use syn::parse::{ParseBuffer, ParseStream, Result};
use syn::token::{Brace, Bracket, Paren};
use syn::{braced, bracketed, parenthesized, MacroDelimiter};

fn parse(input: ParseStream) -> Result<()> {
    let (_delim, _content) = input.call(macro_delimiter)?;
    Ok(())
}

fn macro_delimiter<'a>(input: ParseStream<'a>) -> Result<(MacroDelimiter, ParseBuffer<'a>)> {
    let content;
    let lookahead = input.lookahead1();
    let delim = if input.peek(Paren) {
        MacroDelimiter::Paren(parenthesized!(content in input))
    } else if input.peek(Brace) {
        MacroDelimiter::Brace(braced!(content in input))
    } else if input.peek(Bracket) {
        MacroDelimiter::Bracket(bracketed!(content in input))
    } else {
        return Err(lookahead.error());
    };
    Ok((delim, content))
}