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// Copyright © 2024 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::integer::Integer;
use crate::natural::Natural;
use core::ops::Neg;
use malachite_base::comparison::traits::Min;
use malachite_base::num::arithmetic::traits::{DivisibleByPowerOf2, WrappingNeg};
use malachite_base::num::basic::integers::PrimitiveInt;
use malachite_base::num::basic::traits::Zero;
use malachite_base::num::conversion::traits::{
ConvertibleFrom, OverflowingFrom, SaturatingFrom, WrappingFrom,
};
use malachite_base::num::logic::traits::SignificantBits;
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct UnsignedFromIntegerError;
fn try_from_unsigned<'a, T: TryFrom<&'a Natural>>(
value: &'a Integer,
) -> Result<T, UnsignedFromIntegerError> {
match *value {
Integer { sign: false, .. } => Err(UnsignedFromIntegerError),
Integer {
sign: true,
ref abs,
} => T::try_from(abs).map_err(|_| UnsignedFromIntegerError),
}
}
fn wrapping_from_unsigned<'a, T: WrappingFrom<&'a Natural> + WrappingNeg<Output = T>>(
value: &'a Integer,
) -> T {
match *value {
Integer {
sign: true,
ref abs,
} => T::wrapping_from(abs),
Integer {
sign: false,
ref abs,
} => T::wrapping_from(abs).wrapping_neg(),
}
}
fn saturating_from_unsigned<'a, T: Copy + SaturatingFrom<&'a Natural> + Zero>(
value: &'a Integer,
) -> T {
match *value {
Integer {
sign: true,
ref abs,
} => T::saturating_from(abs),
_ => T::ZERO,
}
}
fn overflowing_from_unsigned<
'a,
T: OverflowingFrom<&'a Natural> + WrappingFrom<&'a Natural> + WrappingNeg<Output = T>,
>(
value: &'a Integer,
) -> (T, bool) {
match *value {
Integer {
sign: true,
ref abs,
} => T::overflowing_from(abs),
Integer {
sign: false,
ref abs,
} => (T::wrapping_from(abs).wrapping_neg(), true),
}
}
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct SignedFromIntegerError;
fn try_from_signed<'a, T: ConvertibleFrom<&'a Integer> + WrappingFrom<&'a Integer>>(
value: &'a Integer,
) -> Result<T, SignedFromIntegerError> {
if T::convertible_from(value) {
Ok(T::wrapping_from(value))
} else {
Err(SignedFromIntegerError)
}
}
fn saturating_from_signed<
'a,
U: PrimitiveInt + SaturatingFrom<&'a Natural>,
S: Min + Neg<Output = S> + SaturatingFrom<U> + WrappingFrom<U>,
>(
value: &'a Integer,
) -> S {
match *value {
Integer {
sign: true,
ref abs,
} => S::saturating_from(U::saturating_from(abs)),
Integer {
sign: false,
ref abs,
} => {
let abs = U::saturating_from(abs);
if abs.get_highest_bit() {
S::MIN
} else {
-S::wrapping_from(abs)
}
}
}
}
fn convertible_from_signed<T: PrimitiveInt>(value: &Integer) -> bool {
match *value {
Integer {
sign: true,
ref abs,
} => abs.significant_bits() < T::WIDTH,
Integer {
sign: false,
ref abs,
} => {
let significant_bits = abs.significant_bits();
significant_bits < T::WIDTH
|| significant_bits == T::WIDTH && abs.divisible_by_power_of_2(T::WIDTH - 1)
}
}
}
macro_rules! impl_from {
($u: ident, $s: ident) => {
impl<'a> TryFrom<&'a Integer> for $u {
type Error = UnsignedFromIntegerError;
/// Converts an [`Integer`] to an unsigned primitive integer, returning an error if the
/// [`Integer`] cannot be represented.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#try_from).
#[inline]
fn try_from(value: &Integer) -> Result<$u, Self::Error> {
try_from_unsigned(value)
}
}
impl<'a> WrappingFrom<&'a Integer> for $u {
/// Converts an [`Integer`] to an unsigned primitive integer, wrapping modulo $2^W$,
/// where $W$ is the width of the primitive integer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#wrapping_from).
#[inline]
fn wrapping_from(value: &Integer) -> $u {
wrapping_from_unsigned(value)
}
}
impl<'a> SaturatingFrom<&'a Integer> for $u {
/// Converts an [`Integer`] to an unsigned primitive integer.
///
/// If the [`Integer`] cannot be represented by the output type, then either zero or the
/// maximum representable value is returned, whichever is closer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#saturating_from).
#[inline]
fn saturating_from(value: &Integer) -> $u {
saturating_from_unsigned(value)
}
}
impl<'a> OverflowingFrom<&'a Integer> for $u {
/// Converts an [`Integer`] to an unsigned primitive integer, wrapping modulo $2^W$,
/// where $W$ is the width of the primitive integer.
///
/// The returned boolean value indicates whether wrapping occurred.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#overflowing_from).
#[inline]
fn overflowing_from(value: &Integer) -> ($u, bool) {
overflowing_from_unsigned(value)
}
}
impl<'a> ConvertibleFrom<&'a Integer> for $u {
/// Determines whether an [`Integer`] can be converted to an unsigned primitive integer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#convertible_from).
#[inline]
fn convertible_from(value: &Integer) -> bool {
value.sign && $u::convertible_from(&value.abs)
}
}
impl<'a> TryFrom<&'a Integer> for $s {
type Error = SignedFromIntegerError;
/// Converts an [`Integer`] to a signed primitive integer, returning an error if the
/// [`Integer`] cannot be represented.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#try_from).
#[inline]
fn try_from(value: &Integer) -> Result<$s, Self::Error> {
try_from_signed(value)
}
}
impl<'a> WrappingFrom<&'a Integer> for $s {
/// Converts an [`Integer`] to a signed primitive integer, wrapping modulo $2^W$, where
/// $W$ is the width of the primitive integer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#wrapping_from).
#[inline]
fn wrapping_from(value: &Integer) -> $s {
$s::wrapping_from($u::wrapping_from(value))
}
}
impl<'a> SaturatingFrom<&'a Integer> for $s {
/// Converts an [`Integer`] to a signed primitive integer.
///
/// If the [`Integer`] cannot be represented by the output type, then either the maximum
/// or the minimum representable value is returned, whichever is closer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#saturating_from).
#[inline]
fn saturating_from(value: &Integer) -> $s {
saturating_from_signed::<$u, $s>(value)
}
}
impl<'a> OverflowingFrom<&'a Integer> for $s {
/// Converts an [`Integer`] to a signed primitive integer, wrapping modulo $2^W$, where
/// $W$ is the width of the primitive integer.
///
/// The returned boolean value indicates whether wrapping occurred.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#overflowing_from).
#[inline]
fn overflowing_from(value: &Integer) -> ($s, bool) {
($s::wrapping_from(value), !$s::convertible_from(value))
}
}
impl<'a> ConvertibleFrom<&'a Integer> for $s {
/// Determines whether an [`Integer`] can be converted to a signed primitive integer.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::primitive_int_from_integer#convertible_from).
#[inline]
fn convertible_from(value: &Integer) -> bool {
convertible_from_signed::<$u>(value)
}
}
};
}
apply_to_unsigned_signed_pairs!(impl_from);