[PATCH 3/3] lib: add field processor for lastmod: prefix

[David Bremner <david@tethera.net>]

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 |  9 +++----
 lib/lastmod-fp.cc                 | 15 ++++++++++++
 lib/lastmod-fp.h                  | 39 +++++++++++++++++++++++++++++++
 lib/open.cc                       |  4 ++--
 test/T570-revision-tracking.sh    | 19 +++++++++++++++
 5 files changed, 80 insertions(+), 6 deletions(-)
 create mode 100644 lib/lastmod-fp.h

diff --git a/doc/man7/notmuch-search-terms.rst b/doc/man7/notmuch-search-terms.rst
index 4f616b7e..acc1c967 100644
--- a/doc/man7/notmuch-search-terms.rst
+++ b/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
-    conjunction with the ``--uuid`` argument to
-    :any:`notmuch-search(1)` to find messages that have changed since
-    an earlier query.
+    were added/removed or filenames changed). Negative revisions are
+    interpreted relative to the most recent database revision (see
+    :option:`count --lastmod`). This is usually used in conjunction
+    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
diff --git a/lib/lastmod-fp.cc b/lib/lastmod-fp.cc
index 5fdaf281..f85efd28 100644
--- a/lib/lastmod-fp.cc
+++ b/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;
+}
+
diff --git a/lib/lastmod-fp.h b/lib/lastmod-fp.h
new file mode 100644
index 00000000..448241f8
--- /dev/null
+++ b/lib/lastmod-fp.h
@@ -0,0 +1,39 @@
+/* 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 */
diff --git a/lib/open.cc b/lib/open.cc
index 30cfcf9e..02ed7285 100644
--- a/lib/open.cc
+++ b/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
@@ -431,8 +432,7 @@ _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,
-									      "lastmod:");
+	notmuch->last_mod_range_processor = new LastModRangeProcessor (notmuch, "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");
diff --git a/test/T570-revision-tracking.sh b/test/T570-revision-tracking.sh
index aaa45468..a7480050 100755
--- a/test/T570-revision-tracking.sh
+++ b/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
-- 
2.35.1
\r