/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at
http://mozilla.org/MPL/2.0/. */
#![deny(warnings)]
//! A procedural macro as a syntactical sugar to `gecko_profiler_label!` macro.
//! You can use this macro on top of functions to automatically append the
//! label frame to the function.
//!
//! Example usage:
//! ```rust
//! #[gecko_profiler_fn_label(DOM)]
//! fn foo(bar: u32) -> u32 {
//! bar
//! }
//!
//! #[gecko_profiler_fn_label(Javascript, IonMonkey)]
//! pub fn bar(baz: i8) -> i8 {
//! baz
//! }
//! ```
//!
//! See the documentation of `gecko_profiler_label!` macro to learn more about
//! its parameters.
extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemFn};
#[proc_macro_attribute]
pub fn gecko_profiler_fn_label(attrs: TokenStream, input: TokenStream) -> TokenStream {
let mut attr_args = Vec::new();
let attr_parser = syn::meta::parser(|meta| {
attr_args.push(meta.path);
Ok(())
});
parse_macro_input!(attrs with attr_parser);
let input = parse_macro_input!(input as ItemFn);
if attr_args.is_empty() || attr_args.len() > 2 {
panic!("Expected one or two arguments as ProfilingCategory or ProfilingCategoryPair but {}
arguments provided!", attr_args.len());
}
let category_name = &attr_args[0];
// Try to get the subcategory if possible. Otherwise, use `None`.
let subcategory_if_provided = match attr_args.get(1) {
Some(subcategory) => quote!(, #subcategory),
None => quote!(),
};
let ItemFn {
attrs,
vis,
sig,
block,
} = input;
let stmts = &block.stmts;
let new_fn = quote! {
#(#attrs)* #vis #sig {
gecko_profiler_label!(#category_name#subcategory_if_provided);
#(#stmts)*
}
};
new_fn.into()
}
