added new rule to parse phrase in the pattern "xxx minutes to <hour-of-day>" (#500)

Summary:
Current:
20 minutes to 2pm tomorrow -> 20 minutes (dimension: Time)

Expected:
20 minutes to 2pm tomorrow -> 1:45pm of next day (dimension: Time)
Pull Request resolved: https://github.com/facebook/duckling/pull/500

Reviewed By: chinmay87

Differential Revision: D22200580

Pulled By: yuanbing

fbshipit-source-id: e47e5b5aaf4e3644c7032096caa75672a8543087

Duckling/Time/EN/Corpus.hs

@@ -1895,4 +1895,7 @@ allExamples = concat
             , "2 upcoming years"
             , "2 upcoming year"
             ]
+  , examples (datetime (2013, 2, 13, 13, 40, 0) Minute)
+             [ "20 minutes to 2pm tomorrow"
+             ]
   ]

Duckling/Time/EN/Rules.hs

@@ -2515,6 +2515,22 @@ ruleUpcomingGrainAlt = Rule
       _ -> Nothing
   }
 
+ruleMinutesToHOD :: Rule
+ruleMinutesToHOD = Rule
+  { name = "<integer> minutes to|till|before <hour-of-day>"
+  , pattern =
+    [ Predicate $ isIntegerBetween 1 59
+    , Predicate $ isGrain TG.Minute
+    , regex "to|till|before|of"
+    , Predicate isAnHourOfDay
+    ]
+  , prod = \tokens -> case tokens of
+      (token:_:_:Token Time td:_) -> do
+        n <- getIntValue token
+        Token Time <$> minutesBefore n td
+      _ -> Nothing
+  }
+
 rules :: [Rule]
 rules =
   [ ruleIntersect
@@ -2651,6 +2667,7 @@ rules =
   , ruleMidDay
   , ruleUpcomingGrain
   , ruleUpcomingGrainAlt
+  , ruleMinutesToHOD
   ]
   ++ ruleInstants
   ++ ruleDaysOfWeek