From ab79b13079ea6c0c7b66e4c5d14686f06ba759ae Mon Sep 17 00:00:00 2001 From: Allan McRae Date: Sun, 3 Jul 2011 10:10:36 +1000 Subject: Add alpm_list_previous method Helper function to get the previous item in a list Signed-off-by: Allan McRae Signed-off-by: Dan McGee --- lib/libalpm/alpm_list.c | 18 ++++++++++++++++++ lib/libalpm/alpm_list.h | 1 + 2 files changed, 19 insertions(+) (limited to 'lib') 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 @@ -555,6 +555,24 @@ 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. * diff --git a/lib/libalpm/alpm_list.h b/lib/libalpm/alpm_list.h index 1f6393a6..27a76d12 100644 --- a/lib/libalpm/alpm_list.h +++ b/lib/libalpm/alpm_list.h @@ -70,6 +70,7 @@ alpm_list_t *alpm_list_reverse(alpm_list_t *list); alpm_list_t *alpm_list_first(const alpm_list_t *list); alpm_list_t *alpm_list_nth(const alpm_list_t *list, size_t n); alpm_list_t *alpm_list_next(const alpm_list_t *list); +alpm_list_t *alpm_list_previous(const alpm_list_t *list, const alpm_list_t *node); alpm_list_t *alpm_list_last(const alpm_list_t *list); void *alpm_list_getdata(const alpm_list_t *entry); -- cgit v1.2.3-70-g09d2