39 lines
1.1 KiB
Rust
39 lines
1.1 KiB
Rust
extern crate proc_macro;
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use proc_macro::*;
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#[proc_macro]
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pub fn a_proc_macro(_item: TokenStream) -> TokenStream {
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"fn ex() { foobar::f(); }".parse().unwrap()
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}
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// inserts foobar::f() to the end of the function
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#[proc_macro_attribute]
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pub fn an_attr_macro(attr: TokenStream, item: TokenStream) -> TokenStream {
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let new_call: TokenStream = "foobar::f();".parse().unwrap();
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let mut tokens = item.into_iter();
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let fn_tok = tokens.next().unwrap();
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let ident_tok = tokens.next().unwrap();
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let args_tok = tokens.next().unwrap();
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let body = match tokens.next().unwrap() {
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TokenTree::Group(g) => {
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let new_g = Group::new(g.delimiter(), new_call);
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let mut outer_g = Group::new(
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g.delimiter(),
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[TokenTree::Group(g.clone()), TokenTree::Group(new_g)].into_iter().collect(),
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);
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if attr.to_string() == "with_span" {
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outer_g.set_span(g.span());
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}
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TokenTree::Group(outer_g)
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}
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_ => unreachable!(),
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};
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let tokens = vec![fn_tok, ident_tok, args_tok, body].into_iter().collect::<TokenStream>();
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tokens
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}
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