Macro syn::braced

macro_rules! braced {
    ($content:ident in $cursor:expr) => { ... };
}

Parse a set of curly braces and expose their content to subsequent parsers.

Example

# use quote::quote;
#
use syn::{braced, token, Ident, Result, Token, Type};
use syn::parse::{Parse, ParseStream};
use syn::punctuated::Punctuated;

// Parse a simplified struct syntax like:
//
//     struct S {
//         a: A,
//         b: B,
//     }
struct Struct {
    struct_token: Token![struct],
    ident: Ident,
    brace_token: token::Brace,
    fields: Punctuated<Field, Token![,]>,
}

struct Field {
    name: Ident,
    colon_token: Token![:],
    ty: Type,
}

impl Parse for Struct {
    fn parse(input: ParseStream) -> Result<Self> {
        let content;
        Ok(Struct {
            struct_token: input.parse()?,
            ident: input.parse()?,
            brace_token: braced!(content in input),
            fields: content.parse_terminated(Field::parse)?,
        })
    }
}

impl Parse for Field {
    fn parse(input: ParseStream) -> Result<Self> {
        Ok(Field {
            name: input.parse()?,
            colon_token: input.parse()?,
            ty: input.parse()?,
        })
    }
}
#
# fn main() {
#     let input = quote! {
#         struct S {
#             a: A,
#             b: B,
#         }
#     };
#     syn::parse2::<Struct>(input).unwrap();
# }