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Rollup merge of rust-lang#48810 - Phlosioneer:32463-impl-integer-for-…
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…wrapping, r=dtolnay

Implement Integer methods for Wrapping

Wrapping<T> now implements:

count_ones, count_zeros, leading_zeros,
trailing_zeros, rotate_left, rotate_right, swap_bytes, from_be,
from_le, to_be, to_le, and pow

where T is:

u8, u16, u32, u64, usize, i8, i16, i32, i64, or isize.

Docs were written for all these methods, as well as examples. The
examples mirror the ones on u8, u16, etc... for consistency.

Closes rust-lang#32463
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@kennytm
kennytm committed Mar 10, 2018
2 parents 0a0c28f + 910d855 commit de827e5
Showing 1 changed file with 309 additions and 0 deletions.
309 changes: 309 additions & 0 deletions src/libcore/num/wrapping.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -317,11 +317,320 @@ macro_rules! wrapping_impl {
}
forward_ref_unop! { impl Neg, neg for Wrapping<$t>,
#[stable(feature = "wrapping_ref", since = "1.14.0")] }

)*)
}

wrapping_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }

macro_rules! wrapping_int_impl {
($($t:ty)*) => ($(
impl Wrapping<$t> {
/// Returns the number of ones in the binary representation of
/// `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i8> = Wrapping(-0b1000_0000);
///
/// assert_eq!(n.count_ones(), 1);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn count_ones(self) -> u32 {
self.0.count_ones()
}

/// Returns the number of zeros in the binary representation of
/// `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i8> = Wrapping(-0b1000_0000);
///
/// assert_eq!(n.count_zeros(), 7);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn count_zeros(self) -> u32 {
self.0.count_zeros()
}

/// Returns the number of leading zeros in the binary representation
/// of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i16> = Wrapping(-1);
///
/// assert_eq!(n.leading_zeros(), 0);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn leading_zeros(self) -> u32 {
self.0.leading_zeros()
}

/// Returns the number of trailing zeros in the binary representation
/// of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i8> = Wrapping(-4);
///
/// assert_eq!(n.trailing_zeros(), 2);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn trailing_zeros(self) -> u32 {
self.0.trailing_zeros()
}

/// Shifts the bits to the left by a specified amount, `n`,
/// wrapping the truncated bits to the end of the resulting
/// integer.
///
/// Please note this isn't the same operation as `>>`!
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
/// let m: Wrapping<i64> = Wrapping(-0x76543210FEDCBA99);
///
/// assert_eq!(n.rotate_left(32), m);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn rotate_left(self, n: u32) -> Self {
Wrapping(self.0.rotate_left(n))
}

/// Shifts the bits to the right by a specified amount, `n`,
/// wrapping the truncated bits to the beginning of the resulting
/// integer.
///
/// Please note this isn't the same operation as `<<`!
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
/// let m: Wrapping<i64> = Wrapping(-0xFEDCBA987654322);
///
/// assert_eq!(n.rotate_right(4), m);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn rotate_right(self, n: u32) -> Self {
Wrapping(self.0.rotate_right(n))
}

/// Reverses the byte order of the integer.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i16> = Wrapping(0b0000000_01010101);
/// assert_eq!(n, Wrapping(85));
///
/// let m = n.swap_bytes();
///
/// assert_eq!(m, Wrapping(0b01010101_00000000));
/// assert_eq!(m, Wrapping(21760));
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn swap_bytes(self) -> Self {
Wrapping(self.0.swap_bytes())
}

/// Converts an integer from big endian to the target's endianness.
///
/// On big endian this is a no-op. On little endian the bytes are
/// swapped.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
///
/// if cfg!(target_endian = "big") {
/// assert_eq!(Wrapping::<i64>::from_be(n), n);
/// } else {
/// assert_eq!(Wrapping::<i64>::from_be(n), n.swap_bytes());
/// }
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn from_be(x: Self) -> Self {
Wrapping(<$t>::from_be(x.0))
}

/// Converts an integer from little endian to the target's endianness.
///
/// On little endian this is a no-op. On big endian the bytes are
/// swapped.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
///
/// if cfg!(target_endian = "little") {
/// assert_eq!(Wrapping::<i64>::from_le(n), n);
/// } else {
/// assert_eq!(Wrapping::<i64>::from_le(n), n.swap_bytes());
/// }
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn from_le(x: Self) -> Self {
Wrapping(<$t>::from_le(x.0))
}

/// Converts `self` to big endian from the target's endianness.
///
/// On big endian this is a no-op. On little endian the bytes are
/// swapped.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
///
/// if cfg!(target_endian = "big") {
/// assert_eq!(n.to_be(), n);
/// } else {
/// assert_eq!(n.to_be(), n.swap_bytes());
/// }
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn to_be(self) -> Self {
Wrapping(self.0.to_be())
}

/// Converts `self` to little endian from the target's endianness.
///
/// On little endian this is a no-op. On big endian the bytes are
/// swapped.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let n: Wrapping<i64> = Wrapping(0x0123456789ABCDEF);
///
/// if cfg!(target_endian = "little") {
/// assert_eq!(n.to_le(), n);
/// } else {
/// assert_eq!(n.to_le(), n.swap_bytes());
/// }
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn to_le(self) -> Self {
Wrapping(self.0.to_le())
}

/// Raises self to the power of `exp`, using exponentiation by
/// squaring.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// let x: Wrapping<i32> = Wrapping(2); // or any other integer type
///
/// assert_eq!(x.pow(4), Wrapping(16));
/// ```
///
/// Results that are too large are wrapped:
///
/// ```
/// #![feature(wrapping_int_impl)]
/// use std::num::Wrapping;
///
/// // 5 ^ 4 = 625, which is too big for a u8
/// let x: Wrapping<u8> = Wrapping(5);
///
/// assert_eq!(x.pow(4).0, 113);
/// ```
#[inline]
#[unstable(feature = "wrapping_int_impl", issue = "32463")]
pub fn pow(self, exp: u32) -> Self {
Wrapping(self.0.wrapping_pow(exp))
}
}
)*)
}

wrapping_int_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }


mod shift_max {
#![allow(non_upper_case_globals)]

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