Add alpm_list_previous method

Helper function to get the previous item in a list

Signed-off-by: Allan McRae <allan@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/libalpm/alpm_list.c b/lib/libalpm/alpm_list.c
index c2b30adc..1976e13d 100644
--- a/lib/libalpm/alpm_list.c
+++ b/lib/libalpm/alpm_list.c
@@ -556,6 +556,24 @@ inline alpm_list_t SYMEXPORT *alpm_list_next(const alpm_list_t *node)
 }
 
 /**
+ * @brief Get the previous element of a list.
+ *
+ * @param list the list head
+ * @param node the list node
+ *
+ * @return the previous element, or NULL when no previous element exist
+ */
+inline alpm_list_t SYMEXPORT *alpm_list_previous(const alpm_list_t *list,
+		const alpm_list_t *node)
+{
+	if(node && node != list) {
+		return node->prev;
+	} else {
+		return NULL;
+	}
+}
+
+/**
  * @brief Get the last item in the list.
  *
  * @param list the list