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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::num::arithmetic::traits::{Parity, SaturatingPow, SaturatingPowAssign};
use crate::num::basic::signeds::PrimitiveSigned;
use crate::num::basic::unsigneds::PrimitiveUnsigned;
fn saturating_pow_unsigned<T: PrimitiveUnsigned>(x: T, exp: u64) -> T {
if exp == 0 {
T::ONE
} else if x < T::TWO {
x
} else if let Some(p) = x.checked_pow(exp) {
p
} else {
T::MAX
}
}
fn saturating_pow_signed<T: PrimitiveSigned>(x: T, exp: u64) -> T {
if exp == 0 {
T::ONE
} else if x == T::ZERO || x == T::ONE {
x
} else if x == T::NEGATIVE_ONE {
if exp.even() { T::ONE } else { T::NEGATIVE_ONE }
} else if let Some(p) = x.checked_pow(exp) {
p
} else if x > T::ZERO || exp.even() {
T::MAX
} else {
T::MIN
}
}
macro_rules! impl_saturating_pow_unsigned {
($t:ident) => {
impl SaturatingPow<u64> for $t {
type Output = $t;
/// This is a wrapper over the `saturating_pow` functions in the standard library, for
/// example [this one](u32::saturating_pow).
#[inline]
fn saturating_pow(self, exp: u64) -> $t {
saturating_pow_unsigned(self, exp)
}
}
};
}
apply_to_unsigneds!(impl_saturating_pow_unsigned);
macro_rules! impl_saturating_pow_signed {
($t:ident) => {
impl SaturatingPow<u64> for $t {
type Output = $t;
/// This is a wrapper over the `saturating_pow` functions in the standard library, for
/// example [this one](i32::saturating_pow).
#[inline]
fn saturating_pow(self, exp: u64) -> $t {
saturating_pow_signed(self, exp)
}
}
};
}
apply_to_signeds!(impl_saturating_pow_signed);
macro_rules! impl_saturating_pow_primitive_int {
($t:ident) => {
impl SaturatingPowAssign<u64> for $t {
/// Raises a number to a power, in place, saturating at the numeric bounds instead of
/// overflowing.
///
/// $$
/// x \gets \\begin{cases}
/// x^y & \text{if} \\quad m \leq x^y \leq M, \\\\
/// M & \text{if} \\quad x^y > M, \\\\
/// m & \text{if} \\quad x^y < m,
/// \\end{cases}
/// $$
/// where $m$ is `Self::MIN` and $M$ is `Self::MAX`.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::saturating_pow#saturating_pow_assign).
#[inline]
fn saturating_pow_assign(&mut self, exp: u64) {
*self = SaturatingPow::saturating_pow(*self, exp);
}
}
};
}
apply_to_primitive_ints!(impl_saturating_pow_primitive_int);