \c make_tuple .
template <class Input1_,
 class Input2_
 >
class make_tuple<Input1_, Input2_, Stopper, Stopper, Stopper, Stopper>
{
 Input1_& i1;
 Input2_& i2;

public:
 //! Standard stream typedef.
 typedef typename stxxl::tuple<
 typename Input1_::value_type,
 typename Input2_::value_type
 > value_type;

private:
 value_type current;

public:
 //! Construction.
 make_tuple(
 Input1_& i1_,
 Input2_& i2_
 ) :
 i1(i1_), i2(i2_)
 {
 if (!empty())
 current = value_type(*i1, *i2);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 make_tuple& operator ++ ()
 {
 ++i1;
 ++i2;

 if (!empty())
 current = value_type(*i1, *i2);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty();
 }
};

//! Creates stream of 3-tuples from 3 input streams.
//!
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \remark A specialization of \c make_tuple .
template <class Input1_,
 class Input2_,
 class Input3_
 >
class make_tuple<Input1_, Input2_, Input3_, Stopper, Stopper, Stopper>
{
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;

public:
 //! Standard stream typedef.
 typedef typename stxxl::tuple<
 typename Input1_::value_type,
 typename Input2_::value_type,
 typename Input3_::value_type
 > value_type;

private:
 value_type current;

public:
 //! Construction.
 make_tuple(
 Input1_& i1_,
 Input2_& i2_,
 Input3_& i3_
 ) :
 i1(i1_), i2(i2_), i3(i3_)
 {
 if (!empty())
 current = value_type(*i1, *i2, *i3);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 make_tuple& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;

 if (!empty())
 current = value_type(*i1, *i2, *i3);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty();
 }
};

//! Creates stream of 4-tuples from 4 input streams.
//!
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \remark A specialization of \c make_tuple .
template <class Input1_,
 class Input2_,
 class Input3_,
 class Input4_
 >
class make_tuple<Input1_, Input2_, Input3_, Input4_, Stopper, Stopper>
{
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;

public:
 //! Standard stream typedef.
 typedef typename stxxl::tuple<
 typename Input1_::value_type,
 typename Input2_::value_type,
 typename Input3_::value_type,
 typename Input4_::value_type
 > value_type;

private:
 value_type current;

public:
 //! Construction.
 make_tuple(
 Input1_& i1_,
 Input2_& i2_,
 Input3_& i3_,
 Input4_& i4_
 ) :
 i1(i1_), i2(i2_), i3(i3_), i4(i4_)
 {
 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 make_tuple& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;

 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() ||
 i4.empty();
 }
};

//! Creates stream of 5-tuples from 5 input streams.
//!
//! \tparam Input1_ type of the 1st input
//! \tparam Input2_ type of the 2nd input
//! \tparam Input3_ type of the 3rd input
//! \tparam Input4_ type of the 4th input
//! \tparam Input5_ type of the 5th input
//! \remark A specialization of \c make_tuple .
template <
 class Input1_,
 class Input2_,
 class Input3_,
 class Input4_,
 class Input5_
 >
class make_tuple<Input1_, Input2_, Input3_, Input4_, Input5_, Stopper>
{
 Input1_& i1;
 Input2_& i2;
 Input3_& i3;
 Input4_& i4;
 Input5_& i5;

public:
 //! Standard stream typedef.
 typedef typename stxxl::tuple<
 typename Input1_::value_type,
 typename Input2_::value_type,
 typename Input3_::value_type,
 typename Input4_::value_type,
 typename Input5_::value_type
 > value_type;

private:
 value_type current;

public:
 //! Construction.
 make_tuple(
 Input1_& i1_,
 Input2_& i2_,
 Input3_& i3_,
 Input4_& i4_,
 Input5_& i5_
 ) :
 i1(i1_), i2(i2_), i3(i3_), i4(i4_), i5(i5_)
 {
 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4, *i5);
 }

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

 const value_type* operator -> () const
 {
 return &current;
 }

 //! Standard stream method.
 make_tuple& operator ++ ()
 {
 ++i1;
 ++i2;
 ++i3;
 ++i4;
 ++i5;

 if (!empty())
 current = value_type(*i1, *i2, *i3, *i4, *i5);

 return *this;
 }

 //! Standard stream method.
 bool empty() const
 {
 return i1.empty() || i2.empty() || i3.empty() ||
 i4.empty() || i5.empty();
 }
};


//! \}

} // namespace stream

STXXL_END_NAMESPACE


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


#endif // !STXXL_STREAM_STREAM_HEADER
// vim: et:ts=4:sw=4