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bundled/Data/ByteString/Base64.hs

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+{-# LANGUAGE CPP #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE Trustworthy #-}
+#endif
+
+-- |
+-- Module      : Data.ByteString.Base64
+-- Copyright   : (c) 2010 Bryan O'Sullivan
+--
+-- License     : BSD-style
+-- Maintainer  : Emily Pillmore <emilypi@cohomolo.gy>,
+--               Herbert Valerio Riedel <hvr@gnu.org>,
+--               Mikhail Glushenkov <mikhail.glushenkov@gmail.com>
+-- Stability   : experimental
+-- Portability : GHC
+--
+-- Fast and efficient encoding and decoding of base64-encoded strings.
+--
+-- @since 0.1.0.0
+module Data.ByteString.Base64
+  ( encode
+  , decode
+  , decodeLenient
+  ) where
+
+import Data.ByteString.Base64.Internal
+import qualified Data.ByteString as B
+import Data.ByteString.Internal (ByteString(..))
+import Data.Word (Word8)
+import Foreign.ForeignPtr (ForeignPtr)
+
+-- | Encode a string into base64 form.  The result will always be a
+-- multiple of 4 bytes in length.
+encode :: ByteString -> ByteString
+encode s = encodeWith Padded (mkEncodeTable alphabet) s
+
+-- | Decode a base64-encoded string. This function strictly follows
+-- the specification in
+-- <http://tools.ietf.org/rfc/rfc4648 RFC 4648>.
+--
+-- (Note: this means that even @"\\n"@ and @"\\r\\n"@ as line breaks are rejected
+-- rather than ignored.  If you are using this in the context of a
+-- standard that overrules RFC 4648 such as HTTP multipart mime bodies,
+-- consider using 'decodeLenient'.)
+decode :: ByteString -> Either String ByteString
+decode s = decodeWithTable Padded decodeFP s
+
+-- | Decode a base64-encoded string.  This function is lenient in
+-- following the specification from
+-- <http://tools.ietf.org/rfc/rfc4648 RFC 4648>, and will not
+-- generate parse errors no matter how poor its input.
+decodeLenient :: ByteString -> ByteString
+decodeLenient s = decodeLenientWithTable decodeFP s
+
+alphabet :: ByteString
+alphabet = B.pack $ [65..90] ++ [97..122] ++ [48..57] ++ [43,47]
+{-# NOINLINE alphabet #-}
+
+decodeFP :: ForeignPtr Word8
+#if MIN_VERSION_bytestring(0,11,0)
+BS decodeFP _ =
+#else
+PS decodeFP _ _ =
+#endif
+  B.pack $ replicate 43 x
+    ++ [62,x,x,x,63]
+    ++ [52..61]
+    ++ [x,x,x,done,x,x,x]
+    ++ [0..25]
+    ++ [x,x,x,x,x,x]
+    ++ [26..51]
+    ++ replicate 133 x
+{-# NOINLINE decodeFP #-}
+
+x :: Integral a => a
+x = 255
+{-# INLINE x #-}