Time/EN: Fix empty group match

Summary: sad_palpatine

Differential Revision: D23718913

fbshipit-source-id: 363bf9a43d8d1cd77405882bc70a7fa1a1de2dbe

Duckling/Time/EN/Rules.hs

@@ -463,11 +463,11 @@ ruleMonthDOMNumeral = Rule
       _ -> Nothing
   }
 
-ruleDOMOfMonth :: Rule
-ruleDOMOfMonth = Rule
-  { name = "<day-of-month> (ordinal or number) of <named-month>"
+ruleTheDOMOfMonth :: Rule
+ruleTheDOMOfMonth = Rule
+  { name = "the <day-of-month> (ordinal or number) of <named-month>"
   , pattern =
-    [ regex "(the)?"
+    [ regex "the"
     , Predicate isDOMValue
     , regex "of|in"
     , Predicate isAMonth
@@ -477,6 +477,19 @@ ruleDOMOfMonth = Rule
       _ -> Nothing
   }
 
+ruleDOMOfMonth :: Rule
+ruleDOMOfMonth = Rule
+  { name = "<day-of-month> (ordinal or number) of <named-month>"
+  , pattern =
+    [ Predicate isDOMValue
+    , regex "of|in"
+    , Predicate isAMonth
+    ]
+  , prod = \tokens -> case tokens of
+      (token:_:Token Time td:_) -> Token Time <$> intersectDOM td token
+      _ -> Nothing
+  }
+
 ruleDOMMonth :: Rule
 ruleDOMMonth = Rule
   { name = "<day-of-month> (ordinal or number) <named-month>"
@@ -2621,6 +2634,7 @@ rules =
   , ruleMonthDOMNumeral
   , ruleDOMMonth
   , ruleDOMOfMonth
+  , ruleTheDOMOfMonth
   , ruleDOMOrdinalMonthYear
   , ruleDOMMonthYear
   , ruleIdesOfMonth