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use std::fmt::{Debug, Display, Formatter};
use std::sync::atomic::{AtomicU32, Ordering};
use seq_macro::seq;
use crate::component::Component;
use crate::util::{gen_mask_64, Array, BitMask, NumberExt};
static NEXT: AtomicU32 = AtomicU32::new(Uid::FIRST_UNIQUE_ID);
static WILDCARD_ID: u32 = 1;
const ID_BITS: BitMask<u64> = BitMask::new(gen_mask_64!(32..=63));
const RELATION_BITS: BitMask<u64> = BitMask::new(gen_mask_64!(6..=31));
const IS_PAIR_BITS: BitMask<u64> = BitMask::new(1 << 0);
/// A unique identifier.
#[derive(Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub struct Uid
{
inner: u64,
}
impl Uid
{
/// The id part of the first unique `Uid`. The ids `0..Uid::FIRST_UNIQUE_ID` are
/// reserved.
pub const FIRST_UNIQUE_ID: u32 = 5;
/// Returns a new unique entity/component ID.
pub fn new_unique() -> Self
{
let id = NEXT.fetch_add(1, Ordering::Relaxed);
Self {
inner: ID_BITS.field_prep(u64::from(id)) | IS_PAIR_BITS.field_prep(0),
}
}
#[must_use]
pub fn wildcard() -> Self
{
Self {
inner: ID_BITS.field_prep(u64::from(WILDCARD_ID))
| IS_PAIR_BITS.field_prep(0),
}
}
/// Returns a new pair UID.
///
/// # Panics
/// Will panic if either the given relation or target is a pair UID.
#[must_use]
pub fn new_pair(params: &PairParams) -> Self
{
assert!(!params.relation.is_pair(), "Pair relation cannot be a pair");
assert!(!params.target.is_pair(), "Pair target cannot be a pair");
Self {
inner: ID_BITS.field_prep(u64::from(params.target.id()))
| RELATION_BITS.field_prep(u64::from(params.relation.id()))
| IS_PAIR_BITS.field_prep(1),
}
}
#[must_use]
pub fn id(&self) -> u32
{
let Ok(id) = u32::try_from(self.inner.field_get(ID_BITS)) else {
unreachable!("Uid id does not fit in u32");
};
id
}
#[must_use]
pub fn is_pair(&self) -> bool
{
let Ok(is_pair) = u8::try_from(self.inner.field_get(IS_PAIR_BITS)) else {
unreachable!();
};
is_pair == 1
}
/// If this `Uid` is a pair, returns the relation `Uid`.
///
/// # Panics
/// Will panic if this `Uid` is not a pair.
#[must_use]
pub fn relation(&self) -> Self
{
assert!(self.is_pair(), "Uid is not a pair");
let Ok(relation) = u32::try_from(self.inner.field_get(RELATION_BITS)) else {
unreachable!("Uid relation does not fit in u32");
};
Self {
inner: ID_BITS.field_prep(u64::from(relation)) | IS_PAIR_BITS.field_prep(0),
}
}
/// Compares the relation of this pair `Uid` with the relation of another pair `Uid`.
///
/// # Panics
/// Will panic if any of the `Uid`s are not a pair.
#[must_use]
pub fn has_same_relation_as(&self, other: Self) -> bool
{
self.relation() == other.relation()
}
/// If this `Uid` is a pair, returns the target `Uid`.
///
/// # Panics
/// Will panic if this `Uid` is not a pair.
#[must_use]
pub fn target(&self) -> Self
{
assert!(self.is_pair(), "Uid is not a pair");
Self {
inner: ID_BITS.field_prep(u64::from(self.id())) | IS_PAIR_BITS.field_prep(0),
}
}
}
impl Debug for Uid
{
fn fmt(&self, formatter: &mut Formatter<'_>) -> std::fmt::Result
{
let mut debug_struct = formatter.debug_struct("Uid");
if self.is_pair() {
return debug_struct
.field("relation", &self.relation())
.field("target", &self.target())
.finish();
}
debug_struct.field("id", &self.id()).finish()
}
}
impl Display for Uid
{
fn fmt(&self, formatter: &mut Formatter<'_>) -> std::fmt::Result
{
if self.is_pair() {
return write!(formatter, "({}, {})", self.relation(), self.target());
}
if *self == Uid::wildcard() {
return write!(formatter, "*");
}
write!(formatter, "{}", self.id())
}
}
#[derive(Debug, Clone)]
pub struct PairParams
{
pub relation: Uid,
pub target: Uid,
}
pub trait With
{
fn uid() -> Uid;
}
impl<ComponentT: Component> With for ComponentT
{
fn uid() -> Uid
{
Self::id()
}
}
pub trait WithUidTuple
{
type UidsArray: Array<Uid>;
fn uids() -> Self::UidsArray;
}
macro_rules! impl_with_uid_tuple {
($c: tt) => {
seq!(I in 0..=$c {
impl<#(WithUid~I: With,)*> WithUidTuple for (#(WithUid~I,)*)
{
type UidsArray = [Uid; $c + 1];
fn uids() -> Self::UidsArray
{
[#(WithUid~I::uid(),)*]
}
}
});
};
}
seq!(C in 0..=16 {
impl_with_uid_tuple!(C);
});
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