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extern crate proc_macro;
use proc_macro::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
#[proc_macro_attribute]
pub fn timed(_attr_ts: TokenStream, fn_ts: TokenStream) -> TokenStream {
let ast = syn::parse(fn_ts.clone()).unwrap();
let func = match parse_function(ast) {
Ok(f) => f,
Err(stream) => return stream,
};
let mut outer = func.clone();
outer.sig.ident = func.sig.ident.to_owned();
let original_func_name = func.sig.ident.to_string();
let inner_block = &func.block;
let span = outer.sig.ident.span();
let block = quote_spanned! {
span=>
{
let timer = ::std::time::Instant::now();
let mut inner = || { #inner_block };
let ret = inner();
crate::log::trace!(
"Duration of `{}`: {:?}",
#original_func_name,
timer.elapsed()
);
ret
}
};
outer.block = syn::parse(block.into()).unwrap();
(quote! {#outer}).into()
}
fn parse_function(item: syn::Item) -> Result<syn::ItemFn, TokenStream> {
match item {
syn::Item::Fn(func) => Ok(func),
i => Err(quote_spanned! {
i.span()=>
compile_error!("`#[timed]` can only be used on functions");
#i
}
.into()),
}
}