Prepare for universal day/month handling in queries.

src/cal-period.scm

@@ -49,6 +49,8 @@
   
   make-cal-period-lookup-table
   lookup-by-cal-period
+
+  cal-ensure-month
   
   cal-period-tests!
   )
@@ -62,7 +64,8 @@
 	 (chicken string)
 	 cal-month
 	 testing
-	 util-tag)
+	 util-tag
+	 cal-day)
 
  ;; Type tag
  (define TAG-CAL-PERIOD (make-tag CAL-PERIOD))
@@ -219,6 +222,12 @@
 	     (cdar lst)
 	     (loop (cdr lst))))))
 
+ ;; Wrapper that accepts either day or month and returns testable month
+ (define (cal-ensure-month v . stop?s)
+   (if (cal-month? v)
+       v
+       (apply cal-day->month v stop?s)))
+
  ;; Performs self-tests of the period module.
  (define (cal-period-tests!)
    (run-tests