Parse a multipart/form-data request, which is usually generated from a HTML form
submission. The parameters can include both text values as well as binary files.
They can be distinguished from the presence of a filename attribute.
parse_multipart(body, boundary)body of the HTTP request. Must be raw or character vector.
boundary string as specified in the Content-Type request header.
A multipart/form-data request consists of a single body which contains one or more
values plus meta-data, separated using a boundary string. This boundary string
is chosen by the client (e.g. the browser) and specified in the Content-Type
header of the HTTP request. There is no escaping; it is up to the client to choose
a boundary string that does not appear in one of the values.
The parser is written in pure R, but still pretty fast because it uses the regex engine.