Struct Optional

#[repr(transparent)]
pub struct Optional<T>(pub T);

Wrap a parser in this to make it always succeed and return an Option.

Tuple Fields

0: T

Trait Implementations

impl<T: TokenTreeExt, X: Parser<T>> Parser<T> for Optional<X>

type Output<'p, 'b> = Option<<X as Parser<T>>::Output<'p, 'b>> where Self: 'p

The output type of this parser.

fn parse<'p, 'b>( &'p self, buf: &mut &'b TokenBuf<T>, ) -> Result<Self::Output<'p, 'b>, Error<T::Span>>

Parse a value from a TokenBuf using this parser.

fn parse_all<'p, 'b>( &'p self, buf: &mut &'b TokenBuf<T>, ) -> Result<Self::Output<'p, 'b>, Error<T::Span>>

Parse a value from a TokenBuf buffer, but return an error if there’s any tokens left in the buffer after parsing.

fn optional(self) -> Optional<Self>

where Self: Sized,

Wrap this parser in Optional to make it always succeed and return an option.