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use std::fmt::{self, Display}; use header::{self, Header, Raw, EntityTag, HttpDate}; /// `If-Range` header, defined in [RFC7233](http://tools.ietf.org/html/rfc7233#section-3.2) /// /// If a client has a partial copy of a representation and wishes to have /// an up-to-date copy of the entire representation, it could use the /// Range header field with a conditional GET (using either or both of /// If-Unmodified-Since and If-Match.) However, if the precondition /// fails because the representation has been modified, the client would /// then have to make a second request to obtain the entire current /// representation. /// /// The `If-Range` header field allows a client to \"short-circuit\" the /// second request. Informally, its meaning is as follows: if the /// representation is unchanged, send me the part(s) that I am requesting /// in Range; otherwise, send me the entire representation. /// /// # ABNF /// /// ```text /// If-Range = entity-tag / HTTP-date /// ``` /// /// # Example values /// /// * `Sat, 29 Oct 1994 19:43:31 GMT` /// * `\"xyzzy\"` /// /// # Examples /// /// ``` /// use hyper::header::{Headers, IfRange, EntityTag}; /// /// let mut headers = Headers::new(); /// headers.set(IfRange::EntityTag(EntityTag::new(false, "xyzzy".to_owned()))); /// ``` /// /// ``` /// use hyper::header::{Headers, IfRange}; /// use std::time::{SystemTime, Duration}; /// /// let mut headers = Headers::new(); /// let fetched = SystemTime::now() - Duration::from_secs(60 * 60 * 24); /// headers.set(IfRange::Date(fetched.into())); /// ``` #[derive(Clone, Debug, PartialEq)] pub enum IfRange { /// The entity-tag the client has of the resource EntityTag(EntityTag), /// The date when the client retrieved the resource Date(HttpDate), } impl Header for IfRange { fn header_name() -> &'static str { static NAME: &'static str = "If-Range"; NAME } fn parse_header(raw: &Raw) -> ::Result<IfRange> { let etag: ::Result<EntityTag> = header::parsing::from_one_raw_str(raw); if let Ok(etag) = etag { return Ok(IfRange::EntityTag(etag)); } let date: ::Result<HttpDate> = header::parsing::from_one_raw_str(raw); if let Ok(date) = date { return Ok(IfRange::Date(date)); } Err(::Error::Header) } fn fmt_header(&self, f: &mut ::header::Formatter) -> ::std::fmt::Result { f.fmt_line(self) } } impl Display for IfRange { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { IfRange::EntityTag(ref x) => Display::fmt(x, f), IfRange::Date(ref x) => Display::fmt(x, f), } } } #[cfg(test)] mod test_if_range { use std::str; use header::*; use super::IfRange as HeaderField; test_header!(test1, vec![b"Sat, 29 Oct 1994 19:43:31 GMT"]); test_header!(test2, vec![b"\"xyzzy\""]); test_header!(test3, vec![b"this-is-invalid"], None::<IfRange>); }