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// numera::number::integer::z::ops::sub
//
//! Implement the subtraction operations.
//
use crate::number::integer::*;
use core::ops::{Sub, SubAssign};
use devela::paste;
macro_rules! impl_integer_sub {
// impl Sub 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_sub![sub: $t + $p + $b];
)+
};
// subtraction operations
//
// impl variants:
// - sub
// - checked_
// - saturating_
// - wrapping_
// - overflowing_
// - modular_ TODO
// - modular_counting_ TODO
(sub: $t:ident + $p:ident + $b:literal) => { paste! {
impl Sub<[<$t$b>]> for [<$t$b>] {
type Output = [<$t$b>];
/// Performs the `-` operation.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
#[inline]
#[must_use]
fn sub(self, rhs: [<$t$b>]) -> Self::Output {
self.sub(rhs)
}
}
impl SubAssign for [<$t$b>] {
/// Performs the `-=` operation.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
#[inline]
fn sub_assign(&mut self, rhs: [<$t$b>]) {
*self = self.add(rhs);
}
}
/// # Subtraction
impl [<$t$b>] {
/// Integer subtraction.
///
/// # Panics
/// Panics in debug, on overflow.
/// While in release, it performs two's complement wrapping.
#[inline]
#[must_use]
pub const fn sub(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0 - rhs.0)
}
/// Checked subtraction.
#[inline]
#[must_use]
pub const fn checked_sub(self, rhs: [<$t$b>]) -> Option<[<$t$b>]> {
if let Some(result) = self.0.checked_sub(rhs.0) {
Some(Self(result))
} else {
None
}
}
/// Saturating subtraction.
/// Computes `self + rhs`, saturating at the numeric bounds instead of overflowing.
#[inline]
#[must_use]
pub const fn saturating_sub(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0.saturating_sub(rhs.0))
}
/// Wrapping (modular) subtraction.
/// Computes `self + rhs`, wrapping around at the boundary of the type.
#[inline]
#[must_use]
pub const fn wrapping_sub(self, rhs: [<$t$b>]) -> [<$t$b>] {
Self(self.0.wrapping_sub(rhs.0))
}
/// Overflowing subtraction.
///
/// Returns a tuple of the subtraction along with a boolean indicating
/// whether an arithmetic overflow would occur. If an overflow would
/// have occurred then the wrapped value is returned.
#[inline]
#[must_use]
pub const fn overflowing_sub(self, rhs: [<$t$b>]) -> ([<$t$b>], bool) {
let (result, overflown) = self.0.overflowing_sub(rhs.0);
(Self(result), overflown)
}
// /// Modular subtraction with a custom `modulo`.
// #[inline]
// #[must_use]
// pub const fn modular_sub(self, rhs: [<$t$b>], modulo: [<$t$b>]) -> [<$t$b>] {
// self.sub(rhs).rem_euclid(modulo)
// }
}
}};
}
impl_integer_sub![
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 Sub<IntegerBig> for IntegerBig {
type Output = IntegerBig;
/// Performs the `-` operation.
#[inline]
#[must_use]
fn sub(self, rhs: IntegerBig) -> Self::Output {
Self(self.0 - rhs.0)
}
}
impl SubAssign for IntegerBig {
/// Performs the `-=` operation.
#[inline]
fn sub_assign(&mut self, rhs: IntegerBig) {
self.0 -= rhs.0;
}
}
}