From 36bf3424e0e231142365dac7ec6f56c8ef038820 Mon Sep 17 00:00:00 2001
From: Ben Sinclair <bsinclai@turing.une.edu.au>
Date: Sat, 5 Apr 2008 14:21:00 +0000
Subject: [PATCH] wibble: forgot to add N.M.Parse...

darcs-hash:20080405142135-87dc9-047cf4196ca0c43fe8994cc415c10ca69a2f7a92.gz
---
 Network/MPD/Parse.hs | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Network/MPD/Parse.hs

diff --git a/Network/MPD/Parse.hs b/Network/MPD/Parse.hs
new file mode 100644
index 0000000..2a14642
--- /dev/null
+++ b/Network/MPD/Parse.hs
@@ -0,0 +1,35 @@
+module Network.MPD.Parse where
+
+import Control.Monad.Error
+import Network.MPD.Utils
+
+type Seconds = Integer
+
+-- | Represents the result of running 'count'.
+data Count =
+    Count { cSongs    :: Integer -- ^ Number of songs matching the query
+          , cPlaytime :: Seconds -- ^ Total play time of matching songs
+          }
+    deriving (Eq, Show)
+
+parseCount :: [String] -> Either String Count
+parseCount = foldM f empty . toAssoc
+        where f a ("songs", x)    = parse parseNum
+                                    (\x' -> a { cSongs = x'}) x
+              f a ("playtime", x) = parse parseNum
+                                    (\x' -> a { cPlaytime = x' }) x
+              f _ x               = Left $ show x
+              empty = Count { cSongs = 0, cPlaytime = 0 }
+
+-- A helper that runs a parser on a string and, depending, on the
+-- outcome, either returns the result of some command applied to the
+-- result, or fails. Used when building structures.
+parse :: Monad m => (String -> Maybe a) -> (a -> b) -> String -> m b
+parse p g x = maybe (fail x) (return . g) (p x)
+
+-- A helper for running a parser returning Maybe on a pair of strings.
+-- Returns Just if both strings where parsed successfully, Nothing otherwise.
+pair :: (String -> Maybe a) -> (String, String) -> Maybe (a, a)
+pair p (x, y) = case (p x, p y) of
+                    (Just a, Just b) -> Just (a, b)
+                    _                -> Nothing
-- 
2.11.4.GIT