Method parse_match_expr

leanr-syntax/src/parser.rs:464–495

Parse match expression

(&mut self)

    /// Parse match expression
    fn parse_match_expr(&mut self) -> crate::Result<Expr> {
        if self.check(&TokenKind::Match) {
            let start = self.advance().span;
            let scrutinee = Box::new(self.parse_app_expr()?);

            self.expect(TokenKind::With)?;

            let mut arms = Vec::new();
            while self.check(&TokenKind::Pipe) {
                self.advance();
                let pattern = self.parse_pattern()?;
                self.expect(TokenKind::FatArrow)?;
                let body = Box::new(self.parse_expr()?);

                arms.push(MatchArm {
                    span: pattern.span().to(body.span()),
                    pattern,
                    body,
                });
            }

            let end = arms.last().map(|a| a.span).unwrap_or(scrutinee.span());

            Ok(Expr::Match {
                span: start.to(end),
                scrutinee,
                arms,
            })
        } else {
            self.parse_app_expr()
        }
    }

    /// Parse application: f x y z
    fn parse_app_expr(&mut self) -> crate::Result<Expr> {