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use crate::{
create_bitset, BitSet, BitSetVec, Entity, EntityIterator, BITSET_SIZE, BITSET_SLICE_COUNT,
};
pub struct Entities {
alive: BitSetVec,
generation: Vec<u32>,
killed: Vec<Entity>,
next_id: usize,
has_deleted: bool,
}
impl Default for Entities {
fn default() -> Self {
Self {
alive: create_bitset(),
generation: vec![0u32; BITSET_SIZE],
killed: vec![],
next_id: 0,
has_deleted: false,
}
}
}
impl Entities {
pub fn create(&mut self) -> Entity {
if !self.has_deleted {
let i = self.next_id;
self.next_id += 1;
self.alive.bit_set(i);
Entity::new(i as u32, self.generation[i])
} else {
let mut section = 0;
while self.alive[section].bit_all() {
section += 1;
if section >= BITSET_SLICE_COUNT {
panic!("Exceeded maximum amount of concurrent entities.");
}
}
let mut i = section * (32 * 8);
while self.alive.bit_test(i) || self.killed.iter().any(|e| e.index() == i as u32) {
i += 1;
}
self.alive.bit_set(i);
if i >= self.next_id {
self.next_id = i + 1;
self.has_deleted = false;
}
Entity::new(i as u32, self.generation[i])
}
}
pub fn is_alive(&self, entity: Entity) -> bool {
self.alive.bit_test(entity.index() as usize)
&& self.generation[entity.index() as usize] == entity.generation()
}
pub fn kill(&mut self, entity: Entity) {
if self.alive.bit_test(entity.index() as usize) {
self.alive.bit_reset(entity.index() as usize);
self.generation[entity.index() as usize] += 1;
self.killed.push(entity);
self.has_deleted = true;
}
}
pub fn killed(&self) -> &Vec<Entity> {
&self.killed
}
pub fn clear_killed(&mut self) {
self.killed.clear();
}
pub fn bitset(&self) -> &BitSetVec {
&self.alive
}
pub fn iter_with_bitset<'a>(&'a self, bitset: std::rc::Rc<BitSetVec>) -> EntityIterator<'a> {
EntityIterator {
current_id: 0,
next_id: self.next_id,
entities: &self.alive,
generations: &self.generation,
bitset,
}
}
}
#[cfg(test)]
mod tests {
use crate::*;
#[test]
fn create_kill_entities() {
let mut entities = Entities::default();
let e1 = entities.create();
let e2 = entities.create();
let e3 = entities.create();
assert_eq!(e1.index(), 0);
assert_eq!(e2.index(), 1);
assert_eq!(e3.index(), 2);
assert_eq!(e1.generation(), 0);
assert!(entities.is_alive(e1));
assert!(entities.is_alive(e2));
assert!(entities.is_alive(e3));
entities.kill(e1);
assert!(!entities.is_alive(e1));
assert!(entities.is_alive(e2));
assert!(entities.is_alive(e3));
let e4 = entities.create();
assert!(!entities.is_alive(e1));
assert!(entities.is_alive(e2));
assert!(entities.is_alive(e3));
assert!(entities.is_alive(e4));
assert_eq!(*entities.killed(), vec![e1]);
entities.clear_killed();
assert_eq!(*entities.killed(), vec![]);
}
#[test]
fn test_interleaved_create_kill() {
let mut entities = Entities::default();
let e1 = entities.create();
assert_eq!(e1.index(), 0);
let e2 = entities.create();
assert_eq!(e2.index(), 1);
entities.kill(e1);
entities.kill(e2);
assert_eq!(entities.is_alive(e1), false);
assert_eq!(entities.is_alive(e2), false);
let e3 = entities.create();
assert_eq!(e3.index(), 2);
let e4 = entities.create();
assert_eq!(e4.index(), 3);
entities.kill(e3);
entities.kill(e4);
assert_eq!(entities.is_alive(e3), false);
assert_eq!(entities.is_alive(e4), false);
}
}