sigils/src/one.rs

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

use std::ops::Mul;

/// Defines a multiplicative identity element for `Self`.
pub trait One: Sized + Mul<Self, Output=Self>
{
   /// Returns the multiplicative identity element of `Self`, `1`.
   ///
   /// # Laws
   ///
   /// ```text
   /// a * 1 = a       ∀ a ∈ Self
   /// 1 * a = a       ∀ a ∈ Self
   /// ```
   ///
   /// # Purity
   ///
   /// This function should return the same result at all times regardless of
   /// external mutable state, for example values stored in TLS or in
   /// `static mut`s.
   fn one() -> Self;
}



macro_rules! one_impl
{
   ($varType: ty, $val: expr) =>
   {
      impl One for $varType
      {
         fn one() -> $varType
         {
            $val
         }
      }
   }
}



one_impl!(u8, 1u8);
one_impl!(u16, 1u16);
one_impl!(u32, 1u32);
one_impl!(u64, 1u64);
one_impl!(usize, 1usize);

one_impl!(i8, 1i8);
one_impl!(i16, 1i16);
one_impl!(i32, 1i32);
one_impl!(i64, 1i64);
one_impl!(isize, 1isize);

one_impl!(f32, 1.0f32);
one_impl!(f64, 1.0f64);