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