Aeson-based pretty-printing of server requests.

1 files changed, 75 insertions, 0 deletions

diff --git a/src/Data/BEncode/Pretty.hs b/src/Data/BEncode/Pretty.hs
new file mode 100644
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+++ b/src/Data/BEncode/Pretty.hs
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+{-# LANGUAGE CPP                #-}
+module Data.BEncode.Pretty where -- (showBEncode) where
+
+import Data.BEncode.Types
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Lazy as BL
+import qualified Data.ByteString.Lazy.Char8 as BL8
+import Data.Text (Text)
+import qualified Data.Text as T
+#ifdef BENCODE_AESON
+import Data.BEncode.BDict hiding (map)
+import Data.Aeson.Types hiding (parse)
+import Data.Aeson.Encode.Pretty
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Vector as Vector
+import Data.Foldable as Foldable
+import Data.Text.Encoding
+import Text.Printf
+#endif
+
+#ifdef BENCODE_AESON
+
+unhex :: Text -> BS.ByteString
+unhex t = BS.pack $ map unhex1 [0 .. BS.length nibs `div` 2]
+ where
+    nibs = encodeUtf8 t
+    unhex1 i = unnib (BS.index nibs (i * 2)) * 0x10
+                + unnib (BS.index nibs (i * 2 + 1))
+    unnib a | a <= 0x39 = a - 0x30
+            | otherwise = a - (0x41 - 10)
+
+hex :: BS.ByteString -> Text
+hex bs = T.concat $ map (T.pack . printf "%02X") $ BS.unpack bs
+
+quote_chr :: Char
+quote_chr = ' '
+
+quote :: Text -> Text
+quote t = quote_chr `T.cons` t `T.snoc` quote_chr
+
+
+instance ToJSON BValue where
+    toJSON (BInteger x) = Number $ fromIntegral x
+    toJSON (BString s) = String $ either (const $ hex s) quote $ decodeUtf8' s
+    toJSON (BList xs) = Array $ Vector.fromList $ map toJSON xs
+    toJSON (BDict d) = toJSON d
+
+instance ToJSON a => ToJSON (BDictMap a) where
+    toJSON d = Object $ HashMap.fromList $ map convert $ toAscList d
+       where
+        convert (k,v) = (decodeUtf8 k,toJSON v)
+
+instance FromJSON BValue where
+    parseJSON (Number x) = pure $ BInteger (truncate x)
+    parseJSON (Bool x)   = pure $ BInteger $ if x then 1 else 0
+    parseJSON (String s)
+        | T.head s==quote_chr = pure $ BString $ encodeUtf8 (T.takeWhile (/=quote_chr) $ T.drop 1 s)
+        | otherwise           = pure $ BString $ unhex s
+    parseJSON (Array v)  = BList <$> traverse parseJSON (Foldable.toList v)
+    parseJSON (Object d) = BDict <$> parseJSON (Object d)
+    parseJSON (Null)     = pure $ BDict Nil
+
+instance FromJSON v => FromJSON (BDictMap v) where
+    parseJSON (Object d) = fromAscList <$> traverse convert (HashMap.toList d)
+        where
+            convert (k,v) = (,) (encodeUtf8 k) <$> parseJSON v
+    parseJSON _ = fail "Not a BDict"
+#endif
+
+showBEncode :: BValue -> BL.ByteString
+#ifdef BENCODE_AESON
+showBEncode b = encodePretty $ toJSON b
+#else
+showBEncode b = BL8.pack (show b)
+#endif