lib: Add support for automatically excluding tags from queries

This is useful for tags like "deleted" and "spam" that people
generally want to exclude from query results.  These exclusions will
be overridden if a tag is explicitly mentioned in a query.

1 files changed, 35 insertions, 0 deletions

diff --git a/lib/query.cc b/lib/query.cc
index b6c0f12d..0b366025 100644
--- a/lib/query.cc
+++ b/lib/query.cc
@@ -27,6 +27,7 @@ struct _notmuch_query {
     notmuch_database_t *notmuch;
     const char *query_string;
     notmuch_sort_t sort;
+    notmuch_string_list_t *exclude_terms;
 };
 
 typedef struct _notmuch_mset_messages {
@@ -76,6 +77,8 @@ notmuch_query_create (notmuch_database_t *notmuch,
 
     query->sort = NOTMUCH_SORT_NEWEST_FIRST;
 
+    query->exclude_terms = _notmuch_string_list_create (query);
+
     return query;
 }
 
@@ -97,6 +100,13 @@ notmuch_query_get_sort (notmuch_query_t *query)
     return query->sort;
 }
 
+void
+notmuch_query_add_tag_exclude (notmuch_query_t *query, const char *tag)
+{
+    char *term = talloc_asprintf (query, "%s%s", _find_prefix ("tag"), tag);
+    _notmuch_string_list_append (query->exclude_terms, term);
+}
+
 /* We end up having to call the destructors explicitly because we had
  * to use "placement new" in order to initialize C++ objects within a
  * block that we allocated with talloc. So C++ is making talloc
@@ -112,6 +122,27 @@ _notmuch_messages_destructor (notmuch_mset_messages_t *messages)
     return 0;
 }
 
+/* Return a query that does not match messages with the excluded tags
+ * registered with the query.  Any tags that explicitly appear in
+ * xquery will not be excluded. */
+static Xapian::Query
+_notmuch_exclude_tags (notmuch_query_t *query, Xapian::Query xquery)
+{
+    for (notmuch_string_node_t *term = query->exclude_terms->head; term;
+	 term = term->next) {
+	Xapian::TermIterator it = xquery.get_terms_begin ();
+	Xapian::TermIterator end = xquery.get_terms_end ();
+	for (; it != end; it++) {
+	    if ((*it).compare (term->string) == 0)
+		break;
+	}
+	if (it == end)
+	    xquery = Xapian::Query (Xapian::Query::OP_AND_NOT,
+				    xquery, Xapian::Query (term->string));
+    }
+    return xquery;
+}
+
 notmuch_messages_t *
 notmuch_query_search_messages (notmuch_query_t *query)
 {
@@ -157,6 +188,8 @@ notmuch_query_search_messages (notmuch_query_t *query)
 					 mail_query, string_query);
 	}
 
+	final_query = _notmuch_exclude_tags (query, final_query);
+
 	enquire.set_weighting_scheme (Xapian::BoolWeight());
 
 	switch (query->sort) {
@@ -436,6 +469,8 @@ notmuch_query_count_messages (notmuch_query_t *query)
 					 mail_query, string_query);
 	}
 
+	final_query = _notmuch_exclude_tags (query, final_query);
+
 	enquire.set_weighting_scheme(Xapian::BoolWeight());
 	enquire.set_docid_order(Xapian::Enquire::ASCENDING);