Struct OnceFn

pub struct OnceFn<T>(pub Cell<Option<T>>);

Helper type for creating a function from a closure which implements FnMut

When called, will take the internal value leaving it empty. If the internal value was already empty it will return a error.

Tuple Fields

0: Cell<Option<T>>

Implementations

impl<T> OnceFn<T>

pub fn new(t: T) -> Self

Methods from Deref<Target = Cell<Option<F>>>

pub fn set(&self, val: T)

Sets the contained value.

Examples

use std::cell::Cell;

let c = Cell::new(5);

c.set(10);

pub fn swap(&self, other: &Cell<T>)

Swaps the values of two Cells.

The difference with std::mem::swap is that this function doesn’t require a &mut reference.

Panics

This function will panic if self and other are different Cells that partially overlap. (Using just standard library methods, it is impossible to create such partially overlapping Cells. However, unsafe code is allowed to e.g. create two &Cell<[i32; 2]> that partially overlap.)

Examples

use std::cell::Cell;

let c1 = Cell::new(5i32);
let c2 = Cell::new(10i32);
c1.swap(&c2);
assert_eq!(10, c1.get());
assert_eq!(5, c2.get());

pub fn replace(&self, val: T) -> T

Replaces the contained value with val, and returns the old contained value.

Examples

use std::cell::Cell;

let cell = Cell::new(5);
assert_eq!(cell.get(), 5);
assert_eq!(cell.replace(10), 5);
assert_eq!(cell.get(), 10);

pub fn get(&self) -> T

Returns a copy of the contained value.

Examples

use std::cell::Cell;

let c = Cell::new(5);

let five = c.get();

pub fn update<F>(&self, f: F) -> T

where F: FnOnce(T) -> T,

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

Updates the contained value using a function and returns the new value.

Examples

#![feature(cell_update)]

use std::cell::Cell;

let c = Cell::new(5);
let new = c.update(|x| x + 1);

assert_eq!(new, 6);
assert_eq!(c.get(), 6);

pub fn as_ptr(&self) -> *mut T

Returns a raw pointer to the underlying data in this cell.

Examples

use std::cell::Cell;

let c = Cell::new(5);

let ptr = c.as_ptr();

pub fn take(&self) -> T

Takes the value of the cell, leaving Default::default() in its place.

Examples

use std::cell::Cell;

let c = Cell::new(5);
let five = c.take();

assert_eq!(five, 5);
assert_eq!(c.into_inner(), 0);

pub fn as_slice_of_cells(&self) -> &[Cell<T>]

Returns a &[Cell<T>] from a &Cell<[T]>

Examples

use std::cell::Cell;

let slice: &mut [i32] = &mut [1, 2, 3];
let cell_slice: &Cell<[i32]> = Cell::from_mut(slice);
let slice_cell: &[Cell<i32>] = cell_slice.as_slice_of_cells();

assert_eq!(slice_cell.len(), 3);

pub fn as_array_of_cells(&self) -> &[Cell<T>; N]

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

Returns a &[Cell<T>; N] from a &Cell<[T; N]>

Examples

#![feature(as_array_of_cells)]
use std::cell::Cell;

let mut array: [i32; 3] = [1, 2, 3];
let cell_array: &Cell<[i32; 3]> = Cell::from_mut(&mut array);
let array_cell: &[Cell<i32>; 3] = cell_array.as_array_of_cells();

Trait Implementations

impl<F> AsRef<Cell<Option<F>>> for OnceFn<F>

fn as_ref(&self) -> &Cell<Option<F>>

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

impl<F> Deref for OnceFn<F>

type Target = Cell<Option<F>>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> From<T> for OnceFn<T>

fn from(value: T) -> Self

Converts to this type from the input type.

impl<'js, R, Fun> IntoJsFunc<'js, ()> for OnceFn<Fun>

where Fun: FnOnce() -> R + 'js, (): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A> IntoJsFunc<'js, (A,)> for OnceFn<Fun>

where Fun: FnOnce(A) -> R + 'js, (A,): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B> IntoJsFunc<'js, (A, B)> for OnceFn<Fun>

where Fun: FnOnce(A, B) -> R + 'js, (A, B): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C> IntoJsFunc<'js, (A, B, C)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C) -> R + 'js, (A, B, C): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C, D> IntoJsFunc<'js, (A, B, C, D)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C, D) -> R + 'js, (A, B, C, D): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C, D, E> IntoJsFunc<'js, (A, B, C, D, E)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C, D, E) -> R + 'js, (A, B, C, D, E): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C, D, E, F> IntoJsFunc<'js, (A, B, C, D, E, F)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C, D, E, F) -> R + 'js, (A, B, C, D, E, F): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C, D, E, F, G> IntoJsFunc<'js, (A, B, C, D, E, F, G)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C, D, E, F, G) -> R + 'js, (A, B, C, D, E, F, G): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.

impl<'js, R, Fun, A, B, C, D, E, F, G, H> IntoJsFunc<'js, (A, B, C, D, E, F, G, H)> for OnceFn<Fun>

where Fun: FnOnce(A, B, C, D, E, F, G, H) -> R + 'js, (A, B, C, D, E, F, G, H): FromParams<'js> + 'js, R: IntoJs<'js> + 'js,

fn param_requirements() -> ParamRequirement

Returns the requirements this function has for the set of arguments used to call this function.

fn call(&self, params: Params<'_, 'js>) -> Result<Value<'js>>

Call the function with the given parameters.