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|
-- |
-- Module : Codec.Binary.Url
-- Copyright : (c) 2009 Magnus Therning
-- License : BSD3
--
-- URL encoding, sometimes referred to as URI encoding or percent encoding.
-- Implemented based on RFC 3986 (<http://tools.ietf.org/html/rfc3986>).
--
-- Further documentation and information can be found at
-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.
module Codec.Binary.Url
( EncIncData(..)
, EncIncRes(..)
, encodeInc
, encode
, DecIncData
, DecIncRes
, decodeInc
, decode
, chop
, unchop
) where
import Codec.Binary.Util
import qualified Data.Map as M
import Data.Char(ord)
import Data.Word(Word8)
import Data.Maybe(isJust, fromJust)
-- {{{1 enc/dec map
_unreservedChars = zip [65..90] "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
++ zip [97..122] "abcdefghijklmnopqrstuvwxyz"
++ zip [48..57] "0123456789"
++ [(45, '-'), (95, '_'), (46, '.'), (126, '~')]
encodeMap :: M.Map Word8 Char
encodeMap = M.fromList _unreservedChars
decodeMap :: M.Map Char Word8
decodeMap = M.fromList [(b, a) | (a, b) <- _unreservedChars]
-- {{{1 encode
-- | Incremental decoder function.
encodeInc :: EncIncData -> EncIncRes String
encodeInc e = eI e
where
enc [] = []
enc (o : os) = case (M.lookup o encodeMap) of
Just c -> c : enc os
Nothing -> ('%' : toHex o) ++ enc os
eI EDone = EFinal []
eI (EChunk bs) = EPart (enc bs) encodeInc
-- | Encode data.
encode :: [Word8] -> String
encode = encoder encodeInc
-- {{{1 decode
-- | Incremental decoder function.
decodeInc :: DecIncData String -> DecIncRes String
decodeInc d = dI [] d
where
dI [] DDone = DFinal [] []
dI lo DDone = DFail [] lo
dI lo (DChunk s) = doDec [] (lo ++ s)
where
doDec acc [] = DPart acc (dI [])
doDec acc s'@('%':c0:c1:cs) = let
o = fromHex [c0, c1]
in if isJust o
then doDec (acc ++ [fromJust o]) cs
else DFail acc s'
doDec acc s'@(c:cs)
| c /= '%' = doDec (acc ++ [fromIntegral $ ord c]) cs
| otherwise = DPart acc (dI s')
-- | Decode data.
decode :: String
-> Maybe [Word8]
decode = decoder decodeInc
-- {{{1 chop
-- | Chop up a string in parts.
chop :: Int -- ^ length of individual lines
-> String
-> [String]
chop n = let
_n = max 1 n
_chop [] = []
_chop cs = take _n cs : _chop (drop _n cs)
in _chop
-- {{{1 unchop
-- | Concatenate the strings into one long string
unchop :: [String]
-> String
unchop = foldr (++) ""
|