Struct OptionCell

pub struct OptionCell<T> { /* private fields */ }

An equivalent of std::cell::OnceCell or once_cell::unsync::OnceCell with an additional transmute helper. To guarantee the helper’s safety, it is defined as a different type from the original OnceCell.

Implementations

impl<T> OptionCell<T>

pub const fn new() -> Self

Creates a new empty cell.

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

Gets the reference to the underlying value. Returns None if the cell is empty.

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

Gets the mutable reference to the underlying Option.

Unlike the original OnceCell, this method returns a mutable reference to the whole Option, as the layout is guaranteed.

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

Sets the contents of this cell to value.

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

where F: FnOnce() -> T,

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

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

Consumes the cell, returning the wrapped Option.

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

Takes the value out of this cell, leaving it empty.

pub fn from_mut(slice: &mut Option<T>) -> &mut Self

Converts an existing mutable reference into OptionCell.

pub fn from_mut_slice(slice: &mut [Option<T>]) -> &mut [Self]

Converts an existing mutable slice into a slice of OptionCell.

Trait Implementations

impl<T> Clone for OptionCell<T>

where T: Clone,

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for OptionCell<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Default for OptionCell<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> From<Option<T>> for OptionCell<T>

fn from(opt: Option<T>) -> Self

Converts to this type from the input type.

impl<T> From<OptionCell<T>> for Option<T>

fn from(cell: OptionCell<T>) -> Self

Converts to this type from the input type.

impl<T> PartialEq for OptionCell<T>

where T: PartialEq<T>,

fn eq(&self, other: &Self) -> bool

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

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

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