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// numera::number::integer::z::ops::mul
//
//! Implement the multiplication operations, and the Product trait.
//
use crate::number::{integer::*, traits::ConstOne};
use core::{
iter::Product,
ops::{Mul, MulAssign},
};
use devela::paste;
macro_rules! impl_integer_mul {
// impl Mul ops for multiple integer types
//
// # Args
// $t: integer base name. e.g. Integer
// $p: inner primitive base name. e.g. i
// $b: integer and primitive bitsize. e.g. 8
( $($t:ident + $p:ident + $b:literal, cast: $bcast:literal);+ ) => {
$( impl_integer_mul![mul: $t + $p + $b]; )+
};
// multiplication operations
//
// impl variants:
// - mul
// - checked_mul_
// - saturating_mul_
// - wrapping_mul_
// - overflowing_mul_
// - modular_mul_ TODO
// - modular_counting_mul_ TODO
(mul: $t:ident + $p:ident + $b:literal) => { paste! {
impl Mul<[<$t$b>]> for [<$t$b>] {
/// Performs the `*` operation.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
type Output = [<$t$b>];
#[inline]
fn mul(self, rhs: [<$t$b>]) -> Self::Output {
self.mul(rhs)
}
}
impl MulAssign for [<$t$b>] {
/// Performs the `*=` operation.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
#[inline]
fn mul_assign(&mut self, rhs: [<$t$b>]) {
self.0 *= rhs.0;
}
}
impl Product for [<$t$b>] {
fn product<I: Iterator<Item=Self>>(iter: I) -> Self {
iter.fold(
[<$t$b>]::ONE,
|a, b| a * b,
)
}
}
impl<'a> Product<&'a [<$t$b>]> for [<$t$b>] {
fn product<I: Iterator<Item=&'a Self>>(iter: I) -> Self {
iter.fold(
[<$t$b>]::ONE,
|a, b| a * *b,
)
}
}
/// # Multiplication
impl [<$t$b>] {
/// Integer multiplication.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
#[inline]
#[must_use]
pub const fn mul(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0 * rhs.0)
}
/// Checked integer multiplication.
///
/// Returns `None` on overflow.
#[inline]
#[must_use]
pub const fn checked_mul(self, rhs: [<$t$b>]) -> Option<[<$t$b>]> {
if let Some(result) = self.0.checked_mul(rhs.0) {
Some(Self(result))
} else {
None
}
}
/// Saturating multiplication.
/// Computes `self + rhs`, saturating at the numeric bounds instead of overflowing.
#[inline]
#[must_use]
pub const fn saturating_mul(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0.saturating_mul(rhs.0))
}
/// Wrapping (modular) multiplication.
/// Computes `self + rhs`, wrapping around at the boundary of the type.
#[inline]
#[must_use]
pub const fn wrapping_mul(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0.wrapping_mul(rhs.0))
}
/// Overflowing multiplication.
///
/// Returns a tuple of the multiplication along with a boolean indicating
/// whether an arithmetic overflow would occur. If an overflow would
/// have occurred then the wrapped value is returned.
#[inline]
#[must_use]
pub const fn overflowing_mul(self, rhs: [<$t$b>]) -> ([<$t$b>], bool) {
let (result, overflown) = self.0.overflowing_mul(rhs.0);
(Self(result), overflown)
}
// /// Modular multiplication with a custom `modulo`.
// #[inline]
// #[must_use]
// // TEST
// pub const fn modular_mul(self, rhs: [<$t$b>], modulo: [<$t$b>]) -> [<$t$b>] {
// self.mul(rhs).rem_euclid(modulo)
//
// }
}
}};
}
impl_integer_mul![
Integer+i+8, cast:16;
Integer+i+16, cast:32;
Integer+i+32, cast:64;
Integer+i+64, cast:128;
Integer+i+128, cast:128
];
#[cfg(feature = "dashu-int")]
mod big {
use super::*;
impl Mul<IntegerBig> for IntegerBig {
type Output = IntegerBig;
/// Performs the `*` operation.
#[inline]
#[must_use]
fn mul(self, rhs: IntegerBig) -> Self::Output {
Self(self.0 * rhs.0)
}
}
impl MulAssign for IntegerBig {
/// Performs the `*=` operation.
#[inline]
fn mul_assign(&mut self, rhs: IntegerBig) {
self.0 *= rhs.0;
}
}
impl Product for IntegerBig {
fn product<I: Iterator<Item = Self>>(iter: I) -> Self {
iter.fold(IntegerBig::new(1), |a, b| a * b)
}
}
impl<'a> Product<&'a IntegerBig> for IntegerBig {
fn product<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
iter.fold(
IntegerBig::new(1),
|a, b| a * b.clone(), // CHECK performance
)
}
}
}