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#[cfg(not(test))] extern crate proc_macro;
#[macro_use] extern crate quote;
extern crate syn;
extern crate synstructure;
#[cfg(not(test))]
#[proc_macro_derive(HeapSizeOf, attributes(ignore_heap_size_of))]
pub fn expand_token_stream(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
expand_string(&input.to_string()).parse().unwrap()
}
fn expand_string(input: &str) -> String {
let mut type_ = syn::parse_macro_input(input).unwrap();
let style = synstructure::BindStyle::Ref.into();
let match_body = synstructure::each_field(&mut type_, &style, |binding| {
let ignore = binding.field.attrs.iter().any(|attr| match attr.value {
syn::MetaItem::Word(ref ident) |
syn::MetaItem::List(ref ident, _) if ident == "ignore_heap_size_of" => {
panic!("#[ignore_heap_size_of] should have an explanation, \
e.g. #[ignore_heap_size_of = \"because reasons\"]");
}
syn::MetaItem::NameValue(ref ident, _) if ident == "ignore_heap_size_of" => {
true
}
_ => false,
});
if ignore {
None
} else if let syn::Ty::Array(..) = binding.field.ty {
Some(quote! {
for item in #binding.iter() {
sum += ::heapsize::HeapSizeOf::heap_size_of_children(item);
}
})
} else {
Some(quote! {
sum += ::heapsize::HeapSizeOf::heap_size_of_children(#binding);
})
}
});
let name = &type_.ident;
let (impl_generics, ty_generics, where_clause) = type_.generics.split_for_impl();
let mut where_clause = where_clause.clone();
for param in &type_.generics.ty_params {
where_clause.predicates.push(syn::WherePredicate::BoundPredicate(syn::WhereBoundPredicate {
bound_lifetimes: Vec::new(),
bounded_ty: syn::Ty::Path(None, param.ident.clone().into()),
bounds: vec![syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: Vec::new(),
trait_ref: syn::parse_path("::heapsize::HeapSizeOf").unwrap(),
},
syn::TraitBoundModifier::None
)],
}))
}
let tokens = quote! {
impl #impl_generics ::heapsize::HeapSizeOf for #name #ty_generics #where_clause {
#[inline]
#[allow(unused_variables, unused_mut, unreachable_code)]
fn heap_size_of_children(&self) -> usize {
let mut sum = 0;
match *self {
#match_body
}
sum
}
}
};
tokens.to_string()
}
#[test]
fn test_struct() {
let mut source = "struct Foo<T> { bar: Bar, baz: T, #[ignore_heap_size_of = \"\"] z: Arc<T> }";
let mut expanded = expand_string(source);
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_heap_size_of", 0);
match_count!("impl<T> ::heapsize::HeapSizeOf for Foo<T> where T: ::heapsize::HeapSizeOf {", 1);
match_count!("sum += ::heapsize::HeapSizeOf::heap_size_of_children(", 2);
source = "struct Bar([Baz; 3]);";
expanded = expand_string(source);
no_space = expanded.replace(" ", "");
match_count!("for item in", 1);
}
#[should_panic(expected = "should have an explanation")]
#[test]
fn test_no_reason() {
expand_string("struct A { #[ignore_heap_size_of] b: C }");
}