Initial commit

crates/std/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "shiny-std"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+fxhash.workspace = true
+hashbrown.workspace = true

crates/std/src/arena/intern.rs

@@ -0,0 +1,147 @@
+//! # Interning arena.
+//!
+//! Additionally, if same value was present on the arena, doesn't add new object, returns old.
+
+use std::hash::{BuildHasherDefault, Hash};
+
+use hashbrown::hash_map::{HashMap, RawEntryMut};
+
+use super::{ptr::Ptr, wonly};
+
+// No raw_entry API on hashset.
+type Bi<P> = HashMap<Mapping<P>, (), BuildHasherDefault<hasher::NoHash>>;
+
+#[derive(Debug, Default, Clone, Copy)]
+struct Mapping<P> {
+    hash: u64,
+    key: P,
+}
+
+impl<P> Hash for Mapping<P> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        // [`hasher::NoHash`] implementation ensures that
+        // hasher stores `write_u64` result only once.
+        state.write_u64(self.hash);
+    }
+}
+
+#[derive(Clone)]
+pub struct Arena<T, P> {
+    objects: wonly::Arena<T, P>,
+    bi: Bi<P>,
+}
+
+impl<T, P> Default for Arena<T, P> {
+    fn default() -> Self {
+        Self {
+            objects: wonly::Arena::new(),
+            bi: Bi::default(),
+        }
+    }
+}
+
+impl<T, P> Arena<T, P> {
+    pub fn modify(&mut self, ptr: P, f: impl FnOnce(&mut T)) -> bool
+    where
+        T: Hash + Eq,
+        P: Ptr,
+    {
+        let Some(object) = self.objects.get(ptr.clone()) else {
+            return false;
+        };
+        let hash = fxhash::hash64(object);
+
+        let entry = self
+            .bi
+            .raw_entry_mut()
+            .from_hash(hash, |m| self.objects.get(m.key.clone()) == Some(object));
+
+        // SAFETY: if we got here, the object is in arena.
+        let object = unsafe { self.objects.get_mut(ptr.clone()).unwrap_unchecked() };
+        f(object);
+
+        let hash = fxhash::hash64(object);
+        entry.and_modify(|k, _| *k = Mapping { hash, key: ptr });
+
+        true
+    }
+
+    pub fn get(&self, ptr: P) -> Option<&T>
+    where
+        P: Ptr,
+    {
+        self.objects.get(ptr)
+    }
+
+    pub fn insert(&mut self, object: T) -> P
+    where
+        P: Ptr,
+        T: Hash + Eq,
+    {
+        let hash = fxhash::hash64(&object);
+        match self.bi.raw_entry_mut().from_hash(hash, |m| {
+            self.objects
+                .get(m.key.clone())
+                .map_or(false, |lhs| lhs == &object)
+        }) {
+            RawEntryMut::Occupied(occup) => occup.into_key().key.clone(),
+            RawEntryMut::Vacant(vacant) => {
+                let key = self.objects.insert(object);
+                vacant.insert_hashed_nocheck(
+                    hash,
+                    Mapping {
+                        hash,
+                        key: key.clone(),
+                    },
+                    (),
+                );
+
+                key
+            }
+        }
+    }
+
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+mod hasher;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::arena::ptr::define;
+
+    define! {
+        struct Token;
+    }
+
+    #[test]
+    fn modification_works() {
+        // Ensure that when modifying the value,
+        // pointer is still valid.
+
+        let mut arena: Arena<u32, Token> = Arena::new();
+        let key100to200 = arena.insert(100);
+        let modified = arena.modify(key100to200, |x| *x = 200);
+
+        assert!(modified);
+        assert_eq!(arena.get(key100to200), Some(&200));
+
+        let key100new = arena.insert(100);
+        assert_ne!(key100to200, key100new);
+
+        assert_eq!(arena.get(key100new), Some(&100));
+        assert_eq!(arena.get(key100to200), Some(&200));
+    }
+
+    #[test]
+    fn it_interns() {
+        let mut arena: Arena<u32, Token> = Arena::new();
+        let key100 = arena.insert(100);
+        let key100again = arena.insert(100);
+
+        assert_eq!(key100, key100again);
+    }
+}

crates/std/src/arena/intern/hasher.rs

@@ -0,0 +1,22 @@
+use std::hash::Hasher;
+
+#[derive(Default, Clone, Copy, PartialEq, Eq)]
+pub struct NoHash(Option<u64>);
+
+impl Hasher for NoHash {
+    fn write_u64(&mut self, i: u64) {
+        if self.0.is_some() {
+            panic!("called write_u64 twice")
+        } else {
+            self.0 = Some(i);
+        }
+    }
+
+    fn write(&mut self, _: &[u8]) {
+        unreachable!()
+    }
+
+    fn finish(&self) -> u64 {
+        self.0.unwrap()
+    }
+}

crates/std/src/arena/macros.rs

@@ -0,0 +1,20 @@
+/// Combination of pointers.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _make_comb {
+    ($(
+        $item:item
+    )*) => {$(
+        #[derive(
+            Debug,
+            Clone,
+            Copy,
+            PartialEq,
+            Eq,
+            PartialOrd,
+            Ord,
+            Hash,
+        )]
+        $item
+    )*};
+}

crates/std/src/arena/mod.rs

@@ -0,0 +1,8 @@
+pub mod intern;
+pub mod wonly;
+
+pub mod ptr;
+
+pub use crate::_make_comb as make_comb;
+
+mod macros;

crates/std/src/arena/ptr.rs

@@ -0,0 +1,59 @@
+use std::{hash::Hash, num::NonZeroU32};
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _ptrs {
+    ($(
+        $(#[$outer:meta])*
+        $vis:vis struct $name:ident;
+    )*) => {$(
+        $(#[$outer])*
+        #[derive(
+            Debug,
+            Clone,
+            Copy,
+            PartialEq,
+            Eq,
+            PartialOrd,
+            Ord,
+            Hash,
+        )]
+        $vis struct $name(::core::num::NonZeroU32);
+
+        impl $name {
+            /// Create instance of the pointer.
+            pub const fn new(v: ::core::num::NonZeroU32) -> Self {
+                Self(v)
+            }
+
+            pub const fn get(&self) -> ::core::num::NonZeroU32 {
+                self.0
+            }
+        }
+
+        impl ::core::convert::From<$name> for ::core::num::NonZeroU32 {
+            fn from(value: $name) -> Self {
+                value.get()
+            }
+        }
+
+        impl ::core::convert::From<::core::num::NonZeroU32> for $name {
+            fn from(value: ::core::num::NonZeroU32) -> Self {
+                Self::new(value)
+            }
+        }
+
+        impl $crate::arena::ptr::Ptr for $name {
+            fn get(&self) -> ::core::num::NonZeroU32 {
+                self.0
+            }
+        }
+    )*};
+}
+
+/// Pointer in arena.
+pub trait Ptr: Copy + Eq + Into<NonZeroU32> + From<NonZeroU32> + Hash {
+    fn get(&self) -> NonZeroU32;
+}
+
+pub use crate::_ptrs as define;

crates/std/src/arena/wonly.rs

@@ -0,0 +1,60 @@
+//! # Write-only arena, without deletion
+
+use std::{marker::PhantomData, num::NonZeroU32};
+
+use super::ptr::Ptr;
+
+#[derive(Clone)]
+pub struct Arena<T, P> {
+    mem: Vec<T>,
+    _ptr_ty: PhantomData<P>,
+}
+
+fn calc_idx(v: NonZeroU32) -> usize {
+    v.get() as usize - 1
+}
+
+impl<T, P> Arena<T, P> {
+    pub fn get_mut(&mut self, ptr: P) -> Option<&mut T>
+    where
+        P: Ptr,
+    {
+        self.mem.get_mut(calc_idx(ptr.into()))
+    }
+
+    pub fn get(&self, ptr: P) -> Option<&T>
+    where
+        P: Ptr,
+    {
+        self.mem.get(calc_idx(ptr.into()))
+    }
+
+    pub fn insert(&mut self, obj: T) -> P
+    where
+        P: Ptr,
+    {
+        let idx = self.mem.len();
+        self.mem.push(obj);
+
+        idx.checked_add(1)
+            .and_then(|v| v.try_into().ok())
+            .and_then(NonZeroU32::new)
+            .expect("shit happens")
+            .into()
+    }
+}
+
+impl<T, P> Default for Arena<T, P> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T, P> Arena<T, P> {
+    pub const fn new() -> Self {
+        Self {
+            mem: Vec::new(),
+            _ptr_ty: PhantomData,
+        }
+    }
+}

crates/std/src/collections.rs

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+use std::hash::BuildHasherDefault;
+
+use fxhash::FxHasher;
+
+pub type HashMap<K, V> = hashbrown::HashMap<K, V, BuildHasherDefault<FxHasher>>;
+pub type HashSet<V> = hashbrown::HashSet<V, BuildHasherDefault<FxHasher>>;

crates/std/src/lib.rs

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+pub mod collections;
+
+pub mod arena;