[WIP PATCH 4/4] lib: Add "lastmod:" queries for filtering by last modification

[Austin Clements <aclements@csail.mit.edu>]

From: Austin Clements <amdragon@mit.edu>

XXX Includes reference to notmuch search --db-revision, which doesn't
exist.
---
 doc/man7/notmuch-search-terms.rst | 8 ++++++++
 lib/database-private.h            | 1 +
 lib/database.cc                   | 4 ++++
 3 files changed, 13 insertions(+)

diff --git a/doc/man7/notmuch-search-terms.rst b/doc/man7/notmuch-search-terms.rst
index 1acdaa0..df76e39 100644
--- a/doc/man7/notmuch-search-terms.rst
+++ b/doc/man7/notmuch-search-terms.rst
@@ -52,6 +52,8 @@ indicate user-supplied values):
 
 -  date:<since>..<until>
 
+-  lastmod:<since>..<until>
+
 The **from:** prefix is used to match the name or address of the sender
 of an email message.
 
@@ -118,6 +120,12 @@ The time range can also be specified using timestamps with a syntax of:
 Each timestamp is a number representing the number of seconds since
 1970-01-01 00:00:00 UTC.
 
+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 **--db-revision** argument to **notmuch search**
+to find messages that have changed since an earlier query.
+
 In addition to individual terms, multiple terms can be combined with
 Boolean operators ( **and**, **or**, **not** , etc.). Each term in the
 query will be implicitly connected by a logical AND if no explicit
diff --git a/lib/database-private.h b/lib/database-private.h
index 0977229..cbca1de 100644
--- a/lib/database-private.h
+++ b/lib/database-private.h
@@ -163,6 +163,7 @@ struct _notmuch_database {
     Xapian::TermGenerator *term_gen;
     Xapian::ValueRangeProcessor *value_range_processor;
     Xapian::ValueRangeProcessor *date_range_processor;
+    Xapian::ValueRangeProcessor *last_mod_range_processor;
 };
 
 /* Prior to database version 3, features were implied by the database
diff --git a/lib/database.cc b/lib/database.cc
index 9bec170..f9aa45d 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -913,6 +913,7 @@ notmuch_database_open (const char *path,
 	notmuch->term_gen->set_stemmer (Xapian::Stem ("english"));
 	notmuch->value_range_processor = new Xapian::NumberValueRangeProcessor (NOTMUCH_VALUE_TIMESTAMP);
 	notmuch->date_range_processor = new ParseTimeValueRangeProcessor (NOTMUCH_VALUE_TIMESTAMP);
+	notmuch->last_mod_range_processor = new Xapian::NumberValueRangeProcessor (NOTMUCH_VALUE_LAST_MOD, "lastmod:");
 
 	notmuch->query_parser->set_default_op (Xapian::Query::OP_AND);
 	notmuch->query_parser->set_database (*notmuch->xapian_db);
@@ -920,6 +921,7 @@ notmuch_database_open (const char *path,
 	notmuch->query_parser->set_stemming_strategy (Xapian::QueryParser::STEM_SOME);
 	notmuch->query_parser->add_valuerangeprocessor (notmuch->value_range_processor);
 	notmuch->query_parser->add_valuerangeprocessor (notmuch->date_range_processor);
+	notmuch->query_parser->add_valuerangeprocessor (notmuch->last_mod_range_processor);
 
 	for (i = 0; i < ARRAY_SIZE (BOOLEAN_PREFIX_EXTERNAL); i++) {
 	    prefix_t *prefix = &BOOLEAN_PREFIX_EXTERNAL[i];
@@ -991,6 +993,8 @@ notmuch_database_close (notmuch_database_t *notmuch)
     notmuch->value_range_processor = NULL;
     delete notmuch->date_range_processor;
     notmuch->date_range_processor = NULL;
+    delete notmuch->last_mod_range_processor;
+    notmuch->last_mod_range_processor = NULL;
 
     return status;
 }
-- 
2.1.0