mru: use double-linked list from list.h

Simplify mru.[ch] and related code by reusing the double-linked list
implementation from list.h instead of a custom one.
This commit is an intermediate step. Our final goal is to get rid of
mru.[ch] at all and inline all logic.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored by: Jeff King <peff@peff.net>
Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 13 insertions, 36 deletions

diff --git a/mru.c b/mru.c
index 9dedae0287..8f3f34c5ba 100644
--- a/mru.c
+++ b/mru.c
@@ -1,50 +1,27 @@
 #include "cache.h"
 #include "mru.h"
 
-void mru_append(struct mru *mru, void *item)
+void mru_append(struct mru *head, void *item)
 {
-	struct mru_entry *cur = xmalloc(sizeof(*cur));
+	struct mru *cur = xmalloc(sizeof(*cur));
 	cur->item = item;
-	cur->prev = mru->tail;
-	cur->next = NULL;
-
-	if (mru->tail)
-		mru->tail->next = cur;
-	else
-		mru->head = cur;
-	mru->tail = cur;
+	list_add_tail(&cur->list, &head->list);
 }
 
-void mru_mark(struct mru *mru, struct mru_entry *entry)
+void mru_mark(struct mru *head, struct mru *entry)
 {
-	/* If we're already at the front of the list, nothing to do */
-	if (mru->head == entry)
-		return;
-
-	/* Otherwise, remove us from our current slot... */
-	if (entry->prev)
-		entry->prev->next = entry->next;
-	if (entry->next)
-		entry->next->prev = entry->prev;
-	else
-		mru->tail = entry->prev;
-
-	/* And insert us at the beginning. */
-	entry->prev = NULL;
-	entry->next = mru->head;
-	if (mru->head)
-		mru->head->prev = entry;
-	mru->head = entry;
+	/* To mark means to put at the front of the list. */
+	list_del(&entry->list);
+	list_add(&entry->list, &head->list);
 }
 
-void mru_clear(struct mru *mru)
+void mru_clear(struct mru *head)
 {
-	struct mru_entry *p = mru->head;
+	struct list_head *pos;
+	struct list_head *tmp;
 
-	while (p) {
-		struct mru_entry *to_free = p;
-		p = p->next;
-		free(to_free);
+	list_for_each_safe(pos, tmp, &head->list) {
+		free(list_entry(pos, struct mru, list));
 	}
-	mru->head = mru->tail = NULL;
+	INIT_LIST_HEAD(&head->list);
 }