Fix bounded numeric parsers

1 files changed, 11 insertions, 8 deletions

diff --git a/lib/Postdelay/TimeSpec/Utils.hs b/lib/Postdelay/TimeSpec/Utils.hs
index 0bce51a..c49ba7a 100644
--- a/lib/Postdelay/TimeSpec/Utils.hs
+++ b/lib/Postdelay/TimeSpec/Utils.hs
@@ -60,10 +60,12 @@ sign = label "sign" $ choice [ char '+' $> id
 boundedNatural :: forall s n m. (Show n, Ord n, Num n, StringParser s m)
                => Bool -- ^ Require number to be padded with zeroes?
                -> Interval n -> m n
-boundedNatural padded (I.intersection (0 <=..< PosInf) -> bounds) = do
-  n <- foldl' (\i l -> i * 10 + l) 0 <$> digitN (fromDigit <$> digitChar) <?> "Natural number cotained in: " ++ show bounds
-  when (not $ n `I.member` bounds) $ fail "Natural number out of bounds"
-  return n
+boundedNatural padded (I.intersection (0 <=..< PosInf) -> bounds)
+  | I.null bounds = empty
+  | otherwise = do
+      n <- foldl' (\i l -> i * 10 + l) 0 <$> digitN (fromDigit <$> digitChar) <?> "Natural number cotained in: " ++ show bounds
+      when (not $ n `I.member` bounds) $ fail "Natural number out of bounds"
+      return n
   where
     digitN :: m n -> m [n]
     digitN p
@@ -78,9 +80,9 @@ boundedNatural padded (I.intersection (0 <=..< PosInf) -> bounds) = do
       | otherwise = error "boundedNatural in undefined state"
 
     minDigits, maxDigits :: Extended Int
-    (minDigits, maxDigits) = ( max 1 . fmap digits . I.lowerBound $ close bounds
-                             , fmap digits . I.upperBound $ close bounds
-                             )
+    (minDigits, maxDigits) = {- traceShowId -} ( max 1 . fmap digits . I.lowerBound $ close bounds
+                                               , fmap digits . I.upperBound $ close bounds
+                                               )
       where
         close int
           | (Finite min, False) <- I.lowerBound' int = close $ interval (Finite $ min + 1, True) (I.upperBound' int)
@@ -95,7 +97,8 @@ boundedRational :: forall s m n. (Show n, RealFrac n, StringParser s m)
                 => Bool -- ^ Require number to be padded with zeroes
                 -> Interval n -> m n
 boundedRational padded (I.intersection (0 <=..< PosInf) -> bounds)
-  = (+) <$> boundedNatural padded wholeBounds <*> fractional <?> "Nonnegative rational contained in: " ++ show bounds
+  | I.null bounds = empty
+  | otherwise = (+) <$> boundedNatural padded wholeBounds <*> fractional <?> "Nonnegative rational contained in: " ++ show bounds
   where
     fractional :: m n
     fractional = reqFractional $ char '.' $> (/ 10) . foldr' (\h t -> h + t / 10) 0 <*> some (fromDigit <$> digitChar)