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/* grecs - Gray's Extensible Configuration System
Copyright (C) 2007-2016 Sergey Poznyakoff
Grecs is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
Grecs 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 General Public License for more details.
You should have received a copy of the GNU General Public License along
with Grecs. If not, see <http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include "grecs.h"
struct node_list {
struct grecs_node *head, *tail;
};
static void
node_list_init(struct node_list *list, struct grecs_node *node)
{
if (node) {
list->head = node;
while (node->next)
node = node->next;
list->tail = node;
} else
list->head = list->tail = NULL;
}
static void
node_list_add(struct node_list *list, struct grecs_node *node)
{
node->next = NULL;
node->prev = list->tail;
if (list->tail)
list->tail->next = node;
else
list->head = node;
list->tail = node;
}
static void
node_list_join(struct node_list *a, struct node_list *b)
{
if (!b->head)
return;
b->head->prev = a->tail;
if (a->tail)
a->tail->next = b->head;
else
a->head = b->head;
a->tail = b->tail;
}
static void
_qsort_nodelist(struct node_list *list,
int (*compare)(struct grecs_node const *,
struct grecs_node const *))
{
struct grecs_node *cur, *middle;
struct node_list high_list, low_list;
int rc;
if (!list->head)
return;
cur = list->head;
do {
cur = cur->next;
if (!cur)
return;
} while ((rc = compare(list->head, cur)) == 0);
/* Select the lower of the two as the middle value */
middle = (rc > 0) ? cur : list->head;
/* Split into two sublists */
node_list_init(&low_list, NULL);
node_list_init(&high_list, NULL);
for (cur = list->head; cur; ) {
struct grecs_node *next = cur->next;
cur->next = NULL;
if (compare(middle, cur) < 0)
node_list_add(&high_list, cur);
else
node_list_add(&low_list, cur);
cur = next;
}
if (!low_list.head)
low_list = high_list;
else if (high_list.head) {
/* Sort both sublists recursively */
_qsort_nodelist(&low_list, compare);
_qsort_nodelist(&high_list, compare);
/* Join both lists in order */
node_list_join(&low_list, &high_list);
}
/* Return the resulting list */
list->head = low_list.head;
list->tail = low_list.tail;
}
struct grecs_node *
grecs_nodelist_sort(struct grecs_node *node,
int (*compare)(struct grecs_node const *,
struct grecs_node const *))
{
struct node_list list;
node_list_init(&list, node);
_qsort_nodelist(&list, compare);
return list.head;
}
void
grecs_tree_sort(struct grecs_node *node,
int (*compare)(struct grecs_node const *,
struct grecs_node const *))
{
if (node && node->down) {
node->down = grecs_nodelist_sort(node->down, compare);
for (node = node->down; node; node = node->next)
grecs_tree_sort(node, compare);
}
}
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