Type Alias Edges

pub type Edges<'a, E> = Cow<'a, [E]>;

Aliased Type

enum Edges<'a, E> {
    Borrowed(&'a [E]),
    Owned(<[E] as ToOwned>::Owned),
}

Variants

Borrowed(&'a [E])

Borrowed data.

Owned(<[E] as ToOwned>::Owned)

Owned data.

Layout

Note: Encountered an error during type layout; the type failed to be normalized.

Implementations

impl<B> Cow<'_, B>

where B: ToOwned + ?Sized,

pub const fn is_borrowed(&self) -> bool

🔬This is a nightly-only experimental API. (cow_is_borrowed)

Returns true if the data is borrowed, i.e. if to_mut would require additional work.

Examples

#![feature(cow_is_borrowed)]
use std::borrow::Cow;

let cow = Cow::Borrowed("moo");
assert!(cow.is_borrowed());

let bull: Cow<'_, str> = Cow::Owned("...moo?".to_string());
assert!(!bull.is_borrowed());

pub const fn is_owned(&self) -> bool

🔬This is a nightly-only experimental API. (cow_is_borrowed)

Returns true if the data is owned, i.e. if to_mut would be a no-op.

Examples

#![feature(cow_is_borrowed)]
use std::borrow::Cow;

let cow: Cow<'_, str> = Cow::Owned("moo".to_string());
assert!(cow.is_owned());

let bull = Cow::Borrowed("...moo?");
assert!(!bull.is_owned());

pub fn to_mut(&mut self) -> &mut <B as ToOwned>::Owned

Acquires a mutable reference to the owned form of the data.

Clones the data if it is not already owned.

Examples

use std::borrow::Cow;

let mut cow = Cow::Borrowed("foo");
cow.to_mut().make_ascii_uppercase();

assert_eq!(
  cow,
  Cow::Owned(String::from("FOO")) as Cow<'_, str>
);

pub fn into_owned(self) -> <B as ToOwned>::Owned

Extracts the owned data.

Clones the data if it is not already owned.

Examples

Calling into_owned on a Cow::Borrowed returns a clone of the borrowed data:

use std::borrow::Cow;

let s = "Hello world!";
let cow = Cow::Borrowed(s);

assert_eq!(
  cow.into_owned(),
  String::from(s)
);

Calling into_owned on a Cow::Owned returns the owned data. The data is moved out of the Cow without being cloned.

use std::borrow::Cow;

let s = "Hello world!";
let cow: Cow<'_, str> = Cow::Owned(String::from(s));

assert_eq!(
  cow.into_owned(),
  String::from(s)
);

Trait Implementations

impl<T> AsRef<T> for Cow<'_, T>

where T: ToOwned + ?Sized,

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a, B> Borrow<B> for Cow<'a, B>

where B: ToOwned + ?Sized,

fn borrow(&self) -> &B

Immutably borrows from an owned value.

impl<B> Clone for Cow<'_, B>

where B: ToOwned + ?Sized,

fn clone(&self) -> Cow<'_, B>

Returns a copy of the value.

fn clone_from(&mut self, source: &Cow<'_, B>)

Performs copy-assignment from source.

impl<B> Debug for Cow<'_, B>

where B: Debug + ToOwned + ?Sized, <B as ToOwned>::Owned: Debug,

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

Formats the value using the given formatter.

impl<B> Default for Cow<'_, B>

where B: ToOwned + ?Sized, <B as ToOwned>::Owned: Default,

fn default() -> Cow<'_, B>

Creates an owned Cow<’a, B> with the default value for the contained owned value.

impl<B> Deref for Cow<'_, B>

where B: ToOwned + ?Sized, <B as ToOwned>::Owned: Borrow<B>,

type Target = B

The resulting type after dereferencing.

fn deref(&self) -> &B

Dereferences the value.

impl<B> Display for Cow<'_, B>

where B: Display + ToOwned + ?Sized, <B as ToOwned>::Owned: Display,

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

Formats the value using the given formatter.

impl<'a, T> From<&'a [T]> for Cow<'a, [T]>

where T: Clone,

fn from(s: &'a [T]) -> Cow<'a, [T]>

Creates a Borrowed variant of Cow from a slice.

This conversion does not allocate or clone the data.

impl<'a, T, const N: usize> From<&'a [T; N]> for Cow<'a, [T]>

where T: Clone,

fn from(s: &'a [T; N]) -> Cow<'a, [T]>

Creates a Borrowed variant of Cow from a reference to an array.

This conversion does not allocate or clone the data.

impl<'a, T> From<&'a Vec<T>> for Cow<'a, [T]>

where T: Clone,

fn from(v: &'a Vec<T>) -> Cow<'a, [T]>

Creates a Borrowed variant of Cow from a reference to Vec.

This conversion does not allocate or clone the data.

impl<'a, T> From<Vec<T>> for Cow<'a, [T]>

where T: Clone,

fn from(v: Vec<T>) -> Cow<'a, [T]>

Creates an Owned variant of Cow from an owned instance of Vec.

This conversion does not allocate or clone the data.

impl<'a, T> FromIterator<T> for Cow<'a, [T]>

where T: Clone,

fn from_iter<I>(it: I) -> Cow<'a, [T]>

where I: IntoIterator<Item = T>,

Creates a value from an iterator.

impl<B> Hash for Cow<'_, B>

where B: Hash + ToOwned + ?Sized,

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

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<B> Ord for Cow<'_, B>

where B: Ord + ToOwned + ?Sized,

fn cmp(&self, other: &Cow<'_, B>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T, U> PartialEq<&[U]> for Cow<'_, [T]>

where T: PartialEq<U> + Clone,

fn eq(&self, other: &&[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U> PartialEq<&mut [U]> for Cow<'_, [T]>

where T: PartialEq<U> + Clone,

fn eq(&self, other: &&mut [U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut [U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a, 'b, B, C> PartialEq<Cow<'b, C>> for Cow<'a, B>

where B: PartialEq<C> + ToOwned + ?Sized, C: ToOwned + ?Sized,

fn eq(&self, other: &Cow<'b, C>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<Vec<U, A>> for Cow<'_, [T]>

where A: Allocator, T: PartialEq<U> + Clone,

fn eq(&self, other: &Vec<U, A>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Vec<U, A>) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a, B> PartialOrd for Cow<'a, B>

where B: PartialOrd + ToOwned + ?Sized,

fn partial_cmp(&self, other: &Cow<'a, B>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<B> DerefPure for Cow<'_, B>

where B: ToOwned + ?Sized, <B as ToOwned>::Owned: Borrow<B>,

impl<B> Eq for Cow<'_, B>

where B: Eq + ToOwned + ?Sized,