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60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* lispsort.c--
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/lib/Attic/lispsort.c,v 1.3 1996/11/06 08:27:14 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <sys/types.h>
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#include <postgres.h>
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#include <nodes/pg_list.h>
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#include <nodes/primnodes.h>
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#include <nodes/plannodes.h>
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#include <nodes/relation.h>
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#include <lib/lispsort.h>
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#include <lib/qsort.h>
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/*
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** lisp_qsort: Takes a lisp list as input, copies it into an array of lisp
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** nodes which it sorts via qsort() with the comparison function
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** as passed into lisp_qsort(), and returns a new list with
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** the nodes sorted. The old list is *not* freed or modified (?)
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*/
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List *lisp_qsort(List *the_list, /* the list to be sorted */
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int (*compare)()) /* function to compare two nodes */
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{
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int i;
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size_t num;
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List **nodearray;
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List *tmp, *output;
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/* find size of list */
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num = length(the_list);
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if (num < 2)
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return(copyObject(the_list));
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/* copy elements of the list into an array */
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nodearray = (List **) palloc(num * sizeof(List *));
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for (tmp = the_list, i = 0; tmp != NIL; tmp = lnext(tmp), i++)
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nodearray[i] = copyObject(lfirst(tmp));
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/* sort the array */
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pg_qsort(nodearray, num, sizeof(List *), compare);
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/* lcons together the array elements */
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output = NIL;
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for (i = num - 1; i >= 0; i--)
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output = lcons(nodearray[i], output);
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return(output);
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}
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