Trait Tracker

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pub(super) trait Tracker<'matcher> {
    // Required methods
    fn prepare(
        &mut self,
        which_matcher: WhichMatcher,
        matcher: &'matcher [MatcherLoc],
    );
    fn before_match_loc(
        &mut self,
        parser: &TtParser,
        matcher: &'matcher MatcherLoc,
    );
    fn matched_one(&mut self, parser: &Parser<'_>, loc_index: usize);
    fn after_arm(
        &mut self,
        result: &ParseResult<FxHashMap<MacroRulesNormalizedIdent, NamedMatch>>,
    );
    fn failure(&mut self, parser: &Parser<'_>);
    fn ambiguity(&mut self, parser: &Parser<'_>);
    fn description() -> &'static str;
    fn recovery() -> Recovery;
}

Required Methods§

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fn prepare( &mut self, which_matcher: WhichMatcher, matcher: &'matcher [MatcherLoc], )

Provide context on the arm that’s about to be matched.

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

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

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fn matched_one(&mut self, parser: &Parser<'_>, loc_index: usize)

A MatcherLoc successfully consumed input from the parser.

This is called for MatcherLoc::Token and MatcherLoc::SequenceSep, which consume single tokens, when they successfully match Parser::token. It is also called for MatcherLoc::MetaVarDecl when non-terminal parsing is guaranteed to occur (i.e. after Parser::nonterminal_may_begin_with() returns true).

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fn after_arm( &mut self, result: &ParseResult<FxHashMap<MacroRulesNormalizedIdent, NamedMatch>>, )

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).

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fn failure(&mut self, parser: &Parser<'_>)

The arm could not be matched successfully.

If the parser is located at token::Eof, it indicates an unexpected end of macro invocation. Otherwise, the parser is located at a token in the middle of the input, and it indicates that no rules in the arm expected the given token.

The parser will return NamedParseResult::Failure after calling this.

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