glib_macros/flags_attribute.rs
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// Take a look at the license at the top of the repository in the LICENSE file.
use heck::{ToKebabCase, ToShoutySnakeCase, ToUpperCamelCase};
use proc_macro2::TokenStream;
use quote::{format_ident, quote, quote_spanned, ToTokens};
use syn::{
punctuated::Punctuated, spanned::Spanned, token::Comma, Attribute, Ident, Variant, Visibility,
};
use crate::utils::{
crate_ident_new, parse_nested_meta_items, parse_optional_nested_meta_items, NestedMetaItem,
};
pub const WRONG_PLACE_MSG: &str = "#[glib::flags] only supports enums";
pub struct AttrInput {
pub enum_name: syn::LitStr,
pub allow_name_conflict: bool,
}
struct FlagsDesc {
variant: Variant,
name: Option<String>,
nick: Option<String>,
skip: bool,
}
impl FlagsDesc {
fn from_attrs(variant: Variant, attrs: &[Attribute]) -> syn::Result<Self> {
let mut name = NestedMetaItem::<syn::LitStr>::new("name").value_required();
let mut nick = NestedMetaItem::<syn::LitStr>::new("nick").value_required();
let mut skip = NestedMetaItem::<syn::LitBool>::new("skip").value_optional();
parse_nested_meta_items(attrs, "flags_value", &mut [&mut name, &mut nick, &mut skip])?;
Ok(Self {
variant,
name: name.value.map(|s| s.value()),
nick: nick.value.map(|s| s.value()),
skip: skip.found || skip.value.map(|b| b.value()).unwrap_or(false),
})
}
}
// Generate glib::gobject_ffi::GFlagsValue structs mapping the enum such as:
// glib::gobject_ffi::GFlagsValue {
// value: MyFlags::A.bits(),
// value_name: "The Name\0" as *const _ as *const _,
// value_nick: "nick\0" as *const _ as *const _,
// },
fn gen_flags_values(
enum_name: &Ident,
enum_variants: &Punctuated<Variant, Comma>,
) -> (TokenStream, usize) {
let crate_ident = crate_ident_new();
// start at one as GFlagsValue array is null-terminated
let mut n = 1;
let recurse = enum_variants
.iter()
.map(|v| FlagsDesc::from_attrs(v.clone(), &v.attrs).unwrap())
.filter(|desc| !desc.skip)
.map(|desc| {
let v = desc.variant;
let name = &v.ident;
let mut value_name = name.to_string().to_upper_camel_case();
let mut value_nick = name.to_string().to_kebab_case();
if let Some(n) = desc.name {
value_name = n;
}
if let Some(n) = desc.nick {
value_nick = n;
}
let value_name = format!("{value_name}\0");
let value_nick = format!("{value_nick}\0");
n += 1;
quote_spanned! {v.span()=>
#crate_ident::gobject_ffi::GFlagsValue {
value: #enum_name::#name.bits(),
value_name: #value_name as *const _ as *const _,
value_nick: #value_nick as *const _ as *const _,
},
}
});
(
quote! {
#(#recurse)*
},
n,
)
}
fn gen_bitflags(
enum_name: &Ident,
visibility: &Visibility,
enum_variants: &Punctuated<Variant, Comma>,
crate_ident: &TokenStream,
) -> TokenStream {
let recurse = enum_variants.iter().map(|v| {
let name = &v.ident;
let disc = v.discriminant.as_ref().expect("missing discriminant");
let value = &disc.1;
quote_spanned! {v.span()=>
const #name = #value;
}
});
quote! {
#crate_ident::bitflags::bitflags! {
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
#visibility struct #enum_name: u32 {
#(#recurse)*
}
}
}
}
fn gen_default(
enum_name: &Ident,
enum_variants: &Punctuated<Variant, Comma>,
) -> Option<TokenStream> {
enum_variants
.iter()
.find(|v| v.attrs.iter().any(|attr| attr.path().is_ident("default")))
.map(|v| {
let default_value = &v.ident;
quote! {
impl Default for #enum_name {
fn default() -> Self {
Self::from_bits_retain(#enum_name::#default_value.bits())
}
}
}
})
}
pub fn impl_flags(attr_meta: AttrInput, input: &mut syn::ItemEnum) -> TokenStream {
let gtype_name = attr_meta.enum_name;
let syn::ItemEnum {
attrs,
ident: name,
vis: visibility,
..
} = input;
let enum_variants = &input.variants;
let (g_flags_values, nb_flags_values) = gen_flags_values(name, enum_variants);
let crate_ident = crate_ident_new();
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,
"flags_dynamic",
&mut [&mut plugin_type, &mut lazy_registration],
);
let register_flags = match found {
Err(e) => return e.to_compile_error(),
Ok(None) => register_flags_as_static(
&crate_ident,
name,
gtype_name,
attr_meta.allow_name_conflict,
g_flags_values,
nb_flags_values,
),
Ok(Some(_)) => {
if attr_meta.allow_name_conflict {
return syn::Error::new_spanned(
input,
"#[flags_dynamic] and #[glib::flags(allow_name_conflict)] are not allowed together",
).to_compile_error();
}
// remove attribute 'flags_dynamic' from the attribute list because it is not a real proc_macro_attribute
attrs.retain(|attr| !attr.path().is_ident("flags_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_flags_as_dynamic(
&crate_ident,
plugin_ty,
lazy_registration,
name,
gtype_name,
g_flags_values,
nb_flags_values,
)
}
};
let bitflags = gen_bitflags(name, visibility, enum_variants, &crate_ident);
let default_impl = gen_default(name, enum_variants);
quote! {
#bitflags
#default_impl
impl #crate_ident::translate::IntoGlib for #name {
type GlibType = u32;
#[inline]
fn into_glib(self) -> u32 {
self.bits()
}
}
impl #crate_ident::translate::FromGlib<u32> for #name {
#[inline]
unsafe fn from_glib(value: u32) -> Self {
Self::from_bits_truncate(value)
}
}
impl #crate_ident::value::ValueType for #name {
type Type = Self;
}
unsafe impl<'a> #crate_ident::value::FromValue<'a> for #name {
type Checker = #crate_ident::value::GenericValueTypeChecker<Self>;
#[inline]
unsafe fn from_value(value: &'a #crate_ident::value::Value) -> Self {
#crate_ident::translate::from_glib(#crate_ident::gobject_ffi::g_value_get_flags(
#crate_ident::translate::ToGlibPtr::to_glib_none(value).0
))
}
}
impl #crate_ident::value::ToValue for #name {
#[inline]
fn to_value(&self) -> #crate_ident::value::Value {
let mut value = #crate_ident::value::Value::for_value_type::<Self>();
unsafe {
#crate_ident::gobject_ffi::g_value_set_flags(
#crate_ident::translate::ToGlibPtrMut::to_glib_none_mut(&mut value).0,
#crate_ident::translate::IntoGlib::into_glib(*self)
)
}
value
}
#[inline]
fn value_type(&self) -> #crate_ident::Type {
<Self as #crate_ident::prelude::StaticType>::static_type()
}
}
impl #crate_ident::HasParamSpec for #name {
type ParamSpec = #crate_ident::ParamSpecFlags;
type SetValue = Self;
type BuilderFn = fn(&::core::primitive::str) -> #crate_ident::ParamSpecFlagsBuilder<Self>;
fn param_spec_builder() -> Self::BuilderFn {
|name| Self::ParamSpec::builder(name)
}
}
impl ::std::convert::From<#name> for #crate_ident::Value {
#[inline]
fn from(v: #name) -> Self {
#crate_ident::value::ToValue::to_value(&v)
}
}
impl #crate_ident::prelude::StaticType for #name {
#[inline]
fn static_type() -> #crate_ident::Type {
Self::register_flags()
}
}
#register_flags
}
}
// Registers the flags as a static type.
fn register_flags_as_static(
crate_ident: &TokenStream,
name: &syn::Ident,
gtype_name: syn::LitStr,
allow_name_conflict: bool,
g_flags_values: TokenStream,
nb_flags_values: usize,
) -> TokenStream {
let type_name_snippet = if allow_name_conflict {
quote! {
unsafe {
let mut i = 0;
loop {
let type_name = ::std::ffi::CString::new(if i == 0 {
#gtype_name
} else {
format!("{}-{}", #gtype_name, i)
})
.unwrap();
if #crate_ident::gobject_ffi::g_type_from_name(type_name.as_ptr()) == #crate_ident::gobject_ffi::G_TYPE_INVALID
{
break type_name;
}
i += 1;
}
}
}
} else {
quote! {
unsafe {
let type_name = ::std::ffi::CString::new(#gtype_name).unwrap();
assert_eq!(
#crate_ident::gobject_ffi::g_type_from_name(type_name.as_ptr()),
#crate_ident::gobject_ffi::G_TYPE_INVALID,
"Type {} has already been registered",
type_name.to_str().unwrap()
);
type_name
}
}
};
// registers the flags on first use (lazy registration).
quote! {
impl #name {
/// Registers the flags only once.
#[inline]
fn register_flags() -> #crate_ident::Type {
static TYPE: ::std::sync::OnceLock<#crate_ident::Type> = ::std::sync::OnceLock::new();
*TYPE.get_or_init(|| {
static mut VALUES: [#crate_ident::gobject_ffi::GFlagsValue; #nb_flags_values] = [
#g_flags_values
#crate_ident::gobject_ffi::GFlagsValue {
value: 0,
value_name: ::std::ptr::null(),
value_nick: ::std::ptr::null(),
},
];
let type_name = #type_name_snippet;
unsafe {
let type_ = #crate_ident::gobject_ffi::g_flags_register_static(type_name.as_ptr(), VALUES.as_ptr());
let type_: #crate_ident::Type = #crate_ident::translate::from_glib(type_);
assert!(type_.is_valid());
type_
}
})
}
}
}
}
// The following implementations follows the lifecycle of plugins and of dynamic types (see [`TypePluginExt`] and [`TypeModuleExt`]).
// Flags can be reregistered as a dynamic type.
fn register_flags_as_dynamic(
crate_ident: &TokenStream,
plugin_ty: TokenStream,
lazy_registration: bool,
name: &syn::Ident,
gtype_name: syn::LitStr,
g_flags_values: TokenStream,
nb_flags_values: usize,
) -> TokenStream {
// Wrap each GFlagsValue to FlagsValue
let g_flags_values_expr: syn::ExprArray = syn::parse_quote! { [#g_flags_values] };
let flags_values_iter = g_flags_values_expr.elems.iter().map(|v| {
quote_spanned! {syn::spanned::Spanned::span(&v)=>
#crate_ident::FlagsValue::unsafe_from(#v),
}
});
let flags_values = quote! {
#crate_ident::enums::FlagsValuesStorage<#nb_flags_values> = unsafe {
#crate_ident::enums::FlagsValuesStorage::<#nb_flags_values>::new([
#(#flags_values_iter)*
])
}
};
// The following implementations follows the lifecycle of plugins and of dynamic types (see [`TypePluginExt`] and [`TypeModuleExt`]).
// Flags can be reregistered as a dynamic type.
if lazy_registration {
// registers the flags 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 flags.
// this implementation relies on a static storage of a weak reference on the plugin and of the GLib type to know if the flags have been registered.
// the registration status type.
let registration_status_type = format_ident!("{}RegistrationStatus", name);
// name of the static variable to store the registration status.
let registration_status = format_ident!(
"{}",
registration_status_type.to_string().to_shouty_snake_case()
);
// name of the static array to store the flags values.
let flags_values_array =
format_ident!("{}_VALUES", name.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);
/// Array of `FlagsValue` for the possible flags values.
static #flags_values_array: #flags_values;
impl #name {
/// Registers the flags 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 flags are already registered as a dynamic type.
#[inline]
fn register_flags() -> #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 flags cannot be registered as a dynamic type.
None => #crate_ident::Type::INVALID,
// plugin has been used and the flags have not been registered yet, so registers tem as a dynamic type.
Some(#registration_status_type(type_plugin, type_)) if !type_.is_valid() => {
*type_ = <#plugin_ty as glib::prelude::DynamicObjectRegisterExt>::register_dynamic_flags(type_plugin.upgrade().unwrap().as_ref(), #gtype_name, #flags_values_array.as_ref());
*type_
},
// plugin has been used and the flags have 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 flags:
/// 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 flags have been already registered as a dynamic type, reregisters them.
/// Flags can be reregistered several times as a dynamic type.
/// If plugin is reused (and has reloaded the implementation) and the flags have 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 flags 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 flags have been registered as a dynamic type at least one time, so re-registers them.
Some(#registration_status_type(_, type_)) if type_.is_valid() => {
*type_ = <#plugin_ty as glib::prelude::DynamicObjectRegisterExt>::register_dynamic_flags(type_plugin, #gtype_name, #flags_values_array.as_ref());
type_.is_valid()
},
// plugin has been used at least one time but the flags have 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 flags:
/// If plugin has been used (or reused) but the flags have 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 flags have 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 flags have not been registered yet as a dynamic type, so cancels the postponed registration.
Some(_) => {
*registration_status = None;
true
}
}
}
}
}
} else {
// registers immediately the flags as a dynamic type.
// name of the static variable to store the GLib type.
let gtype_status = format_ident!("{}_G_TYPE", name.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 #name {
/// Do nothing as the flags has been registered on implementation load.
#[inline]
fn register_flags() -> #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 flags as a dynamic type within the plugin.
/// The flags can be registered several times as a dynamic type.
#[inline]
pub fn on_implementation_load(type_plugin: &#plugin_ty) -> bool {
static VALUES: #flags_values;
let gtype = #crate_ident::translate::IntoGlib::into_glib(<#plugin_ty as glib::prelude::DynamicObjectRegisterExt>::register_dynamic_flags(type_plugin, #gtype_name, VALUES.as_ref()));
#gtype_status.store(gtype, ::std::sync::atomic::Ordering::Release);
gtype != #crate_ident::gobject_ffi::G_TYPE_INVALID
}
/// Do nothing as flags registered as dynamic types are never unregistered.
#[inline]
pub fn on_implementation_unload(type_plugin_: &#plugin_ty) -> bool {
true
}
}
}
}
}