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use std::time::SystemTime; use ::HeaderValue; use util::{EntityTag, HttpDate}; use super::{LastModified, ETag}; /// `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 /// /// ``` /// # extern crate headers; /// use headers::IfRange; /// use std::time::{SystemTime, Duration}; /// /// let fetched = SystemTime::now() - Duration::from_secs(60 * 60 * 24); /// let if_range = IfRange::date(fetched); /// ``` #[derive(Clone, Debug, PartialEq, Header)] pub struct IfRange(IfRange_); impl IfRange { /// Create an `IfRange` header with an entity tag. pub fn etag(tag: ETag) -> IfRange { IfRange(IfRange_::EntityTag(tag.0)) } /// Create an `IfRange` header with a date value. pub fn date(time: SystemTime) -> IfRange { IfRange(IfRange_::Date(time.into())) } /// Checks if the resource has been modified, or if the range request /// can be served. pub fn is_modified(&self, _etag: Option<&ETag>, last_modified: Option<&LastModified>) -> bool { match self.0 { IfRange_::Date(since) => last_modified.map(|time| since < time.0).unwrap_or(true), IfRange_::EntityTag(_) => true, } } } #[derive(Clone, Debug, PartialEq)] enum IfRange_ { /// The entity-tag the client has of the resource EntityTag(EntityTag), /// The date when the client retrieved the resource Date(HttpDate), } impl ::util::TryFromValues for IfRange_ { fn try_from_values<'i, I>(values: &mut I) -> Result<Self, ::Error> where I: Iterator<Item = &'i HeaderValue>, { values .next() .and_then(|val| { if let Some(tag) = EntityTag::from_val(val) { return Some(IfRange_::EntityTag(tag)); } let date = HttpDate::from_val(val)?; Some(IfRange_::Date(date)) }) .ok_or_else(::Error::invalid) } } impl<'a> From<&'a IfRange_> for HeaderValue { fn from(if_range: &'a IfRange_) -> HeaderValue { match *if_range { IfRange_::EntityTag(ref tag) => tag.into(), IfRange_::Date(ref date) => date.into(), } } } /* #[cfg(test)] mod tests { use std::str; use *; 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>); } */