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Implement rust-lang#88581
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jhpratt committed Sep 2, 2021
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167 changes: 167 additions & 0 deletions library/core/src/num/int_macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
104 changes: 104 additions & 0 deletions library/core/src/num/uint_macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1758,6 +1758,110 @@ macro_rules! uint_impl {
self % rhs
}

/// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
///
/// This is the same as performing `self / rhs` for all unsigned integers.
///
/// # Panics
///
/// This function will panic if `rhs` is 0.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[inline(always)]
#[rustc_inherit_overflow_checks]
pub const fn div_floor(self, rhs: Self) -> Self {
self / rhs
}

/// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
///
/// # Panics
///
/// This function will panic if `rhs` is 0.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(int_roundings)]
#[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
/// ```
#[unstable(feature = "int_roundings", issue = "88581")]
#[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 {
d + 1
} else {
d
}
}

/// Calculates the smallest value greater 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);")]
/// ```
#[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 {
match self % rhs {
0 => self,
r => self + (rhs - r)
}
}

/// Calculates the smallest value greater than or equal to `self` that
/// is a multiple of `rhs`. If `rhs` is negative,
///
/// # 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!(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> {
match try_opt!(self.checked_rem(rhs)) {
0 => Some(self),
r => self.checked_add(try_opt!(rhs.checked_sub(r)))
}
}

/// Returns `true` if and only if `self == 2^k` for some `k`.
///
/// # Examples
Expand Down
1 change: 1 addition & 0 deletions library/core/tests/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@
#![feature(unsized_tuple_coercion)]
#![feature(const_option)]
#![feature(integer_atomics)]
#![feature(int_roundings)]
#![feature(slice_group_by)]
#![feature(trusted_random_access)]
#![feature(unsize)]
Expand Down
49 changes: 49 additions & 0 deletions library/core/tests/num/int_macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -289,6 +289,55 @@ macro_rules! int_module {
assert_eq!(r.saturating_pow(3), -8 as $T);
assert_eq!(r.saturating_pow(0), 1 as $T);
}

#[test]
fn test_div_floor() {
let a: $T = 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);
}

#[test]
fn test_div_ceil() {
let a: $T = 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);
}

#[test]
fn test_next_multiple_of() {
assert_eq!((16 as $T).next_multiple_of(8), 16);
assert_eq!((23 as $T).next_multiple_of(8), 24);
assert_eq!((16 as $T).next_multiple_of(-8), 16);
assert_eq!((23 as $T).next_multiple_of(-8), 16);
assert_eq!((-16 as $T).next_multiple_of(8), -16);
assert_eq!((-23 as $T).next_multiple_of(8), -16);
assert_eq!((-16 as $T).next_multiple_of(-8), -16);
assert_eq!((-23 as $T).next_multiple_of(-8), -24);
assert_eq!(MIN.next_multiple_of(-1), MIN);
}

#[test]
fn test_checked_next_multiple_of() {
assert_eq!((16 as $T).checked_next_multiple_of(8), Some(16));
assert_eq!((23 as $T).checked_next_multiple_of(8), Some(24));
assert_eq!((16 as $T).checked_next_multiple_of(-8), Some(16));
assert_eq!((23 as $T).checked_next_multiple_of(-8), Some(16));
assert_eq!((-16 as $T).checked_next_multiple_of(8), Some(-16));
assert_eq!((-23 as $T).checked_next_multiple_of(8), Some(-16));
assert_eq!((-16 as $T).checked_next_multiple_of(-8), Some(-16));
assert_eq!((-23 as $T).checked_next_multiple_of(-8), Some(-24));
assert_eq!((1 as $T).checked_next_multiple_of(0), None);
assert_eq!(MAX.checked_next_multiple_of(2), None);
assert_eq!(MIN.checked_next_multiple_of(-3), None);
assert_eq!(MIN.checked_next_multiple_of(-1), Some(MIN));
}
}
};
}
25 changes: 25 additions & 0 deletions library/core/tests/num/uint_macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -205,6 +205,31 @@ macro_rules! uint_module {
assert_eq!(r.overflowing_pow(2), (1 as $T, true));
assert_eq!(r.saturating_pow(2), MAX);
}

#[test]
fn test_div_floor() {
assert_eq!((8 as $T).div_floor(3), 2);
}

#[test]
fn test_div_ceil() {
assert_eq!((8 as $T).div_ceil(3), 3);
}

#[test]
fn test_next_multiple_of() {
assert_eq!((16 as $T).next_multiple_of(8), 16);
assert_eq!((23 as $T).next_multiple_of(8), 24);
assert_eq!(MAX.next_multiple_of(1), MAX);
}

#[test]
fn test_checked_next_multiple_of() {
assert_eq!((16 as $T).checked_next_multiple_of(8), Some(16));
assert_eq!((23 as $T).checked_next_multiple_of(8), Some(24));
assert_eq!((1 as $T).checked_next_multiple_of(0), None);
assert_eq!(MAX.checked_next_multiple_of(2), None);
}
}
};
}

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