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

   1 //! The different types of `Any` for use in a map.
   2 //!
   3 //! This stuff is all based on `std::any`, but goes a little further, with `CloneAny` being a
   4 //! cloneable `Any` and with the `Send` and `Sync` bounds possible on both `Any` and `CloneAny`.
   5
   6 use std::fmt;
   7 use std::any::Any as StdAny;
   8
   9 #[doc(hidden)]
  10 pub trait CloneToAny {
  11     /// Clone `self` into a new `Box<CloneAny>` object.
  12     fn clone_to_any(&self) -> Box<CloneAny>;
  13
  14     /// Clone `self` into a new `Box<CloneAny + Send>` object.
  15     fn clone_to_any_send(&self) -> Box<CloneAny + Send> where Self: Send;
  16
  17     /// Clone `self` into a new `Box<CloneAny + Sync>` object.
  18     fn clone_to_any_sync(&self) -> Box<CloneAny + Sync> where Self: Sync;
  19
  20     /// Clone `self` into a new `Box<CloneAny + Send + Sync>` object.
  21     fn clone_to_any_send_sync(&self) -> Box<CloneAny + Send + Sync> where Self: Send + Sync;
  22 }
  23
  24 impl<T: Any + Clone> CloneToAny for T {
  25     #[inline]
  26     fn clone_to_any(&self) -> Box<CloneAny> {
  27         Box::new(self.clone())
  28     }
  29
  30     #[inline]
  31     fn clone_to_any_send(&self) -> Box<CloneAny + Send> where Self: Send {
  32         Box::new(self.clone())
  33     }
  34
  35     #[inline]
  36     fn clone_to_any_sync(&self) -> Box<CloneAny + Sync> where Self: Sync {
  37         Box::new(self.clone())
  38     }
  39
  40     #[inline]
  41     fn clone_to_any_send_sync(&self) -> Box<CloneAny + Send + Sync> where Self: Send + Sync {
  42         Box::new(self.clone())
  43     }
  44 }
  45
  46 macro_rules! define {
  47     (CloneAny) => {
  48         /// A type to emulate dynamic typing.
  49         ///
  50         /// Every type with no non-`'static` references implements `Any`.
  51         define!(CloneAny remainder);
  52     };
  53     (Any) => {
  54         /// A type to emulate dynamic typing with cloning.
  55         ///
  56         /// Every type with no non-`'static` references that implements `Clone` implements `Any`.
  57         define!(Any remainder);
  58     };
  59     ($t:ident remainder) => {
  60         /// See the [`std::any` documentation](https://doc.rust-lang.org/std/any/index.html) for
  61         /// more details on `Any` in general.
  62         ///
  63         /// This trait is not `std::any::Any` but rather a type extending that for this library’s
  64         /// purposes so that it can be combined with marker traits like
  65         /// <code><a class=trait title=core::marker::Send
  66         /// href=http://doc.rust-lang.org/std/marker/trait.Send.html>Send</a></code> and
  67         /// <code><a class=trait title=core::marker::Sync
  68         /// href=http://doc.rust-lang.org/std/marker/trait.Sync.html>Sync</a></code>.
  69         ///
  70         define!($t trait);
  71     };
  72     (CloneAny trait) => {
  73         /// See also [`Any`](trait.Any.html) for a version without the `Clone` requirement.
  74         pub trait CloneAny: Any + CloneToAny { }
  75         impl<T: StdAny + Clone> CloneAny for T { }
  76     };
  77     (Any trait) => {
  78         /// See also [`CloneAny`](trait.CloneAny.html) for a cloneable version of this trait.
  79         pub trait Any: StdAny { }
  80         impl<T: StdAny> Any for T { }
  81     };
  82 }
  83
  84 macro_rules! impl_clone {
  85     ($t:ty, $method:ident) => {
  86         impl Clone for Box<$t> {
  87             #[inline]
  88             fn clone(&self) -> Box<$t> {
  89                 (**self).$method()
  90             }
  91         }
  92     }
  93 }
  94
  95 #[allow(missing_docs)]  // Bogus warning (it’s not public outside the crate), ☹
  96 pub trait UncheckedAnyExt: Any {
  97     unsafe fn downcast_ref_unchecked<T: Any>(&self) -> &T;
  98     unsafe fn downcast_mut_unchecked<T: Any>(&mut self) -> &mut T;
  99     unsafe fn downcast_unchecked<T: Any>(self: Box<Self>) -> Box<T>;
 100 }
 101
 102 #[doc(hidden)]
 103 /// A trait for the conversion of an object into a boxed trait object.
 104 pub trait IntoBox<A: ?Sized + UncheckedAnyExt>: Any {
 105     /// Convert self into the appropriate boxed form.
 106     fn into_box(self) -> Box<A>;
 107 }
 108
 109 macro_rules! implement {
 110     ($base:ident, $(+ $bounds:ident)*) => {
 111         impl fmt::Debug for $base $(+ $bounds)* {
 112             #[inline]
 113             fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 114                 f.pad(stringify!($base $(+ $bounds)*))
 115             }
 116         }
 117
 118         impl UncheckedAnyExt for $base $(+ $bounds)* {
 119             #[inline]
 120             unsafe fn downcast_ref_unchecked<T: 'static>(&self) -> &T {
 121                 &*(self as *const Self as *const T)
 122             }
 123
 124             #[inline]
 125             unsafe fn downcast_mut_unchecked<T: 'static>(&mut self) -> &mut T {
 126                 &mut *(self as *mut Self as *mut T)
 127             }
 128
 129             #[inline]
 130             unsafe fn downcast_unchecked<T: 'static>(self: Box<Self>) -> Box<T> {
 131                 Box::from_raw(Box::into_raw(self) as *mut T)
 132             }
 133         }
 134
 135         impl<T: $base $(+ $bounds)*> IntoBox<$base $(+ $bounds)*> for T {
 136             #[inline]
 137             fn into_box(self) -> Box<$base $(+ $bounds)*> {
 138                 Box::new(self)
 139             }
 140         }
 141     }
 142 }
 143
 144 define!(Any);
 145 implement!(Any,);
 146 implement!(Any, + Send);
 147 implement!(Any, + Sync);
 148 implement!(Any, + Send + Sync);
 149 implement!(CloneAny,);
 150 implement!(CloneAny, + Send);
 151 implement!(CloneAny, + Sync);
 152 implement!(CloneAny, + Send + Sync);
 153
 154 define!(CloneAny);
 155 impl_clone!(CloneAny, clone_to_any);
 156 impl_clone!((CloneAny + Send), clone_to_any_send);
 157 impl_clone!((CloneAny + Sync), clone_to_any_sync);
 158 impl_clone!((CloneAny + Send + Sync), clone_to_any_send_sync);