mirror_ubuntu-kernels/rust/macros/concat_idents.rs

24 lines
712 B
Rust

// SPDX-License-Identifier: GPL-2.0
use proc_macro::{token_stream, Ident, TokenStream, TokenTree};
use crate::helpers::expect_punct;
fn expect_ident(it: &mut token_stream::IntoIter) -> Ident {
if let Some(TokenTree::Ident(ident)) = it.next() {
ident
} else {
panic!("Expected Ident")
}
}
pub(crate) fn concat_idents(ts: TokenStream) -> TokenStream {
let mut it = ts.into_iter();
let a = expect_ident(&mut it);
assert_eq!(expect_punct(&mut it), ',');
let b = expect_ident(&mut it);
assert!(it.next().is_none(), "only two idents can be concatenated");
let res = Ident::new(&format!("{a}{b}"), b.span());
TokenStream::from_iter([TokenTree::Ident(res)])
}