use lalrpop_util::ErrorRecovery;
use crate::bnf::{Syntax, Rule, Expression, List, Term};

grammar<'env>(errors: &'env mut Vec<ErrorRecovery<usize, Token<'input>, &'static str>>);

extern {
    type Location = usize;
    type Error = &'static str;
}

pub Syntax: Syntax = {
    <Rule> => Syntax::from_rule(<>),
    <head: Rule> <tail: Syntax> => Syntax::from_rule(head).with_more(tail),
};

Rule: Rule = {
    ";"* "<" <lhs: RuleName> ">" "::=" <rhs: Expression> ";" => Rule::new(lhs, rhs),
};

Expression: Expression = {
    <List> => Expression::from_list(<>),
    <head: List> "|" <tail: Expression> => Expression::from_list(head).with_more(tail),
};

List: List = {
    <Term> => List::from_term(<>),
    <head: Term> <tail: List> => List::from_term(head).with_more(tail),
};

Term: Term = {
    <Literal> => Term::new_literal(<>).unwrap(),
    "<" <RuleName> ">" => Term::new_rule_name(<>),
};

Literal: String = r#""([^\\"]|\\")+""# => <>.to_owned();

RuleName: String = r#"[A-Za-z][A-Za-z0-9-]*"# => <>.to_owned();