jdm.rs

#![allow(dead_code)]

struct Tokenizer<'t>(&'t str);

struct ParserInput<'t>(Tokenizer<'t>);

struct Parser<'i: 't, 't> {
    tokenizer: &'t mut ParserInput<'i>,
}

enum ParseError<'i, E> {
    Foo(&'i str),
    Custom(E),
}

impl<'i: 't, 't> Parser<'i, 't> {
    fn parse_comma_separated<T, F, E>(&mut self, parse_one: F) -> Result<T, ParseError<'i, E>>
    where F: for<'ttt> FnMut(&mut Parser<'i, 'ttt>) -> Result<T, ParseError<'i, E>> {
        self.parse_until_before(parse_one)
    }

    fn parse_entirely<T, F, E>(&mut self, parse: F) -> Result<T, ParseError<'i, E>>
    where F: FnOnce(&mut Parser<'i, 't>) -> Result<T, ParseError<'i, E>> {
        parse(self)
    }
}

trait ParseUntilBefore<'i> {
    fn parse_until_before<T, F, E>(&mut self, parse: F) -> Result<T, ParseError<'i, E>>
        where F: for<'ttt> FnOnce(&mut Parser<'i, 'ttt>) -> Result<T, ParseError<'i, E>>;
}

impl<'i, 't> ParseUntilBefore<'i> for Parser<'i, 't> {
    fn parse_until_before<T, F, E>(&mut self, parse: F) -> Result<T, ParseError<'i, E>>
        where F: for<'ttt> FnOnce(&mut Parser<'i, 'ttt>) -> Result<T, ParseError<'i, E>>
    {
        let result;
        // Introduce a new scope to limit duration of nested_parser’s borrow
        {
            let mut delimited_parser = Parser {
                tokenizer: self.tokenizer,
            };
            result = delimited_parser.parse_entirely(parse);
        }
        result
    }
}

struct DeclarationListParser<'i: 't, 't: 'a, 'a> {
    input: &'a mut Parser<'i, 't>,
}

impl<'i: 't, 't: 'a, 'a> DeclarationListParser<'i, 't, 'a> {
    fn foo(&mut self) {
        let _: Result<(), ParseError<()>> = self.input.parse_until_before(|_input| Ok(()));
    }
}

trait Foo {
    type Error;
}

enum SelectorError<'i> {
    Foo(&'i str),
}

fn parse<'i, 't>(input: &mut Parser<'i, 't>)
                 -> Result<(), ParseError<'i, SelectorError<'i>>>
{
    input.parse_comma_separated(|input| parse_selector(input))
}

fn parse_selector<'i, 't>(_input: &mut Parser<'i, 't>)
                          -> Result<(), ParseError<'i, SelectorError<'i>>>
{
    Ok(())
}

trait QualifiedRuleParserResult<'i> {
    type Prelude;
    type Error;
}

trait QualifiedRuleParser<'i, 't>: QualifiedRuleParserResult<'i> {
    fn parse_prelude(&mut self, _input: &mut Parser<'i, 't>)
                     -> Result<Self::Prelude, ParseError<'i, Self::Error>>;
}

impl<'i> QualifiedRuleParserResult<'i> for () {
    type Prelude = ();
    type Error = SelectorError<'i>;
}

impl<'i, 't> QualifiedRuleParser<'i, 't> for () {
    fn parse_prelude(&mut self, input: &mut Parser<'i, 't>)
                         -> Result<Self::Prelude, ParseError<'i, Self::Error>> {
        Err(ParseError::Foo(""))
    }
}

fn parse_qualified_rule<'i: 't, 't, P, E>(input: &mut Parser<'i, 't>, parser: &mut P)
                                          -> Result<P::Prelude, ParseError<'i, E>>
    where P: for<'ttt> QualifiedRuleParser<'i, 'ttt, Error = E>,
          P: QualifiedRuleParserResult<'i, Error = E>,
{
    <Parser<'i, 't> as ParseUntilBefore<'i>>::parse_until_before(input, |input| {
        parser.parse_prelude(input)
    })
}

fn main() {
}