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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::integer::Integer;
use crate::natural::Natural;
use malachite_base::num::basic::traits::Zero;
use malachite_base::num::conversion::traits::{ConvertibleFrom, SaturatingFrom};
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct NaturalFromIntegerError;
impl TryFrom<Integer> for Natural {
type Error = NaturalFromIntegerError;
/// Converts an [`Integer`] to a [`Natural`], taking the [`Natural`] by value. If the
/// [`Integer`] is negative, an error is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::strings::ToDebugString;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(
/// Natural::try_from(Integer::from(123)).to_debug_string(),
/// "Ok(123)"
/// );
/// assert_eq!(
/// Natural::try_from(Integer::from(-123)).to_debug_string(),
/// "Err(NaturalFromIntegerError)"
/// );
/// assert_eq!(
/// Natural::try_from(Integer::from(10u32).pow(12)).to_debug_string(),
/// "Ok(1000000000000)"
/// );
/// assert_eq!(
/// Natural::try_from(-Integer::from(10u32).pow(12)).to_debug_string(),
/// "Err(NaturalFromIntegerError)"
/// );
/// ```
fn try_from(value: Integer) -> Result<Self, Self::Error> {
match value {
Integer { sign: false, .. } => Err(NaturalFromIntegerError),
Integer { sign: true, abs } => Ok(abs),
}
}
}
impl<'a> TryFrom<&'a Integer> for Natural {
type Error = NaturalFromIntegerError;
/// Converts an [`Integer`] to a [`Natural`], taking the [`Natural`] by reference. If the
/// [`Integer`] is negative, an error is returned.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.significant_bits()`.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::strings::ToDebugString;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(
/// Natural::try_from(&Integer::from(123)).to_debug_string(),
/// "Ok(123)"
/// );
/// assert_eq!(
/// Natural::try_from(&Integer::from(-123)).to_debug_string(),
/// "Err(NaturalFromIntegerError)"
/// );
/// assert_eq!(
/// Natural::try_from(&Integer::from(10u32).pow(12)).to_debug_string(),
/// "Ok(1000000000000)"
/// );
/// assert_eq!(
/// Natural::try_from(&(-Integer::from(10u32).pow(12))).to_debug_string(),
/// "Err(NaturalFromIntegerError)"
/// );
/// ```
fn try_from(value: &'a Integer) -> Result<Self, Self::Error> {
match *value {
Integer { sign: false, .. } => Err(NaturalFromIntegerError),
Integer {
sign: true,
ref abs,
} => Ok(abs.clone()),
}
}
}
impl SaturatingFrom<Integer> for Natural {
/// Converts an [`Integer`] to a [`Natural`], taking the [`Natural`] by value. If the
/// [`Integer`] is negative, 0 is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::num::conversion::traits::SaturatingFrom;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::saturating_from(Integer::from(123)), 123);
/// assert_eq!(Natural::saturating_from(Integer::from(-123)), 0);
/// assert_eq!(
/// Natural::saturating_from(Integer::from(10u32).pow(12)),
/// 1000000000000u64
/// );
/// assert_eq!(Natural::saturating_from(-Integer::from(10u32).pow(12)), 0);
/// ```
fn saturating_from(value: Integer) -> Self {
match value {
Integer { sign: false, .. } => Self::ZERO,
Integer { sign: true, abs } => abs,
}
}
}
impl<'a> SaturatingFrom<&'a Integer> for Natural {
/// Converts an [`Integer`] to a [`Natural`], taking the [`Natural`] by reference. If the
/// [`Integer`] is negative, 0 is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::num::conversion::traits::SaturatingFrom;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::saturating_from(&Integer::from(123)), 123);
/// assert_eq!(Natural::saturating_from(&Integer::from(-123)), 0);
/// assert_eq!(
/// Natural::saturating_from(&Integer::from(10u32).pow(12)),
/// 1000000000000u64
/// );
/// assert_eq!(Natural::saturating_from(&-Integer::from(10u32).pow(12)), 0);
/// ```
fn saturating_from(value: &'a Integer) -> Self {
match *value {
Integer { sign: false, .. } => Self::ZERO,
Integer {
sign: true,
ref abs,
} => abs.clone(),
}
}
}
impl ConvertibleFrom<Integer> for Natural {
/// Determines whether an [`Integer`] can be converted to a [`Natural`] (when the [`Integer`] is
/// non-negative). Takes the [`Integer`] by value.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::num::conversion::traits::ConvertibleFrom;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::convertible_from(Integer::from(123)), true);
/// assert_eq!(Natural::convertible_from(Integer::from(-123)), false);
/// assert_eq!(
/// Natural::convertible_from(Integer::from(10u32).pow(12)),
/// true
/// );
/// assert_eq!(
/// Natural::convertible_from(-Integer::from(10u32).pow(12)),
/// false
/// );
/// ```
#[inline]
fn convertible_from(value: Integer) -> bool {
value.sign
}
}
impl<'a> ConvertibleFrom<&'a Integer> for Natural {
/// Determines whether an [`Integer`] can be converted to a [`Natural`] (when the [`Integer`] is
/// non-negative). Takes the [`Integer`] by reference.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::Pow;
/// use malachite_base::num::conversion::traits::ConvertibleFrom;
/// use malachite_nz::integer::Integer;
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Natural::convertible_from(&Integer::from(123)), true);
/// assert_eq!(Natural::convertible_from(&Integer::from(-123)), false);
/// assert_eq!(
/// Natural::convertible_from(&Integer::from(10u32).pow(12)),
/// true
/// );
/// assert_eq!(
/// Natural::convertible_from(&-Integer::from(10u32).pow(12)),
/// false
/// );
/// ```
#[inline]
fn convertible_from(value: &'a Integer) -> bool {
value.sign
}
}