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/*-------------------------------------------------------------------------
*
* lispsort.c--
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/lib/Attic/lispsort.c,v 1.2 1996/10/31 10:26:33 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
#include <sys/types.h>
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/primnodes.h"
#include "nodes/plannodes.h"
#include "nodes/relation.h"
#include "lib/lispsort.h"
#include "utils/palloc.h"
#include "lib/qsort.h"
/*
** lisp_qsort: Takes a lisp list as input, copies it into an array of lisp
** nodes which it sorts via qsort() with the comparison function
** as passed into lisp_qsort(), and returns a new list with
** the nodes sorted. The old list is *not* freed or modified (?)
*/
List *lisp_qsort(List *the_list, /* the list to be sorted */
int (*compare)()) /* function to compare two nodes */
{
int i;
size_t num;
List **nodearray;
List *tmp, *output;
/* find size of list */
num = length(the_list);
if (num < 2)
return(copyObject(the_list));
/* copy elements of the list into an array */
nodearray = (List **) palloc(num * sizeof(List *));
for (tmp = the_list, i = 0; tmp != NIL; tmp = lnext(tmp), i++)
nodearray[i] = copyObject(lfirst(tmp));
/* sort the array */
pg_qsort(nodearray, num, sizeof(List *), compare);
/* lcons together the array elements */
output = NIL;
for (i = num - 1; i >= 0; i--)
output = lcons(nodearray[i], output);
return(output);
}
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