[PATCH 1/2] WIP: refactor tag search into library routine

[David Bremner]

---
 lib/notmuch.h    | 13 +++++++++++++
 lib/query.cc     | 35 +++++++++++++++++++++++++++++++++++
 notmuch-search.c | 24 ++++--------------------
 3 files changed, 52 insertions(+), 20 deletions(-)

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 2faa146..927ea3c 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -927,6 +927,19 @@ notmuch_messages_t *
 notmuch_query_search_messages (notmuch_query_t *query);
 
 /**
+ * Execute a query for tags, outputing a notmuch_tags_t object
+ * which can be used to iterate over the results. The output
+ * tags object is owned by the query and as such, will only be
+ * valid until notmuch_query_destroy.
+ *
+ * @param[in] query   the query to collect tags for
+ * @param[out] out    the return tags list
+ *
+ */
+notmuch_status_t
+notmuch_query_search_tags (notmuch_query_t *query, notmuch_tags_t **out);
+
+/**
  * Destroy a notmuch_query_t along with any associated resources.
  *
  * This will in turn destroy any notmuch_threads_t and
diff --git a/lib/query.cc b/lib/query.cc
index 7eb73a1..7245b12 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -310,6 +310,41 @@ _notmuch_query_search_documents (notmuch_query_t *query,
     }
 }
 
+notmuch_status_t
+notmuch_query_search_tags  (notmuch_query_t *query, notmuch_tags_t **tags)
+{
+    notmuch_messages_t *messages = NULL;
+    notmuch_database_t *notmuch = notmuch_query_get_database (query);
+    notmuch_status_t status = NOTMUCH_STATUS_SUCCESS;
+    const char *query_string = notmuch_query_get_query_string (query);
+
+    if (tags == NULL)
+	return NOTMUCH_STATUS_NULL_POINTER;
+
+    /* Special-case query of "*"  or '' for better performance. */
+    if (strcmp (query_string, "*") == 0 || *query_string == '\0') {
+	*tags = notmuch_database_get_all_tags (notmuch);
+	if (*tags == NULL)
+	    status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
+    } else {
+	notmuch_status_t status;
+	status = notmuch_query_search_messages_st (query, &messages);
+	if (status)
+	    goto DONE;
+
+	*tags = notmuch_messages_collect_tags (messages);
+	talloc_steal (query, *tags);
+	if (*tags == NULL)
+	    status = NOTMUCH_STATUS_OUT_OF_MEMORY;
+    }
+
+ DONE:
+    if (messages)
+	notmuch_messages_destroy (messages);
+
+    return status;
+}
+
 notmuch_bool_t
 _notmuch_mset_messages_valid (notmuch_messages_t *messages)
 {
diff --git a/notmuch-search.c b/notmuch-search.c
index 8c65d5a..8722735 100644
--- a/notmuch-search.c
+++ b/notmuch-search.c
@@ -611,31 +611,18 @@ do_search_messages (search_context_t *ctx)
     return 0;
 }
 
+
 static int
 do_search_tags (const search_context_t *ctx)
 {
-    notmuch_messages_t *messages = NULL;
     notmuch_tags_t *tags;
     const char *tag;
     sprinter_t *format = ctx->format;
     notmuch_query_t *query = ctx->query;
-    notmuch_database_t *notmuch = ctx->notmuch;
-
-    /* should the following only special case if no excluded terms
-     * specified? */
-
-    /* Special-case query of "*" for better performance. */
-    if (strcmp (notmuch_query_get_query_string (query), "*") == 0) {
-	tags = notmuch_database_get_all_tags (notmuch);
-    } else {
-	notmuch_status_t status;
-	status = notmuch_query_search_messages_st (query, &messages);
-	if (print_status_query ("notmuch search", query, status))
-	    return 1;
 
-	tags = notmuch_messages_collect_tags (messages);
-    }
-    if (tags == NULL)
+    if (print_status_query ("notmuch search",
+			    query,
+			    notmuch_query_search_tags (query, &tags)))
 	return 1;
 
     format->begin_list (format);
@@ -653,9 +640,6 @@ do_search_tags (const search_context_t *ctx)
 
     notmuch_tags_destroy (tags);
 
-    if (messages)
-	notmuch_messages_destroy (messages);
-
     format->end (format);
 
     return 0;
-- 
2.8.1