Module MrMime_base64

module MrMime_base64: sig .. end

module Decoder: sig .. end

module Encoder: sig .. end

module Input: module type of RingBuffer.Committed 
  with type 'a t = 'a RingBuffer.Committed.t

type Parser.err += 

Special processing is performed if fewer than 24 bits are available at the end of the data. A full encoding quantum is always completed at the end of a body. When fewer than 24 inputs bits are available in an input group, zero bits are added (on the right) to form an integral number of 6-bit groups. Padding at the end of the data is performed using the "=" character.

Since all Base64 input is an integral number of octets, only the following cases can arise:

• the final quantum of encoding input is an integral multiple of 24 bits; here the final unit of encoded output will be an integral multiple of 4 characters with no "=" padding.
• the final quantum of encoding input is exactly 8 bits; here, the final unit of encoded output will be two characters followed by two "=" padding characters.
• the final quantum of encoding input is exactly 16 bits; here the final unit of encoded output will be three characters followed by on "=" padding character.
• in another case, the decoder returns Wrong_padding.

type 'a decoder 

The type for Base64 decoder.

type decoding = [ `Continue
       | `Dirty of string
       | `End of string
       | `Error of Parser.err
       | `String of string ] 

val decoder : unit Parser.t * unit Parser.t ->
       'a Input.t -> 'a decoder

decoder (boundary, rollback) input is a Base64 decoder that inputs from input. boundary specifies the limit of the decoding and rollback allows the decoder to keep the boundary inside the input.

val decoder_src : 'a decoder -> 'a Input.t

decoder_src decoder is decoder's input source.

val decode : 'a decoder -> decoding

decode decoder is:

• `Continue if decoder awaits for more input. The client must use MrMime_base64.src to provide it.
• `Dirty s if decoder has a padding error or if the character is not a valid Base64 character (see is_b64). If the client is interested in a best-effort decoding it can still continue to decode after an dirty chunk.
• `Error exn if decoder has a padding error (Wrong_padding error) - in this case, the client doest not trust the content - or a parsing error.
• `String s if a chunk s was decoded.
• `End s if the last chunk s was decoded - when the decoder arises one time this value, it returns only this value after the client recall decode.

val src : 'a decoder -> string -> int -> int -> unit

src decoder buf off len provides decoder with len bytes to read, starting at off in buf. This byte range is read by calls to MrMime_base64.decode until `Continue is returned. To signal the end of input call the function with len = 0.