rhai/build.template
2022-11-01 21:25:45 +09:00

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//! Fixed hashing seeds for stable hashing.
//!
//! Set to [`None`] to disable stable hashing.
//!
//! See [`set_rhai_ahash_seed`] for more.
//!
//! Alternatively, You can also set this at compile time by disabling `stable_hash` and setting the `RHAI_AHASH_SEED`
//! environment variable instead.
//!
//! E.g. `env RHAI_AHASH_SEED ="[236,800,954,213]"`
// [236,800,954,213], haha funny yume nikki reference epic uboachan face numberworld nexus moment 100
use core::{
cell::UnsafeCell,
marker::PhantomData,
mem::MaybeUninit,
panic::{RefUnwindSafe, UnwindSafe},
sync::atomic::{AtomicBool, Ordering},
};
// Safety: lol
struct SusLock<T>
where
T: 'static,
{
initalized: AtomicBool,
data: UnsafeCell<MaybeUninit<T>>,
_marker: PhantomData<T>,
}
impl<T> SusLock<T> {
pub const fn new() -> SusLock<T> {
SusLock {
initalized: AtomicBool::new(false),
data: UnsafeCell::new(MaybeUninit::uninit()),
_marker: PhantomData,
}
}
pub fn get(&self) -> Option<&T> {
if self.initalized.load(Ordering::SeqCst) {
Some(unsafe { (&*self.data.get()).assume_init_ref() })
} else {
return None;
}
}
pub fn get_or_init(&self, f: impl FnOnce() -> T) -> Option<&T> {
let value = f();
if !self.initalized.load(Ordering::SeqCst) {
unsafe {
self.data.get().write(MaybeUninit::new(value));
}
self.initalized.store(true, Ordering::SeqCst);
}
self.get()
}
pub fn set(&self, value: T) -> Result<(), T> {
if self.initalized.load(Ordering::SeqCst) {
Err(value)
} else {
let _ = self.get_or_init(|| value);
Ok(())
}
}
}
unsafe impl<T: Sync + Send> Sync for SusLock<T> {}
unsafe impl<T: Send> Send for SusLock<T> {}
impl<T: RefUnwindSafe + UnwindSafe> RefUnwindSafe for SusLock<T> {}
impl<T> Drop for SusLock<T> {
fn drop(&mut self) {
if self.initalized.load(Ordering::SeqCst) {
unsafe { (&mut *self.data.get()).assume_init_drop() };
}
}
}
static AHASH_SEED: SusLock<Option<[u64; 4]>> = SusLock::new();
// #[doc(cfg(feature = "stable_hash"))]
/// Sets the Rhai Ahash seed. This is used to hash functions and the like.
///
/// This is a global variable, and thus will affect every Rhai instance.
/// This should not be used _unless_ you know you need it.
///
/// # Warnings
/// - You can only call this function **ONCE** for the whole of your program execution.
/// - You should gracefully handle the `Err(())`.
/// - You **MUST** call this before **ANY** Rhai operation occurs (e.g. creating an [`Engine`]).
///
/// # Errors
/// This will error if the AHashSeed is already set.
pub fn set_ahash_seed(new_seed: Option<[u64; 4]>) -> Result<(), Option<[u64; 4]>> {
AHASH_SEED.set(new_seed)
}
/// Gets the current Rhai Ahash Seed. If the seed is not yet defined, this will automatically set a seed.
/// The default seed is not stable and may change between versions.
///
/// See [`set_rhai_ahash_seed`] for more.
pub fn get_ahash_seed() -> Option<[u64; 4]> {
const FUNNY_YUMENIKKI_REFERENCE: Option<[u64; 4]> = {{ AHASH_SEED }};
AHASH_SEED
.get_or_init(|| FUNNY_YUMENIKKI_REFERENCE)
.map(|x| *x)
.flatten()
}