[PATCH 20/25] lib/thread-fp: factor out query expansion

[David Bremner <david@tethera.net>]

The non-obvious choice of creating the query outside the factored-out
code is so the the new function can be used with different query
syntaxes.
---
 lib/database-private.h |  5 +++++
 lib/query.cc           | 26 ++++++++++++++++++++++++++
 lib/thread-fp.cc       | 25 +++++++++----------------
 3 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/lib/database-private.h b/lib/database-private.h
index 9706c17e..72b74807 100644
--- a/lib/database-private.h
+++ b/lib/database-private.h
@@ -300,4 +300,9 @@ _notmuch_database_setup_standard_query_fields (notmuch_database_t *notmuch);
 notmuch_status_t
 _notmuch_database_setup_user_query_fields (notmuch_database_t *notmuch);
 
+/* query.cc */
+notmuch_status_t
+_notmuch_query_expand_to_threads (notmuch_query_t *subquery,
+				  Xapian::Query &output, std::string &msg);
+
 #endif
diff --git a/lib/query.cc b/lib/query.cc
index 46bc1373..0916860e 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -796,3 +796,29 @@ notmuch_query_get_database (const notmuch_query_t *query)
 {
     return query->notmuch;
 }
+
+notmuch_status_t
+_notmuch_query_expand_to_threads (notmuch_query_t *subquery, Xapian::Query &output, std::string &msg)
+{
+    notmuch_messages_t *messages;
+    std::set<std::string> terms;
+    notmuch_status_t status;
+    const std::string thread_prefix =  _find_prefix ("thread");
+
+    status = notmuch_query_search_messages (subquery, &messages);
+    if (status) {
+	msg = "failed to search messages for subquery";
+	return NOTMUCH_STATUS_ILLEGAL_ARGUMENT;
+    }
+
+    for (; notmuch_messages_valid (messages); notmuch_messages_move_to_next (messages)) {
+	std::string term = thread_prefix;
+	notmuch_message_t *message;
+	message = notmuch_messages_get (messages);
+	term += _notmuch_message_get_thread_id_only (message);
+	terms.insert (term);
+    }
+    output = Xapian::Query (Xapian::Query::OP_OR, terms.begin (), terms.end ());
+
+    return NOTMUCH_STATUS_SUCCESS;
+}
diff --git a/lib/thread-fp.cc b/lib/thread-fp.cc
index 06708ef2..d0680a22 100644
--- a/lib/thread-fp.cc
+++ b/lib/thread-fp.cc
@@ -34,28 +34,21 @@ ThreadFieldProcessor::operator() (const std::string & str)
 	if (str.size () <= 1 || str.at (str.size () - 1) != '}') {
 	    throw Xapian::QueryParserError ("missing } in '" + str + "'");
 	} else {
+	    notmuch_query_t *subquery;
+	    Xapian::Query query;
+	    std::string msg;
 	    std::string subquery_str = str.substr (1, str.size () - 2);
-	    notmuch_query_t *subquery = notmuch_query_create (notmuch, subquery_str.c_str ());
-	    notmuch_messages_t *messages;
-	    std::set<std::string> terms;
 
+	    subquery = notmuch_query_create (notmuch, subquery_str.c_str ());
 	    if (! subquery)
-		throw Xapian::QueryParserError ("failed to create subquery for '" + subquery_str +
-						"'");
+		throw Xapian::QueryParserError ("failed to create subquery for '" +
+						subquery_str + "'");
 
-	    status = notmuch_query_search_messages (subquery, &messages);
+	    status = _notmuch_query_expand_to_threads (subquery, query, msg);
 	    if (status)
-		throw Xapian::QueryParserError ("failed to search messages for '" + subquery_str +
-						"'");
+		throw Xapian::QueryParserError (msg);
 
-	    for (; notmuch_messages_valid (messages); notmuch_messages_move_to_next (messages)) {
-		std::string term = thread_prefix;
-		notmuch_message_t *message;
-		message = notmuch_messages_get (messages);
-		term += _notmuch_message_get_thread_id_only (message);
-		terms.insert (term);
-	    }
-	    return Xapian::Query (Xapian::Query::OP_OR, terms.begin (), terms.end ());
+	    return query;
 	}
     } else {
 	/* literal thread id */
-- 
2.30.2