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use proc_macro::TokenStream;
use quote::quote;
use syn::{parse::Nothing, Block, ItemFn};
#[proc_macro_attribute]
pub fn expose_caller_modpath(attr: TokenStream, input: TokenStream) -> TokenStream {
syn::parse_macro_input!(attr as Nothing);
let proc_err = syn::Error::new(
proc_macro::Span::call_site().into(),
"#[expose_caller_modpath] can only be used on #[proc_macro_attribute] functions",
)
.to_compile_error()
.into();
match syn::parse::<ItemFn>(input) {
Err(_) => proc_err,
Ok(input) => {
if !input
.attrs
.clone()
.into_iter()
.any(|attr| attr.path.is_ident("proc_macro_attribute"))
{
return proc_err;
}
let mut inject = syn::parse2::<Block>(quote! {{
if std::env::var(caller_modpath::UUID_ENV_VAR_NAME).is_ok() {
return caller_modpath::gen_second_pass();
}
caller_modpath::gen_first_pass(env!("CARGO_CRATE_NAME"));
}})
.unwrap();
let attrs = input.attrs;
let vis = input.vis;
let sig = input.sig;
let mut block = input.block;
inject.stmts.append(&mut block.stmts);
(quote! {
#(#attrs)*
#vis #sig
#inject
})
.into()
}
}
}