Struct Maybe

pub struct Maybe<Inner: Parser> { /* private fields */ }

Maybe is a combinator returning Option for a parser returning T, meaning it does not stop parsing if an optional input was not encountered. It is very similar to a Repeat parser with RepeatSpec::Max(1).

Implementations

impl<Inner: Parser> Maybe<Inner>

pub fn new(p: Inner) -> Maybe<Inner>

Trait Implementations

impl<R, P: Parser<Result = R>> Parser for Maybe<P>

type Result = Option<R>

fn parse( &mut self, st: &mut ParseState<impl Iterator<Item = char>>, ) -> ParseResult<Self::Result>

parse consumes input from st and returns a result or an error.

fn apply<R2, F: Fn(Self::Result) -> ParseResult<R2>>( self, f: F, ) -> Transform<Self::Result, R2, Self, F>

where Self: Sized,

apply transforms the result of this parser using a Transform combinator.

fn then<R2, P: Parser<Result = R2>>(self, p: P) -> Then<Self, P>

where Self: Sized,

then attempts to parse input, and if it succeeds, executes parser p, only returning p’s result. This is useful for chaining parsers of which the results are not need.