[notmuch] [PATCH 5/5] Added backwards iterator to tags

[Ruben Pollan]

Added the functions notmuch_tags_move_to_prevoius,
notmuch_tags_move_to_last and  notmuch_tags_move_to_first to notmuch
library. With them is possible to iterate backwards on tags.

* notmuch_tags_move_to_prevoius do the opposite than
  notmuch_tags_move_to_next, getting the tags iterator one
  position backwards.

* notmuch_tags_move_to_last move the iterator to the first last tag.

* notmuch_tags_move_to_first move the iterator to the first valid tag.
---
 lib/notmuch.h |   28 ++++++++++++++++++++++++++++
 lib/tags.c    |   21 +++++++++++++++++++++
 2 files changed, 49 insertions(+), 0 deletions(-)

diff --git a/lib/notmuch.h b/lib/notmuch.h
index b96b624..dc668dc 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -1022,6 +1022,15 @@ notmuch_tags_valid (notmuch_tags_t *tags);
 const char *
 notmuch_tags_get (notmuch_tags_t *tags);
 
+/* Move the 'tags' iterator to the first tag.
+ *
+ * After that the 'tags' iterator will be set to the first valid 
+ * tag, so it can be use to iterate with 
+ * notmuch_tags_move_to_next.
+ */
+void
+notmuch_tags_move_to_first (notmuch_tags_t *tags);
+
 /* Move the 'tags' iterator to the next tag.
  *
  * If 'tags' is already pointing at the last tag then the iterator
@@ -1035,6 +1044,25 @@ notmuch_tags_get (notmuch_tags_t *tags);
 void
 notmuch_tags_move_to_next (notmuch_tags_t *tags);
 
+/* Move the 'tags' iterator to the last tag.
+ *
+ * After that the 'tags' iterator will be set to the last valid 
+ * tag, so it can be use to iterate with 
+ * notmuch_tags_move_to_previous.
+ */
+void
+notmuch_tags_move_to_last (notmuch_tags_t *tags);
+
+/* Move the 'tags' iterator to the previous tag.
+ *
+ * If 'tags' is already pointing at the first tag then the
+ * iterator will be moved to a point just beyond that first tag,
+ * (where notmuch_tags_valid will return FALSE and
+ * notmuch_tags_get will return NULL).
+ */
+void
+notmuch_tags_move_to_previous (notmuch_tags_t *tags);
+
 /* Destroy a notmuch_tags_t object.
  *
  * It's not strictly necessary to call this function. All memory from
diff --git a/lib/tags.c b/lib/tags.c
index 8fe4a3f..9c9a897 100644
--- a/lib/tags.c
+++ b/lib/tags.c
@@ -105,6 +105,12 @@ notmuch_tags_get (notmuch_tags_t *tags)
 }
 
 void
+notmuch_tags_move_to_first (notmuch_tags_t *tags)
+{
+    tags->iterator = g_list_first (tags->tags);
+}
+
+void
 notmuch_tags_move_to_next (notmuch_tags_t *tags)
 {
     if (tags->iterator == NULL)
@@ -114,6 +120,21 @@ notmuch_tags_move_to_next (notmuch_tags_t *tags)
 }
 
 void
+notmuch_tags_move_to_last (notmuch_tags_t *tags)
+{
+    tags->iterator = g_list_last (tags->tags);
+}
+
+void
+notmuch_tags_move_to_previous (notmuch_tags_t *tags)
+{
+    if (tags->iterator == NULL)
+	return;
+
+    tags->iterator = tags->iterator->prev;
+}
+
+void
 notmuch_tags_destroy (notmuch_tags_t *tags)
 {
     talloc_free (tags);
-- 
1.7.0