http_types/conditional/last_modified.rs
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use crate::headers::{HeaderName, HeaderValue, Headers, ToHeaderValues, LAST_MODIFIED};
use crate::utils::{fmt_http_date, parse_http_date};
use std::fmt::Debug;
use std::option;
use std::time::SystemTime;
/// The last modification date of a resource.
///
/// # Specifications
///
/// - [RFC 7232, section 2.2: Last-Modified](https://tools.ietf.org/html/rfc7232#section-2.2)
///
/// # Examples
///
/// ```
/// # fn main() -> http_types::Result<()> {
/// #
/// use http_types::Response;
/// use http_types::conditional::LastModified;
/// use std::time::{SystemTime, Duration};
///
/// let time = SystemTime::now() + Duration::from_secs(5 * 60);
/// let last_modified = LastModified::new(time);
///
/// let mut res = Response::new(200);
/// last_modified.apply(&mut res);
///
/// let last_modified = LastModified::from_headers(res)?.unwrap();
///
/// // HTTP dates only have second-precision.
/// let elapsed = time.duration_since(last_modified.modified())?;
/// assert_eq!(elapsed.as_secs(), 0);
/// #
/// # Ok(()) }
/// ```
#[derive(Debug, Ord, PartialOrd, Eq, PartialEq)]
pub struct LastModified {
instant: SystemTime,
}
impl LastModified {
/// Create a new instance of `LastModified`.
pub fn new(instant: SystemTime) -> Self {
Self { instant }
}
/// Returns the last modification time listed.
pub fn modified(&self) -> SystemTime {
self.instant
}
/// Create an instance of `LastModified` from a `Headers` instance.
pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
let headers = match headers.as_ref().get(LAST_MODIFIED) {
Some(headers) => headers,
None => return Ok(None),
};
// If we successfully parsed the header then there's always at least one
// entry. We want the last entry.
let header = headers.iter().last().unwrap();
let instant = parse_http_date(header.as_str())?;
Ok(Some(Self { instant }))
}
/// Insert a `HeaderName` + `HeaderValue` pair into a `Headers` instance.
pub fn apply(&self, mut headers: impl AsMut<Headers>) {
headers.as_mut().insert(LAST_MODIFIED, self.value());
}
/// Get the `HeaderName`.
pub fn name(&self) -> HeaderName {
LAST_MODIFIED
}
/// Get the `HeaderValue`.
pub fn value(&self) -> HeaderValue {
let output = fmt_http_date(self.instant);
// SAFETY: the internal string is validated to be ASCII.
unsafe { HeaderValue::from_bytes_unchecked(output.into()) }
}
}
impl ToHeaderValues for LastModified {
type Iter = option::IntoIter<HeaderValue>;
fn to_header_values(&self) -> crate::Result<Self::Iter> {
// A HeaderValue will always convert into itself.
Ok(self.value().to_header_values().unwrap())
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::headers::Headers;
use std::time::Duration;
#[test]
fn smoke() -> crate::Result<()> {
let time = SystemTime::now() + Duration::from_secs(5 * 60);
let last_modified = LastModified::new(time);
let mut headers = Headers::new();
last_modified.apply(&mut headers);
let last_modified = LastModified::from_headers(headers)?.unwrap();
// HTTP dates only have second-precision
let elapsed = time.duration_since(last_modified.modified())?;
assert_eq!(elapsed.as_secs(), 0);
Ok(())
}
#[test]
fn bad_request_on_parse_error() {
let mut headers = Headers::new();
headers.insert(LAST_MODIFIED, "<nori ate the tag. yum.>");
let err = LastModified::from_headers(headers).unwrap_err();
assert_eq!(err.status(), 400);
}
}