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Code Issues Releases Wiki Activity

Quality / QualityItem improvements (#2486)

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This commit is contained in:
Rob Ede
2021-12-05 03:38:08 +00:00
committed by GitHub
parent d89c706cd6
commit e1a2d9c606
16 changed files with 494 additions and 257 deletions
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216
actix-http/src/header/shared/quality_item.rs
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@@ -1,85 +1,36 @@
use std::{
cmp,
convert::{TryFrom, TryInto},
fmt, str,
};
use derive_more::{Display, Error};
use std::{cmp, convert::TryFrom as _, fmt, str};
use crate::error::ParseError;
const MAX_QUALITY: u16 = 1000;
const MAX_FLOAT_QUALITY: f32 = 1.0;
/// Represents a quality used in quality values.
///
/// Can be created with the [`q`] function.
///
/// # Implementation notes
///
/// The quality value is defined as a number between 0 and 1 with three decimal
/// places. This means there are 1001 possible values. Since floating point
/// numbers are not exact and the smallest floating point data type (`f32`)
/// consumes four bytes, hyper uses an `u16` value to store the
/// quality internally. For performance reasons you may set quality directly to
/// a value between 0 and 1000 e.g. `Quality(532)` matches the quality
/// `q=0.532`.
///
/// [RFC 7231 §5.3.1](https://datatracker.ietf.org/doc/html/rfc7231#section-5.3.1) gives more
/// information on quality values in HTTP header fields.
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub struct Quality(u16);
impl Quality {
/// # Panics
/// Panics in debug mode when value is not in the range 0.0 <= n <= 1.0.
fn from_f32(value: f32) -> Self {
// Check that `value` is within range should be done before calling this method.
// Just in case, this debug_assert should catch if we were forgetful.
debug_assert!(
(0.0f32..=1.0f32).contains(&value),
"q value must be between 0.0 and 1.0"
);
Quality((value * MAX_QUALITY as f32) as u16)
}
}
impl Default for Quality {
fn default() -> Quality {
Quality(MAX_QUALITY)
}
}
#[derive(Debug, Clone, Display, Error)]
pub struct QualityOutOfBounds;
impl TryFrom<u16> for Quality {
type Error = QualityOutOfBounds;
fn try_from(value: u16) -> Result<Self, Self::Error> {
if (0..=MAX_QUALITY).contains(&value) {
Ok(Quality(value))
} else {
Err(QualityOutOfBounds)
}
}
}
impl TryFrom<f32> for Quality {
type Error = QualityOutOfBounds;
fn try_from(value: f32) -> Result<Self, Self::Error> {
if (0.0..=MAX_FLOAT_QUALITY).contains(&value) {
Ok(Quality::from_f32(value))
} else {
Err(QualityOutOfBounds)
}
}
}
use super::Quality;
/// Represents an item with a quality value as defined
/// in [RFC 7231 §5.3.1](https://datatracker.ietf.org/doc/html/rfc7231#section-5.3.1).
///
/// # Parsing and Formatting
/// This wrapper be used to parse header value items that have a q-factor annotation as well as
/// serialize items with a their q-factor.
///
/// # Ordering
/// Since this context of use for this type is header value items, ordering is defined for
/// `QualityItem`s but _only_ considers the item's quality. Order of appearance should be used as
/// the secondary sorting parameter; i.e., a stable sort over the quality values will produce a
/// correctly sorted sequence.
///
/// # Examples
/// ```
/// # use actix_http::header::{QualityItem, q};
/// let q_item: QualityItem<String> = "hello;q=0.3".parse().unwrap();
/// assert_eq!(&q_item.item, "hello");
/// assert_eq!(q_item.quality, q(0.3));
///
/// // note that format is normalized compared to parsed item
/// assert_eq!(q_item.to_string(), "hello; q=0.3");
///
/// // item with q=0.3 is greater than item with q=0.1
/// let q_item_fallback: QualityItem<String> = "abc;q=0.1".parse().unwrap();
/// assert!(q_item > q_item_fallback);
/// ```
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct QualityItem<T> {
/// The wrapped contents of the field.
@@ -93,12 +44,22 @@ impl<T> QualityItem<T> {
/// Constructs a new `QualityItem` from an item and a quality value.
///
/// The item can be of any type. The quality should be a value in the range [0, 1].
pub fn new(item: T, quality: Quality) -> QualityItem<T> {
pub fn new(item: T, quality: Quality) -> Self {
QualityItem { item, quality }
}
/// Constructs a new `QualityItem` from an item, using the maximum q-value.
pub fn max(item: T) -> Self {
Self::new(item, Quality::MAX)
}
/// Constructs a new `QualityItem` from an item, using the minimum q-value.
pub fn min(item: T) -> Self {
Self::new(item, Quality::MIN)
}
}
impl<T: PartialEq> cmp::PartialOrd for QualityItem<T> {
impl<T: PartialEq> PartialOrd for QualityItem<T> {
fn partial_cmp(&self, other: &QualityItem<T>) -> Option<cmp::Ordering> {
self.quality.partial_cmp(&other.quality)
}
@@ -108,10 +69,12 @@ impl<T: fmt::Display> fmt::Display for QualityItem<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.item, f)?;
match self.quality.0 {
MAX_QUALITY => Ok(()),
0 => f.write_str("; q=0"),
x => write!(f, "; q=0.{}", format!("{:03}", x).trim_end_matches('0')),
match self.quality {
// q-factor value is implied for max value
Quality::MAX => Ok(()),
Quality::MIN => f.write_str("; q=0"),
q => write!(f, "; q={}", q),
}
}
}
@@ -119,78 +82,58 @@ impl<T: fmt::Display> fmt::Display for QualityItem<T> {
impl<T: str::FromStr> str::FromStr for QualityItem<T> {
type Err = ParseError;
fn from_str(qitem_str: &str) -> Result<Self, Self::Err> {
if !qitem_str.is_ascii() {
fn from_str(q_item_str: &str) -> Result<Self, Self::Err> {
if !q_item_str.is_ascii() {
return Err(ParseError::Header);
}
// Set defaults used if parsing fails.
let mut raw_item = qitem_str;
let mut quality = 1f32;
// set defaults used if quality-item parsing fails, i.e., item has no q attribute
let mut raw_item = q_item_str;
let mut quality = Quality::MAX;
// TODO: MSRV(1.52): use rsplit_once
let parts: Vec<_> = qitem_str.rsplitn(2, ';').map(str::trim).collect();
let parts = q_item_str
.rsplit_once(';')
.map(|(item, q_attr)| (item.trim(), q_attr.trim()));
if parts.len() == 2 {
if let Some((val, q_attr)) = parts {
// example for item with q-factor:
//
// gzip; q=0.65
// ^^^^^^ parts[0]
// ^^ start
// ^^^^ q_val
// ^^^^ parts[1]
// gzip;q=0.65
// ^^^^ val
// ^^^^^^ q_attr
// ^^ q
// ^^^^ q_val
if parts[0].len() < 2 {
if q_attr.len() < 2 {
// Can't possibly be an attribute since an attribute needs at least a name followed
// by an equals sign. And bare identifiers are forbidden.
return Err(ParseError::Header);
}
let start = &parts[0][0..2];
let q = &q_attr[0..2];
if start == "q=" || start == "Q=" {
let q_val = &parts[0][2..];
if q == "q=" || q == "Q=" {
let q_val = &q_attr[2..];
if q_val.len() > 5 {
// longer than 5 indicates an over-precise q-factor
return Err(ParseError::Header);
}
let q_value = q_val.parse::<f32>().map_err(|_| ParseError::Header)?;
let q_value =
Quality::try_from(q_value).map_err(|_| ParseError::Header)?;
if (0f32..=1f32).contains(&q_value) {
quality = q_value;
raw_item = parts[1];
} else {
return Err(ParseError::Header);
}
quality = q_value;
raw_item = val;
}
}
let item = raw_item.parse::<T>().map_err(|_| ParseError::Header)?;
// we already checked above that the quality is within range
Ok(QualityItem::new(item, Quality::from_f32(quality)))
Ok(QualityItem::new(item, quality))
}
}
/// Convenience function to wrap a value in a `QualityItem`
/// Sets `q` to the default 1.0
pub fn qitem<T>(item: T) -> QualityItem<T> {
QualityItem::new(item, Quality::default())
}
/// Convenience function to create a `Quality` from a float or integer.
///
/// Implemented for `u16` and `f32`. Panics if value is out of range.
pub fn q<T>(val: T) -> Quality
where
T: TryInto<Quality>,
T::Error: fmt::Debug,
{
// TODO: on next breaking change, handle unwrap differently
val.try_into().unwrap()
}
#[cfg(test)]
mod tests {
use super::*;
@@ -245,7 +188,7 @@ mod tests {
#[test]
fn test_quality_item_fmt_q_1() {
use Encoding::*;
let x = qitem(Chunked);
let x = QualityItem::max(Chunked);
assert_eq!(format!("{}", x), "chunked");
}
#[test]
@@ -344,25 +287,8 @@ mod tests {
fn test_quality_item_ordering() {
let x: QualityItem<Encoding> = "gzip; q=0.5".parse().ok().unwrap();
let y: QualityItem<Encoding> = "gzip; q=0.273".parse().ok().unwrap();
let comparision_result: bool = x.gt(&y);
assert!(comparision_result)
}
#[test]
fn test_quality() {
assert_eq!(q(0.5), Quality(500));
}
#[test]
#[should_panic]
fn test_quality_invalid() {
q(-1.0);
}
#[test]
#[should_panic]
fn test_quality_invalid2() {
q(2.0);
let comparison_result: bool = x.gt(&y);
assert!(comparison_result)
}
#[test]