glib_macros/object_impl_attributes/subclass.rs
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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::TokenStream;
use quote::{format_ident, quote, ToTokens};
pub fn impl_object_subclass(input: super::Input) -> TokenStream {
let crate_ident = crate::utils::crate_ident_new();
let super::Input {
attrs,
generics,
trait_path,
self_ty,
unsafety,
items,
meta_dynamic,
} = input;
let register_object_subclass = if let Some(dynamic) = meta_dynamic {
let plugin_ty = dynamic
.plugin_type
.map(|p| p.into_token_stream())
.unwrap_or(quote!(#crate_ident::TypeModule));
register_object_subclass_as_dynamic(
&crate_ident,
&self_ty,
&plugin_ty,
dynamic.lazy_registration,
)
} else {
register_object_subclass_as_static(&crate_ident, &self_ty)
};
let mut has_new = false;
let mut has_parent_type = false;
let mut has_interfaces = false;
let mut has_instance = false;
let mut has_class = false;
for item in items.iter() {
match item {
syn::ImplItem::Fn(method) => {
let name = &method.sig.ident;
if name == "new" || name == "with_class" {
has_new = true;
}
}
syn::ImplItem::Type(type_) => {
let name = &type_.ident;
if name == "ParentType" {
has_parent_type = true;
} else if name == "Interfaces" {
has_interfaces = true;
} else if name == "Instance" {
has_instance = true;
} else if name == "Class" {
has_class = true;
}
}
_ => {}
}
}
let parent_type_opt = (!has_parent_type).then(|| {
quote!(
type ParentType = #crate_ident::Object;
)
});
let interfaces_opt = (!has_interfaces).then(|| {
quote!(
type Interfaces = ();
)
});
let new_opt = (!has_new).then(|| {
quote! {
#[inline]
fn new() -> Self {
::std::default::Default::default()
}
}
});
let class_opt = (!has_class)
.then(|| quote!(type Class = #crate_ident::subclass::basic::ClassStruct<Self>;));
let instance_opt = (!has_instance)
.then(|| quote!(type Instance = #crate_ident::subclass::basic::InstanceStruct<Self>;));
quote! {
#(#attrs)*
#unsafety impl #generics #trait_path for #self_ty {
#parent_type_opt
#interfaces_opt
#class_opt
#instance_opt
#new_opt
#(#items)*
}
unsafe impl #crate_ident::subclass::types::ObjectSubclassType for #self_ty {
#[inline]
fn type_data() -> ::std::ptr::NonNull<#crate_ident::subclass::TypeData> {
static mut DATA: #crate_ident::subclass::TypeData =
#crate_ident::subclass::types::TypeData::new();
unsafe { ::std::ptr::NonNull::new_unchecked(::std::ptr::addr_of_mut!(DATA)) }
}
#[inline]
fn type_() -> #crate_ident::Type {
Self::register_type();
unsafe {
let data = Self::type_data();
let type_ = data.as_ref().type_();
type_
}
}
}
#register_object_subclass
#[doc(hidden)]
impl #crate_ident::subclass::types::FromObject for #self_ty {
type FromObjectType = <Self as #crate_ident::subclass::types::ObjectSubclass>::Type;
#[inline]
fn from_object(obj: &Self::FromObjectType) -> &Self {
<Self as #crate_ident::subclass::types::ObjectSubclassExt>::from_obj(obj)
}
}
#[doc(hidden)]
impl #crate_ident::clone::Downgrade for #self_ty {
type Weak = #crate_ident::subclass::ObjectImplWeakRef<#self_ty>;
#[inline]
fn downgrade(&self) -> Self::Weak {
let ref_counted = #crate_ident::subclass::prelude::ObjectSubclassExt::ref_counted(self);
#crate_ident::clone::Downgrade::downgrade(&ref_counted)
}
}
impl #self_ty {
#[inline]
pub fn downgrade(&self) -> <Self as #crate_ident::clone::Downgrade>::Weak {
#crate_ident::clone::Downgrade::downgrade(self)
}
}
#[doc(hidden)]
impl ::std::borrow::ToOwned for #self_ty {
type Owned = #crate_ident::subclass::ObjectImplRef<#self_ty>;
#[inline]
fn to_owned(&self) -> Self::Owned {
#crate_ident::subclass::prelude::ObjectSubclassExt::ref_counted(self)
}
}
#[doc(hidden)]
impl ::std::borrow::Borrow<#self_ty> for #crate_ident::subclass::ObjectImplRef<#self_ty> {
#[inline]
fn borrow(&self) -> &#self_ty {
self
}
}
}
}
// Registers the object subclass as a static type.
fn register_object_subclass_as_static(
crate_ident: &TokenStream,
self_ty: &syn::Ident,
) -> TokenStream {
// registers the object subclass on first use (lazy registration).
quote! {
impl #self_ty {
/// Registers the type only once.
#[inline]
fn register_type() {
static ONCE: ::std::sync::Once = ::std::sync::Once::new();
ONCE.call_once(|| {
#crate_ident::subclass::register_type::<Self>();
})
}
}
}
}
// The following implementations follows the lifecycle of plugins and of dynamic types (see [`TypePluginExt`] and [`TypeModuleExt`]).
// An object subclass can be reregistered as a dynamic type.
fn register_object_subclass_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 subclass can be reregistered as a dynamic type.
if lazy_registration {
// registers the object subclass 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 subclass.
// this implementation relies on a static storage of a weak reference on the plugin and of the GLib type to know if the object subclass 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 subclass 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 subclass is already registered as a dynamic type.
#[inline]
fn register_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 subclass cannot be registered as a dynamic type.
None => (),
// plugin has been used and the object subclass 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_type::<#plugin_ty, Self>(&(type_plugin.upgrade().unwrap()));
},
// plugin has been used and the object subclass has already been registered as a dynamic type.
Some(_) => ()
}
}
/// Depending on the plugin lifecycle state and on the registration status of the object subclass:
/// 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 subclass has been already registered as a dynamic type, reregisters it.
/// An object subclass can be reregistered several times as a dynamic type.
/// If plugin is reused (and has reloaded the implementation) and the object subclass 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 subclass 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 subclass 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_type::<#plugin_ty, Self>(type_plugin);
type_.is_valid()
},
// plugin has been used at least one time but the object subclass 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 subclass:
/// If plugin has been used (or reused) but the object subclass 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 subclass 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 subclass has not been registered yet as a dynamic type, so cancels the postponed registration.
Some(_) => {
*registration_status = None;
true
}
}
}
}
}
} else {
// registers immediately the object subclass as a dynamic type.
quote! {
impl #self_ty {
/// Do nothing as the object subclass has been registered on implementation load.
#[inline]
fn register_type() { }
/// Registers the object subclass as a dynamic type within the plugin.
/// The object subclass can be registered several times as a dynamic type.
#[inline]
pub fn on_implementation_load(type_plugin: &#plugin_ty) -> bool {
let type_ = #crate_ident::subclass::register_dynamic_type::<#plugin_ty, Self>(type_plugin);
type_ != #crate_ident::Type::INVALID
}
/// Do nothing as object subclasses registered as dynamic types are never unregistered.
#[inline]
pub fn on_implementation_unload(type_plugin_: &#plugin_ty) -> bool {
true
}
}
}
}
}