// ==========================================================================
//                 SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2013, Knut Reinert, FU Berlin
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of Knut Reinert or the FU Berlin nor the names of
//       its contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL KNUT REINERT OR THE FU BERLIN BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
//
// ==========================================================================
// Author: David Weese <david.weese@fu-berlin.de>
// ==========================================================================

#ifndef SEQAN_HEADER_PIPE_SHIFTER_H
#define SEQAN_HEADER_PIPE_SHIFTER_H

namespace SEQAN_NAMESPACE_MAIN
{

//namespace SEQAN_NAMESPACE_PIPELINING
//{

//    template < int delta, bool omitBlank = false, bool _echoing = (delta < 0) >
//    struct Shifter;
    template < int delta, bool omitBlank = false, bool _echoing = true >
    struct Shifter;

/*!
 * @class Shifter
 * 
 * @extends Pipe
 * 
 * @headerfile seqan/pipe.h
 * 
 * @brief Shifts the input stream by <tt>delta</tt> elements.
 * 
 * @signature template <typename TInput, int DELTA[, bool OMIT_BLANK]>
 *            class Pipe<TInput, Shifter<DELTA, OMIT_BLANK> >;
 * 
 * @tparam TInput     The type of the pipeline module this module reads from.
 * @tparam OMIT_BLANK Omit undefined entries.  If <tt>true</tt>, the output stream is <tt>|delta|</tt> elements shorter
 *                    than the input stream.  If <tt>false</tt>, the lengths are equal and blanks (default constructed
 *                    elements) are inserted on the cut-off-opposite side, defaults to false.
 * @tparam DELTA      The shift size. For the output stream holds <tt>out[i]=in[i+delta]</tt>.  For <tt>delta>0</tt>
 *                    the input stream is cut of at the beginning and for <tt>delta<0</tt> at the end.
 * 
 * @section Remarks
 * 
 * The output type equals the input type.
 */

/**
.Spec.Shifter:
..cat:Pipelining
..general:Class.Pipe
..summary:Shifts the input stream by $delta$ elements.
..signature:Pipe<TInput, Shifter<delta, omitBlank> >
..param.TInput:The type of the pipeline module this module reads from.
..param.delta:The shift size. For the output stream holds $out[i]=in[i+delta]$.
...remarks:For $delta>0$ the input stream is cut of at the beginning and for $delta<0$ at the end.
..param.omitBlank:Omit undefined entries.
..param.omitBlank:If $true$, the output stream is $|delta|$ elements shorter than the input stream.
..param.omitBlank:If $false$, the lengths are equal and blanks (default constructed elements) are inserted on the cut-off-opposite side.
...default:$false$
..remarks:The output type equals the input type.
..include:seqan/pipe.h
*/

    //////////////////////////////////////////////////////////////////////////////
    // echoer class
    template < typename TInput, int delta, bool omitBlank >
    struct Pipe< TInput, Shifter<delta, omitBlank, true> >
    {
        TInput                      &in;
        typename Size<Pipe>::Type	blankCounter, charCounter;
		typename Value<Pipe>::Type	blank;
        
        Pipe(TInput& _in):
            in(_in),
			blank()	{}

        inline typename Value<Pipe>::Type const & operator*() {
			if (blankCounter)	return blank;
			else				return *in;
        }

        inline Pipe& operator++() {
			if (blankCounter)
				--blankCounter;
			else {
				++in;
				--charCounter;
			}
            return *this;
        }
    };


	template < typename TInput, int delta, bool omitBlank >
    struct Pipe< TInput, Shifter<delta, omitBlank, false> >
    {
        TInput                      &in;
        typename Size<Pipe>::Type	blankCounter, charCounter;
		typename Value<Pipe>::Type	blank;
        
        Pipe(TInput& _in):
            in(_in),
			blank()	{}

        inline typename Value<Pipe>::Type const & operator*() {
			if (charCounter)	return *in;
			else				return blank;
        }

        inline Pipe& operator++() {
			if (charCounter) {
				++in;
				--charCounter;
			} else
				--blankCounter;
            return *this;
        }
    };


    //////////////////////////////////////////////////////////////////////////////
    // global pipe functions
    template < typename TInput, int delta, bool omitBlank >
	inline bool control(Pipe< TInput, Shifter< delta, omitBlank, false > > &me, ControlBeginRead const &command) {
        if (!control(me.in, command)) return false;
		for(typename Size<TInput>::Type i = 0; i < delta && !eof(me.in); ++i)
			++me.in;
		me.blankCounter = (omitBlank)? 0: delta;
		me.charCounter = length(me.in) - delta;
		return !eof(me.in);
	}

    template < typename TInput, int delta, bool omitBlank >
	inline bool control(Pipe< TInput, Shifter< delta, omitBlank, true > > &me, ControlBeginRead const &command) {
        if (!control(me.in, command)) return false;
		me.blankCounter = (omitBlank)? 0: -delta;
		me.charCounter = length(me.in) + delta;
		return true;
	}




    template < typename TInput, int delta, bool _echoing >
    inline Size< Pipe< TInput, Shifter< delta, true, _echoing > > >
    length(Pipe< TInput, Shifter< delta, true, _echoing > > const &me) {
        return length(me.in) - abs(delta);
    }

    template < typename TInput, int delta, bool omitBlank, bool _echoing >
	inline bool control(Pipe< TInput, Shifter< delta, omitBlank, _echoing > > &me, ControlEof const &/*command*/) {
		return me.charCounter == 0 && me.blankCounter == 0;
    }

    template < typename TInput, int delta, bool omitBlank, bool _echoing >
	inline bool control(Pipe< TInput, Shifter< delta, omitBlank, _echoing > > &me, ControlEos const &/*command*/) {
		return control(me, ControlEof());
    }

//}

}

#endif
