[][src]Struct rustc_data_structures::sync::Once

pub struct Once<T>(Lock<Option<T>>, PhantomData<T>);
🔬 This is a nightly-only experimental API. (rustc_private)

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A type whose inner value can be written once and then will stay read-only

Methods

impl<T> Once<T>
[src]

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

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Creates an Once value which is uninitialized

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

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Consumes the value and returns Some(T) if it was initialized

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

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Tries to initialize the inner value to value. Returns None if the inner value was uninitialized and value was consumed setting it otherwise if the inner value was already set it returns value back to the caller

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Tries to initialize the inner value to value. Returns None if the inner value was uninitialized and value was consumed setting it otherwise if the inner value was already set it asserts that value is equal to the inner value and then returns value back to the caller

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Tries to initialize the inner value to value and panics if it was already initialized

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Tries to initialize the inner value by calling the closure while ensuring that no-one else can access the value in the mean time by holding a lock for the duration of the closure. If the value was already initialized the closure is not called and false is returned, otherwise if the value from the closure initializes the inner value, true is returned

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Tries to initialize the inner value by calling the closure without ensuring that no-one else can access it. This mean when this is called from multiple threads, multiple closures may concurrently be computing a value which the inner value should take. Only one of these closures are used to actually initialize the value. If some other closure already set the value, we return the value our closure computed wrapped in a Option. If our closure set the value, None is returned. If the value is already initialized, the closure is not called and None is returned.

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Tries to initialize the inner value by calling the closure without ensuring that no-one else can access it. This mean when this is called from multiple threads, multiple closures may concurrently be computing a value which the inner value should take. Only one of these closures are used to actually initialize the value. If some other closure already set the value, we assert that it our closure computed a value equal to the value already set and then we return the value our closure computed wrapped in a Option. If our closure set the value, None is returned. If the value is already initialized, the closure is not called and None is returned.

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

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Tries to get a reference to the inner value, returns None if it is not yet initialized

Important traits for &'a mut R

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Gets reference to the inner value, panics if it is not yet initialized

Important traits for &'a mut R

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

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Gets reference to the inner value, panics if it is not yet initialized

Auto Trait Implementations

impl<T> Send for Once<T> where
    T: Send

impl<T> !Sync for Once<T>

Blanket Implementations

impl<T> Erased for T
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impl<T> Send for T where
    T: ?Sized
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impl<T> Sync for T where
    T: ?Sized
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impl<T> From for T
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Performs the conversion.

impl<T, U> Into for T where
    U: From<T>, 
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Performs the conversion.

impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> Borrow for T where
    T: ?Sized
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Important traits for &'a mut R

Immutably borrows from an owned value. Read more

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

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

Performs the conversion.

impl<T> BorrowMut for T where
    T: ?Sized
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Important traits for &'a mut R

Mutably borrows from an owned value. Read more

impl<T> Any for T where
    T: 'static + ?Sized
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🔬 This is a nightly-only experimental API. (get_type_id)

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more

impl<E> SpecializationError for E
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🔬 This is a nightly-only experimental API. (rustc_private)

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Create an error for a missing method specialization. Defaults to panicking with type, trait & method names. S is the encoder/decoder state type, T is the type being encoded/decoded, and the arguments are the names of the trait and method that should've been overridden. Read more

impl<T> Erased for T