# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1512427657 -3600
# Node ID 28fe0ad38cd487845c6bd5ae04e9117dccfe9a45
# Parent  94338c98305bf4bd35566f49505d9015dfa34889
Introduced validation of qualifier arguments using the check_values function.

diff -r 94338c98305b -r 28fe0ad38cd4 vRecurrence.py
--- a/vRecurrence.py	Mon Dec 04 22:35:42 2017 +0100
+++ b/vRecurrence.py	Mon Dec 04 23:47:37 2017 +0100
@@ -221,13 +221,20 @@
         # Accept interval indicators for frequency qualifier parameterisation.
 
         elif key == "INTERVAL":
-            interval = int(value)
+            interval = max(1, int(value))
             continue
 
         # Accept result set selection, truncation and enumerators as qualifiers.
 
         elif key in ("BYSETPOS", "COUNT") or enum.has_key(key):
-            qualifier = (key, {"values" : get_qualifier_values(key, value)})
+            values = get_qualifier_values(key, value)
+
+            # Ignore bad qualifier values.
+
+            if not values:
+                continue
+
+            qualifier = (key, {"values" : values})
 
         # Ignore other items.
 
@@ -250,31 +257,50 @@
     suitable values.
     """
 
-    # For non-weekday selection, obtain a list of numbers.
-
-    if qualifier != "BYDAY":
-        return map(int, value.split(","))
-
-    # For weekday selection, obtain the weekday number and instance number.
-
     values = []
 
-    for part in value.split(","):
-        index, weekday = part[:-2], part[-2:]
+    for v in value.split(","):
+        try:
+            # For non-weekday selection, obtain a list of numbers, each in a tuple.
 
-        weekday_number = weekdays.get(weekday)
-        if not weekday_number:
-            continue
+            if qualifier != "BYDAY":
+                to_check = (int(v),)
+
+            # For weekday selection, obtain a list of tuples containing the weekday
+            # and instance number.
+
+            else:
+                # Split the two-letter weekday code from the preceding text.
 
-        if index:
-            index = int(index)
-        else:
-            index = None
+                index, weekday = v[:-2], v[-2:]
+                to_check = (weekday, int_or_empty(index))
+
+        except ValueError:
+            return None
+
+        checked = check_values(qualifier, to_check)
 
-        values.append((weekday_number, index))
+        # Get single values for non-weekday details.
+
+        if qualifier != "BYDAY":
+            checked = checked[0]
+
+        if not checked:
+            return None
+
+        values.append(checked)
 
     return values
 
+def int_or_empty(value):
+
+    "Return 'value' as an integer or None if null. Raises ValueError."
+
+    if value:
+        return int(value)
+    else:
+        return None
+
 def make_selectors(qualifiers):
 
     """