Stable Hash: Add feature, adjust CI, modify build.rs, add new API for accessing and setting the ahash seed in config.rs, make config.rs public

src/config.rs

@@ -1,7 +1,50 @@
-//! Configuration settings for this Rhai build
+//! Fixed hashing seeds for stable hashing.
 //!
-//! This file is auto-generated from `build.template`
+//! 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
 
-/// Fixed hashing seeds for stable hashing.
-/// Set to [`None`] to disable stable hashing.
-pub const AHASH_SEED: Option<[u64; 4]> = None;
+#[cfg(feature = "stable_hash")]
+use std::sync::OnceLock;
+
+#[cfg(not(feature = "stable_hash"))]
+const AHASH_SEED: Option<[u64; 4]> = None;
+#[cfg(feature = "stable_hash")]
+static AHASH_SEED: OnceLock<Option<[u64; 4]>> = OnceLock::new();
+
+#[cfg(feature = "stable_hash")]
+// #[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.
+///
+/// **WARNING**:
+/// - 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`]).
+pub fn set_rhai_ahash_seed(new_seed: Option<[u64; 4]>) -> Result<(), Option<[u64; 4]>> {
+    AHASH_SEED.set(new_seed)
+}
+
+#[cfg(feature = "stable_hash")]
+/// Gets the current Rhai Ahash Seed.
+///
+/// See [`set_rhai_ahash_seed`] for more.
+pub fn get_rhai_ahash_seed() -> Option<[u64; 4]> {
+    AHASH_SEED.get().map(|x| *x).flatten()
+}
+
+#[cfg(not(feature = "stable_hash"))]
+/// Gets the current Rhai Ahash Seed.
+///
+/// See [`AHASH_SEED`] and [`set_rhai_ahash_seed`] for more.
+pub fn get_rhai_ahash_seed() -> Option<[u64; 4]> {
+    AHASH_SEED
+}

src/func/hashing.rs

@@ -77,7 +77,7 @@ impl BuildHasher for StraightHasherBuilder {
 #[inline(always)]
 #[must_use]
 pub fn get_hasher() -> ahash::AHasher {
-    match config::AHASH_SEED {
+    match config::get_rhai_ahash_seed() {
         Some([seed1, seed2, seed3, seed4]) if seed1 | seed2 | seed3 | seed4 != 0 => {
             ahash::RandomState::with_seeds(seed1, seed2, seed3, seed4).build_hasher()
         }

src/lib.rs

@@ -71,6 +71,8 @@
 #![allow(clippy::negative_feature_names)]
 #![allow(clippy::module_inception)]
 
+#![cfg_attr(feature = "stable_hash", feature(once_cell))]
+
 #[cfg(feature = "no_std")]
 extern crate alloc;
 
@@ -83,7 +85,7 @@ use std::prelude::v1::*;
 // Internal modules
 mod api;
 mod ast;
-mod config;
+pub mod config;
 mod engine;
 mod eval;
 mod func;