bevy_ecs/world/
spawn_batch.rs1use crate::{
2 bundle::{Bundle, BundleSpawner},
3 entity::Entity,
4 world::World,
5};
6use std::iter::FusedIterator;
7
8pub struct SpawnBatchIter<'w, I>
13where
14 I: Iterator,
15 I::Item: Bundle,
16{
17 inner: I,
18 spawner: BundleSpawner<'w>,
19}
20
21impl<'w, I> SpawnBatchIter<'w, I>
22where
23 I: Iterator,
24 I::Item: Bundle,
25{
26 #[inline]
27 pub(crate) fn new(world: &'w mut World, iter: I) -> Self {
28 world.flush();
31
32 let change_tick = world.change_tick();
33
34 let (lower, upper) = iter.size_hint();
35 let length = upper.unwrap_or(lower);
36 world.entities.reserve(length as u32);
37
38 let mut spawner = BundleSpawner::new::<I::Item>(world, change_tick);
39 spawner.reserve_storage(length);
40
41 Self {
42 inner: iter,
43 spawner,
44 }
45 }
46}
47
48impl<I> Drop for SpawnBatchIter<'_, I>
49where
50 I: Iterator,
51 I::Item: Bundle,
52{
53 fn drop(&mut self) {
54 for _ in &mut *self {}
56 unsafe { self.spawner.flush_commands() };
59 }
60}
61
62impl<I> Iterator for SpawnBatchIter<'_, I>
63where
64 I: Iterator,
65 I::Item: Bundle,
66{
67 type Item = Entity;
68
69 fn next(&mut self) -> Option<Entity> {
70 let bundle = self.inner.next()?;
71 unsafe { Some(self.spawner.spawn(bundle)) }
73 }
74
75 fn size_hint(&self) -> (usize, Option<usize>) {
76 self.inner.size_hint()
77 }
78}
79
80impl<I, T> ExactSizeIterator for SpawnBatchIter<'_, I>
81where
82 I: ExactSizeIterator<Item = T>,
83 T: Bundle,
84{
85 fn len(&self) -> usize {
86 self.inner.len()
87 }
88}
89
90impl<I, T> FusedIterator for SpawnBatchIter<'_, I>
91where
92 I: FusedIterator<Item = T>,
93 T: Bundle,
94{
95}