Enum Nullable

Source

pub enum Nullable<T> {
    Null,
    Value(T),
}

Expand description

A T or null at the JS boundary.

Nullable<T> is the Rust-side type for a JS value of type T | null, as Option<T> is for T | undefined, and Option<Nullable<T>> is the union T | null | undefined. All three are accepted in the same positions: as an argument or return value of exported and imported functions, as a public field of an exported struct, and as a closure argument or return value, including the &/&mut reference forms Option<T> supports.

Type	JS type	JS → Rust	Rust → JS
`Option<T>`	`T \| undefined`	`undefined` and `null` → `None`; anything else goes to `T`’s conversion	`None` → `undefined`
`Nullable<T>`	`T \| null`	`null` → `Null`; anything else, `undefined` included, goes to `T`’s conversion	`Null` → `null`
`Option<Nullable<T>>`	`T \| null \| undefined`	`undefined` → `None`, `null` → `Some(Null)`, else `Some(Value(..))`	`None` → `undefined`, `Some(Null)` → `null`

The Option layer of Option<Nullable<T>> treats only undefined as None, since null has to reach the Nullable layer. opt.and_then(Nullable::value) collapses the union to an Option<T>. No other nesting is supported: Nullable<Nullable<T>>, Nullable<Option<T>> and Option<Option<T>> do not cross the boundary.

Both may also name a slot of a js-sys Function<fn(..)> signature or a Promise<T> resolution. Where a js-sys container’s type-erased methods marshal the element itself, as Array::get and Map::get do, the element must be a handle: use the JS-side JsOption<T> and JsNullable<T> there, which stay JS values rather than converting.

Variants§

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Null

JS null.

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Value(T)

A value.

Enum Nullable Copy item path

Variants§

Null

Value(T)

Implementations§

impl<T> Nullable<T>

pub const fn is_null(&self) -> bool

pub const fn is_value(&self) -> bool

pub const fn as_ref(&self) -> Nullable<&T>

pub fn as_mut(&mut self) -> Nullable<&mut T>

pub fn map<U, F>(self, f: F) -> Nullable<U>where F: FnOnce(T) -> U,

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

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

pub fn unwrap(self) -> T

§Panics

pub fn expect(self, msg: &str) -> T

§Panics

pub fn unwrap_or(self, default: T) -> T

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

pub fn unwrap_or_default(self) -> Twhere T: Default,

pub fn is_value_and(self, f: impl FnOnce(T) -> bool) -> bool

pub fn is_null_or(self, f: impl FnOnce(T) -> bool) -> bool

pub fn ok_or<E>(self, err: E) -> Result<T, E>

pub fn ok_or_else<E, F>(self, err: F) -> Result<T, E>where F: FnOnce() -> E,

pub fn and_then<U, F>(self, f: F) -> Nullable<U>where F: FnOnce(T) -> Nullable<U>,

pub fn filter<P>(self, predicate: P) -> Nullable<T>where P: FnOnce(&T) -> bool,

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

pub fn replace(&mut self, value: T) -> Nullable<T>

pub fn iter(&self) -> IntoIter<&T> ⓘ

pub fn iter_mut(&mut self) -> IntoIter<&mut T> ⓘ

impl<T> Nullable<T>where T: Deref,

pub fn as_deref(&self) -> Nullable<&<T as Deref>::Target>

impl<T> Nullable<T>where T: DerefMut,

pub fn as_deref_mut(&mut self) -> Nullable<&mut <T as Deref>::Target>

impl<T> Nullable<&T>where T: Copy,

pub fn copied(self) -> Nullable<T>

impl<T> Nullable<&T>where T: Clone,

pub fn cloned(self) -> Nullable<T>

impl<T> Nullable<&mut T>where T: Copy,

pub fn copied(self) -> Nullable<T>

impl<T> Nullable<&mut T>where T: Clone,

pub fn cloned(self) -> Nullable<T>

Trait Implementations§

impl<T> Clone for Nullable<T>where T: Clone,

fn clone(&self) -> Nullable<T>

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

impl<T> Copy for Nullable<T>where T: Copy,

impl<T> Debug for Nullable<T>where T: Debug,

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

impl<T> Default for Nullable<T>

fn default() -> Nullable<T>

impl<T> Eq for Nullable<T>where T: Eq,

impl<T> ErasableGeneric for Nullable<T>where T: ErasableGeneric,

type Repr = Nullable<<T as ErasableGeneric>::Repr>

impl<T> From<Nullable<T>> for JsNullable<T>where T: JsGeneric,

fn from(nullable: Nullable<T>) -> JsNullable<T>

impl<T> From<Option<T>> for Nullable<T>

fn from(option: Option<T>) -> Nullable<T>

impl<T> From<T> for Nullable<T>

fn from(value: T) -> Nullable<T>

impl<T> FromWasmAbi for Nullable<T>where T: NullableFromWasmAbi,

type Abi = <T as MaybeFromWasmAbi>::MaybeAbi

unsafe fn from_abi(js: <T as MaybeFromWasmAbi>::MaybeAbi) -> Nullable<T>

impl<T> Hash for Nullable<T>where T: Hash,

fn hash<__H>(&self, state: &mut __H)where __H: Hasher,

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

impl<T> IntoIterator for Nullable<T>

type Item = T

type IntoIter = IntoIter<T>

fn into_iter(self) -> <Nullable<T> as IntoIterator>::IntoIter

impl<'a, T> IntoIterator for &'a Nullable<T>

type Item = &'a T

type IntoIter = IntoIter<&'a T>

fn into_iter(self) -> <&'a Nullable<T> as IntoIterator>::IntoIter

impl<'a, T> IntoIterator for &'a mut Nullable<T>

type Item = &'a mut T

type IntoIter = IntoIter<&'a mut T>

fn into_iter(self) -> <&'a mut Nullable<T> as IntoIterator>::IntoIter

impl<T> IntoWasmAbi for Nullable<T>where T: NullableIntoWasmAbi,

type Abi = <T as MaybeIntoWasmAbi>::MaybeAbi

Enum Nullable

pub fn map<U, F>(self, f: F) -> Nullable<U>
where F: FnOnce(T) -> U,

pub fn unwrap_or_else<F>(self, f: F) -> T
where F: FnOnce() -> T,

pub fn unwrap_or_default(self) -> T
where T: Default,

pub fn ok_or_else<E, F>(self, err: F) -> Result<T, E>
where F: FnOnce() -> E,

pub fn and_then<U, F>(self, f: F) -> Nullable<U>
where F: FnOnce(T) -> Nullable<U>,

pub fn filter<P>(self, predicate: P) -> Nullable<T>
where P: FnOnce(&T) -> bool,

impl<T> Nullable<T>
where T: Deref,

impl<T> Nullable<T>
where T: DerefMut,

impl<T> Nullable<&T>
where T: Copy,

impl<T> Nullable<&T>
where T: Clone,

impl<T> Nullable<&mut T>
where T: Copy,

impl<T> Nullable<&mut T>
where T: Clone,

impl<T> Clone for Nullable<T>
where T: Clone,

impl<T> Copy for Nullable<T>
where T: Copy,

impl<T> Debug for Nullable<T>
where T: Debug,

impl<T> Eq for Nullable<T>
where T: Eq,

impl<T> ErasableGeneric for Nullable<T>
where T: ErasableGeneric,

impl<T> From<Nullable<T>> for JsNullable<T>
where T: JsGeneric,

impl<T> FromWasmAbi for Nullable<T>
where T: NullableFromWasmAbi,

impl<T> Hash for Nullable<T>
where T: Hash,

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

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

impl<T> IntoWasmAbi for Nullable<T>
where T: NullableIntoWasmAbi,

impl<'a, T> IntoWasmAbi for &'a Nullable<T>
where T: WasmDescribe, Nullable<&'a T>: IntoWasmAbi,

impl<T> OptionFromWasmAbi for Nullable<T>
where T: NullableFromWasmAbi,

impl<T> OptionIntoWasmAbi for Nullable<T>
where T: NullableIntoWasmAbi,

impl<'a, T> OptionIntoWasmAbi for &'a Nullable<T>
where T: WasmDescribe, Nullable<&'a T>: OptionIntoWasmAbi,

impl<T> Ord for Nullable<T>
where T: Ord,

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

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

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

fn clamp_to<R>(self, range: R) -> Self
where Self: Sized, R: ClampBounds<Self>,

impl<T> PartialEq for Nullable<T>
where T: PartialEq,

impl<T> PartialOrd for Nullable<T>
where T: PartialOrd,

impl<T> Promising for Nullable<T>
where T: Promising,

impl<T> StructuralPartialEq for Nullable<T>
where T: PartialEq,

impl<T> TryFromJsValue for Nullable<T>
where T: TryFromJsValue,

impl<'a, Target> UpcastFrom<&'a str> for Nullable<Target>
where Target: UpcastFrom<&'a str>,

impl<UpcastWrapTarget> UpcastFrom<AggregateError> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<AggregateError>,

impl<T, UpcastWrapTarget> UpcastFrom<Array<T>> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Array<T>>,

impl<UpcastWrapTarget> UpcastFrom<ArrayBuffer> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<ArrayBuffer>,

impl<UpcastWrapTarget> UpcastFrom<ArrayBufferOptions> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<ArrayBufferOptions>,

impl<UpcastWrapTarget> UpcastFrom<AsyncDisposableStack> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<AsyncDisposableStack>,

impl<T, UpcastWrapTarget> UpcastFrom<AsyncGenerator<T>> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<AsyncGenerator<T>>,

impl<T, UpcastWrapTarget> UpcastFrom<AsyncIterator<T>> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<AsyncIterator<T>>,

impl<UpcastWrapTarget> UpcastFrom<Base64Options> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Base64Options>,

impl<UpcastWrapTarget> UpcastFrom<BigInt64Array> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<BigInt64Array>,

impl<UpcastWrapTarget> UpcastFrom<BigInt> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<BigInt>,

impl<UpcastWrapTarget> UpcastFrom<BigUint64Array> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<BigUint64Array>,

impl<UpcastWrapTarget> UpcastFrom<Boolean> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Boolean>,

impl<UpcastWrapTarget> UpcastFrom<Collator> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Collator>,

impl<UpcastWrapTarget> UpcastFrom<CollatorOptions> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<CollatorOptions>,

impl<UpcastWrapTarget> UpcastFrom<CompileError> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<CompileError>,

impl<UpcastWrapTarget> UpcastFrom<CompileOptions> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<CompileOptions>,

impl<UpcastWrapTarget> UpcastFrom<DataView> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DataView>,

impl<UpcastWrapTarget> UpcastFrom<Date> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Date>,

impl<UpcastWrapTarget> UpcastFrom<DateTimeFormat> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DateTimeFormat>,

impl<UpcastWrapTarget> UpcastFrom<DateTimeFormatOptions> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DateTimeFormatOptions>,

impl<UpcastWrapTarget> UpcastFrom<DateTimeFormatPart> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DateTimeFormatPart>,

impl<UpcastWrapTarget> UpcastFrom<DateTimeRangeFormatPart> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DateTimeRangeFormatPart>,

impl<UpcastWrapTarget> UpcastFrom<DisplayNames> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DisplayNames>,

impl<UpcastWrapTarget> UpcastFrom<DisplayNamesOptions> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DisplayNamesOptions>,

impl<UpcastWrapTarget> UpcastFrom<DisposableStack> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DisposableStack>,

impl<UpcastWrapTarget> UpcastFrom<Duration> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<Duration>,

impl<UpcastWrapTarget> UpcastFrom<DurationFormat> for Nullable<UpcastWrapTarget>
where __UpcastWrapTarget: UpcastFrom<DurationFormat>,