--
module OptionalConfiguration (
OptionalConfiguration(..),
+ merge_maybe,
+ merge_monoid,
from_rc )
where
import System.IO.Error ( catchIOError )
import System.IO ( hPutStrLn, stderr )
+-- Harbl library imports.
+import Network.DNS.RBL.Weight ( Weight )
+
-- Local imports.
import Hosts ( Hosts(..) )
import Lists ( Lists(..) )
data OptionalConfiguration =
OptionalConfiguration {
hosts :: Hosts,
- lists :: Lists }
+ lists :: Lists,
+ threshold :: Maybe Weight }
deriving (Show, Data, Typeable)
+-- | Choose a nonempty monoid from our two arguments, preferring the
+-- second. So if the second monoid is non-'mempty', we'll return
+-- that. Otherwise the first.
+--
+-- ==== _Examples_
+--
+-- The second list is preferred if both are nonempty:
+--
+-- >>> merge_monoid [1,2] [3,4]
+-- [3,4]
+--
+-- However, if the second list is empty, the first is returned:
+--
+-- >>> merge_monoid [1,2] []
+-- [1,2]
+--
+-- And if both are empty, we return the first (i.e. empty) list:
+--
+-- >>> merge_monoid [] []
+-- []
+--
+merge_monoid :: (Eq a, Monoid a) => a -> a -> a
+merge_monoid l1 l2 = if l2 == mempty then l1 else l2
+
+
+-- | Like 'merge_monoid', except for optional things. We take two
+-- (potentially 'Nothing') values, and then try to choose a
+-- non-'Nothing' one, preferring the second argument.
+--
+-- ==== _Examples_
+--
+-- The second is preferred if it is non-'Nothing':
+--
+-- >>> merge_maybes (Just 3) (Just 4)
+-- Just 4
+--
+-- >>> merge_maybes Nothing (Just 4)
+-- Just 4
+--
+-- However, if the second argument is 'Nothing', the first is
+-- returned:
+--
+-- >>> merge_maybes (Just 1) Nothing
+-- Just 1
+--
+-- If both are 'Nothing', we return 'Nothing':
+--
+-- >>> merge_maybes Nothing Nothing
+-- Nothing
+--
+merge_maybes :: (Maybe a) -> (Maybe a) -> (Maybe a)
+merge_maybes _ y@(Just _) = y
+merge_maybes x@(Just _) Nothing = x
+merge_maybes Nothing Nothing = Nothing
+
+
+-- | Return the (thing contained in the) second argument if it is
+-- non-'Nothing'. Otherwise return the first argument.
+--
+-- ==== _Examples_
+--
+-- The second is preferred if it is non-'Nothing':
+--
+-- >>> merge_maybe 3 (Just 4)
+-- 4
+--
+-- However, if the second argument is 'Nothing', the first is
+-- returned:
+--
+-- >>> merge_maybe 1 Nothing
+-- 1
+--
+merge_maybe :: a -> Maybe a -> a
+merge_maybe x Nothing = x
+merge_maybe _ (Just y) = y
+
+
-- | The Monoid instance for these lets us \"combine\" two
-- OptionalConfigurations. The \"combine\" operation that we'd like to
-- perform is, essentially, to mash them together. So if we have two
--
instance Monoid OptionalConfiguration where
-- | An empty OptionalConfiguration.
- mempty = OptionalConfiguration (Hosts []) (Lists [])
-
+ mempty = OptionalConfiguration mempty mempty Nothing
-- | Combine @cfg1@ and @cfg2@, giving precedence to @cfg2@.
- -- XML files can only be specified on the command-line, so we
- -- just join them together here.
- cfg1 `mappend` cfg2 =
- OptionalConfiguration all_hosts all_lists
+ cfg1 `mappend` cfg2 = OptionalConfiguration hs ls t
where
- all_hosts = Hosts $ (get_hosts $ hosts cfg1) ++ (get_hosts $ hosts cfg2)
- all_lists = Lists $ (get_lists $ lists cfg1) ++ (get_lists $ lists cfg2)
-
+ hs = merge_monoid (hosts cfg1) (hosts cfg2)
+ ls = merge_monoid (lists cfg1) (lists cfg2)
+ t = merge_maybes (threshold cfg1) (threshold cfg2)
-- | Obtain an OptionalConfiguration from harblrc in either the global
cfg <- DC.load [ DC.Optional global_config_path,
DC.Optional user_config_path ]
cfg_lists <- DC.lookup cfg "lists"
- let cfg_hosts = Hosts [] -- This won't be in the config file.
- return $ OptionalConfiguration cfg_hosts (fromMaybe def cfg_lists)
+ cfg_hosts <- DC.lookup cfg "hosts"
+ cfg_threshold <- DC.lookup cfg "threshold"
+ return $ OptionalConfiguration
+ (fromMaybe def cfg_hosts)
+ (fromMaybe def cfg_lists)
+ cfg_threshold