ydb/contrib/tools/ragel5/aapl/insertsort.h

/*
 *  Copyright 2002 Adrian Thurston <thurston@cs.queensu.ca>
 */

/*  This file is part of Aapl.
 *
 *  Aapl is free software; you can redistribute it and/or modify it under the
 *  terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 2.1 of the License, or (at your option)
 *  any later version.
 *
 *  Aapl 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 Lesser General Public License for
 *  more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with Aapl; if not, write to the Free Software Foundation, Inc., 59
 *  Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#ifndef _AAPL_INSERTSORT_H
#define _AAPL_INSERTSORT_H

#ifdef AAPL_NAMESPACE
namespace Aapl {
#endif

/**
 * \addtogroup sort 
 * @{
 */

/** 
 * \class InsertSort
 * \brief Insertion sort an array of data.
 *
 * InsertSort can be used to sort any array of objects of type T provided a
 * compare class is given. InsertSort is in-place. It does not require any
 * temporary storage.
 *
 * Objects are not made aware that they are being moved around in memory.
 * Assignment operators, constructors and destructors are never invoked by the
 * sort.
 *
 * InsertSort runs in O(n^2) time. It is most useful when sorting small arrays.
 * where it can outperform the O(n*log(n)) sorters due to its simplicity.
 * InsertSort is a not a stable sort. Elements with the same key will not have
 * their relative ordering preserved.
 */

/*@}*/

/* InsertSort. */
template <class T, class Compare> class InsertSort
	: public Compare
{
public:
	/* Sorting interface routine. */
	void sort(T *data, long len);
};


/**
 * \brief Insertion sort an array of data.
 */
template <class T, class Compare> 
	void InsertSort<T,Compare>::sort(T *data, long len)
{
	/* For each next largest spot in the sorted array... */
	for ( T *dest = data; dest < data+len-1; dest++ ) {
		/* Find the next smallest element in the unsorted array. */
		T *smallest = dest;
		for ( T *src = dest+1; src < data+len; src++ ) {
			/* If src is smaller than the current src, then use it. */
			if ( compare( *src, *smallest ) < 0 )
				smallest = src;
		}

		if ( smallest != dest ) {
			/* Swap dest, smallest. */
			char tmp[sizeof(T)];
			memcpy( tmp, dest, sizeof(T) );
			memcpy( dest, smallest, sizeof(T) );
			memcpy( smallest, tmp, sizeof(T) );
		}
	}
}

#ifdef AAPL_NAMESPACE
}
#endif

#endif /* _AAPL_INSERTSORT_H */