Method visit_pattern

crates/ruff_python_parser/src/semantic_errors.rs:2122–2331

(&mut self, pattern: &'a Pattern)

impl<'a, Ctx: SemanticSyntaxContext> MatchPatternVisitor<'a, Ctx> {
    fn visit_pattern(&mut self, pattern: &'a Pattern) {
        // test_ok class_keyword_in_case_pattern
        // match 2:
        //     case Class(x=x): ...

        // test_err multiple_assignment_in_case_pattern
        // match 2:
        //     case [y, z, y]: ...  # MatchSequence
        //     case [y, z, *y]: ...  # MatchSequence
        //     case [y, y, y]: ...  # MatchSequence multiple
        //     case {1: x, 2: x}: ...  # MatchMapping duplicate pattern
        //     case {1: x, **x}: ...  # MatchMapping duplicate in **rest
        //     case Class(x, x): ...  # MatchClass positional
        //     case Class(y=x, z=x): ...  # MatchClass keyword
        //     case [x] | {1: x} | Class(y=x, z=x): ...  # MatchOr
        //     case x as x: ...  # MatchAs

        // test_err multiple_starred_names_in_sequence_pattern
        // match subject:
        //     case *first, *second, *third: ...
        match pattern {
            Pattern::MatchValue(_) | Pattern::MatchSingleton(_) => {}
            Pattern::MatchStar(ast::PatternMatchStar { name, .. }) => {
                if let Some(name) = name {
                    self.insert(name);
                }
            }
            Pattern::MatchSequence(ast::PatternMatchSequence { patterns, .. }) => {
                let mut seen_star_pattern = false;
                for pattern in patterns {
                    if pattern.is_match_star() {
                        if seen_star_pattern {
                            SemanticSyntaxChecker::add_error(
                                self.ctx,
                                SemanticSyntaxErrorKind::MultipleStarredNamesInSequencePattern,
                                pattern.range(),
                            );
                        }
                        seen_star_pattern = true;
                    }
                    self.visit_pattern(pattern);
                }
            }
            Pattern::MatchMapping(ast::PatternMatchMapping {
                keys,
                patterns,
                rest,
                ..
            }) => {
                for pattern in patterns {
                    self.visit_pattern(pattern);
                }
                if let Some(rest) = rest {
                    self.insert(rest);
                }

                let mut seen = FxHashSet::default();
                for key in keys