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extern crate proc_macro;
use proc_macro::{TokenStream, TokenTree, Group};
fn find_my_ident(tokens: TokenStream) -> Option<TokenStream> {
for token in tokens {
if let TokenTree::Ident(ident) = &token {
if ident.to_string() == "hidden_ident" {
return Some(vec![token].into_iter().collect())
}
} else if let TokenTree::Group(g) = token {
if let Some(stream) = find_my_ident(g.stream()) {
return Some(stream)
}
}
}
return None;
}
#[proc_macro_derive(WeirdDerive)]
pub fn weird_derive(item: TokenStream) -> TokenStream {
let my_ident = find_my_ident(item).expect("Missing 'my_ident'!");
let tokens: TokenStream = "call_it!();".parse().unwrap();
let final_call = tokens.into_iter().map(|tree| {
if let TokenTree::Group(g) = tree {
return Group::new(g.delimiter(), my_ident.clone()).into()
} else {
return tree
}
}).collect();
final_call
}
#[proc_macro]
pub fn recollect(item: TokenStream) -> TokenStream {
item.into_iter().collect()
}
#[proc_macro_attribute]
pub fn recollect_attr(_attr: TokenStream, mut item: TokenStream) -> TokenStream {
item.into_iter().collect()
}
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