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winit-core: new crate + split out as_any

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This commit is contained in:
Kirill Chibisov 2025-05-01 19:25:15 +09:00
parent bf0bde8067
commit 3493a20173
8 changed files with 73 additions and 4 deletions
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70
src/utils.rs
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@ -1,70 +0,0 @@
use std::any::Any;
// NOTE: This is `pub`, but isn't actually exposed outside the crate.
// NOTE: Marked as `#[doc(hidden)]` and underscored, because they can be quite difficult to use
// correctly, see discussion in #4160.
// FIXME: Remove and replace with a coercion once rust-lang/rust#65991 is in MSRV (1.86).
#[doc(hidden)]
pub trait AsAny: Any {
#[doc(hidden)]
fn __as_any(&self) -> &dyn Any;
#[doc(hidden)]
fn __as_any_mut(&mut self) -> &mut dyn Any;
#[doc(hidden)]
fn __into_any(self: Box<Self>) -> Box<dyn Any>;
}
impl<T: Any> AsAny for T {
#[inline(always)]
fn __as_any(&self) -> &dyn Any {
self
}
#[inline(always)]
fn __as_any_mut(&mut self) -> &mut dyn Any {
self
}
#[inline(always)]
fn __into_any(self: Box<Self>) -> Box<dyn Any> {
self
}
}
macro_rules! impl_dyn_casting {
($trait:ident) => {
impl dyn $trait + '_ {
/// Downcast to the backend concrete type.
///
/// Returns `None` if the object was not from that backend.
pub fn cast_ref<T: $trait>(&self) -> Option<&T> {
let this: &dyn std::any::Any = self.__as_any();
this.downcast_ref::<T>()
}
/// Mutable downcast to the backend concrete type.
///
/// Returns `None` if the object was not from that backend.
pub fn cast_mut<T: $trait>(&mut self) -> Option<&mut T> {
let this: &mut dyn std::any::Any = self.__as_any_mut();
this.downcast_mut::<T>()
}
/// Owned downcast to the backend concrete type.
///
/// Returns `Err` with `self` if the object was not from that backend.
pub fn cast<T: $trait>(self: Box<Self>) -> Result<Box<T>, Box<Self>> {
let reference: &dyn std::any::Any = self.__as_any();
if reference.is::<T>() {
let this: Box<dyn std::any::Any> = self.__into_any();
// Unwrap is okay, we just checked the type of `self` is `T`.
Ok(this.downcast::<T>().unwrap())
} else {
Err(self)
}
}
}
};
}
pub(crate) use impl_dyn_casting;