headers/common/
if_unmodified_since.rs

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1use std::time::SystemTime;
2use util::HttpDate;
3
4/// `If-Unmodified-Since` header, defined in
5/// [RFC7232](http://tools.ietf.org/html/rfc7232#section-3.4)
6///
7/// The `If-Unmodified-Since` header field makes the request method
8/// conditional on the selected representation's last modification date
9/// being earlier than or equal to the date provided in the field-value.
10/// This field accomplishes the same purpose as If-Match for cases where
11/// the user agent does not have an entity-tag for the representation.
12///
13/// # ABNF
14///
15/// ```text
16/// If-Unmodified-Since = HTTP-date
17/// ```
18///
19/// # Example values
20///
21/// * `Sat, 29 Oct 1994 19:43:31 GMT`
22///
23/// # Example
24///
25/// ```
26/// # extern crate headers;
27/// use headers::IfUnmodifiedSince;
28/// use std::time::{SystemTime, Duration};
29///
30/// let time = SystemTime::now() - Duration::from_secs(60 * 60 * 24);
31/// let if_unmod = IfUnmodifiedSince::from(time);
32/// ```
33#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
34pub struct IfUnmodifiedSince(HttpDate);
35
36derive_header! {
37    IfUnmodifiedSince(_),
38    name: IF_UNMODIFIED_SINCE
39}
40
41impl IfUnmodifiedSince {
42    /// Check if the supplied time passes the precondtion.
43    pub fn precondition_passes(&self, last_modified: SystemTime) -> bool {
44        self.0 >= last_modified.into()
45    }
46}
47
48impl From<SystemTime> for IfUnmodifiedSince {
49    fn from(time: SystemTime) -> IfUnmodifiedSince {
50        IfUnmodifiedSince(time.into())
51    }
52}
53
54impl From<IfUnmodifiedSince> for SystemTime {
55    fn from(date: IfUnmodifiedSince) -> SystemTime {
56        date.0.into()
57    }
58}
59
60#[cfg(test)]
61mod tests {
62    use super::*;
63    use std::time::Duration;
64
65    #[test]
66    fn precondition_passes() {
67        let newer = SystemTime::now();
68        let exact = newer - Duration::from_secs(2);
69        let older = newer - Duration::from_secs(4);
70
71        let if_unmod = IfUnmodifiedSince::from(exact);
72        assert!(!if_unmod.precondition_passes(newer));
73        assert!(if_unmod.precondition_passes(exact));
74        assert!(if_unmod.precondition_passes(older));
75    }
76}
headers/common/if_unmodified_since.rs

headers/common/
if_unmodified_since.rs
