parsing_test.rs

Test grammar:
glurp_grammar! {
    R: String => { Optional(R) ~ Char('R') } on {|opt, r| {
        if Some(acc) = opt {
            push(r); 
            acc
        } else {
            String::new()
        }
    }};
}

Test:
let mut parser = Parser::new();
parser.start_from(R);
println!("{:#?}", parser.parse("RRRRRR"));

Result:
Ok(
    [
        Node {
            rule: 1,
            alt: 0,
            children: [
                Node {
                    rule: 2,
                    alt: 0,
                    children: [
                        Node {
                            rule: 1,
                            alt: 0,
                            children: [
                                Node {
                                    rule: 2,
                                    alt: 0,
                                    children: [
                                        Node {
                                            rule: 1,
                                            alt: 0,
                                            children: [
                                                Node {
                                                    rule: 2,
                                                    alt: 0,
                                                    children: [
                                                        Node {
                                                            rule: 1,
                                                            alt: 0,
                                                            children: [
                                                                Node {
                                                                    rule: 2,
                                                                    alt: 0,
                                                                    children: [
                                                                        Node {
                                                                            rule: 1,
                                                                            alt: 0,
                                                                            children: [
                                                                                Node {
                                                                                    rule: 2,
                                                                                    alt: 0,
                                                                                    children: [
                                                                                        Node {
                                                                                            rule: 1,
                                                                                            alt: 0,
                                                                                            children: [
                                                                                                EmptyNode,
                                                                                                Node {
                                                                                                    rule: 3,
                                                                                                    alt: 0,
                                                                                                    children: [
                                                                                                        Leaf(
                                                                                                            'R'
                                                                                                        )
                                                                                                    ]
                                                                                                }
                                                                                            ]
                                                                                        }
                                                                                    ]
                                                                                },
                                                                                Node {
                                                                                    rule: 3,
                                                                                    alt: 0,
                                                                                    children: [
                                                                                        Leaf(
                                                                                            'R'
                                                                                        )
                                                                                    ]
                                                                                }
                                                                            ]
                                                                        }
                                                                    ]
                                                                },
                                                                Node {
                                                                    rule: 3,
                                                                    alt: 0,
                                                                    children: [
                                                                        Leaf(
                                                                            'R'
                                                                        )
                                                                    ]
                                                                }
                                                            ]
                                                        }
                                                    ]
                                                },
                                                Node {
                                                    rule: 3,
                                                    alt: 0,
                                                    children: [
                                                        Leaf(
                                                            'R'
                                                        )
                                                    ]
                                                }
                                            ]
                                        }
                                    ]
                                },
                                Node {
                                    rule: 3,
                                    alt: 0,
                                    children: [
                                        Leaf(
                                            'R'
                                        )
                                    ]
                                }
                            ]
                        }
                    ]
                },
                Node {
                    rule: 3,
                    alt: 0,
                    children: [
                        Leaf(
                            'R'
                        )
                    ]
                }
            ]
        }
    ]
)