lib: add field processor for lastmod: prefix

By sharing the existing logic used by the sexp query parser, this
allows negative lastmod revisions to be interpreted as relative to the
most recent revision.

doc/man7/notmuch-search-terms.rst

@@ -153,10 +153,11 @@ date:<since>..<until> or date:<date>
 lastmod:<initial-revision>..<final-revision>
     The **lastmod:** prefix can be used to restrict the result by the
     database revision number of when messages were last modified (tags
-    were added/removed or filenames changed). This is usually used in
+    were added/removed or filenames changed). Negative revisions are
-    conjunction with the ``--uuid`` argument to
+    interpreted relative to the most recent database revision (see
-    :any:`notmuch-search(1)` to find messages that have changed since
+    :option:`count --lastmod`). This is usually used in conjunction
-    an earlier query.
+    with the ``--uuid`` argument to :any:`notmuch-search(1)` to find
+    messages that have changed since an earlier query.
 
 query:<name>
     The **query:** prefix allows queries to refer to previously saved

lib/lastmod-fp.cc

@@ -21,6 +21,7 @@
  */
 
 #include "database-private.h"
+#include "lastmod-fp.h"
 
 notmuch_status_t
 _notmuch_lastmod_strings_to_query (notmuch_database_t *notmuch,
@@ -66,3 +67,17 @@ _notmuch_lastmod_strings_to_query (notmuch_database_t *notmuch,
 			    Xapian::sortable_serialise (to_idx));
     return NOTMUCH_STATUS_SUCCESS;
 }
+
+Xapian::Query
+LastModRangeProcessor::operator() (const std::string &begin, const std::string &end)
+{
+
+    Xapian::Query output;
+    std::string msg;
+
+    if (_notmuch_lastmod_strings_to_query (notmuch, begin, end, output, msg))
+	throw Xapian::QueryParserError (msg);
+
+    return output;
+}
+

lib/lastmod-fp.h

@@ -0,0 +1,41 @@
+/* lastmod-fp.h - database revision query glue
+ *
+ * This file is part of notmuch.
+ *
+ * Copyright © 2022 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_LASTMOD_FP_H
+#define NOTMUCH_LASTMOD_FP_H
+
+#include <xapian.h>
+
+class LastModRangeProcessor : public Xapian::RangeProcessor {
+protected:
+    notmuch_database_t *notmuch;
+
+public:
+    LastModRangeProcessor (notmuch_database_t *notmuch_, const std::string prefix_)
+	:  Xapian::RangeProcessor (NOTMUCH_VALUE_LAST_MOD, prefix_, 0), notmuch (notmuch_)
+    {
+    }
+
+    Xapian::Query operator() (const std::string &begin, const std::string &end);
+};
+
+#endif /* NOTMUCH_LASTMOD_FP_H */

lib/open.cc

@@ -3,6 +3,7 @@
 
 #include "database-private.h"
 #include "parse-time-vrp.h"
+#include "lastmod-fp.h"
 #include "path-util.h"
 
 #if HAVE_XAPIAN_DB_RETRY_LOCK
@@ -489,8 +490,7 @@ _finish_open (notmuch_database_t *notmuch,
 	notmuch->value_range_processor = new Xapian::NumberRangeProcessor (NOTMUCH_VALUE_TIMESTAMP);
 	notmuch->date_range_processor = new ParseTimeRangeProcessor (NOTMUCH_VALUE_TIMESTAMP,
 								     "date:");
-	notmuch->last_mod_range_processor = new Xapian::NumberRangeProcessor (NOTMUCH_VALUE_LAST_MOD,
+	notmuch->last_mod_range_processor = new LastModRangeProcessor (notmuch, "lastmod:");
-									      "lastmod:");
 	notmuch->query_parser->set_default_op (Xapian::Query::OP_AND);
 	notmuch->query_parser->set_database (*notmuch->xapian_db);
 	notmuch->stemmer = new Xapian::Stem ("english");

test/T570-revision-tracking.sh

@@ -103,4 +103,23 @@ if [ $NOTMUCH_HAVE_SFSEXP -eq 1 ]; then
     test_expect_equal 1 "$count"
 fi
 
+test_begin_subtest 'exclude one message using negative lastmod'
+total=$(notmuch count '*')
+notmuch tag +${RANDOM} id:4EFC743A.3060609@april.org
+count=$(notmuch count lastmod:-1..)
+test_expect_equal 1 "$count"
+
+test_begin_subtest 'exclude one message using negative lastmod (second param)'
+total=$(notmuch count '*')
+notmuch tag +${RANDOM} id:4EFC743A.3060609@april.org
+count=$(notmuch count lastmod:..-1)
+test_expect_equal 51 "$count"
+
+test_begin_subtest 'negative lastmod (two parameters)'
+notmuch tag +${RANDOM} '*'
+before=$(notmuch count --lastmod '*' | cut -f3)
+notmuch tag +${RANDOM} id:4EFC743A.3060609@april.org
+count=$(notmuch count lastmod:-100..$before)
+test_expect_equal 51 "$count"
+
 test_done