#![allow(unused_variables)]
#![allow(unused_must_use)]

use syn::{parse_str, parenthesized, bracketed, braced};
use syn::parse::{Parse, ParseStream, Result};

#[derive(Debug)] struct A {}
#[derive(Debug)] struct B {}
#[derive(Debug)] struct C {}

impl Parse for A {
    fn parse(input: ParseStream) -> Result<A> {
        let content;
        parenthesized!(content in input);
        Ok(A {})
    }
}

impl Parse for B {
    fn parse(input: ParseStream) -> Result<B> {
        let content;
        bracketed!(content in input);
        Ok(B {})
    }
}

impl Parse for C {
    fn parse(input: ParseStream) -> Result<C> {
        let content;
        braced!(content in input);
        Ok(C {})
    }
}

fn main() {
    dbg!(parse_str::<A>(""));
    dbg!(parse_str::<A>("()"));
    dbg!(parse_str::<A>("( )"));
    dbg!(parse_str::<A>("(1)"));
    dbg!(parse_str::<A>("(a)"));
    dbg!(parse_str::<A>("(\"string\")"));

    dbg!(parse_str::<B>(""));
    dbg!(parse_str::<B>("[]"));
    dbg!(parse_str::<B>("[ ]"));
    dbg!(parse_str::<B>("[1]"));
    dbg!(parse_str::<B>("[a]"));
    dbg!(parse_str::<B>("[\"string\"]"));

    dbg!(parse_str::<C>(""));
    dbg!(parse_str::<C>("{}"));
    dbg!(parse_str::<C>("{ }"));
    dbg!(parse_str::<C>("{1}"));
    dbg!(parse_str::<C>("{a}"));
    dbg!(parse_str::<C>("{\"string\"}"));
}