use crate::{Error, Nodes};

use pest::Parser as PestParser;

use pest::RuleType;

/// A trait that provides methods to parse strings.

/// Do not implement manually; instead use the [`parser`] macro provided by this crate.

///

/// [`parser`]: macro@crate::parser

pub trait Parser {

    type Rule: RuleType;

    #[doc(hidden)]

    type AliasedRule: RuleType;

    type Parser: PestParser<Self::Rule>;

    #[doc(hidden)]

    fn rule_alias(rule: Self::Rule) -> Self::AliasedRule;

    #[doc(hidden)]

    fn allows_shortcut(rule: Self::Rule) -> bool;

    /// Parses a `&str` starting from `rule`

    fn parse<'i>(

        rule: Self::Rule,

        input_str: &'i str,

    ) -> Result<Nodes<'i, Self::Rule, ()>, Error<Self::Rule>> {

        Self::parse_with_userdata(rule, input_str, ())

    }

    /// Parses a `&str` starting from `rule`, carrying `user_data` through the parser methods.

    fn parse_with_userdata<'i, D>(

        rule: Self::Rule,

        input_str: &'i str,

        user_data: D,

    ) -> Result<Nodes<'i, Self::Rule, D>, Error<Self::Rule>> {

        let pairs = Self::Parser::parse(rule, input_str)?;

        Ok(Nodes::new(input_str, pairs, user_data))

    }

}