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// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
use crate::alloc::vec::Vec;
use core::any::{type_name, TypeId};
use core::ptr::NonNull;
use core::{fmt, mem};
use crate::archetype::TypeInfo;
use crate::Component;
/// A dynamically typed collection of components
///
/// Bundles composed of exactly the same types are semantically equivalent, regardless of order. The
/// interface of this trait, except `has` is a private implementation detail.
#[allow(clippy::missing_safety_doc)]
pub unsafe trait DynamicBundle {
/// Returns a `TypeId` uniquely identifying the set of components, if known
#[doc(hidden)]
fn key(&self) -> Option<TypeId> {
None
}
/// Checks if the Bundle contains the given `T`:
///
/// ```
/// # use hecs::DynamicBundle;
///
/// let my_bundle = (0i32, 10.0f32);
/// assert!(my_bundle.has::<i32>());
/// assert!(my_bundle.has::<f32>());
/// assert!(!my_bundle.has::<usize>());
/// ```
fn has<T: Component>(&self) -> bool {
self.with_ids(|types| types.contains(&TypeId::of::<T>()))
}
/// Invoke a callback on the fields' type IDs, sorted by descending alignment then id
#[doc(hidden)]
fn with_ids<T>(&self, f: impl FnOnce(&[TypeId]) -> T) -> T;
/// Obtain the fields' TypeInfos, sorted by descending alignment then id
#[doc(hidden)]
fn type_info(&self) -> Vec<TypeInfo>;
/// Allow a callback to move all components out of the bundle
///
/// Must invoke `f` only with a valid pointer and the pointee's type and size.
#[doc(hidden)]
unsafe fn put(self, f: impl FnMut(*mut u8, TypeInfo));
}
/// A statically typed collection of components
///
/// Bundles composed of exactly the same types are semantically equivalent, regardless of order. The
/// interface of this trait is a private implementation detail.
#[allow(clippy::missing_safety_doc)]
pub unsafe trait Bundle: DynamicBundle {
#[doc(hidden)]
fn with_static_ids<T>(f: impl FnOnce(&[TypeId]) -> T) -> T;
/// Obtain the fields' TypeInfos, sorted by descending alignment then id
#[doc(hidden)]
fn with_static_type_info<T>(f: impl FnOnce(&[TypeInfo]) -> T) -> T;
/// Construct `Self` by moving components out of pointers fetched by `f`
///
/// # Safety
///
/// `f` must produce pointers to the expected fields. The implementation must not read from any
/// pointers if any call to `f` returns `None`.
#[doc(hidden)]
unsafe fn get(f: impl FnMut(TypeInfo) -> Option<NonNull<u8>>) -> Result<Self, MissingComponent>
where
Self: Sized;
}
/// A dynamically typed collection of cloneable components
#[allow(clippy::missing_safety_doc)]
pub unsafe trait DynamicBundleClone: DynamicBundle {
/// Allow a callback to move all components out of the bundle
///
/// Must invoke `f` only with a valid pointer, the pointee's type and size, and a `DynamicClone`
/// constructed for the pointee's type.
#[doc(hidden)]
unsafe fn put_with_clone(self, f: impl FnMut(*mut u8, TypeInfo, DynamicClone));
}
#[derive(Copy, Clone)]
/// Type-erased [`Clone`] implementation
pub struct DynamicClone {
pub(crate) func: unsafe fn(*const u8, &mut dyn FnMut(*mut u8, TypeInfo)),
}
impl DynamicClone {
/// Create a new type ereased cloner for the type T
pub fn new<T: Component + Clone>() -> Self {
Self {
func: |src, f| {
let mut tmp = unsafe { (*src.cast::<T>()).clone() };
f((&mut tmp as *mut T).cast(), TypeInfo::of::<T>());
core::mem::forget(tmp);
},
}
}
}
/// Error indicating that an entity did not have a required component
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct MissingComponent(&'static str);
impl MissingComponent {
/// Construct an error representing a missing `T`
pub fn new<T: Component>() -> Self {
Self(type_name::<T>())
}
}
impl fmt::Display for MissingComponent {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "missing {} component", self.0)
}
}
#[cfg(feature = "std")]
impl std::error::Error for MissingComponent {}
macro_rules! tuple_impl {
($($name: ident),*) => {
unsafe impl<$($name: Component),*> DynamicBundle for ($($name,)*) {
fn has<T: Component>(&self) -> bool {
false $(|| TypeId::of::<$name>() == TypeId::of::<T>())*
}
fn key(&self) -> Option<TypeId> {
Some(TypeId::of::<Self>())
}
fn with_ids<T>(&self, f: impl FnOnce(&[TypeId]) -> T) -> T {
Self::with_static_ids(f)
}
fn type_info(&self) -> Vec<TypeInfo> {
Self::with_static_type_info(|info| info.to_vec())
}
#[allow(unused_variables, unused_mut)]
unsafe fn put(self, mut f: impl FnMut(*mut u8, TypeInfo)) {
#[allow(non_snake_case)]
let ($(mut $name,)*) = self;
$(
f(
(&mut $name as *mut $name).cast::<u8>(),
TypeInfo::of::<$name>()
);
mem::forget($name);
)*
}
}
unsafe impl<$($name: Component + Clone),*> DynamicBundleClone for ($($name,)*) {
// Compiler false positive warnings
#[allow(unused_variables, unused_mut)]
unsafe fn put_with_clone(self, mut f: impl FnMut(*mut u8, TypeInfo, DynamicClone)) {
#[allow(non_snake_case)]
let ($(mut $name,)*) = self;
$(
f(
(&mut $name as *mut $name).cast::<u8>(),
TypeInfo::of::<$name>(),
DynamicClone::new::<$name>()
);
mem::forget($name);
)*
}
}
unsafe impl<$($name: Component),*> Bundle for ($($name,)*) {
fn with_static_ids<T>(f: impl FnOnce(&[TypeId]) -> T) -> T {
const N: usize = count!($($name),*);
let mut xs: [(usize, TypeId); N] = [$((mem::align_of::<$name>(), TypeId::of::<$name>())),*];
xs.sort_unstable_by(|x, y| x.0.cmp(&y.0).reverse().then(x.1.cmp(&y.1)));
let mut ids = [TypeId::of::<()>(); N];
for (slot, &(_, id)) in ids.iter_mut().zip(xs.iter()) {
*slot = id;
}
f(&ids)
}
fn with_static_type_info<T>(f: impl FnOnce(&[TypeInfo]) -> T) -> T {
const N: usize = count!($($name),*);
let mut xs: [TypeInfo; N] = [$(TypeInfo::of::<$name>()),*];
xs.sort_unstable();
f(&xs)
}
#[allow(unused_variables, unused_mut)]
unsafe fn get(mut f: impl FnMut(TypeInfo) -> Option<NonNull<u8>>) -> Result<Self, MissingComponent> {
#[allow(non_snake_case)]
let ($(mut $name,)*) = ($(
f(TypeInfo::of::<$name>()).ok_or_else(MissingComponent::new::<$name>)?
.as_ptr()
.cast::<$name>(),)*
);
Ok(($($name.read(),)*))
}
}
}
}
macro_rules! count {
() => { 0 };
($x: ident $(, $rest: ident)*) => { 1 + count!($($rest),*) };
}
smaller_tuples_too!(tuple_impl, O, N, M, L, K, J, I, H, G, F, E, D, C, B, A);