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use std::fmt;
use std::ascii::AsciiExt;
use header::{Header, HeaderFormat, parsing};
/// The `Pragma` header defined by HTTP/1.0.
///
/// > The "Pragma" header field allows backwards compatibility with
/// > HTTP/1.0 caches, so that clients can specify a "no-cache" request
/// > that they will understand (as Cache-Control was not defined until
/// > HTTP/1.1). When the Cache-Control header field is also present and
/// > understood in a request, Pragma is ignored.
/// > In HTTP/1.0, Pragma was defined as an extensible field for
/// > implementation-specified directives for recipients. This
/// > specification deprecates such extensions to improve interoperability.
///
/// Spec: https://tools.ietf.org/html/rfc7234#section-5.4
#[derive(Clone, PartialEq, Debug)]
pub enum Pragma {
/// Corresponds to the `no-cache` value.
NoCache,
/// Every value other than `no-cache`.
Ext(String),
}
impl Header for Pragma {
fn header_name() -> &'static str {
"Pragma"
}
fn parse_header(raw: &[Vec<u8>]) -> Option<Pragma> {
parsing::from_one_raw_str(raw).and_then(|s: String| {
let slice = &s.to_ascii_lowercase()[];
match slice {
"" => None,
"no-cache" => Some(Pragma::NoCache),
_ => Some(Pragma::Ext(s)),
}
})
}
}
impl HeaderFormat for Pragma {
fn fmt_header(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Pragma::NoCache => write!(f, "no-cache"),
Pragma::Ext(ref string) => write!(f, "{}", string),
}
}
}
#[test]
fn test_parse_header() {
let a: Pragma = Header::parse_header([b"no-cache".to_vec()].as_slice()).unwrap();
let b = Pragma::NoCache;
assert_eq!(a, b);
let c: Pragma = Header::parse_header([b"FoObar".to_vec()].as_slice()).unwrap();
let d = Pragma::Ext("FoObar".to_string());
assert_eq!(c, d);
}