From 3b76adf9e2c026dd03b820f4c6eab50e25444113 Mon Sep 17 00:00:00 2001
From: Austin Clements <amdragon@MIT.EDU>
Date: Sat, 14 Jan 2012 19:17:33 -0500
Subject: [PATCH] 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.
---
 lib/notmuch-private.h |  2 +-
 lib/notmuch.h         |  6 ++++++
 lib/query.cc          | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index 60a932fc..7bf153e0 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -458,7 +458,7 @@ typedef struct _notmuch_string_node {
     struct _notmuch_string_node *next;
 } notmuch_string_node_t;
 
-typedef struct _notmuch_string_list {
+typedef struct visible _notmuch_string_list {
     int length;
     notmuch_string_node_t *head;
     notmuch_string_node_t **tail;
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 9f23a106..7929fe72 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -457,6 +457,12 @@ notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort);
 notmuch_sort_t
 notmuch_query_get_sort (notmuch_query_t *query);
 
+/* Add a tag that will be excluded from the query results by default.
+ * This exclusion will be overridden if this tag appears explicitly in
+ * the query. */
+void
+notmuch_query_add_tag_exclude (notmuch_query_t *query, const char *tag);
+
 /* Execute a query for threads, returning a notmuch_threads_t object
  * which can be used to iterate over the results. The returned threads
  * object is owned by the query and as such, will only be valid until
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);