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, 42 insertions, 0 deletions

diff --git a/lib/thread-fp.h b/lib/thread-fp.h
new file mode 100644
index 00000000..13725978
--- /dev/null
+++ b/lib/thread-fp.h
@@ -0,0 +1,42 @@
+/* thread-fp.h - thread field processor glue
+ *
+ * This file is part of notmuch.
+ *
+ * Copyright © 2017 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>
+ */
+
+#ifndef NOTMUCH_THREAD_FP_H
+#define NOTMUCH_THREAD_FP_H
+
+#include <xapian.h>
+#include "notmuch.h"
+
+#if HAVE_XAPIAN_FIELD_PROCESSOR
+class ThreadFieldProcessor : public Xapian::FieldProcessor {
+ protected:
+    Xapian::QueryParser &parser;
+    notmuch_database_t *notmuch;
+
+ public:
+    ThreadFieldProcessor (Xapian::QueryParser &parser_, notmuch_database_t *notmuch_)
+	: parser(parser_), notmuch(notmuch_) { };
+
+    Xapian::Query operator()(const std::string & str);
+};
+#endif
+#endif /* NOTMUCH_THREAD_FP_H */