src/unchecked_any.rs - anymap blob - Chris Morgan’s Git repositories

   1 use raw::Any;
   2 use std::mem;
   3 #[cfg(feature = "nightly")]
   4 use std::raw::TraitObject;
   5
   6 #[cfg(not(feature = "nightly"))]
   7 #[repr(C)]
   8 #[allow(raw_pointer_derive)]
   9 #[derive(Copy, Clone)]
  10 struct TraitObject {
  11     pub data: *mut (),
  12     pub vtable: *mut (),
  13 }
  14
  15 #[allow(missing_docs)]  // Bogus warning (it’s not public outside the crate), ☹
  16 pub trait UncheckedAnyExt {
  17     unsafe fn downcast_ref_unchecked<T: 'static>(&self) -> &T;
  18     unsafe fn downcast_mut_unchecked<T: 'static>(&mut self) -> &mut T;
  19     unsafe fn downcast_unchecked<T: 'static>(self: Box<Self>) -> Box<T>;
  20 }
  21
  22 impl UncheckedAnyExt for Any {
  23     unsafe fn downcast_ref_unchecked<T: 'static>(&self) -> &T {
  24         mem::transmute(mem::transmute::<_, TraitObject>(self).data)
  25     }
  26
  27     unsafe fn downcast_mut_unchecked<T: 'static>(&mut self) -> &mut T {
  28         mem::transmute(mem::transmute::<_, TraitObject>(self).data)
  29     }
  30
  31     unsafe fn downcast_unchecked<T: 'static>(self: Box<Any>) -> Box<T> {
  32         mem::transmute(mem::transmute::<_, TraitObject>(self).data)
  33     }
  34 }