use std::str::FromStr;

use pest::Span;
use pest::iterators::Pair;
use pest::error::{Error,ErrorVariant};


pub trait PairExt<R> where R: pest::RuleType {
	fn parse<T, E>(&self) -> Result<T, Error<R>> where T: FromStr<Err = E>, E: ToString;
}

impl<'l, R> PairExt<R> for Pair<'l, R> where R: pest::RuleType {
	fn parse<T, E>(&self) -> Result<T, Error<R>> where T: FromStr<Err = E>, E: ToString {
		self.as_str().parse().map_err(|e| to_parse_error(self.as_span(), &e))
	}
}

pub(crate) fn to_parse_error<E, R>(span: Span, e: &E) -> Error<R> where E: ToString, R: pest::RuleType {
	let var: ErrorVariant<R> = ErrorVariant::CustomError { message: e.to_string() };
	Error::new_from_span(var, span)
}