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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//TODO(eijebong): Remove this once typed headers figure out quality
// This is copy pasted from the old hyper headers to avoid hardcoding everything
// (I would probably also make some silly mistakes while migrating...)
use std::{fmt, str};
use http::header::HeaderValue;
use mime::Mime;
/// A quality value, as specified in [RFC7231].
///
/// Quality values are decimal numbers between 0 and 1 (inclusive) with up to 3 fractional digits of precision.
///
/// [RFC7231]: https://tools.ietf.org/html/rfc7231#section-5.3.1
#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
pub struct Quality(u16);
impl Quality {
/// Creates a quality value from a value between 0 and 1000 inclusive.
///
/// This is semantically divided by 1000 to produce a value between 0 and 1.
///
/// # Panics
///
/// Panics if the value is greater than 1000.
pub fn from_u16(quality: u16) -> Quality {
assert!(quality <= 1000);
Quality(quality)
}
}
/// A value paired with its "quality" as defined in [RFC7231].
///
/// Quality items are used in content negotiation headers such as `Accept` and `Accept-Encoding`.
///
/// [RFC7231]: https://tools.ietf.org/html/rfc7231#section-5.3
#[derive(Clone, Debug, PartialEq)]
pub struct QualityItem<T> {
pub item: T,
pub quality: Quality,
}
impl<T> QualityItem<T> {
/// Creates a new quality item.
pub fn new(item: T, quality: Quality) -> QualityItem<T> {
QualityItem { item, quality }
}
}
impl<T> fmt::Display for QualityItem<T>
where
T: fmt::Display,
{
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(&self.item, fmt)?;
match self.quality.0 {
1000 => Ok(()),
0 => fmt.write_str("; q=0"),
mut x => {
fmt.write_str("; q=0.")?;
let mut digits = *b"000";
digits[2] = (x % 10) as u8 + b'0';
x /= 10;
digits[1] = (x % 10) as u8 + b'0';
x /= 10;
digits[0] = (x % 10) as u8 + b'0';
let s = str::from_utf8(&digits[..]).unwrap();
fmt.write_str(s.trim_end_matches('0'))
},
}
}
}
pub fn quality_to_value(q: Vec<QualityItem<Mime>>) -> HeaderValue {
HeaderValue::from_str(
&q.iter()
.map(|q| q.to_string())
.collect::<Vec<String>>()
.join(", "),
)
.unwrap()
}
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