actix_web/http/header/preference.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70
use std::{
fmt::{self, Write as _},
str,
};
/// A wrapper for types used in header values where wildcard (`*`) items are allowed but the
/// underlying type does not support them.
///
/// For example, we use the `language-tags` crate for the [`AcceptLanguage`](super::AcceptLanguage)
/// typed header but it does not parse `*` successfully. On the other hand, the `mime` crate, used
/// for [`Accept`](super::Accept), has first-party support for wildcard items so this wrapper is not
/// used in those header types.
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Hash)]
pub enum Preference<T> {
/// A wildcard value.
Any,
/// A valid `T`.
Specific(T),
}
impl<T> Preference<T> {
/// Returns true if preference is the any/wildcard (`*`) value.
pub fn is_any(&self) -> bool {
matches!(self, Self::Any)
}
/// Returns true if preference is the specific item (`T`) variant.
pub fn is_specific(&self) -> bool {
matches!(self, Self::Specific(_))
}
/// Returns reference to value in `Specific` variant, if it is set.
pub fn item(&self) -> Option<&T> {
match self {
Preference::Specific(ref item) => Some(item),
Preference::Any => None,
}
}
/// Consumes the container, returning the value in the `Specific` variant, if it is set.
pub fn into_item(self) -> Option<T> {
match self {
Preference::Specific(item) => Some(item),
Preference::Any => None,
}
}
}
impl<T: fmt::Display> fmt::Display for Preference<T> {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Preference::Any => f.write_char('*'),
Preference::Specific(item) => fmt::Display::fmt(item, f),
}
}
}
impl<T: str::FromStr> str::FromStr for Preference<T> {
type Err = T::Err;
#[inline]
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.trim() {
"*" => Ok(Self::Any),
other => other.parse().map(Preference::Specific),
}
}
}