X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FTSN%2FPicklers.hs;h=3135d6ae194d483f3704755d46063cc513393808;hb=f0425854304197ab5ad47293b27b2e0b188cb844;hp=09c3a3b1000ac983251108afb5e570bdb40eb8c5;hpb=6eb1c7477c2d4d3cace6d1b865a5efbec21300a7;p=dead%2Fhtsn-import.git

diff --git a/src/TSN/Picklers.hs b/src/TSN/Picklers.hs
index 09c3a3b..3135d6a 100644
--- a/src/TSN/Picklers.hs
+++ b/src/TSN/Picklers.hs
@@ -1,9 +1,12 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+
 -- | (Un)picklers for data types present in The Sports Network XML
 --   feed.
 --
 module TSN.Picklers (
   pickler_tests,
   xp_ambiguous_time,
+  xp_attr_option,
   xp_date,
   xp_date_padded,
   xp_datetime,
@@ -270,8 +273,8 @@ xp_datetime =
 --
 --   >>> import Data.Maybe ( fromJust )
 --   >>> :{
---         let parse_date :: String -> Maybe UTCTime;
---         parse_date = parseTime defaultTimeLocale date_format;
+--         let parse_date :: String -> Maybe UTCTime
+--             parse_date = parseTime defaultTimeLocale date_format
 --       :}
 --
 --   >>> let dates = [ "1/" ++ (d : "/1970") | d <- ['1'..'9'] ]
@@ -474,9 +477,12 @@ xp_time_stamp :: PU UTCTime
 xp_time_stamp =
   (parse_time_stamp, from_time_stamp) `xpWrapMaybe` xpText
   where
+    -- | We have to re-pad the time_stamp_format with a leading and
+    --   trailing space; see the documentation of 'time_stamp_format'
+    --   for more information.
     from_time_stamp :: UTCTime -> String
     from_time_stamp =
-      formatTime defaultTimeLocale time_stamp_format
+      formatTime defaultTimeLocale (" " ++ time_stamp_format ++ " ")
 
 
 
@@ -566,6 +572,23 @@ xp_early_line_date =
         fmt = "%A, %B %-d" ++ upper_suffix ++ " (" ++ date_format_padded ++ ")"
 
 
+-- | This is a replacement for @xpOption xpFoo@ within an 'xpAttr'.
+--   There's a bug <https://github.com/UweSchmidt/hxt/issues/39> in
+--   newer versions of HXT that prevents us from using the usual
+--   'xpOption' solution, so this is our stopgap. It should work on
+--   any type that can be unpickled with a plain read/show.
+--
+xp_attr_option ::  forall a. (Read a, Show a) => PU (Maybe a)
+xp_attr_option =
+  (to_a, from_a) `xpWrap` xpText
+  where
+    to_a :: String -> Maybe a
+    to_a = readMaybe
+
+    from_a :: Maybe a -> String
+    from_a Nothing  = ""
+    from_a (Just x) = show x
+
 
 -- | Create an 'XmlTree' containing only the given text. This is
 --   useful for testing (un)picklers, where we don't want to have to