From: Eric Wong <normalperson@yhbt.net>
To: ccan@lists.ozlabs.org
Cc: david@gibson.dropbear.id.au, spew@80x24.org,
Eric Wong <normalperson@yhbt.net>
Subject: [RESEND PATCH 2/5] list: list_swap to exchange elements
Date: Fri, 24 Oct 2014 22:02:29 +0000 [thread overview]
Message-ID: <1414188152-24228-3-git-send-email-normalperson@yhbt.net> (raw)
In-Reply-To: <1414188152-24228-1-git-send-email-normalperson@yhbt.net>
This allows deleting and re-inserting an element in place
of the deleted element without branching.
Signed-off-by: Eric Wong <normalperson@yhbt.net>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
ccan/list/list.h | 33 +++++++++++++++++++++++++++++++++
ccan/list/test/run.c | 23 +++++++++++++++++++++--
2 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/ccan/list/list.h b/ccan/list/list.h
index 5c1159f..983675b 100644
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -369,6 +369,39 @@ static inline void list_del_from(struct list_head *h, struct list_node *n)
}
/**
+ * list_swap - swap out an entry from an (unknown) linked list for a new one.
+ * @o: the list_node to replace from the list.
+ * @n: the list_node to insert in place of the old one.
+ *
+ * Note that this leaves @o in an undefined state; it can be added to
+ * another list, but not deleted/swapped again.
+ *
+ * See also:
+ * list_del()
+ *
+ * Example:
+ * struct child x1, x2;
+ * LIST_HEAD(xh);
+ *
+ * list_add(&xh, &x1.list);
+ * list_swap(&x1.list, &x2.list);
+ */
+#define list_swap(o, n) list_swap_(o, n, LIST_LOC)
+static inline void list_swap_(struct list_node *o,
+ struct list_node *n,
+ const char* abortstr)
+{
+ (void)list_debug_node(o, abortstr);
+ *n = *o;
+ n->next->prev = n;
+ n->prev->next = n;
+#ifdef CCAN_LIST_DEBUG
+ /* Catch use-after-del. */
+ o->next = o->prev = NULL;
+#endif
+}
+
+/**
* list_entry - convert a list_node back into the structure containing it.
* @n: the list_node
* @type: the type of the entry
diff --git a/ccan/list/test/run.c b/ccan/list/test/run.c
index 2f1acc7..3067445 100644
--- a/ccan/list/test/run.c
+++ b/ccan/list/test/run.c
@@ -19,13 +19,13 @@ static LIST_HEAD(static_list);
int main(int argc, char *argv[])
{
struct parent parent;
- struct child c1, c2, c3, *c, *n;
+ struct child c1, c2, c3, x1, *c, *n;
unsigned int i;
struct list_head list = LIST_HEAD_INIT(list);
opaque_t *q, *nq;
struct list_head opaque_list = LIST_HEAD_INIT(opaque_list);
- plan_tests(79);
+ plan_tests(84);
/* Test LIST_HEAD, LIST_HEAD_INIT, list_empty and check_list */
ok1(list_empty(&static_list));
ok1(list_check(&static_list, NULL));
@@ -253,5 +253,24 @@ int main(int argc, char *argv[])
}
ok1(i == 3);
+ /* test list_swap */
+ list_swap(&c3.list, &x1.list);
+ ok1(list_check(&parent.children, "list_swap"));
+ i = 0;
+ list_for_each(&parent.children, c, list) {
+ switch (i++) {
+ case 0:
+ ok1(c == &c1);
+ break;
+ case 1:
+ ok1(c == &x1);
+ break;
+ case 2:
+ ok1(c == &c2);
+ break;
+ }
+ }
+ ok1(i == 3);
+
return exit_status();
}
--
EW
next prev parent reply other threads:[~2014-10-24 22:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-24 22:02 [PATCH 0/5] new ccan/list functionality Eric Wong
2014-10-24 22:02 ` [RESEND PATCH 1/5] list: list_add_after and list_add_before functions Eric Wong
2014-10-24 22:02 ` Eric Wong [this message]
2014-10-24 22:02 ` [PATCH 3/5] list: new list_for_each{,_safe}_off_dir_ macros Eric Wong
2014-11-03 9:14 ` David Gibson
2014-10-24 22:02 ` [PATCH 4/5] list: add list_for_each_rev_off macro Eric Wong
2014-11-03 9:16 ` David Gibson
2014-10-24 22:02 ` [PATCH 5/5] list: add list_for_each_rev_safe{,_off} macros Eric Wong
2014-11-03 9:30 ` David Gibson
2014-12-18 19:40 ` Eric Wong
2015-03-30 6:27 ` [ccan] [PATCH 5/5] list: add list_for_each_rev_safe{, _off} macros Rusty Russell
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