lib: add thread subqueries.

This change allows queries of the form

 thread:{from:me} and thread:{from:jian} and not thread:{from:dave}

This is still somewhat brute-force, but it's a big improvement over
both the shell script solution and the previous proposal [1], because it
does not build the whole thread structure just generate a
query. A further potential optimization is to replace the calls to
notmuch with more specialized Xapian code; in particular it's not
likely that reading all of the message metadata is a win here.

[1]: id:20170820213240.20526-1-david@tethera.net

1 files changed, 67 insertions, 0 deletions

diff --git a/lib/thread-fp.cc b/lib/thread-fp.cc
new file mode 100644
index 00000000..75339ffa
--- /dev/null
+++ b/lib/thread-fp.cc
@@ -0,0 +1,67 @@
+/* thread-fp.cc - "thread:" field processor glue
+ *
+ * This file is part of notmuch.
+ *
+ * Copyright © 2018 David Bremner
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/ .
+ *
+ * Author: David Bremner <david@tethera.net>
+ */
+
+#include "database-private.h"
+#include "thread-fp.h"
+#include <iostream>
+
+#if HAVE_XAPIAN_FIELD_PROCESSOR
+
+Xapian::Query
+ThreadFieldProcessor::operator() (const std::string & str)
+{
+    notmuch_status_t status;
+    const char *thread_prefix = _find_prefix ("thread");
+
+    if (str.at (0) == '{') {
+	if (str.size () <= 1 || str.at (str.size () - 1) != '}') {
+	    throw Xapian::QueryParserError ("missing } in '" + str + "'");
+	} else {
+	    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;
+
+	    if (! subquery)
+		throw Xapian::QueryParserError ("failed to create subquery for '" + subquery_str + "'");
+
+	    status = notmuch_query_search_messages (subquery, &messages);
+	    if (status)
+		throw Xapian::QueryParserError ("failed to search messages for '" + subquery_str + "'");
+
+	    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 (message);
+		terms.insert (term);
+	    }
+	    return Xapian::Query (Xapian::Query::OP_OR, terms.begin (), terms.end ());
+	}
+    } else {
+	/* literal thread id */
+	std::string term = thread_prefix + str;
+	return Xapian::Query (term);
+    }
+
+}
+#endif