average.rs - source
Description: Source of the Rust file `/Users/erlendbasso/.cargo/registry/src/github.com-1ecc6299db9ec823/num-integer-0.1.45/src/average.rs`.
Keywords: rust, rustlang, rust-lang

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    use core::ops::{BitAnd, BitOr, BitXor, Shr};
    use Integer;

    /// Provides methods to compute the average of two integers, without overflows.
    pub trait Average: Integer {
        /// Returns the ceiling value of the average of `self` and `other`.
        /// -- `⌈(self + other)/2⌉`
        ///
        /// # Examples
        ///
        /// ```
        /// use num_integer::Average;
        ///
        /// assert_eq!(( 3).average_ceil(&10),  7);
        /// assert_eq!((-2).average_ceil(&-5), -3);
        /// assert_eq!(( 4).average_ceil(& 4),  4);
        ///
        /// assert_eq!(u8::max_value().average_ceil(&2), 129);
        /// assert_eq!(i8::min_value().average_ceil(&-1), -64);
        /// assert_eq!(i8::min_value().average_ceil(&i8::max_value()), 0);
        /// ```
        ///
        fn average_ceil(&self, other: &Self) -> Self;

        /// Returns the floor value of the average of `self` and `other`.
        /// -- `⌊(self + other)/2⌋`
        ///
        /// # Examples
        ///
        /// ```
        /// use num_integer::Average;
        ///
        /// assert_eq!(( 3).average_floor(&10),  6);
        /// assert_eq!((-2).average_floor(&-5), -4);
        /// assert_eq!(( 4).average_floor(& 4),  4);
        ///
        /// assert_eq!(u8::max_value().average_floor(&2), 128);
        /// assert_eq!(i8::min_value().average_floor(&-1), -65);
        /// assert_eq!(i8::min_value().average_floor(&i8::max_value()), -1);
        /// ```
        ///
        fn average_floor(&self, other: &Self) -> Self;
    }

    impl<I> Average for I
    where
        I: Integer + Shr<usize, Output = I>,
        for<'a, 'b> &'a I:
            BitAnd<&'b I, Output = I> + BitOr<&'b I, Output = I> + BitXor<&'b I, Output = I>,
    {
        // The Henry Gordon Dietz implementation as shown in the Hacker's Delight,
        // see http://aggregate.org/MAGIC/#Average%20of%20Integers

        /// Returns the floor value of the average of `self` and `other`.
        #[inline]
        fn average_floor(&self, other: &I) -> I {
            (self & other) + ((self ^ other) >> 1)
        }

        /// Returns the ceil value of the average of `self` and `other`.
        #[inline]
        fn average_ceil(&self, other: &I) -> I {
            (self | other) - ((self ^ other) >> 1)
        }
    }

    /// Returns the floor value of the average of `x` and `y` --
    /// see [Average::average_floor](trait.Average.html#tymethod.average_floor).
    #[inline]
    pub fn average_floor<T: Average>(x: T, y: T) -> T {
        x.average_floor(&y)
    }
    /// Returns the ceiling value of the average of `x` and `y` --
    /// see [Average::average_ceil](trait.Average.html#tymethod.average_ceil).
    #[inline]
    pub fn average_ceil<T: Average>(x: T, y: T) -> T {
        x.average_ceil(&y)
    }