Postgres95 1.01 Distribution - Virgin Sources

src/backend/lib/lispsort.c

@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * lispsort.c--
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/lib/Attic/lispsort.c,v 1.1.1.1 1996/07/09 06:21:29 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#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);
+}