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