+
+ /**
+ * Look up the creation timestamp for a given notice ID, even
+ * if it's been deleted.
+ *
+ * @param int $id
+ * @return mixed string recorded creation timestamp, or false if can't be found
+ */
+ public static function getAsTimestamp($id)
+ {
+ if (!$id) {
+ return false;
+ }
+
+ $notice = Notice::staticGet('id', $id);
+ if ($notice) {
+ return $notice->created;
+ }
+
+ $deleted = Deleted_notice::staticGet('id', $id);
+ if ($deleted) {
+ return $deleted->created;
+ }
+
+ return false;
+ }
+
+ /**
+ * Build an SQL 'where' fragment for timestamp-based sorting from a since_id
+ * parameter, matching notices posted after the given one (exclusive).
+ *
+ * If the referenced notice can't be found, will return false.
+ *
+ * @param int $id
+ * @param string $idField
+ * @param string $createdField
+ * @return mixed string or false if no match
+ */
+ public static function whereSinceId($id, $idField='id', $createdField='created')
+ {
+ $since = Notice::getAsTimestamp($id);
+ if ($since) {
+ return sprintf("($createdField = '%s' and $idField > %d) or ($createdField > '%s')", $since, $id, $since);
+ }
+ return false;
+ }
+
+ /**
+ * Build an SQL 'where' fragment for timestamp-based sorting from a since_id
+ * parameter, matching notices posted after the given one (exclusive), and
+ * if necessary add it to the data object's query.
+ *
+ * @param DB_DataObject $obj
+ * @param int $id
+ * @param string $idField
+ * @param string $createdField
+ * @return mixed string or false if no match
+ */
+ public static function addWhereSinceId(DB_DataObject $obj, $id, $idField='id', $createdField='created')
+ {
+ $since = self::whereSinceId($id);
+ if ($since) {
+ $obj->whereAdd($since);
+ }
+ }
+
+ /**
+ * Build an SQL 'where' fragment for timestamp-based sorting from a max_id
+ * parameter, matching notices posted before the given one (inclusive).
+ *
+ * If the referenced notice can't be found, will return false.
+ *
+ * @param int $id
+ * @param string $idField
+ * @param string $createdField
+ * @return mixed string or false if no match
+ */
+ public static function whereMaxId($id, $idField='id', $createdField='created')
+ {
+ $max = Notice::getAsTimestamp($id);
+ if ($max) {
+ return sprintf("($createdField < '%s') or ($createdField = '%s' and $idField <= %d)", $max, $max, $id);
+ }
+ return false;
+ }
+
+ /**
+ * Build an SQL 'where' fragment for timestamp-based sorting from a max_id
+ * parameter, matching notices posted before the given one (inclusive), and
+ * if necessary add it to the data object's query.
+ *
+ * @param DB_DataObject $obj
+ * @param int $id
+ * @param string $idField
+ * @param string $createdField
+ * @return mixed string or false if no match
+ */
+ public static function addWhereMaxId(DB_DataObject $obj, $id, $idField='id', $createdField='created')
+ {
+ $max = self::whereMaxId($id);
+ if ($max) {
+ $obj->whereAdd($max);
+ }
+ }