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extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemFn, parse_quote, Block, Expr, Token, punctuated::Punctuated};
use syn::parse::Parser;
#[proc_macro_attribute]
pub fn trace_with(attr: TokenStream, input: TokenStream) -> TokenStream {
let parser = Punctuated::<Expr, Token![,]>::parse_terminated;
let mut with_args: Vec<_> = parser.parse(attr).unwrap().into_iter().collect();
let with: Expr = with_args.remove(0);
let mut input = parse_macro_input!(input as ItemFn);
let fn_name = input.ident.clone();
let inner_block = input.block;
let retty = input.decl.output.clone();
let trace_wrapper: Block = parse_quote! {
{
use ::call_trace::Trace as _;
let __ctx = ::call_trace::CallContext {
file: file!(),
line: line!(),
fn_name: stringify!(#fn_name),
};
#with.on_pre(&__ctx);
let __r = {
let mut __f = || #retty #inner_block;
__f()
};
#with.on_post(&__ctx);
__r
}
};
input.block = Box::new(trace_wrapper);
TokenStream::from(quote! { #input })
}