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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 http://mozilla.org/MPL/2.0/. */
extern crate proc_macro;
#[macro_use] extern crate quote;
extern crate syn;
#[proc_macro_derive(DomObject)]
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 type_ = syn::parse_macro_input(input).unwrap();
let fields = if let syn::Body::Struct(syn::VariantData::Struct(ref fields)) = type_.body {
fields
} 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 = &type_.ident;
let (impl_generics, ty_generics, where_clause) = type_.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::jsapi::MutableHandleValue) {
let object = ::dom::bindings::reflector::DomObject::reflector(self).get_jsobject();
object.to_jsval(cx, rval)
}
}
impl #impl_generics ::dom::bindings::reflector::DomObject for #name #ty_generics #where_clause {
#[inline]
fn reflector(&self) -> &::dom::bindings::reflector::Reflector {
self.#first_field_name.reflector()
}
}
impl #impl_generics ::dom::bindings::reflector::MutDomObject for #name #ty_generics #where_clause {
fn init_reflector(&mut self, obj: *mut ::js::jsapi::JSObject) {
self.#first_field_name.init_reflector(obj);
}
}
};
let mut params = quote::Tokens::new();
params.append_separated(type_.generics.ty_params.iter().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 bound = syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: vec![],
trait_ref: syn::parse_path("::dom::bindings::reflector::DomObject").unwrap(),
},
syn::TraitBoundModifier::None
);
let mut generics = type_.generics.clone();
generics.ty_params.push(syn::TyParam {
attrs: vec![],
ident: "__T".into(),
bounds: vec![bound],
default: None,
});
let (impl_generics, _, where_clause) = generics.split_for_impl();
items.append(quote! {
trait ShouldNotImplDomObject {}
impl #impl_generics ShouldNotImplDomObject for ((#params), __T) #where_clause {}
}.as_str());
let dummy_const = syn::Ident::new(format!("_IMPL_DOMOBJECT_FOR_{}", name));
let tokens = quote! {
#[allow(non_upper_case_globals)]
const #dummy_const: () = { #items };
};
tokens.to_string()
}
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