X-Git-Url: https://git.chrismorgan.info/anymap/blobdiff_plain/34028c35e70de959ec61758db88dfc84f75764cf..8f041216babc57cbd1b89e169aaf66163822e4b2:/src/raw.rs

diff --git a/src/raw.rs b/src/raw.rs
index 17c3869..73c20e2 100644
--- a/src/raw.rs
+++ b/src/raw.rs
@@ -5,12 +5,12 @@
 use std::any::TypeId;
 use std::borrow::Borrow;
 use std::collections::hash_map::{self, HashMap};
+use std::convert::TryInto;
 use std::hash::Hash;
 use std::hash::{Hasher, BuildHasherDefault};
 #[cfg(test)]
 use std::mem;
 use std::ops::{Index, IndexMut};
-use std::ptr;
 
 use any::{Any, UncheckedAnyExt};
 
@@ -22,11 +22,13 @@ struct TypeIdHasher {
 impl Hasher for TypeIdHasher {
     #[inline]
     fn write(&mut self, bytes: &[u8]) {
-        // This expects to receive one and exactly one 64-bit value
-        debug_assert!(bytes.len() == 8);
-        unsafe {
-            ptr::copy_nonoverlapping(&bytes[0] as *const u8 as *const u64, &mut self.value, 1)
-        }
+        // This expects to receive exactly one 64-bit value, and there’s no realistic chance of
+        // that changing, but I don’t want to depend on something that isn’t expressly part of the
+        // contract for safety. But I’m OK with release builds putting everything in one bucket
+        // if it *did* change (and debug builds panicking).
+        debug_assert_eq!(bytes.len(), 8);
+        let _ = bytes.try_into()
+            .map(|array| self.value = u64::from_ne_bytes(array));
     }
 
     #[inline]
@@ -38,6 +40,7 @@ fn type_id_hasher() {
     fn verify_hashing_with(type_id: TypeId) {
         let mut hasher = TypeIdHasher::default();
         type_id.hash(&mut hasher);
+        // SAFETY: u64 is valid for all bit patterns.
         assert_eq!(hasher.finish(), unsafe { mem::transmute::<TypeId, u64>(type_id) });
     }
     // Pick a variety of types, just to demonstrate it’s all sane. Normal, zero-sized, unsized, &c.
@@ -56,7 +59,7 @@ fn type_id_hasher() {
 /// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it
 /// doesn’t tend to be so very useful. Still, if you need it, it’s here.
 #[derive(Debug)]
-pub struct RawMap<A: ?Sized + UncheckedAnyExt = Any> {
+pub struct RawMap<A: ?Sized + UncheckedAnyExt = dyn Any> {
     inner: HashMap<TypeId, Box<A>, BuildHasherDefault<TypeIdHasher>>,
 }
 
@@ -70,13 +73,6 @@ impl<A: ?Sized + UncheckedAnyExt> Clone for RawMap<A> where Box<A>: Clone {
     }
 }
 
-impl<A: ?Sized + UncheckedAnyExt> Default for RawMap<A> {
-    #[inline]
-    fn default() -> RawMap<A> {
-        RawMap::new()
-    }
-}
-
 impl_common_methods! {
     field: RawMap.inner;
     new() => HashMap::with_hasher(Default::default());
@@ -213,10 +209,11 @@ impl<A: ?Sized + UncheckedAnyExt> RawMap<A> {
     }
 
     /// Inserts a key-value pair from the map. If the key already had a value present in the map,
-    /// that value is returned. Otherwise, None is returned.
+    /// that value is returned. Otherwise, `None` is returned.
     ///
-    /// It is the caller’s responsibility to ensure that the key corresponds with the type ID of
-    /// the value. If they do not, memory safety may be violated.
+    /// # Safety
+    ///
+    /// `key` and the type ID of `value` must match, or *undefined behaviour* occurs.
     #[inline]
     pub unsafe fn insert(&mut self, key: TypeId, value: Box<A>) -> Option<Box<A>> {
         self.inner.insert(key, value)
@@ -285,8 +282,9 @@ impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
     /// Ensures a value is in the entry by inserting the default if empty, and returns
     /// a mutable reference to the value in the entry.
     ///
-    /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
-    /// the type ID of `value`. If they do not, memory safety may be violated.
+    /// # Safety
+    ///
+    /// The type ID of `default` must match the entry’s key, or *undefined behaviour* occurs.
     #[inline]
     pub unsafe fn or_insert(self, default: Box<A>) -> &'a mut A {
         match self {
@@ -298,8 +296,10 @@ impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> {
     /// Ensures a value is in the entry by inserting the result of the default function if empty,
     /// and returns a mutable reference to the value in the entry.
     ///
-    /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
-    /// the type ID of `value`. If they do not, memory safety may be violated.
+    /// # Safety
+    ///
+    /// The type ID of the value returned by `default` must match the entry’s key,
+    /// or *undefined behaviour* occurs.
     #[inline]
     pub unsafe fn or_insert_with<F: FnOnce() -> Box<A>>(self, default: F) -> &'a mut A {
         match self {
@@ -331,8 +331,9 @@ impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 
     /// Sets the value of the entry, and returns the entry's old value.
     ///
-    /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
-    /// the type ID of `value`. If they do not, memory safety may be violated.
+    /// # Safety
+    ///
+    /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs.
     #[inline]
     pub unsafe fn insert(&mut self, value: Box<A>) -> Box<A> {
         self.inner.insert(value)
@@ -347,10 +348,11 @@ impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> {
 
 impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> {
     /// Sets the value of the entry with the VacantEntry's key,
-    /// and returns a mutable reference to it
+    /// and returns a mutable reference to it.
+    ///
+    /// # Safety
     ///
-    /// It is the caller’s responsibility to ensure that the key of the entry corresponds with
-    /// the type ID of `value`. If they do not, memory safety may be violated.
+    /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs.
     #[inline]
     pub unsafe fn insert(self, value: Box<A>) -> &'a mut A {
         &mut **self.inner.insert(value)