tetsy_util_mem_derive/
lib.rs

1// Copyright 2020 Parity Technologies
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9//! A crate for deriving the MallocSizeOf trait.
10//!
11//! This is a copy of Servo malloc_size_of_derive code, modified to work with
12//! our `tetsy_util_mem` library
13
14extern crate proc_macro2;
15#[macro_use]
16extern crate syn;
17#[macro_use]
18extern crate synstructure;
19
20#[cfg(not(test))]
21decl_derive!([MallocSizeOf, attributes(ignore_malloc_size_of)] => malloc_size_of_derive);
22
23fn malloc_size_of_derive(s: synstructure::Structure) -> proc_macro2::TokenStream {
24	let match_body = s.each(|binding| {
25		let ignore = binding.ast().attrs.iter().any(|attr| match attr.parse_meta().unwrap() {
26			syn::Meta::Path(ref path) | syn::Meta::List(syn::MetaList { ref path, .. })
27				if path.is_ident("ignore_malloc_size_of") =>
28			{
29				panic!(
30					"#[ignore_malloc_size_of] should have an explanation, \
31					 e.g. #[ignore_malloc_size_of = \"because reasons\"]"
32				);
33			}
34			syn::Meta::NameValue(syn::MetaNameValue { ref path, .. }) if path.is_ident("ignore_malloc_size_of") => true,
35			_ => false,
36		});
37		if ignore {
38			None
39		} else if let syn::Type::Array(..) = binding.ast().ty {
40			Some(quote! {
41				for item in #binding.iter() {
42					sum += tetsy_util_mem::MallocSizeOf::size_of(item, ops);
43				}
44			})
45		} else {
46			Some(quote! {
47				sum += tetsy_util_mem::MallocSizeOf::size_of(#binding, ops);
48			})
49		}
50	});
51
52	let ast = s.ast();
53	let name = &ast.ident;
54	let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
55	let mut where_clause = where_clause.unwrap_or(&parse_quote!(where)).clone();
56	for param in ast.generics.type_params() {
57		let ident = &param.ident;
58		where_clause.predicates.push(parse_quote!(#ident: tetsy_util_mem::MallocSizeOf));
59	}
60
61	let tokens = quote! {
62		impl #impl_generics tetsy_util_mem::MallocSizeOf for #name #ty_generics #where_clause {
63			#[inline]
64			#[allow(unused_variables, unused_mut, unreachable_code)]
65			fn size_of(&self, ops: &mut tetsy_util_mem::MallocSizeOfOps) -> usize {
66				let mut sum = 0;
67				match *self {
68					#match_body
69				}
70				sum
71			}
72		}
73	};
74
75	tokens
76}
tetsy_util_mem_derive/lib.rs

tetsy_util_mem_derive/
lib.rs
