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use std::time::SystemTime;
use super::{ETag, LastModified};
use util::{EntityTag, HttpDate};
use HeaderValue;
///
/// 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)]
pub struct IfRange(IfRange_);
derive_header! {
IfRange(_),
name: IF_RANGE
}
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(ref entity) => {
etag.map(|etag| !etag.0.strong_eq(entity)).unwrap_or(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>);
}
*/
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_is_modified_etag() {
let etag = ETag::from_static("\"xyzzy\"");
let if_range = IfRange::etag(etag.clone());
assert!(!if_range.is_modified(Some(&etag), None));
let etag = ETag::from_static("W/\"xyzzy\"");
assert!(if_range.is_modified(Some(&etag), None));
}
}