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use proc_macro2::TokenStream;
use proc_macro_error::abort_call_site;
use quote::quote;
pub const WRONG_PLACE_MSG: &str =
"This macro should be used on `impl` block for `glib::ObjectInterface` trait";
pub fn impl_object_interface(input: &syn::ItemImpl) -> TokenStream {
let mut has_prerequisites = false;
for item in &input.items {
if let syn::ImplItem::Type(type_) = item {
let name = type_.ident.to_string();
if name == "Prerequisites" {
has_prerequisites = true;
}
}
}
let syn::ItemImpl {
attrs,
generics,
trait_,
self_ty,
unsafety,
items,
..
} = &input;
let prerequisites_opt = if has_prerequisites {
None
} else {
Some(quote!(
type Prerequisites = ();
))
};
let crate_ident = crate::utils::crate_ident_new();
let trait_path = match &trait_ {
Some(path) => &path.1,
None => abort_call_site!(WRONG_PLACE_MSG),
};
quote! {
#(#attrs)*
#unsafety impl#generics #trait_path for #self_ty {
#prerequisites_opt
#(#items)*
}
unsafe impl #crate_ident::subclass::interface::ObjectInterfaceType for #self_ty {
fn type_() -> #crate_ident::Type {
static ONCE: std::sync::Once = std::sync::Once::new();
static mut TYPE: #crate_ident::Type = #crate_ident::Type::INVALID;
ONCE.call_once(|| {
let type_ = #crate_ident::subclass::register_interface::<Self>();
unsafe {
TYPE = type_;
}
});
unsafe {
assert!(TYPE.is_valid());
TYPE
}
}
}
}
}