sigils/src/bounded.rs

// SPDX-License-Identifier: Apache-2.0
// Sealed with Magistamp.

/// Primitive types that have upper and lower bounds.
pub trait Bounded
{
   /// The minimum value for this type.
   const MIN: Self;

   /// The maximum value for this type.
   const MAX: Self;
}



/// A macro for making implementation of
/// the Bounded trait easier.
macro_rules! bounded_trait_impl
{
   ($T: ty, $minVal: expr, $maxVal: expr) =>
   {
      impl Bounded for $T
      {
         const MIN: $T = $minVal;

         const MAX: $T = $maxVal;
      }
   }
}


// Implement the Bounded for all the primitive types.
bounded_trait_impl!(u8, 0u8, !0u8);
bounded_trait_impl!(u16, 0u16, !0u16);
bounded_trait_impl!(u32, 0u32, !0u32);
bounded_trait_impl!(u64, 0u64, !0u64);
bounded_trait_impl!(usize, 0usize, !0usize);

bounded_trait_impl!(i8, (!0i8 ^ (!0u8 >> 1u8) as i8),
                        !(!0i8 ^ (!0u8 >> 1u8) as i8));
bounded_trait_impl!(i16, (!0i16 ^ (!0u16 >> 1u16) as i16),
                         !(!0i16 ^ (!0u16 >> 1u16) as i16));
bounded_trait_impl!(i32, (!0i32 ^ (!0u32 >> 1u32) as i32),
                         !(!0i32 ^ (!0u32 >> 1u32) as i32));
bounded_trait_impl!(i64, (!0i64 ^ (!0u64 >> 1u64) as i64),
                         !(!0i64 ^ (!0u64 >> 1u64) as i64));
bounded_trait_impl!(isize, (!0isize ^ (!0usize >> 1usize) as isize),
                           !(!0isize ^ (!0usize >> 1usize) as isize));

bounded_trait_impl!(f32, -3.40282347e+38f32, 3.40282347e+38f32);
bounded_trait_impl!(f64, -1.7976931348623157e+308f64,
                         1.7976931348623157e+308f64);



#[cfg(test)]
mod tests
{
   macro_rules! bounds_test
   {
      ($T: ident, $func_name: ident, $minVal: expr, $maxVal: expr) =>
      {
         #[test]
         fn $func_name()
         {
            assert_eq!($T::MIN, $minVal);
            assert_eq!($T::MAX, $maxVal);
         }
      }
   }

   bounds_test!(u8, min_max_u8, 0u8, !0u8);
   bounds_test!(u16, min_max_u16, 0u16, !0u16);
   bounds_test!(u32, min_max_u32, 0u32, !0u32);
   bounds_test!(u64, min_max_u64, 0u64, !0u64);
   bounds_test!(usize, min_max_usize, 0usize, !0usize);

   bounds_test!(i8, min_max_i8,
    -1i8 << (((::std::mem::size_of::<i8>() as i8)*8i8)-1i8),
    !(-1i8 << (((::std::mem::size_of::<i8>() as i8)*8i8)-1i8)));
   bounds_test!(i16, min_max_i16,
    -1i16 << (((::std::mem::size_of::<i16>() as i16)*8i16)-1i16),
    !(-1i16 << (((::std::mem::size_of::<i16>() as i16)*8i16)-1i16)));
   bounds_test!(i32, min_max_i32,
    -1i32 << (((::std::mem::size_of::<i32>() as i32)*8i32)-1i32),
    !(-1i32 << (((::std::mem::size_of::<i32>() as i32)*8i32)-1i32)));
   bounds_test!(i64, min_max_i64,
    -1i64 << (((::std::mem::size_of::<i64>() as i64)*8i64)-1i64),
    !(-1i64 << (((::std::mem::size_of::<i64>() as i64)*8i64)-1i64)));
   bounds_test!(isize, min_max_isize,
    -1isize << (((::std::mem::size_of::<isize>() as isize)*8isize)-1isize),
    !(-1isize << (((::std::mem::size_of::<isize>() as isize)*8isize)-1isize)));

   bounds_test!(f32, min_max_f32,
                -3.40282347e+38f32, 3.40282347e+38f32);
   bounds_test!(f64, min_max_f64,
                -1.7976931348623157e+308f64,
                1.7976931348623157e+308f64);
}