A bit more parsing, still not done
Getty Ritter
8 years ago
| 1 | 1 | {-# LANGUAGE OverloadedStrings #-} |
| 2 | {-# LANGUAGE ViewPatterns #-} | |
| 2 | 3 | |
| 3 | 4 | module Data.Eben where |
| 4 | 5 | |
| 12 | 13 | import Data.Map.Strict (Map) |
| 13 | 14 | import qualified Data.Map as M |
| 14 | 15 | import Data.Monoid ((<>)) |
| 16 | import Data.Word (Word8) | |
| 15 | 17 | |
| 16 | 18 | data Value |
| 17 | 19 | = List [Value] |
| 18 | 20 | | Dict (Map B.ByteString Value) |
| 19 | | String B.ByteString | |
| 20 | 21 | | Integer Int64 |
| 21 | 22 | | Float Float |
| 23 | | String B.ByteString | |
| 22 | 24 | deriving (Eq, Show, Read) |
| 23 | 25 | |
| 24 | decode :: ByteString -> Either String Value | |
| 25 | decode bs = case BS.uncons bs of | |
| 26 | ('l', rs) -> () | |
| 27 | ('d', rs) -> () | |
| 28 | ('i', rs) -> () | |
| 29 | ('f', rs) -> () | |
| 30 | (i , rs) | |
| 31 | | isDigit i -> | |
| 26 | decode :: ByteString -> Maybe (Value, ByteString) | |
| 27 | decode bs = go | |
| 28 | where go = case BS.uncons bs of | |
| 29 | Just (108, rs) -> decodeList | |
| 30 | Just (100, rs) -> decodeDict | |
| 31 | Just (105, rs) -> decodeInt | |
| 32 | Just (102, rs) -> decodeFloat | |
| 33 | Just (i , rs) | |
| 34 | | isDigit (fromIntegral i) -> | |
| 35 | let (is, rs') = BS.break (== 58) rs | |
| 36 | len = toNum (toDigit i) is | |
| 37 | (str, rs'') = BS.splitAt len (BS.tail rs') | |
| 38 | in Just (String (BS.toStrict str), rs'') | |
| 39 | | otherwise -> Nothing | |
| 40 | ||
| 41 | isDigit :: Word8 -> Bool | |
| 42 | isDigit n = n >= 48 && n <= 57 | |
| 43 | ||
| 44 | toDigit :: Word8 -> Int64 | |
| 45 | toDigit n = fromIntegral n - 48 | |
| 46 | ||
| 47 | toNum :: Int64 -> ByteString -> Int64 | |
| 48 | toNum n (BS.uncons->Just(b, bs)) = | |
| 49 | toNum (n * 10 + fromIntegral b) bs | |
| 50 | toNum n _ = n | |
| 51 | ||
| 32 | 52 | |
| 33 | 53 | encode :: Value -> ByteString |
| 34 | 54 | encode = BL.toLazyByteString . go |