+use std::hash::{Hash, Hasher, Writer};
+use std::mem::{transmute, transmute_copy};
+use std::raw::TraitObject;
+
+struct TypeIdHasher;
+
+struct TypeIdState {
+ value: u64,
+}
+
+impl Writer for TypeIdState {
+ #[inline(always)]
+ fn write(&mut self, bytes: &[u8]) {
+ // This expects to receive one and exactly one 64-bit value
+ debug_assert!(bytes.len() == 8);
+ unsafe {
+ std::ptr::copy_nonoverlapping_memory(&mut self.value,
+ transmute(&bytes[0]),
+ 1)
+ }
+ }
+}
+
+impl Hasher<TypeIdState> for TypeIdHasher {
+ fn hash<Sized? T: Hash<TypeIdState>>(&self, value: &T) -> u64 {
+ let mut state = TypeIdState {
+ value: 0,
+ };
+ value.hash(&mut state);
+ state.value
+ }
+}
+
+/// An extension of `AnyRefExt` allowing unchecked downcasting of trait objects to `&T`.
+trait UncheckedAnyRefExt<'a> {
+ /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
+ /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
+ unsafe fn as_ref_unchecked<T: 'static>(self) -> &'a T;
+}
+
+impl<'a> UncheckedAnyRefExt<'a> for &'a Any + 'a {
+ #[inline]
+ unsafe fn as_ref_unchecked<T: 'static>(self) -> &'a T {
+ // Get the raw representation of the trait object
+ let to: TraitObject = transmute_copy(&self);
+
+ // Extract the data pointer
+ transmute(to.data)
+ }
+}
+
+/// An extension of `AnyMutRefExt` allowing unchecked downcasting of trait objects to `&mut T`.
+trait UncheckedAnyMutRefExt<'a> {
+ /// Returns a reference to the boxed value, assuming that it is of type `T`. This should only be
+ /// called if you are ABSOLUTELY CERTAIN of `T` as you will get really wacky output if it’s not.
+ unsafe fn as_mut_unchecked<T: 'static>(self) -> &'a mut T;
+}
+
+impl<'a> UncheckedAnyMutRefExt<'a> for &'a mut Any + 'a {
+ #[inline]
+ unsafe fn as_mut_unchecked<T: 'static>(self) -> &'a mut T {
+ // Get the raw representation of the trait object
+ let to: TraitObject = transmute_copy(&self);
+
+ // Extract the data pointer
+ transmute(to.data)
+ }
+}