bevy/crates/bevy_ecs/hecs/src/bundle.rs
Carter Anderson c81ab99dac cargo fmt
2020-07-10 01:37:06 -07:00

149 lines
5.1 KiB
Rust

// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// modified by Bevy contributors
use crate::alloc::{vec, vec::Vec};
use core::{
any::{type_name, TypeId},
fmt, mem,
ptr::NonNull,
};
use crate::{archetype::TypeInfo, Component};
/// A dynamically typed collection of components
pub trait DynamicBundle {
/// 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, its type, and the pointee's size. A `false`
/// return value indicates that the value was not moved and should be dropped.
#[doc(hidden)]
unsafe fn put(self, f: impl FnMut(*mut u8, TypeId, usize) -> bool);
}
/// A statically typed collection of components
pub 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 static_type_info() -> Vec<TypeInfo>;
/// 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(TypeId, usize) -> Option<NonNull<u8>>,
) -> Result<Self, MissingComponent>
where
Self: Sized;
}
/// 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),*) => {
impl<$($name: Component),*> DynamicBundle for ($($name,)*) {
fn with_ids<T>(&self, f: impl FnOnce(&[TypeId]) -> T) -> T {
Self::with_static_ids(f)
}
fn type_info(&self) -> Vec<TypeInfo> {
Self::static_type_info()
}
#[allow(unused_variables, unused_mut)]
unsafe fn put(self, mut f: impl FnMut(*mut u8, TypeId, usize) -> bool) {
#[allow(non_snake_case)]
let ($(mut $name,)*) = self;
$(
if f(
(&mut $name as *mut $name).cast::<u8>(),
TypeId::of::<$name>(),
mem::size_of::<$name>()
) {
mem::forget($name)
}
)*
}
}
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::<$name>())),*];
xs.sort_unstable_by(|x, y| x.0.cmp(&y.0).reverse().then(x.1.cmp(&y.1)));
let mut ids = [TypeId::of::<()>(); N];
for (slot, &(_, id)) in ids.iter_mut().zip(xs.iter()) {
*slot = id;
}
f(&ids)
}
fn static_type_info() -> Vec<TypeInfo> {
let mut xs = vec![$(TypeInfo::of::<$name>()),*];
xs.sort_unstable();
xs
}
#[allow(unused_variables, unused_mut)]
unsafe fn get(mut f: impl FnMut(TypeId, usize) -> Option<NonNull<u8>>) -> Result<Self, MissingComponent> {
#[allow(non_snake_case)]
let ($(mut $name,)*) = ($(
f(TypeId::of::<$name>(), mem::size_of::<$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);