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Implement #88581

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Jacob Pratt 2021-09-02 01:28:47 -04:00
parent 76e755cf4a
commit 727a4fc7e3
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167
library/core/src/num/int_macros.rs
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@ -1746,6 +1746,173 @@ macro_rules! int_impl {
}
}
/// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
///
/// # Panics
///
/// This function will panic if `rhs` is 0 or the division results in overflow.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("let a: ", stringify!($SelfT)," = 8;")]
/// let b = 3;
///
/// assert_eq!(a.div_floor(b), 2);
/// assert_eq!(a.div_floor(-b), -3);
/// assert_eq!((-a).div_floor(b), -3);
/// assert_eq!((-a).div_floor(-b), 2);
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_inherit_overflow_checks]
pub const fn div_floor(self, rhs: Self) -> Self {
let d = self / rhs;
let r = self % rhs;
if (r > 0 && rhs < 0) || (r < 0 && rhs > 0) {
d - 1
} else {
d
}
}
/// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
///
/// # Panics
///
/// This function will panic if `rhs` is 0 or the division results in overflow.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("let a: ", stringify!($SelfT)," = 8;")]
/// let b = 3;
///
/// assert_eq!(a.div_ceil(b), 3);
/// assert_eq!(a.div_ceil(-b), -2);
/// assert_eq!((-a).div_ceil(b), -2);
/// assert_eq!((-a).div_ceil(-b), 3);
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_inherit_overflow_checks]
pub const fn div_ceil(self, rhs: Self) -> Self {
let d = self / rhs;
let r = self % rhs;
if (r > 0 && rhs > 0) || (r < 0 && rhs < 0) {
d + 1
} else {
d
}
}
/// If `rhs` is positive, calculates the smallest value greater than or
/// equal to `self` that is a multiple of `rhs`. If `rhs` is negative,
/// calculates the largest value less than or equal to `self` that is a
/// multiple of `rhs`.
///
/// # Panics
///
/// This function will panic if `rhs` is 0 or the operation results in overflow.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
#[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
#[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(-8), 16);")]
#[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(-8), 16);")]
#[doc = concat!("assert_eq!((-16_", stringify!($SelfT), ").next_multiple_of(8), -16);")]
#[doc = concat!("assert_eq!((-23_", stringify!($SelfT), ").next_multiple_of(8), -16);")]
#[doc = concat!("assert_eq!((-16_", stringify!($SelfT), ").next_multiple_of(-8), -16);")]
#[doc = concat!("assert_eq!((-23_", stringify!($SelfT), ").next_multiple_of(-8), -24);")]
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_inherit_overflow_checks]
pub const fn next_multiple_of(self, rhs: Self) -> Self {
// This would otherwise fail when calculating `r` when self == T::MIN.
if rhs == -1 {
return self;
}
let r = self % rhs;
let m = if (r > 0 && rhs < 0) || (r < 0 && rhs > 0) {
r + rhs
} else {
r
};
if m == 0 {
self
} else {
self + (rhs - m)
}
}
/// If `rhs` is positive, calculates the smallest value greater than or
/// equal to `self` that is a multiple of `rhs`. If `rhs` is negative,
/// calculates the largest value less than or equal to `self` that is a
/// multiple of `rhs`. Returns `None` if `rhs` is zero or the operation
/// would result in overflow.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
#[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
#[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(-8), Some(16));")]
#[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(-8), Some(16));")]
#[doc = concat!("assert_eq!((-16_", stringify!($SelfT), ").checked_next_multiple_of(8), Some(-16));")]
#[doc = concat!("assert_eq!((-23_", stringify!($SelfT), ").checked_next_multiple_of(8), Some(-16));")]
#[doc = concat!("assert_eq!((-16_", stringify!($SelfT), ").checked_next_multiple_of(-8), Some(-16));")]
#[doc = concat!("assert_eq!((-23_", stringify!($SelfT), ").checked_next_multiple_of(-8), Some(-24));")]
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_inherit_overflow_checks]
pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
// This would otherwise fail when calculating `r` when self == T::MIN.
if rhs == -1 {
return Some(self);
}
let r = try_opt!(self.checked_rem(rhs));
let m = if (r > 0 && rhs < 0) || (r < 0 && rhs > 0) {
try_opt!(r.checked_add(rhs))
} else {
r
};
if m == 0 {
Some(self)
} else {
self.checked_add(try_opt!(rhs.checked_sub(m)))
}
}
/// Returns the logarithm of the number with respect to an arbitrary base.
///
/// This method might not be optimized owing to implementation details;