Add notmuch_message_get_thread_ids function

Along with all of the notmuch_thread_ids_t iterator functions.
Using a consistent idiom seems better here rather than returning
a comma-separated string and forcing the user to parse it.

1 files changed, 82 insertions, 6 deletions

diff --git a/notmuch.h b/notmuch.h
index df432bc..41987b5 100644
--- a/notmuch.h
+++ b/notmuch.h
@@ -67,6 +67,7 @@ typedef struct _notmuch_query notmuch_query_t;
 typedef struct _notmuch_results notmuch_results_t;
 typedef struct _notmuch_message notmuch_message_t;
 typedef struct _notmuch_tags notmuch_tags_t;
+typedef struct _notmuch_thread_ids notmuch_thread_ids_t;
 
 /* Create a new, empty notmuch database located at 'path'.
  *
@@ -304,24 +305,59 @@ notmuch_message_get_message_id (notmuch_message_t *message);
  *     notmuch_tags_t *tags;
  *     const char *tag;
  *
- *     message = notmuch_results_get (results);
+ *     message = notmuch_database_find_message (database, message_id);
  *
  *     for (tags = notmuch_message_get_tags (message);
  *          notmuch_tags_has_more (tags);
  *          notmuch_result_advance (tags))
  *     {
- *         tag = notmuch_tags_get_string (tags);
+ *         tag = notmuch_tags_get (tags);
  *         ....
  *     }
  *
- * Note: If you are finished with a message before its containing
- * query, you can call notmuch_message_destroy to clean up some memory
- * sooner. If you don't call it, all the memory will still be
- * reclaimed when the query is destroyed.
+ *     notmuch_message_destroy (message);
+ *
+ * Note that there's no explicit destructor needed for the
+ * notmuch_tags_t object. (For consistency, we do provide a
+ * notmuch_tags_destroy function, but there's no good reason to call
+ * it if the message is about to be destroyed).
  */
 notmuch_tags_t *
 notmuch_message_get_tags (notmuch_message_t *message);
 
+/* Get the thread IDs for 'message', returning a notmuch_thread_ids_t
+ * object which can be used to iterate over all thread IDs.
+ *
+ * The thread_ids object is owned by the message and as such, will
+ * only be valid for as long as the message is valid, (which is until
+ * the query from which it derived is destroyed).
+ *
+ * Typical usage might be:
+ *
+ *     notmuch_message_t *message;
+ *     notmuch_thread_ids_t *thread_ids;
+ *     const char *thread_id;
+ *
+ *     message = notmuch_database_find_message (database, message_id);
+ *
+ *     for (thread_ids = notmuch_message_get_thread_ids (message);
+ *          notmuch_thread_ids_has_more (thread_ids);
+ *          notmuch_thread_ids_advance (thread_ids))
+ *     {
+ *         thread_id = notmuch_thread_ids_get (thread_ids);
+ *         ....
+ *     }
+ *
+ *     notmuch_message_destroy (message);
+ *
+ * Note that there's no explicit destructor needed for the
+ * notmuch_thread_ids_t object. (For consistency, we do provide a
+ * notmuch_thread_ids_destroy function, but there's no good reason to
+ * call it if the message is about to be destroyed).
+ */
+notmuch_thread_ids_t *
+notmuch_message_get_thread_ids (notmuch_message_t *message);
+
 /* Destroy a notmuch_message_t object.
  *
  * It can be useful to call this function in the case of a single
@@ -373,6 +409,46 @@ notmuch_tags_advance (notmuch_tags_t *results);
 void
 notmuch_tags_destroy (notmuch_tags_t *tags);
 
+/* Does the given notmuch_thread_ids_t object contain any more thread IDs.
+ *
+ * When this function returns TRUE, notmuch_thread_ids_get will return a
+ * valid string. Whereas when this function returns FALSE,
+ * notmuch_thread_ids_get will return NULL.
+ *
+ * See the documentation of notmuch_message_get_thread_ids for example code
+ * showing how to iterate over a notmuch_thread_ids_t object.
+ */
+notmuch_bool_t
+notmuch_thread_ids_has_more (notmuch_thread_ids_t *thread_ids);
+
+/* Get the current thread ID from 'thread_ids' as a string.
+ *
+ * Note: The returned string belongs to 'thread_ids' and has a lifetime
+ * identical to it (and the query to which it utlimately belongs).
+ *
+ * See the documentation of notmuch_message_get_thread_ids for example code
+ * showing how to iterate over a notmuch_thread_ids_t object.
+ */
+const char *
+notmuch_thread_ids_get (notmuch_thread_ids_t *thread_ids);
+
+/* Advance the 'thread_ids' iterator to the next tag.
+ *
+ * See the documentation of notmuch_message_get_thread_ids for example code
+ * showing how to iterate over a notmuch_thread_ids_t object.
+ */
+void
+notmuch_thread_ids_advance (notmuch_thread_ids_t *thread_ids);
+
+/* Destroy a notmuch_thread_ids_t object.
+ *
+ * It's not strictly necessary to call this function. All memory from
+ * the notmuch_thread_ids_t object will be reclaimed when the containg
+ * message or query objects are destroyed.
+ */
+void
+notmuch_thread_ids_destroy (notmuch_thread_ids_t *thread_ids);
+
 NOTMUCH_END_DECLS
 
 #endif