pub enum MaybeOwned<'a, TOwned, TBorrowed: ?Sized = TOwned> {
    Owned(TOwned),
    Borrowed(&'a TBorrowed),
}
Expand description

A value that may be owned or not. Similar to std::borrow::Cow but does not require Clone.

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Owned(TOwned)

An owned value.

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Borrowed(&'a TBorrowed)

A borrowed value.

Trait Implementations§

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impl<'a, TOwned, TBorrowed> Borrow<TBorrowed> for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: ?Sized,

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fn borrow(&self) -> &TBorrowed

Immutably borrows from an owned value. Read more
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impl<'a, TOwned, TBorrowed> Clone for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Clone, TBorrowed: ?Sized,

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fn clone(&self) -> Self

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<'a, TOwned: Debug, TBorrowed: Debug + ?Sized> Debug for MaybeOwned<'a, TOwned, TBorrowed>

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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<'a, TOwned, TBorrowed> Deref for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: ?Sized,

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type Target = TBorrowed

The resulting type after dereferencing.
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fn deref(&self) -> &TBorrowed

Dereferences the value.
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impl<'a, 'k, TOwned, TBorrowed> Key<'k> for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: KeyEncoding<TOwned, Error = TOwned::Error> + PartialEq + ?Sized, TOwned: Key<'k> + PartialEq<TBorrowed>,

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const CAN_OWN_BYTES: bool = TOwned::CAN_OWN_BYTES

If true, this type can benefit from an owned Vec<u8>. This flag is used as a hint of whether to attempt to do memcpy operations in some decoding operations to avoid extra allocations.
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fn from_ord_bytes<'e>(bytes: ByteSource<'k, 'e>) -> Result<Self, Self::Error>

Deserialize a sequence of bytes previously encoded with KeyEncoding::as_ord_bytes.
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fn first_value() -> Result<Self, NextValueError>

Return the first value in sequence for this type. Not all types implement this.
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fn next_value(&self) -> Result<Self, NextValueError>

Return the next value in sequence for this type. Not all types implement this. Instead of wrapping/overflowing, None should be returned.
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impl<'a, 'k, TOwned, TBorrowed> KeyEncoding for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: KeyEncoding<TOwned, Error = TOwned::Error> + PartialEq + ?Sized, TOwned: Key<'k> + PartialEq<TBorrowed>,

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type Error = <TOwned as KeyEncoding>::Error

The error type that can be produced by either serialization or deserialization.
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const LENGTH: Option<usize> = TBorrowed::LENGTH

The size of the key, if constant. If this type doesn’t produce the same number of bytes for each value, this should be None.
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fn describe<Visitor>(visitor: &mut Visitor)where Visitor: KeyVisitor,

Describes this type by invoking functions on visitor describing the key being encoded. Read more
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fn as_ord_bytes(&self) -> Result<Cow<'_, [u8]>, Self::Error>

Convert self into a Cow<'_, [u8]> containing bytes that are able to be compared via memcmp in a way that is comptaible with its own Ord implementation.
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impl<'a, TOwned, TBorrowed> PartialEq<TBorrowed> for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: PartialEq + ?Sized,

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fn eq(&self, other: &TBorrowed) -> 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<'a, TOwned, TBorrowed> PartialEq for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: PartialEq + ?Sized,

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fn eq(&self, other: &Self) -> 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<'a, TOwned, TBorrowed> PartialOrd<TBorrowed> for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: PartialOrd + ?Sized,

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fn partial_cmp(&self, other: &TBorrowed) -> 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<'a, TOwned, TBorrowed> PartialOrd for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Borrow<TBorrowed>, TBorrowed: PartialOrd + ?Sized,

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fn partial_cmp(&self, other: &Self) -> 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

Auto Trait Implementations§

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impl<'a, TOwned, TBorrowed: ?Sized> RefUnwindSafe for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: RefUnwindSafe, TOwned: RefUnwindSafe,

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impl<'a, TOwned, TBorrowed: ?Sized> Send for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: Sync, TOwned: Send,

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impl<'a, TOwned, TBorrowed: ?Sized> Sync for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: Sync, TOwned: Sync,

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impl<'a, TOwned, TBorrowed: ?Sized> Unpin for MaybeOwned<'a, TOwned, TBorrowed>where TOwned: Unpin,

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impl<'a, TOwned, TBorrowed: ?Sized> UnwindSafe for MaybeOwned<'a, TOwned, TBorrowed>where TBorrowed: RefUnwindSafe, TOwned: 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> 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 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, 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