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// Take a look at the license at the top of the repository in the LICENSE file.
use heck::ToShoutySnakeCase;
use proc_macro2::{Span, TokenStream};
use quote::{format_ident, quote, ToTokens};
use crate::utils::{parse_optional_nested_meta_items, NestedMetaItem};
pub const WRONG_PLACE_MSG: &str =
"This macro should be used on `impl` block for `glib::ObjectInterface` trait";
pub fn impl_object_interface(input: &mut syn::ItemImpl) -> syn::Result<TokenStream> {
let crate_ident = crate::utils::crate_ident_new();
let syn::ItemImpl {
attrs,
generics,
trait_,
self_ty,
unsafety,
items,
..
} = input;
let self_ty_as_ident = match &**self_ty {
syn::Type::Path(syn::TypePath { path, .. }) => path.require_ident(),
_ => Err(syn::Error::new_spanned(
&self_ty,
"expected this path to be an identifier",
)),
}?;
let mut plugin_type = NestedMetaItem::<syn::Path>::new("plugin_type").value_required();
let mut lazy_registration =
NestedMetaItem::<syn::LitBool>::new("lazy_registration").value_required();
let found = parse_optional_nested_meta_items(
&*attrs,
"object_interface_dynamic",
&mut [&mut plugin_type, &mut lazy_registration],
)?;
let register_object_interface = match found {
None => register_object_interface_as_static(&crate_ident, self_ty_as_ident),
Some(_) => {
// remove attribute 'object_interface_dynamic' from the attribute list because it is not a real proc_macro_attribute
attrs.retain(|attr| !attr.path().is_ident("object_interface_dynamic"));
let plugin_ty = plugin_type
.value
.map(|p| p.into_token_stream())
.unwrap_or(quote!(#crate_ident::TypeModule));
let lazy_registration = lazy_registration.value.map(|b| b.value).unwrap_or_default();
register_object_interface_as_dynamic(
&crate_ident,
self_ty_as_ident,
plugin_ty,
lazy_registration,
)
}
};
let mut has_prerequisites = false;
for item in items.iter() {
if let syn::ImplItem::Type(type_) = item {
let name = type_.ident.to_string();
if name == "Prerequisites" {
has_prerequisites = true;
}
}
}
let prerequisites_opt = if has_prerequisites {
None
} else {
Some(quote!(
type Prerequisites = ();
))
};
let trait_path = &trait_
.as_ref()
.ok_or_else(|| syn::Error::new(Span::call_site(), WRONG_PLACE_MSG))?
.1;
Ok(quote! {
#(#attrs)*
#unsafety impl #generics #trait_path for #self_ty {
#prerequisites_opt
#(#items)*
}
unsafe impl #crate_ident::subclass::interface::ObjectInterfaceType for #self_ty {
#[inline]
fn type_() -> #crate_ident::Type {
Self::register_interface()
}
}
#register_object_interface
})
}
// Registers the object interface as a static type.
fn register_object_interface_as_static(
crate_ident: &TokenStream,
self_ty: &syn::Ident,
) -> TokenStream {
// registers the interface on first use (lazy registration).
quote! {
impl #self_ty {
/// Registers the interface only once.
#[inline]
fn register_interface() -> #crate_ident::Type {
static TYPE: ::std::sync::OnceLock<#crate_ident::Type> = ::std::sync::OnceLock::new();
*TYPE.get_or_init(|| unsafe {
#crate_ident::subclass::register_interface::<Self>()
})
}
}
}
}
// The following implementations follows the lifecycle of plugins and of dynamic types (see [`TypePluginExt`] and [`TypeModuleExt`]).
// An object interface can be reregistered as a dynamic type.
fn register_object_interface_as_dynamic(
crate_ident: &TokenStream,
self_ty: &syn::Ident,
plugin_ty: TokenStream,
lazy_registration: bool,
) -> TokenStream {
// The following implementations follows the lifecycle of plugins and of dynamic types (see [`TypePluginExt`] and [`TypeModuleExt`]).
// An object interface can be reregistered as a dynamic type.
if lazy_registration {
// registers the object interface as a dynamic type on the first use (lazy registration).
// a weak reference on the plugin is stored and will be used later on the first use of the object interface.
// this implementation relies on a static storage of a weak reference on the plugin and of the GLib type to know if the object interface has been registered.
// the registration status type.
let registration_status_type = format_ident!("{}RegistrationStatus", self_ty);
// name of the static variable to store the registration status.
let registration_status = format_ident!(
"{}",
registration_status_type.to_string().to_shouty_snake_case()
);
quote! {
/// The registration status type: a tuple of the weak reference on the plugin and of the GLib type.
struct #registration_status_type(<#plugin_ty as #crate_ident::clone::Downgrade>::Weak, #crate_ident::Type);
unsafe impl Send for #registration_status_type {}
/// The registration status protected by a mutex guarantees so that no other threads are concurrently accessing the data.
static #registration_status: ::std::sync::Mutex<Option<#registration_status_type>> = ::std::sync::Mutex::new(None);
impl #self_ty {
/// Registers the object interface as a dynamic type within the plugin only once.
/// Plugin must have been used at least once.
/// Do nothing if plugin has never been used or if the object interface is already registered as a dynamic type.
#[inline]
fn register_interface() -> #crate_ident::Type {
let mut registration_status = #registration_status.lock().unwrap();
match ::std::ops::DerefMut::deref_mut(&mut registration_status) {
// plugin has never been used, so the object interface cannot be registered as a dynamic type.
None => #crate_ident::Type::INVALID,
// plugin has been used and the object interface has not been registered yet, so registers it as a dynamic type.
Some(#registration_status_type(type_plugin, type_)) if !type_.is_valid() => {
*type_ = #crate_ident::subclass::register_dynamic_interface::<#plugin_ty, Self>(&(type_plugin.upgrade().unwrap()));
*type_
},
// plugin has been used and the object interface has already been registered as a dynamic type.
Some(#registration_status_type(_, type_)) => *type_
}
}
/// Depending on the plugin lifecycle state and on the registration status of the object interface:
/// If plugin is used (and has loaded the implementation) for the first time, postpones the registration and stores a weak reference on the plugin.
/// If plugin is reused (and has reloaded the implementation) and the object interface has been already registered as a dynamic type, reregisters it.
/// An object interface can be reregistered several times as a dynamic type.
/// If plugin is reused (and has reloaded the implementation) and the object interface has not been registered yet as a dynamic type, do nothing.
#[inline]
pub fn on_implementation_load(type_plugin: &#plugin_ty) -> bool {
let mut registration_status = #registration_status.lock().unwrap();
match ::std::ops::DerefMut::deref_mut(&mut registration_status) {
// plugin has never been used (this is the first time), so postpones registration of the object interface as a dynamic type on the first use.
None => {
*registration_status = Some(#registration_status_type(#crate_ident::clone::Downgrade::downgrade(type_plugin), #crate_ident::Type::INVALID));
true
},
// plugin has been used at least one time and the object interface has been registered as a dynamic type at least one time, so re-registers it.
Some(#registration_status_type(_, type_)) if type_.is_valid() => {
*type_ = #crate_ident::subclass::register_dynamic_interface::<#plugin_ty, Self>(type_plugin);
type_.is_valid()
},
// plugin has been used at least one time but the object interface has not been registered yet as a dynamic type, so keeps postponed registration.
Some(_) => {
true
}
}
}
/// Depending on the plugin lifecycle state and on the registration status of the object interface:
/// If plugin has been used (or reused) but the object interface has not been registered yet as a dynamic type, cancels the postponed registration by deleting the weak reference on the plugin.
/// Else do nothing.
#[inline]
pub fn on_implementation_unload(type_plugin_: &#plugin_ty) -> bool {
let mut registration_status = #registration_status.lock().unwrap();
match ::std::ops::DerefMut::deref_mut(&mut registration_status) {
// plugin has never been used, so unload implementation is unexpected.
None => false,
// plugin has been used at least one time and the object interface has been registered as a dynamic type at least one time.
Some(#registration_status_type(_, type_)) if type_.is_valid() => true,
// plugin has been used at least one time but the object interface has not been registered yet as a dynamic type, so cancels the postponed registration.
Some(_) => {
*registration_status = None;
true
}
}
}
}
}
} else {
// registers immediately the object interface as a dynamic type.
// name of the static variable to store the GLib type.
let gtype_status = format_ident!("{}_G_TYPE", self_ty.to_string().to_shouty_snake_case());
quote! {
/// The GLib type which can be safely shared between threads.
static #gtype_status: ::std::sync::atomic::AtomicUsize = ::std::sync::atomic::AtomicUsize::new(#crate_ident::gobject_ffi::G_TYPE_INVALID);
impl #self_ty {
/// Do nothing as the object interface has been registered on implementation load.
#[inline]
fn register_interface() -> #crate_ident::Type {
let gtype = #gtype_status.load(::std::sync::atomic::Ordering::Acquire);
unsafe { <#crate_ident::Type as #crate_ident::translate::FromGlib<#crate_ident::ffi::GType>>::from_glib(gtype) }
}
/// Registers the object interface as a dynamic type within the plugin.
/// The object interface can be registered several times as a dynamic type.
#[inline]
pub fn on_implementation_load(type_plugin: &#plugin_ty) -> bool {
let gtype = #crate_ident::translate::IntoGlib::into_glib(#crate_ident::subclass::register_dynamic_interface::<#plugin_ty, Self>(type_plugin));
#gtype_status.store(gtype, ::std::sync::atomic::Ordering::Release);
gtype != #crate_ident::gobject_ffi::G_TYPE_INVALID
}
/// Do nothing as object interfaces registered as dynamic types are never unregistered.
#[inline]
pub fn on_implementation_unload(type_plugin_: &#plugin_ty) -> bool {
true
}
}
}
}
}