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/* 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 https://mozilla.org/MPL/2.0/. */
#![recursion_limit = "128"]
use quote::{quote, TokenStreamExt};
use syn::parse_quote;
#[proc_macro_derive(DomObject)]
pub fn expand_token_stream(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = syn::parse(input).unwrap();
expand_dom_object(input).into()
}
fn expand_dom_object(input: syn::DeriveInput) -> proc_macro2::TokenStream {
let fields = if let syn::Data::Struct(syn::DataStruct { ref fields, .. }) = input.data {
fields.iter().collect::<Vec<&syn::Field>>()
} else {
panic!("#[derive(DomObject)] should only be applied on proper structs")
};
let (first_field, fields) = fields
.split_first()
.expect("#[derive(DomObject)] should not be applied on empty structs");
let first_field_name = first_field.ident.as_ref().unwrap();
let mut field_types = vec![];
for field in fields {
if !field_types.contains(&&field.ty) {
field_types.push(&field.ty);
}
}
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
let mut items = quote! {
impl #impl_generics ::js::conversions::ToJSValConvertible for #name #ty_generics #where_clause {
#[allow(unsafe_code)]
unsafe fn to_jsval(&self,
cx: *mut js::jsapi::JSContext,
rval: js::rust::MutableHandleValue) {
let object = crate::dom::bindings::reflector::DomObject::reflector(self).get_jsobject();
object.to_jsval(cx, rval)
}
}
impl #impl_generics crate::dom::bindings::reflector::DomObject for #name #ty_generics #where_clause {
#[inline]
fn reflector(&self) -> &crate::dom::bindings::reflector::Reflector {
self.#first_field_name.reflector()
}
}
impl #impl_generics crate::dom::bindings::reflector::MutDomObject for #name #ty_generics #where_clause {
unsafe fn init_reflector(&self, obj: *mut js::jsapi::JSObject) {
self.#first_field_name.init_reflector(obj);
}
}
};
let mut params = proc_macro2::TokenStream::new();
params.append_separated(input.generics.type_params().map(|param| ¶m.ident), ", ");
// For each field in the struct, we implement ShouldNotImplDomObject for a
// pair of all the type parameters of the DomObject and and the field type.
// This allows us to support parameterized DOM objects
// such as IteratorIterable<T>.
items.append_all(field_types.iter().map(|ty| {
quote! {
impl #impl_generics ShouldNotImplDomObject for ((#params), #ty) #where_clause {}
}
}));
let mut generics = input.generics.clone();
generics.params.push(parse_quote!(
__T: crate::dom::bindings::reflector::DomObject
));
let (impl_generics, _, where_clause) = generics.split_for_impl();
items.append_all(quote! {
trait ShouldNotImplDomObject {}
impl #impl_generics ShouldNotImplDomObject for ((#params), __T) #where_clause {}
});
let dummy_const = syn::Ident::new(
&format!("_IMPL_DOMOBJECT_FOR_{}", name),
proc_macro2::Span::call_site(),
);
let tokens = quote! {
#[allow(non_upper_case_globals)]
const #dummy_const: () = { #items };
};
tokens
}
|
