Type of emitters.

An emitters is able to produce from the given header a pusher which is able to save contents and a unique ID to be able to get the content furthermore.

Type of a simple element.

An element is a part in sense of the multipart/form-data format. A part can contains multiple parts. It has systematically a Header.t.

Type of multipart/form-data contents.

• a Leaf is a content with a simple header.
• a Multipart is a list of possibly empty (option) sub-elements - indeed, we can have a multipart inside a multipart.

parser ~emitters content_type creates an angstrom's parser which can process a multipart/form-data input. For each Leaf, the parser calls emitters to be able to save contents and get a reference of it.

A simple use of it is to generate an unique ID and associate it to a Buffer.t such as:

  let gen = let v = ref (-1) in fun () -> incr v ; !v in
  let tbl = Hashtbl.create 0x10 in
  let emitters () =
    let idx = gen () in
    let buf = Buffer.create 0x100 in
    (function None -> ()
            | Some str -> Buffer.add_string buf str), idx in
  parser ~emitters content_type 

With such style, a mapping exists between the returned value t and tbl. At the end, the user is able to extract contents with these values.

In some contexts, something else such as an Lwt_stream.t/asynchronous stream can be used instead a Buffer.t.

of_stream stream content_type returns, if it succeeds, a value t with an associative list of unique ID and contents.

of_string str content_type returns, if it succeeds, a value t with an associative list of unique ID and contents.