initial

src/upcast.rs

@@ -0,0 +1,79 @@
+
+pub trait Upcast<T> {
+    fn upcast(self) -> T;
+}
+
+pub trait IntoUsize {
+    fn into_usize(self) -> usize;
+}
+
+macro_rules! gen_upcast {
+    ($from:ty => $into:ty) => {
+        impl Upcast<$into> for $from {
+            fn upcast(self) -> $into {
+                self as $into
+            }
+        }
+    }
+}
+
+// Unsigned
+gen_upcast!(u8      => u8);
+gen_upcast!(u8      => u16);
+gen_upcast!(u8      => u32);
+gen_upcast!(u8      => u64);
+gen_upcast!(u16     => u16);
+gen_upcast!(u16     => u32);
+gen_upcast!(u16     => u64);
+gen_upcast!(u32     => u32);
+gen_upcast!(u32     => u64);
+gen_upcast!(u64     => u64);
+
+// Signed
+gen_upcast!(i8      => i8);
+gen_upcast!(i8      => i16);
+gen_upcast!(i8      => i32);
+gen_upcast!(i8      => i64);
+gen_upcast!(i16     => i16);
+gen_upcast!(i16     => i32);
+gen_upcast!(i16     => i64);
+gen_upcast!(i32     => i32);
+gen_upcast!(i32     => i64);
+gen_upcast!(i64     => i64);
+
+// Pointer Sized
+
+gen_upcast!(u8      => usize);
+gen_upcast!(i8      => isize);
+gen_upcast!(u16     => usize);
+gen_upcast!(i16     => isize);
+
+#[cfg(any(target_pointer_width = "64", target_pointer_width = "32"))]
+gen_upcast!(u32     => usize);
+
+#[cfg(any(target_pointer_width = "64", target_pointer_width = "32"))]
+gen_upcast!(i32     => isize);
+
+gen_upcast!(isize   => isize);
+gen_upcast!(usize   => usize);
+
+
+impl IntoUsize for usize {
+    fn into_usize(self) -> usize { self }
+}
+
+impl<T> IntoUsize for *const T {
+    fn into_usize(self) -> usize { self as usize }
+}
+
+impl<T> IntoUsize for *mut T {
+    fn into_usize(self) -> usize { self as usize }
+}
+
+impl<T> IntoUsize for &T {
+    fn into_usize(self) -> usize { self as *const _ as usize }
+}
+
+impl<T> IntoUsize for &mut T {
+    fn into_usize(self) -> usize { self as *mut _ as usize }
+}