http-types-0.7.0: Network/HTTP/Types/URI.hs
{-# LANGUAGE OverloadedStrings #-}
module Network.HTTP.Types.URI
(
-- * Query string
QueryItem
, Query
, SimpleQueryItem
, SimpleQuery
, simpleQueryToQuery
, renderQuery
, renderQueryBuilder
, renderSimpleQuery
, parseQuery
, parseSimpleQuery
-- ** Text query string (UTF8 encoded)
, QueryText
, queryTextToQuery
, queryToQueryText
, renderQueryText
, parseQueryText
-- * Path segments
, encodePathSegments
, decodePathSegments
, encodePathSegmentsRelative
-- * Path (segments + query string)
, encodePath
, decodePath
-- * URL encoding / decoding
, urlEncodeBuilder
, urlEncode
, urlDecode
)
where
import Control.Arrow
import Data.Bits
import Data.Char
import Data.List
import Data.Maybe
import Data.Monoid
import Data.Text (Text)
import Data.Text.Encoding (encodeUtf8, decodeUtf8With)
import Data.Text.Encoding.Error (lenientDecode)
import Data.Word
import qualified Blaze.ByteString.Builder as Blaze
import qualified Data.ByteString as B
import Data.ByteString.Char8 () {-IsString-}
-- | Query item
type QueryItem = (B.ByteString, Maybe B.ByteString)
-- | Query.
--
-- General form: a=b&c=d, but if the value is Nothing, it becomes
-- a&c=d.
type Query = [QueryItem]
-- | Like Query, but with 'Text' instead of 'B.ByteString' (UTF8-encoded).
type QueryText = [(Text, Maybe Text)]
-- | Convert 'QueryText' to 'Query'.
queryTextToQuery :: QueryText -> Query
queryTextToQuery = map $ encodeUtf8 *** fmap encodeUtf8
-- | Convert 'QueryText' to a 'Blaze.Builder'.
renderQueryText :: Bool -- ^ prepend a question mark?
-> QueryText
-> Blaze.Builder
renderQueryText b = renderQueryBuilder b . queryTextToQuery
-- | Convert 'Query' to 'QueryText' (leniently decoding the UTF-8).
queryToQueryText :: Query -> QueryText
queryToQueryText =
map $ go *** fmap go
where
go = decodeUtf8With lenientDecode
-- | Parse 'QueryText' from a 'B.ByteString'. See 'parseQuery' for details.
parseQueryText :: B.ByteString -> QueryText
parseQueryText = queryToQueryText . parseQuery
-- | Simplified Query item type without support for parameter-less items.
type SimpleQueryItem = (B.ByteString, B.ByteString)
-- | Simplified Query type without support for parameter-less items.
type SimpleQuery = [SimpleQueryItem]
-- | Convert 'SimpleQuery' to 'Query'.
simpleQueryToQuery :: SimpleQuery -> Query
simpleQueryToQuery = map (\(a, b) -> (a, Just b))
-- | Convert 'Query' to a 'Builder'.
renderQueryBuilder :: Bool -- ^ prepend a question mark?
-> Query
-> Blaze.Builder
renderQueryBuilder _ [] = mempty
-- FIXME replace mconcat + map with foldr
renderQueryBuilder qmark' (p:ps) = mconcat
$ go (if qmark' then qmark else mempty) p
: map (go amp) ps
where
qmark = Blaze.copyByteString "?"
amp = Blaze.copyByteString "&"
equal = Blaze.copyByteString "="
go sep (k, mv) = mconcat [
sep
, urlEncodeBuilder True k
, case mv of
Nothing -> mempty
Just v -> equal `mappend` urlEncodeBuilder True v
]
-- | Convert 'Query' to 'ByteString'.
renderQuery :: Bool -- ^ prepend question mark?
-> Query -> B.ByteString
renderQuery qm = Blaze.toByteString . renderQueryBuilder qm
-- | Convert 'SimpleQuery' to 'ByteString'.
renderSimpleQuery :: Bool -- ^ prepend question mark?
-> SimpleQuery -> B.ByteString
renderSimpleQuery useQuestionMark = renderQuery useQuestionMark . simpleQueryToQuery
-- | Split out the query string into a list of keys and values. A few
-- importants points:
--
-- * The result returned is still bytestrings, since we perform no character
-- decoding here. Most likely, you will want to use UTF-8 decoding, but this is
-- left to the user of the library.
--
-- * Percent decoding errors are ignored. In particular, "%Q" will be output as
-- "%Q".
parseQuery :: B.ByteString -> Query
parseQuery = parseQueryString' . dropQuestion
where
dropQuestion q =
case B.uncons q of
Just (63, q') -> q'
_ -> q
parseQueryString' q | B.null q = []
parseQueryString' q =
let (x, xs) = breakDiscard queryStringSeparators q
in parsePair x : parseQueryString' xs
where
parsePair x =
let (k, v) = B.breakByte 61 x -- equal sign
v'' =
case B.uncons v of
Just (_, v') -> Just $ urlDecode True v'
_ -> Nothing
in (urlDecode True k, v'')
queryStringSeparators :: B.ByteString
queryStringSeparators = B.pack [38,59] -- ampersand, semicolon
-- | Break the second bytestring at the first occurence of any bytes from
-- the first bytestring, discarding that byte.
breakDiscard :: B.ByteString -> B.ByteString -> (B.ByteString, B.ByteString)
breakDiscard seps s =
let (x, y) = B.break (`B.elem` seps) s
in (x, B.drop 1 y)
-- | Parse 'SimpleQuery' from a 'ByteString'.
parseSimpleQuery :: B.ByteString -> SimpleQuery
parseSimpleQuery = map (second $ fromMaybe B.empty) . parseQuery
ord8 :: Char -> Word8
ord8 = fromIntegral . ord
unreservedQS, unreservedPI :: [Word8]
unreservedQS = map ord8 "-_.~"
unreservedPI = map ord8 "-_.~:@&=+$,"
-- | Percent-encoding for URLs.
urlEncodeBuilder' :: [Word8] -> B.ByteString -> Blaze.Builder
urlEncodeBuilder' extraUnreserved = mconcat . map encodeChar . B.unpack
where
encodeChar ch | unreserved ch = Blaze.fromWord8 ch
| otherwise = h2 ch
unreserved ch | ch >= 65 && ch <= 90 = True -- A-Z
| ch >= 97 && ch <= 122 = True -- a-z
| ch >= 48 && ch <= 57 = True -- 0-9
unreserved c = c `elem` extraUnreserved
h2 v = let (a, b) = v `divMod` 16 in Blaze.fromWord8s [37, h a, h b] -- percent (%)
h i | i < 10 = 48 + i -- zero (0)
| otherwise = 65 + i - 10 -- 65: A
-- | Percent-encoding for URLs (using 'Blaze.Builder').
urlEncodeBuilder
:: Bool -- ^ Whether input is in query string. True: Query string, False: Path element
-> B.ByteString
-> Blaze.Builder
urlEncodeBuilder True = urlEncodeBuilder' unreservedQS
urlEncodeBuilder False = urlEncodeBuilder' unreservedPI
-- | Percent-encoding for URLs.
urlEncode :: Bool -> B.ByteString -> B.ByteString
urlEncode q = Blaze.toByteString . urlEncodeBuilder q
-- | Percent-decoding.
urlDecode :: Bool -- ^ Whether to decode '+' to ' '
-> B.ByteString -> B.ByteString
urlDecode replacePlus z = fst $ B.unfoldrN (B.length z) go z
where
go bs =
case B.uncons bs of
Nothing -> Nothing
Just (43, ws) | replacePlus -> Just (32, ws) -- plus to space
Just (37, ws) -> Just $ fromMaybe (37, ws) $ do -- percent
(x, xs) <- B.uncons ws
x' <- hexVal x
(y, ys) <- B.uncons xs
y' <- hexVal y
Just $ (combine x' y', ys)
Just (w, ws) -> Just (w, ws)
hexVal w
| 48 <= w && w <= 57 = Just $ w - 48 -- 0 - 9
| 65 <= w && w <= 70 = Just $ w - 55 -- A - F
| 97 <= w && w <= 102 = Just $ w - 87 -- a - f
| otherwise = Nothing
combine :: Word8 -> Word8 -> Word8
combine a b = shiftL a 4 .|. b
-- | Encodes a list of path segments into a valid URL fragment.
--
-- This function takes the following three steps:
--
-- * UTF-8 encodes the characters.
--
-- * Performs percent encoding on all unreserved characters, as well as \:\@\=\+\$,
--
-- * Prepends each segment with a slash.
--
-- For example:
--
-- > encodePathSegments [\"foo\", \"bar\", \"baz\"]
--
-- \"\/foo\/bar\/baz\"
--
-- > encodePathSegments [\"foo bar\", \"baz\/bin\"]
--
-- \"\/foo\%20bar\/baz\%2Fbin\"
--
-- > encodePathSegments [\"שלום\"]
--
-- \"\/%D7%A9%D7%9C%D7%95%D7%9D\"
--
-- Huge thanks to Jeremy Shaw who created the original implementation of this
-- function in web-routes and did such thorough research to determine all
-- correct escaping procedures.
encodePathSegments :: [Text] -> Blaze.Builder
encodePathSegments [] = mempty
encodePathSegments (x:xs) =
Blaze.copyByteString "/"
`mappend` encodePathSegment x
`mappend` encodePathSegments xs
-- | Like encodePathSegments, but without the initial slash.
encodePathSegmentsRelative :: [Text] -> Blaze.Builder
encodePathSegmentsRelative xs = mconcat $ intersperse (Blaze.copyByteString "/") (map encodePathSegment xs)
encodePathSegment :: Text -> Blaze.Builder
encodePathSegment = urlEncodeBuilder False . encodeUtf8
-- | Parse a list of path segments from a valid URL fragment.
decodePathSegments :: B.ByteString -> [Text]
decodePathSegments "" = []
decodePathSegments "/" = []
decodePathSegments a =
go $ drop1Slash a
where
drop1Slash bs =
case B.uncons bs of
Just (47, bs') -> bs' -- 47 == /
_ -> bs
go bs =
let (x, y) = B.breakByte 47 bs
in decodePathSegment x :
if B.null y
then []
else go $ B.drop 1 y
decodePathSegment :: B.ByteString -> Text
decodePathSegment = decodeUtf8With lenientDecode . urlDecode False
-- | Encode a whole path (path segments + query).
encodePath :: [Text] -> Query -> Blaze.Builder
encodePath x [] = encodePathSegments x
encodePath x y = encodePathSegments x `mappend` renderQueryBuilder True y
-- | Decode a whole path (path segments + query).
decodePath :: B.ByteString -> ([Text], Query)
decodePath b =
let (x, y) = B.breakByte 63 b -- question mark
in (decodePathSegments x, parseQuery y)