Trait rustc_expand::mbe::macro_rules::Tracker

pub(super) trait Tracker<'matcher> {
    type Failure;

    // Required methods
    fn build_failure(
        tok: Token,
        position: usize,
        msg: &'static str
    ) -> Self::Failure;
    fn description() -> &'static str;

    // Provided methods
    fn before_match_loc(
        &mut self,
        _parser: &TtParser,
        _matcher: &'matcher MatcherLoc
    ) { ... }
    fn after_arm(
        &mut self,
        _result: &ParseResult<FxHashMap<MacroRulesNormalizedIdent, NamedMatch>, Self::Failure>
    ) { ... }
    fn recovery() -> Recovery { ... }
}

Required Associated Types

type Failure

The contents of ParseResult::Failure.

Required Methods

fn build_failure( tok: Token, position: usize, msg: &'static str ) -> Self::Failure

Arm failed to match. If the token is token::Eof, it indicates an unexpected end of macro invocation. Otherwise, it indicates that no rules expected the given token. The usize is the approximate position of the token in the input token stream.

fn description() -> &'static str

For tracing.

Provided Methods

fn before_match_loc( &mut self, _parser: &TtParser, _matcher: &'matcher MatcherLoc )

This is called before trying to match next MatcherLoc on the current token.

fn after_arm( &mut self, _result: &ParseResult<FxHashMap<MacroRulesNormalizedIdent, NamedMatch>, Self::Failure> )

This is called after an arm has been parsed, either successfully or unsuccessfully. When this is called, before_match_loc was called at least once (with a MatcherLoc::Eof).

fn recovery() -> Recovery

Object Safety

This trait is not object safe.

Implementors

impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx, 'matcher>

type Failure = (Token, usize, &'static str)

impl<'matcher> Tracker<'matcher> for FailureForwarder

type Failure = (Token, usize, &'static str)

impl<'matcher> Tracker<'matcher> for NoopTracker

type Failure = ()