Struct zoon::State

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pub struct State<T> {
    pub inner: UnsafeCell<Option<T>>,
}

Fields

inner: UnsafeCell<Option<T>>

Implementations

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impl<T> State<T>

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pub const fn new() -> State<T>

Creates a new empty state.

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

Gets the reference to the underlying value.

Returns None if the state is empty.

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pub fn get_mut(&mut self) -> Option<&mut T>

Gets the mutable reference to the underlying value.

Returns None if the state is empty.

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pub fn set(&self, value: T) -> Result<(), T>

Sets the contents of the state to value.

Errors

This method returns Ok(()) if the state was seted

Examples

use zoon::State;
let state = State::new();
assert!(state.get().is_none());

assert_eq!(state.set(92), Ok(()));
assert_eq!(state.set(920), Ok(()));

assert!(state.get().is_some());

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pub fn get_or_init<F>(&self, f: F) -> &Twhere
F: FnOnce() -> T,

Gets the contents of the state, initializing it with f if the state was empty.

Panics

If f panics, the panic is propagated to the caller, and the state remains uninitialized.

It is an error to reentrantly initialize the state from f. Doing so results in a panic.

Examples

use zoon::State;
let state = State::new();
let value = state.get_or_init(|| 92);
assert_eq!(value, &92);
let value = state.get_or_init(|| unreachable!());
assert_eq!(value, &92);

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pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E>where
F: FnOnce() -> Result<T, E>,

Gets the contents of the state, initializing it with f if the state was empty. If the state was empty and f failed, an error is returned.

Panics

If f panics, the panic is propagated to the caller, and the state remains uninitialized.

It is an error to reentrantly initialize the state from f. Doing so results in a panic.

Examples

use zoon::State;
let state = State::new();
assert_eq!(state.get_or_try_init(|| Err(())), Err(()));
assert!(state.get().is_none());
let value = state.get_or_try_init(|| -> Result<i32, ()> {
    Ok(92)
});
assert_eq!(value, Ok(&92));
assert_eq!(state.get(), Some(&92))

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

Consumes the state, returning the wrapped value.

Returns None if the state was empty.

Examples

use zoon::State;
let state: State<String> = State::new();
assert_eq!(state.into_inner(), None);

let state = State::new();
state.set("hello".to_string()).unwrap();
assert_eq!(state.into_inner(), Some("hello".to_string()));

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pub fn take(&mut self) -> Option<T>

Takes the value out of this State, moving it back to an uninitialized state.

Has no effect and returns None if the State hasn’t been initialized.

Safety is guaranteed by requiring a mutable reference.

Examples

use zoon::State;
let mut state: State<String> = State::new();
assert_eq!(state.take(), None);

let mut state = State::new();
state.set("hello".to_string()).unwrap();
assert_eq!(state.take(), Some("hello".to_string()));
assert_eq!(state.get(), None);