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// Copyright 2016-2017 The Servo Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! A crate for deriving the MallocSizeOf trait.
extern crate proc_macro2;
#[macro_use]
extern crate syn;
#[macro_use]
extern crate synstructure;
#[cfg(not(test))]
decl_derive!([MallocSizeOf, attributes(ignore_malloc_size_of, conditional_malloc_size_of)] => malloc_size_of_derive);
fn malloc_size_of_derive(s: synstructure::Structure) -> proc_macro2::TokenStream {
let match_body = s.each(|binding| {
let mut ignore = false;
let mut conditional = false;
for attr in binding.ast().attrs.iter() {
match attr.meta {
syn::Meta::Path(ref path) | syn::Meta::List(syn::MetaList { ref path, .. }) => {
assert!(
!path.is_ident("ignore_malloc_size_of"),
"#[ignore_malloc_size_of] should have an explanation, \
e.g. #[ignore_malloc_size_of = \"because reasons\"]"
);
if path.is_ident("conditional_malloc_size_of") {
conditional = true;
}
}
syn::Meta::NameValue(syn::MetaNameValue { ref path, .. }) => {
if path.is_ident("ignore_malloc_size_of") {
ignore = true;
}
if path.is_ident("conditional_malloc_size_of") {
conditional = true;
}
}
}
}
assert!(
!ignore || !conditional,
"ignore_malloc_size_of and conditional_malloc_size_of are incompatible"
);
if ignore {
return None;
}
let path = if conditional {
quote! { ::malloc_size_of::MallocConditionalSizeOf::conditional_size_of }
} else {
quote! { ::malloc_size_of::MallocSizeOf::size_of }
};
if let syn::Type::Array(..) = binding.ast().ty {
Some(quote! {
for item in #binding.iter() {
sum += #path(item, ops);
}
})
} else {
Some(quote! {
sum += #path(#binding, ops);
})
}
});
let ast = s.ast();
let name = &ast.ident;
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let mut where_clause = where_clause.unwrap_or(&parse_quote!(where)).clone();
for param in ast.generics.type_params() {
let ident = ¶m.ident;
where_clause
.predicates
.push(parse_quote!(#ident: ::malloc_size_of::MallocSizeOf));
}
let tokens = quote! {
impl #impl_generics ::malloc_size_of::MallocSizeOf for #name #ty_generics #where_clause {
#[inline]
#[allow(unused_variables, unused_mut, unreachable_code)]
fn size_of(&self, ops: &mut ::malloc_size_of::MallocSizeOfOps) -> usize {
let mut sum = 0;
match *self {
#match_body
}
sum
}
}
};
tokens
}
#[test]
fn test_struct() {
let source = syn::parse_str(
"struct Foo<T> { bar: Bar, baz: T, #[ignore_malloc_size_of = \"\"] z: Arc<T> }",
)
.unwrap();
let source = synstructure::Structure::new(&source);
let expanded = malloc_size_of_derive(source).to_string();
let mut no_space = expanded.replace(" ", "");
macro_rules! match_count {
($e: expr, $count: expr) => {
assert_eq!(
no_space.matches(&$e.replace(" ", "")).count(),
$count,
"counting occurences of {:?} in {:?} (whitespace-insensitive)",
$e,
expanded
)
};
}
match_count!("struct", 0);
match_count!("ignore_malloc_size_of", 0);
match_count!("impl<T> ::malloc_size_of::MallocSizeOf for Foo<T> where T: ::malloc_size_of::MallocSizeOf {", 1);
match_count!("sum += ::malloc_size_of::MallocSizeOf::size_of(", 2);
let source = syn::parse_str("struct Bar([Baz; 3]);").unwrap();
let source = synstructure::Structure::new(&source);
let expanded = malloc_size_of_derive(source).to_string();
no_space = expanded.replace(" ", "");
match_count!("for item in", 1);
}
#[should_panic(expected = "should have an explanation")]
#[test]
fn test_no_reason() {
let input = syn::parse_str("struct A { #[ignore_malloc_size_of] b: C }").unwrap();
malloc_size_of_derive(synstructure::Structure::new(&input));
}