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|
use std::hash::{DefaultHasher, Hash, Hasher};
use crate::component::{
IsOptional as ComponentIsOptional,
Metadata as ComponentMetadata,
};
/// Archetype ID.
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub struct Id
{
hash: u64,
}
impl Id
{
pub fn from_components_metadata(
components_metadata: &impl AsRef<[ComponentMetadata]>,
) -> Self
{
if components_metadata.as_ref().len() == 0 {
return Self { hash: 0 };
}
debug_assert!(
components_metadata
.as_ref()
.is_sorted_by_key(|comp_metadata| comp_metadata.id),
"Cannot create archetype ID from a unsorted component metadata list"
);
let component_ids =
components_metadata
.as_ref()
.iter()
.filter_map(|component_metadata| {
if component_metadata.is_optional == ComponentIsOptional::Yes {
return None;
}
Some(component_metadata.id)
});
let mut hasher = DefaultHasher::new();
for component_id in component_ids {
component_id.hash(&mut hasher);
}
let hash = hasher.finish();
assert_ne!(
hash, 0,
"Archetype ID 0 is reserved for a archetype with zero components"
);
Self { hash }
}
}
|
