headers/common/
if_modified_since.rs

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1use std::time::SystemTime;
2use util::HttpDate;
3
4/// `If-Modified-Since` header, defined in
5/// [RFC7232](http://tools.ietf.org/html/rfc7232#section-3.3)
6///
7/// The `If-Modified-Since` header field makes a GET or HEAD request
8/// method conditional on the selected representation's modification date
9/// being more recent than the date provided in the field-value.
10/// Transfer of the selected representation's data is avoided if that
11/// data has not changed.
12///
13/// # ABNF
14///
15/// ```text
16/// If-Modified-Since = HTTP-date
17/// ```
18///
19/// # Example values
20/// * `Sat, 29 Oct 1994 19:43:31 GMT`
21///
22/// # Example
23///
24/// ```
25/// # extern crate headers;
26/// use headers::IfModifiedSince;
27/// use std::time::{Duration, SystemTime};
28///
29/// let time = SystemTime::now() - Duration::from_secs(60 * 60 * 24);
30/// let if_mod = IfModifiedSince::from(time);
31/// ```
32#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
33pub struct IfModifiedSince(HttpDate);
34
35derive_header! {
36    IfModifiedSince(_),
37    name: IF_MODIFIED_SINCE
38}
39
40impl IfModifiedSince {
41    /// Check if the supplied time means the resource has been modified.
42    pub fn is_modified(&self, last_modified: SystemTime) -> bool {
43        self.0 < last_modified.into()
44    }
45}
46
47impl From<SystemTime> for IfModifiedSince {
48    fn from(time: SystemTime) -> IfModifiedSince {
49        IfModifiedSince(time.into())
50    }
51}
52
53impl From<IfModifiedSince> for SystemTime {
54    fn from(date: IfModifiedSince) -> SystemTime {
55        date.0.into()
56    }
57}
58
59#[cfg(test)]
60mod tests {
61    use super::*;
62    use std::time::Duration;
63
64    #[test]
65    fn is_modified() {
66        let newer = SystemTime::now();
67        let exact = newer - Duration::from_secs(2);
68        let older = newer - Duration::from_secs(4);
69
70        let if_mod = IfModifiedSince::from(exact);
71        assert!(if_mod.is_modified(newer));
72        assert!(!if_mod.is_modified(exact));
73        assert!(!if_mod.is_modified(older));
74    }
75}
headers/common/if_modified_since.rs

headers/common/
if_modified_since.rs
