pub enum Preference<T> {
    Any,
    Specific(T),
}
Expand description

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 typed header but it does not parse * successfully. On the other hand, the mime crate, used for Accept, has first-party support for wildcard items so this wrapper is not used in those header types.

Variants§

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Any

A wildcard value.

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Specific(T)

A valid T.

Implementations§

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impl<T> Preference<T>

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pub fn is_any(&self) -> bool

Returns true if preference is the any/wildcard (*) value.

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pub fn is_specific(&self) -> bool

Returns true if preference is the specific item (T) variant.

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pub fn item(&self) -> Option<&T>

Returns reference to value in Specific variant, if it is set.

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pub fn into_item(self) -> Option<T>

Consumes the container, returning the value in the Specific variant, if it is set.

Trait Implementations§

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impl<T: Clone> Clone for Preference<T>

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fn clone(&self) -> Preference<T>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T: Debug> Debug for Preference<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<T: Display> Display for Preference<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<T: FromStr> FromStr for Preference<T>

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type Err = <T as FromStr>::Err

The associated error which can be returned from parsing.
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fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type. Read more
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impl<T: Hash> Hash for Preference<T>

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fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl<T: PartialEq> PartialEq<Preference<T>> for Preference<T>

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fn eq(&self, other: &Preference<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<T: PartialOrd> PartialOrd<Preference<T>> for Preference<T>

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fn partial_cmp(&self, other: &Preference<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl<T: Copy> Copy for Preference<T>

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impl<T: Eq> Eq for Preference<T>

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impl<T> StructuralEq for Preference<T>

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impl<T> StructuralPartialEq for Preference<T>

Auto Trait Implementations§

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impl<T> RefUnwindSafe for Preference<T>where T: RefUnwindSafe,

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impl<T> Send for Preference<T>where T: Send,

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impl<T> Sync for Preference<T>where T: Sync,

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impl<T> Unpin for Preference<T>where T: Unpin,

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impl<T> UnwindSafe for Preference<T>where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CallHasher for Twhere T: Hash + ?Sized,

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fn get_hash<H, B>(value: &H, build_hasher: &B) -> u64where H: Hash + ?Sized, B: BuildHasher,

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impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Same<T> for T

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type Output = T

Should always be Self
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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for Twhere T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more