Struct Optional 

pub struct Optional { /* private fields */ }

An optional chain expression, as defined by the spec.

Optional chaining allows for short-circuiting property accesses and function calls, which will return undefined instead of returning an error if the access target or the call is either undefined or null.

An example of optional chaining:

const adventurer = {
  name: 'Alice',
  cat: {
    name: 'Dinah'
  }
};

console.log(adventurer.cat?.name); // Dinah
console.log(adventurer.dog?.name); // undefined

Implementations

impl Optional

pub fn new( target: Expression, chain: Box<[OptionalOperation]>, span: Span, ) -> Optional

Creates a new Optional expression.

pub fn target(&self) -> &Expression

Gets the target of this Optional expression.

pub fn chain(&self) -> &[OptionalOperation]

Gets the chain of accesses and calls that will be applied to the target at runtime.

Trait Implementations

impl Clone for Optional

fn clone(&self) -> Optional

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Optional

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Optional

fn deserialize<__D>( __deserializer: __D, ) -> Result<Optional, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'a> From<&'a Optional> for NodeRef<'a>

fn from(node: &'a Optional) -> NodeRef<'a>

Converts to this type from the input type.

impl<'a> From<&'a mut Optional> for NodeRefMut<'a>

fn from(node: &'a mut Optional) -> NodeRefMut<'a>

Converts to this type from the input type.

impl From<Optional> for Expression

fn from(opt: Optional) -> Expression

Converts to this type from the input type.

impl PartialEq for Optional

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

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

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

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

impl Serialize for Optional

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Spanned for Optional

fn span(&self) -> Span

Returns a span from the current type.

impl ToInternedString for Optional

fn to_interned_string(&self, interner: &Interner) -> String

Converts a given element to a string using an interner.

impl VisitWith for Optional

fn visit_with<'a, V>( &'a self, visitor: &mut V, ) -> ControlFlow<<V as Visitor<'a>>::BreakTy>

where V: Visitor<'a>,

Visit this node with the provided visitor.

fn visit_with_mut<'a, V>( &'a mut self, visitor: &mut V, ) -> ControlFlow<<V as VisitorMut<'a>>::BreakTy>

where V: VisitorMut<'a>,

Visit this node with the provided visitor mutably, allowing the visitor to modify private fields.

impl StructuralPartialEq for Optional