Push the rrule_event_overlaps function into the 8.1 compatibility functions.

dba/rrule_functions-8.1.sql

@@ -652,3 +652,53 @@ BEGIN
   END LOOP;
 END;
 $$ LANGUAGE 'plpgsql' IMMUTABLE STRICT;
+
+
+------------------------------------------------------------------------------------------------------
+-- In most cases we just want to know if there *is* an event overlapping the range, so we have a
+-- specific function for that.  Note that this is *not* strict, and can be called with NULLs.
+------------------------------------------------------------------------------------------------------
+CREATE or REPLACE FUNCTION rrule_event_overlaps( TIMESTAMP WITH TIME ZONE, TIMESTAMP WITH TIME ZONE, TEXT, TIMESTAMP WITH TIME ZONE, TIMESTAMP WITH TIME ZONE )
+                                         RETURNS BOOLEAN AS $$
+DECLARE
+  dtstart ALIAS FOR $1;
+  dtend ALIAS FOR $2;
+  repeatrule ALIAS FOR $3;
+  in_mindate ALIAS FOR $4;
+  in_maxdate ALIAS FOR $5;
+  base_date TIMESTAMP WITH TIME ZONE;
+  mindate TIMESTAMP WITH TIME ZONE;
+  maxdate TIMESTAMP WITH TIME ZONE;
+BEGIN
+
+  IF dtstart IS NULL THEN
+    RETURN NULL;
+  END IF;
+  IF dtend IS NULL THEN
+    base_date := dtstart;
+  ELSE
+    base_date := dtend;
+  END IF;
+
+  IF in_mindate IS NULL THEN
+    mindate := current_date - '10 years'::interval;
+  ELSE
+    mindate := in_mindate;
+  END IF;
+
+  IF in_maxdate IS NULL THEN
+    maxdate := current_date + '10 years'::interval;
+  ELSE
+    -- If we add the duration onto the event, then an overlap occurs if dtend <= increased end of range.
+    maxdate := in_maxdate + (base_date - dtstart);
+  END IF;
+
+  IF repeatrule IS NULL THEN
+    RETURN (dtstart <= maxdate AND base_date >= mindate);
+  END IF;
+
+  SELECT d INTO mindate FROM rrule_event_instances_range( base_date, repeatrule, mindate, maxdate, 60 ) d LIMIT 1;
+  RETURN FOUND;
+
+END;
+$$ LANGUAGE 'plpgsql' IMMUTABLE;