base64
Copyright(c) 2019-2026 Emily Pillmore
LicenseBSD-style
MaintainerEmily Pillmore <emilypi@cohomolo.gy>
Stabilitystable
Portabilitynon-portable
Safe HaskellNone
LanguageHaskell2010

Data.Text.Short.Encoding.Base64

Description

This module contains ShortText-valued combinators implementing the RFC 4648 specification for the Base64 encoding format. This includes lenient decoding variants, and external + internal validations for canonicity.

Synopsis

Encoding

encodeBase64 :: ShortText -> Base64 'StdPadded ShortText Source #

Encode a ShortText value in Base64 with padding.

See: RFC-4648 section 4

Examples:

>>> encodeBase64 "Sun"
"U3Vu"

Decoding

decodeBase64 :: forall (k :: Alphabet). StdAlphabet k => Base64 k ShortText -> ShortText Source #

Decode a padded Base64-encoded ShortText value

See: RFC-4648 section 4

Examples:

>>> decodeBase64 $ assertBase64 @'StdPadded "U3Vu"
"Sun"

decodeBase64Untyped :: ShortText -> Either Text ShortText Source #

Decode a padded Base64-encoded ShortText value

See: RFC-4648 section 4

Examples:

>>> decodeBase64Untyped "U3Vu"
Right "Sun"
>>> decodeBase64Untyped "U3V"
Left "Base64-encoded bytestring requires padding"
>>> decodeBase64Untyped "U3V="
Left "non-canonical encoding detected at offset: 2"

decodeBase64UntypedWith Source #

Arguments

:: (ShortByteString -> Either err ShortText)

convert a bytestring to text (e.g. decodeUtf8')

-> ShortByteString

Input text to decode

-> Either (Base64Error err) ShortText 

Attempt to decode an untyped ShortByteString value as Base64, converting from ByteString to ShortText according to some encoding function. In practice, This is something like decodeUtf8', which may produce an error.

See: RFC-4648 section 4

Example:

decodeBase64UntypedWith decodeUtf8'
  :: ShortByteString -> Either (Base64Error UnicodeException) ShortText

decodeBase64Lenient :: ShortText -> ShortText Source #

Leniently decode an untyped Base64-encoded ShortText value. This function will not generate parse errors. If input data contains padding chars, then the input will be parsed up until the first pad character.

Note: This is not RFC 4648-compliant.

Examples:

>>> decodeBase64Lenient "U3Vu"
"Sun"
>>> decodeBase64Lenient "U3V"
"Su"
>>> decodeBase64Lenient "U3V="
"Su"

Parsing

parseBase64 :: ShortText -> Either Text (Base64 'StdPadded ShortText) Source #

Parse a canonical, padded Base64-encoded ShortText value.

Checks the alphabet, length, padding, and unused padding bits. On success, returns the original encoded value wrapped in Base64, ready for decodeBase64. On failure, returns the same error as decodeBase64Untyped. The input is neither decoded nor normalized in the returned value.

This validates the Base64 encoding, not the UTF-8 validity of the decoded bytes. Use decodeBase64UntypedWith to check the decoded text encoding.

Examples:

>>> parseBase64 "U3Vu"
Right "U3Vu"
>>> fmap decodeBase64 (parseBase64 "U3Vu")
Right "Sun"
>>> parseBase64 "U3V"
Left "Base64-encoded bytestring requires padding"
>>> parseBase64 "U3V="
Left "non-canonical encoding detected at offset: 2"

Since: 2.0