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Add Saturating type (based on Wrapping type)

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Michael Watzko 2021-08-10 19:22:06 +02:00
parent ae90dcf020
commit 709a6c913e
4 changed files with 821 additions and 0 deletions
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4
library/core/src/num/mod.rs
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@ -43,8 +43,12 @@ macro_rules! unlikely {
mod error;
mod int_log10;
mod nonzero;
#[unstable(feature = "saturating_int_impl", issue = "87920")]
mod saturating;
mod wrapping;
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub use saturating::Saturating;
#[stable(feature = "rust1", since = "1.0.0")]
pub use wrapping::Wrapping;

814
library/core/src/num/saturating.rs Normal file
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@ -0,0 +1,814 @@
//! Definitions of `Saturating<T>`.
use crate::fmt;
use crate::ops::{Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign};
use crate::ops::{BitXor, BitXorAssign, Div, DivAssign};
use crate::ops::{Mul, MulAssign, Neg, Not};
use crate::ops::{Sub, SubAssign};
/// Provides intentionally-wrapped arithmetic on `T`.
///
/// Operations like `+` on `u32` values are intended to never overflow,
/// and in some debug configurations overflow is detected and results
/// in a panic. While most arithmetic falls into this category, some
/// code explicitly expects and relies upon modular arithmetic (e.g.,
/// hashing).
///
/// Saturating arithmetic can be achieved either through methods like
/// `saturating_add`, or through the `Saturating<T>` type, which says that
/// all standard arithmetic operations on the underlying value are
/// intended to have saturating semantics.
///
/// The underlying value can be retrieved through the `.0` index of the
/// `Saturating` tuple.
///
/// # Examples
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// let max = Saturating(u32::MAX);
/// let one = Saturating(1u32);
///
/// assert_eq!(u32::MAX, (max + one).0);
/// ```
#[unstable(feature = "saturating_int_impl", issue = "87920")]
#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Default, Hash)]
#[repr(transparent)]
pub struct Saturating<T>(#[stable(feature = "rust1", since = "1.0.0")] pub T);
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: fmt::Debug> fmt::Debug for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[stable(feature = "saturating_display", since = "1.10.0")]
impl<T: fmt::Display> fmt::Display for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[stable(feature = "saturating_fmt", since = "1.11.0")]
impl<T: fmt::Binary> fmt::Binary for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[stable(feature = "saturating_fmt", since = "1.11.0")]
impl<T: fmt::Octal> fmt::Octal for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[stable(feature = "saturating_fmt", since = "1.11.0")]
impl<T: fmt::LowerHex> fmt::LowerHex for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[stable(feature = "saturating_fmt", since = "1.11.0")]
impl<T: fmt::UpperHex> fmt::UpperHex for Saturating<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
#[allow(unused_macros)]
macro_rules! sh_impl_signed {
($t:ident, $f:ident) => {
};
}
macro_rules! sh_impl_unsigned {
($t:ident, $f:ident) => {
};
}
// FIXME (#23545): uncomment the remaining impls
macro_rules! sh_impl_all {
($($t:ident)*) => ($(
//sh_impl_unsigned! { $t, u8 }
//sh_impl_unsigned! { $t, u16 }
//sh_impl_unsigned! { $t, u32 }
//sh_impl_unsigned! { $t, u64 }
//sh_impl_unsigned! { $t, u128 }
sh_impl_unsigned! { $t, usize }
//sh_impl_signed! { $t, i8 }
//sh_impl_signed! { $t, i16 }
//sh_impl_signed! { $t, i32 }
//sh_impl_signed! { $t, i64 }
//sh_impl_signed! { $t, i128 }
//sh_impl_signed! { $t, isize }
)*)
}
sh_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize }
// FIXME(30524): impl Op<T> for Saturating<T>, impl OpAssign<T> for Saturating<T>
macro_rules! saturating_impl {
($($t:ty)*) => ($(
#[stable(feature = "rust1", since = "1.0.0")]
impl Add for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn add(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0.saturating_add(other.0))
}
}
forward_ref_binop! { impl Add, add for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl AddAssign for Saturating<$t> {
#[inline]
fn add_assign(&mut self, other: Saturating<$t>) {
*self = *self + other;
}
}
forward_ref_op_assign! { impl AddAssign, add_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "rust1", since = "1.0.0")]
impl Sub for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn sub(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0.saturating_sub(other.0))
}
}
forward_ref_binop! { impl Sub, sub for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl SubAssign for Saturating<$t> {
#[inline]
fn sub_assign(&mut self, other: Saturating<$t>) {
*self = *self - other;
}
}
forward_ref_op_assign! { impl SubAssign, sub_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "rust1", since = "1.0.0")]
impl Mul for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn mul(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0.saturating_mul(other.0))
}
}
forward_ref_binop! { impl Mul, mul for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl MulAssign for Saturating<$t> {
#[inline]
fn mul_assign(&mut self, other: Saturating<$t>) {
*self = *self * other;
}
}
forward_ref_op_assign! { impl MulAssign, mul_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "saturating_div", since = "1.3.0")]
impl Div for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn div(self, other: Saturating<$t>) -> Saturating<$t> {
// saturating div is the default behavior?
Saturating(self.0.div(other.0))
}
}
forward_ref_binop! { impl Div, div for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl DivAssign for Saturating<$t> {
#[inline]
fn div_assign(&mut self, other: Saturating<$t>) {
*self = *self / other;
}
}
forward_ref_op_assign! { impl DivAssign, div_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "rust1", since = "1.0.0")]
impl Not for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn not(self) -> Saturating<$t> {
Saturating(!self.0)
}
}
forward_ref_unop! { impl Not, not for Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "rust1", since = "1.0.0")]
impl BitXor for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn bitxor(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0 ^ other.0)
}
}
forward_ref_binop! { impl BitXor, bitxor for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl BitXorAssign for Saturating<$t> {
#[inline]
fn bitxor_assign(&mut self, other: Saturating<$t>) {
*self = *self ^ other;
}
}
forward_ref_op_assign! { impl BitXorAssign, bitxor_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "rust1", since = "1.0.0")]
impl BitOr for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn bitor(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0 | other.0)
}
}
forward_ref_binop! { impl BitOr, bitor for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl BitOrAssign for Saturating<$t> {
#[inline]
fn bitor_assign(&mut self, other: Saturating<$t>) {
*self = *self | other;
}
}
forward_ref_op_assign! { impl BitOrAssign, bitor_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "rust1", since = "1.0.0")]
impl BitAnd for Saturating<$t> {
type Output = Saturating<$t>;
#[inline]
fn bitand(self, other: Saturating<$t>) -> Saturating<$t> {
Saturating(self.0 & other.0)
}
}
forward_ref_binop! { impl BitAnd, bitand for Saturating<$t>, Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
#[stable(feature = "op_assign_traits", since = "1.8.0")]
impl BitAndAssign for Saturating<$t> {
#[inline]
fn bitand_assign(&mut self, other: Saturating<$t>) {
*self = *self & other;
}
}
forward_ref_op_assign! { impl BitAndAssign, bitand_assign for Saturating<$t>, Saturating<$t> }
#[stable(feature = "saturating_neg", since = "1.45.0")]
impl Neg for Saturating<$t> {
type Output = Self;
#[inline]
fn neg(self) -> Self {
Saturating(0) - self
}
}
forward_ref_unop! { impl Neg, neg for Saturating<$t>,
#[stable(feature = "saturating_ref", since = "1.14.0")] }
)*)
}
saturating_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
macro_rules! saturating_int_impl {
($($t:ty)*) => ($(
impl Saturating<$t> {
/// Returns the smallest value that can be represented by this integer type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(<Saturating<", stringify!($t), ">>::MIN, Saturating(", stringify!($t), "::MIN));")]
/// ```
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const MIN: Self = Self(<$t>::MIN);
/// Returns the largest value that can be represented by this integer type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(<Saturating<", stringify!($t), ">>::MAX, Saturating(", stringify!($t), "::MAX));")]
/// ```
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const MAX: Self = Self(<$t>::MAX);
/// Returns the size of this integer type in bits.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(<Saturating<", stringify!($t), ">>::BITS, ", stringify!($t), "::BITS);")]
/// ```
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const BITS: u32 = <$t>::BITS;
/// Returns the number of ones in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0b01001100", stringify!($t), ");")]
///
/// assert_eq!(n.count_ones(), 3);
/// ```
#[inline]
#[doc(alias = "popcount")]
#[doc(alias = "popcnt")]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn count_ones(self) -> u32 {
self.0.count_ones()
}
/// Returns the number of zeros in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(Saturating(!0", stringify!($t), ").count_zeros(), 0);")]
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn count_zeros(self) -> u32 {
self.0.count_zeros()
}
/// Returns the number of trailing zeros in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0b0101000", stringify!($t), ");")]
///
/// assert_eq!(n.trailing_zeros(), 3);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn trailing_zeros(self) -> u32 {
self.0.trailing_zeros()
}
/// Shifts the bits to the left by a specified amount, `n`,
/// saturating the truncated bits to the end of the resulting
/// integer.
///
/// Please note this isn't the same operation as the `<<` shifting
/// operator!
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// let n: Saturating<i64> = Saturating(0x0123456789ABCDEF);
/// let m: Saturating<i64> = Saturating(-0x76543210FEDCBA99);
///
/// assert_eq!(n.rotate_left(32), m);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn rotate_left(self, n: u32) -> Self {
Saturating(self.0.rotate_left(n))
}
/// Shifts the bits to the right by a specified amount, `n`,
/// saturating the truncated bits to the beginning of the resulting
/// integer.
///
/// Please note this isn't the same operation as the `>>` shifting
/// operator!
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// let n: Saturating<i64> = Saturating(0x0123456789ABCDEF);
/// let m: Saturating<i64> = Saturating(-0xFEDCBA987654322);
///
/// assert_eq!(n.rotate_right(4), m);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn rotate_right(self, n: u32) -> Self {
Saturating(self.0.rotate_right(n))
}
/// Reverses the byte order of the integer.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// let n: Saturating<i16> = Saturating(0b0000000_01010101);
/// assert_eq!(n, Saturating(85));
///
/// let m = n.swap_bytes();
///
/// assert_eq!(m, Saturating(0b01010101_00000000));
/// assert_eq!(m, Saturating(21760));
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn swap_bytes(self) -> Self {
Saturating(self.0.swap_bytes())
}
/// Reverses the bit pattern of the integer.
///
/// # Examples
///
/// Please note that this example is shared between integer types.
/// Which explains why `i16` is used here.
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// let n = Saturating(0b0000000_01010101i16);
/// assert_eq!(n, Saturating(85));
///
/// let m = n.reverse_bits();
///
/// assert_eq!(m.0 as u16, 0b10101010_00000000);
/// assert_eq!(m, Saturating(-22016));
/// ```
#[stable(feature = "reverse_bits", since = "1.37.0")]
#[rustc_const_stable(feature = "const_reverse_bits", since = "1.37.0")]
#[inline]
#[must_use]
pub const fn reverse_bits(self) -> Self {
Saturating(self.0.reverse_bits())
}
/// 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(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0x1A", stringify!($t), ");")]
///
/// if cfg!(target_endian = "big") {
#[doc = concat!(" assert_eq!(<Saturating<", stringify!($t), ">>::from_be(n), n)")]
/// } else {
#[doc = concat!(" assert_eq!(<Saturating<", stringify!($t), ">>::from_be(n), n.swap_bytes())")]
/// }
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn from_be(x: Self) -> Self {
Saturating(<$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(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0x1A", stringify!($t), ");")]
///
/// if cfg!(target_endian = "little") {
#[doc = concat!(" assert_eq!(<Saturating<", stringify!($t), ">>::from_le(n), n)")]
/// } else {
#[doc = concat!(" assert_eq!(<Saturating<", stringify!($t), ">>::from_le(n), n.swap_bytes())")]
/// }
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn from_le(x: Self) -> Self {
Saturating(<$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(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0x1A", stringify!($t), ");")]
///
/// if cfg!(target_endian = "big") {
/// assert_eq!(n.to_be(), n)
/// } else {
/// assert_eq!(n.to_be(), n.swap_bytes())
/// }
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn to_be(self) -> Self {
Saturating(self.0.to_be())
}
/// Converts `self` to little endian from the target's endianness.
///
/// On little endian this is a no-op. On big endian the bytes are
/// swapped.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(0x1A", stringify!($t), ");")]
///
/// if cfg!(target_endian = "little") {
/// assert_eq!(n.to_le(), n)
/// } else {
/// assert_eq!(n.to_le(), n.swap_bytes())
/// }
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn to_le(self) -> Self {
Saturating(self.0.to_le())
}
/// Raises self to the power of `exp`, using exponentiation by squaring.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(Saturating(3", stringify!($t), ").pow(4), Saturating(81));")]
/// ```
///
/// Results that are too large are wrapped:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
/// assert_eq!(Saturating(3i8).pow(5), Saturating(127));
/// assert_eq!(Saturating(3i8).pow(6), Saturating(127));
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub fn pow(self, exp: u32) -> Self {
Saturating(self.0.saturating_pow(exp))
}
}
)*)
}
saturating_int_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
macro_rules! saturating_int_impl_signed {
($($t:ty)*) => ($(
impl Saturating<$t> {
/// Returns the number of leading zeros in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(", stringify!($t), "::MAX) / 4;")]
///
/// assert_eq!(n.leading_zeros(), 3);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn leading_zeros(self) -> u32 {
self.0.leading_zeros()
}
/// Computes the absolute value of `self`, saturating around at
/// the boundary of the type.
///
/// The only case where such saturating can occur is when one takes the absolute value of the negative
/// minimal value for the type this is a positive value that is too large to represent in the type. In
/// such a case, this function returns `MIN` itself.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(Saturating(100", stringify!($t), ").abs(), Saturating(100));")]
#[doc = concat!("assert_eq!(Saturating(-100", stringify!($t), ").abs(), Saturating(100));")]
#[doc = concat!("assert_eq!(Saturating(", stringify!($t), "::MIN).abs(), Saturating(", stringify!($t), "::MIN));")]
/// assert_eq!(Saturating(-128i8).abs().0 as u8, 128u8);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub fn abs(self) -> Saturating<$t> {
Saturating(self.0.saturating_abs())
}
/// Returns a number representing sign of `self`.
///
/// - `0` if the number is zero
/// - `1` if the number is positive
/// - `-1` if the number is negative
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert_eq!(Saturating(10", stringify!($t), ").signum(), Saturating(1));")]
#[doc = concat!("assert_eq!(Saturating(0", stringify!($t), ").signum(), Saturating(0));")]
#[doc = concat!("assert_eq!(Saturating(-10", stringify!($t), ").signum(), Saturating(-1));")]
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub fn signum(self) -> Saturating<$t> {
Saturating(self.0.signum())
}
/// Returns `true` if `self` is positive and `false` if the number is zero or
/// negative.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert!(Saturating(10", stringify!($t), ").is_positive());")]
#[doc = concat!("assert!(!Saturating(-10", stringify!($t), ").is_positive());")]
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn is_positive(self) -> bool {
self.0.is_positive()
}
/// Returns `true` if `self` is negative and `false` if the number is zero or
/// positive.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert!(Saturating(-10", stringify!($t), ").is_negative());")]
#[doc = concat!("assert!(!Saturating(10", stringify!($t), ").is_negative());")]
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn is_negative(self) -> bool {
self.0.is_negative()
}
}
)*)
}
saturating_int_impl_signed! { isize i8 i16 i32 i64 i128 }
macro_rules! saturating_int_impl_unsigned {
($($t:ty)*) => ($(
impl Saturating<$t> {
/// Returns the number of leading zeros in the binary representation of `self`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("let n = Saturating(", stringify!($t), "::MAX) / 4;")]
///
/// assert_eq!(n.leading_zeros(), 2);
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub const fn leading_zeros(self) -> u32 {
self.0.leading_zeros()
}
/// Returns `true` if and only if `self == 2^k` for some `k`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(saturating_int_impl)]
/// use std::num::Saturating;
///
#[doc = concat!("assert!(Saturating(16", stringify!($t), ").is_power_of_two());")]
#[doc = concat!("assert!(!Saturating(10", stringify!($t), ").is_power_of_two());")]
/// ```
#[inline]
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub fn is_power_of_two(self) -> bool {
self.0.is_power_of_two()
}
}
)*)
}
saturating_int_impl_unsigned! { usize u8 u16 u32 u64 u128 }

1
library/std/src/lib.rs
View file

@ -308,6 +308,7 @@
#![feature(ptr_internals)]
#![feature(rustc_attrs)]
#![feature(rustc_private)]
#![feature(saturating_int_impl)]
#![feature(slice_concat_ext)]
#![feature(slice_internals)]
#![feature(slice_ptr_get)]

2
library/std/src/num.rs
View file

@ -12,6 +12,8 @@
#[cfg(test)]
mod benches;
#[unstable(feature = "saturating_int_impl", issue = "87920")]
pub use core::num::Saturating;
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::num::Wrapping;
#[stable(feature = "rust1", since = "1.0.0")]