65 lines
2.1 KiB
Rust
65 lines
2.1 KiB
Rust
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use std::{any::TypeId, alloc::Layout, cell::{RefCell, Ref, RefMut}, ptr::NonNull, alloc};
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/// Shorthand for `Send + Sync + 'static`, so it never needs to be implemented manually.
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/* pub trait Resource: Send + Sync + 'static {}
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impl<T: Send + Sync + 'static> Resource for T {} */
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/// A type erased storage for a Resource.
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///
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/// A pointer instead of a generic is used since Rust may have no idea of the type of the data.
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pub struct ResourceData {
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data: RefCell<NonNull<u8>>,
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type_id: TypeId,
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layout: Layout,
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}
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impl ResourceData {
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pub fn new<T: 'static>(mut data: T) -> Self {
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let layout = Layout::new::<T>();
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let ptr = unsafe {
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if let Some(ptr) = NonNull::new(alloc::alloc(layout)) {
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let data = (&mut data as *mut T) as *mut u8; // thx i hate it
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std::ptr::copy_nonoverlapping(data, ptr.as_ptr(), 1);
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ptr
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} else {
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alloc::handle_alloc_error(layout)
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}
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};
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Self {
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data: RefCell::new(ptr),
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type_id: TypeId::of::<T>(),
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layout,
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}
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}
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/// Returns a boolean indicating whether or not T is of the same type that is inside this Resource
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pub fn is<T: 'static>(&self) -> bool {
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self.type_id == TypeId::of::<T>()
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}
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/// Borrow the data inside of the resource.
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///
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/// # Safety
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///
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/// If the type of T is not the same as the expected type, it will panic.
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pub fn get<'a, T: 'static>(&'a self) -> Ref<'a, T> {
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assert!(TypeId::of::<T>() == self.type_id);
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let data = self.data.borrow();
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Ref::map(data, |ptr| unsafe { &*ptr.cast().as_ptr() })
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}
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/// Mutably borrow the data inside of the resource.
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///
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/// # Safety
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///
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/// If the type of T is not the same as the expected type, it will panic.
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pub fn get_mut<'a, T: 'static>(&'a self) -> RefMut<'a, T> {
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assert!(TypeId::of::<T>() == self.type_id);
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let data = self.data.borrow_mut();
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RefMut::map(data, |ptr| unsafe { &mut *ptr.cast().as_ptr() })
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}
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}
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