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authorAlex Crawford <alex.crawford@coreos.com>2015-08-03 23:11:53 -0700
committerAlex Crawford <alex.crawford@coreos.com>2015-08-04 03:23:43 -0700
commitdbe465c93ea8a87da95919d3f0ee802865802cfa (patch)
tree1cc0d50e2a026e988a85672d531383f97776af7c
parent58a2e9acd8216f55b004e5432f76a851f7b233c0 (diff)
basic: add LIST_INSERT_BEFORE
Similar in function to LIST_INSERT_AFTER, this will insert a new element into the list before the specified position. If the specified position is NULL, the element is added as the tail of the list.
-rw-r--r--src/basic/list.h26
-rw-r--r--src/test/test-list.c44
2 files changed, 70 insertions, 0 deletions
diff --git a/src/basic/list.h b/src/basic/list.h
index 2939216adb..760abcdab3 100644
--- a/src/basic/list.h
+++ b/src/basic/list.h
@@ -123,6 +123,32 @@
} \
} while(false)
+/* Insert an item before another one (a = where, b = what) */
+#define LIST_INSERT_BEFORE(name,head,a,b) \
+ do { \
+ typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
+ assert(_b); \
+ if (!_a) { \
+ if (!*_head) { \
+ _b->name##_next = NULL; \
+ _b->name##_prev = NULL; \
+ *_head = _b; \
+ } else { \
+ typeof(*(head)) *_tail = (head); \
+ while (_tail->name##_next) \
+ _tail = _tail->name##_next; \
+ _b->name##_next = NULL; \
+ _b->name##_prev = _tail; \
+ _tail->name##_next = _b; \
+ } \
+ } else { \
+ if ((_b->name##_prev = _a->name##_prev)) \
+ _b->name##_prev->name##_next = _b; \
+ _b->name##_next = _a; \
+ _a->name##_prev = _b; \
+ } \
+ } while(false)
+
#define LIST_JUST_US(name,item) \
(!(item)->name##_prev && !(item)->name##_next) \
diff --git a/src/test/test-list.c b/src/test/test-list.c
index f6da1a7053..160064d06a 100644
--- a/src/test/test-list.c
+++ b/src/test/test-list.c
@@ -99,6 +99,50 @@ int main(int argc, const char *argv[]) {
assert_se(items[1].item_prev == &items[3]);
assert_se(items[3].item_prev == NULL);
+ LIST_REMOVE(item, head, &items[1]);
+ assert_se(LIST_JUST_US(item, &items[1]));
+
+ assert_se(items[0].item_next == NULL);
+ assert_se(items[2].item_next == &items[0]);
+ assert_se(items[3].item_next == &items[2]);
+
+ assert_se(items[0].item_prev == &items[2]);
+ assert_se(items[2].item_prev == &items[3]);
+ assert_se(items[3].item_prev == NULL);
+
+ LIST_INSERT_BEFORE(item, head, &items[2], &items[1]);
+ assert_se(items[0].item_next == NULL);
+ assert_se(items[2].item_next == &items[0]);
+ assert_se(items[1].item_next == &items[2]);
+ assert_se(items[3].item_next == &items[1]);
+
+ assert_se(items[0].item_prev == &items[2]);
+ assert_se(items[2].item_prev == &items[1]);
+ assert_se(items[1].item_prev == &items[3]);
+ assert_se(items[3].item_prev == NULL);
+
+ LIST_REMOVE(item, head, &items[0]);
+ assert_se(LIST_JUST_US(item, &items[0]));
+
+ assert_se(items[2].item_next == NULL);
+ assert_se(items[1].item_next == &items[2]);
+ assert_se(items[3].item_next == &items[1]);
+
+ assert_se(items[2].item_prev == &items[1]);
+ assert_se(items[1].item_prev == &items[3]);
+ assert_se(items[3].item_prev == NULL);
+
+ LIST_INSERT_BEFORE(item, head, NULL, &items[0]);
+ assert_se(items[0].item_next == NULL);
+ assert_se(items[2].item_next == &items[0]);
+ assert_se(items[1].item_next == &items[2]);
+ assert_se(items[3].item_next == &items[1]);
+
+ assert_se(items[0].item_prev == &items[2]);
+ assert_se(items[2].item_prev == &items[1]);
+ assert_se(items[1].item_prev == &items[3]);
+ assert_se(items[3].item_prev == NULL);
+
LIST_REMOVE(item, head, &items[0]);
assert_se(LIST_JUST_US(item, &items[0]));