use crate::Rational;
use malachite_base::num::arithmetic::traits::DivRound;
use malachite_base::num::basic::traits::Zero;
use malachite_base::num::conversion::traits::{ConvertibleFrom, RoundingFrom};
use malachite_base::rounding_modes::RoundingMode;
use malachite_nz::natural::Natural;
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct NaturalFromRationalError;
impl TryFrom<Rational> for Natural {
type Error = NaturalFromRationalError;
/// Converts a [`Rational`] to a [`Natural`](malachite_nz::natural::Natural), taking the
/// [`Rational`] by value. If the [`Rational`] is negative or not an integer, an error is
/// returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_nz::natural::Natural;
/// use malachite_q::conversion::natural_from_rational::NaturalFromRationalError;
/// use malachite_q::Rational;
///
/// assert_eq!(Natural::try_from(Rational::from(123)).unwrap(), 123);
/// assert_eq!(Natural::try_from(Rational::from(-123)), Err(NaturalFromRationalError));
/// assert_eq!(
/// Natural::try_from(Rational::from_signeds(22, 7)),
/// Err(NaturalFromRationalError)
/// );
/// ```
fn try_from(x: Rational) -> Result<Natural, Self::Error> {
if x.sign && x.denominator == 1u32 {
Ok(x.numerator)
} else {
Err(NaturalFromRationalError)
}
}
}
impl<'a> TryFrom<&'a Rational> for Natural {
type Error = NaturalFromRationalError;
/// Converts a [`Rational`] to a [`Natural`](malachite_nz::natural::Natural), taking the
/// [`Rational`] by reference. If the [`Rational`] is negative or not an integer, 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 `x.significant_bits()`.
///
/// # Examples
/// ```
/// use malachite_nz::natural::Natural;
/// use malachite_q::conversion::natural_from_rational::NaturalFromRationalError;
/// use malachite_q::Rational;
///
/// assert_eq!(Natural::try_from(&Rational::from(123)).unwrap(), 123);
/// assert_eq!(Natural::try_from(&Rational::from(-123)), Err(NaturalFromRationalError));
/// assert_eq!(
/// Natural::try_from(&Rational::from_signeds(22, 7)),
/// Err(NaturalFromRationalError)
/// );
/// ```
fn try_from(x: &Rational) -> Result<Natural, Self::Error> {
if x.sign && x.denominator == 1u32 {
Ok(x.numerator.clone())
} else {
Err(NaturalFromRationalError)
}
}
}
impl<'a> ConvertibleFrom<&'a Rational> for Natural {
/// Determines whether a [`Rational`] can be converted to a
/// [`Natural`](malachite_nz::natural::Natural) (when the [`Rational`] is non-negative and an
/// integer), taking the [`Rational`] by reference.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::conversion::traits::ConvertibleFrom;
/// use malachite_nz::natural::Natural;
/// use malachite_q::Rational;
///
/// assert_eq!(Natural::convertible_from(&Rational::from(123)), true);
/// assert_eq!(Natural::convertible_from(&Rational::from(-123)), false);
/// assert_eq!(Natural::convertible_from(&Rational::from_signeds(22, 7)), false);
/// ```
#[inline]
fn convertible_from(x: &Rational) -> bool {
x.sign && x.denominator == 1u32
}
}
impl RoundingFrom<Rational> for Natural {
/// Converts a [`Rational`] to a [`Natural`](malachite_nz::natural::Natural), using a
/// specified [`RoundingMode`](malachite_base::rounding_modes::RoundingMode) and taking the
/// [`Rational`] by value.
///
/// If the [`Rational`] is negative, then it will be rounded to zero when the
/// [`RoundingMode`](malachite_base::rounding_modes::RoundingMode) is `Ceiling`, `Down`, or
/// `Nearest`. Otherwise, this function will panic.
///
/// # Worst-case complexity
/// $T(n) = O(n \log n \log\log n)$
///
/// $M(n) = O(n \log n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `x.significant_bits()`.
///
/// # Panics
/// Panics if the [`Rational`] is not an integer and `rm` is `Exact`, or if the [`Rational`] is
/// less than zero and `rm` is not `Down`, `Ceiling`, or `Nearest`.
///
/// # Examples
/// ```
/// use malachite_base::num::conversion::traits::RoundingFrom;
/// use malachite_base::rounding_modes::RoundingMode;
/// use malachite_nz::natural::Natural;
/// use malachite_q::Rational;
///
/// assert_eq!(Natural::rounding_from(Rational::from(123), RoundingMode::Exact), 123);
///
/// assert_eq!(Natural::rounding_from(Rational::from_signeds(22, 7), RoundingMode::Floor), 3);
/// assert_eq!(Natural::rounding_from(Rational::from_signeds(22, 7), RoundingMode::Down), 3);
/// assert_eq!(
/// Natural::rounding_from(Rational::from_signeds(22, 7), RoundingMode::Ceiling),
/// 4
/// );
/// assert_eq!(Natural::rounding_from(Rational::from_signeds(22, 7), RoundingMode::Up), 4);
/// assert_eq!(
/// Natural::rounding_from(Rational::from_signeds(22, 7), RoundingMode::Nearest),
/// 3
/// );
///
/// assert_eq!(Natural::rounding_from(Rational::from(-123), RoundingMode::Down), 0);
/// assert_eq!(Natural::rounding_from(Rational::from(-123), RoundingMode::Ceiling), 0);
/// assert_eq!(Natural::rounding_from(Rational::from(-123), RoundingMode::Nearest), 0);
/// ```
fn rounding_from(x: Rational, rm: RoundingMode) -> Natural {
if x.sign {
x.numerator.div_round(x.denominator, rm)
} else if rm == RoundingMode::Down
|| rm == RoundingMode::Ceiling
|| rm == RoundingMode::Nearest
{
Natural::ZERO
} else {
panic!(
"Cannot round negative Rational to Natural using RoundingMode {}",
rm
);
}
}
}
impl<'a> RoundingFrom<&'a Rational> for Natural {
/// Converts a [`Rational`] to a [`Natural`](malachite_nz::natural::Natural), using a
/// specified [`RoundingMode`](malachite_base::rounding_modes::RoundingMode) and taking the
/// [`Rational`] by reference.
///
/// If the [`Rational`] is negative, then it will be rounded to zero when the
/// [`RoundingMode`](malachite_base::rounding_modes::RoundingMode) is `Ceiling`, `Down`, or
/// `Nearest`. Otherwise, this function will panic.
///
/// # Worst-case complexity
/// $T(n) = O(n \log n \log\log n)$
///
/// $M(n) = O(n \log n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `x.significant_bits()`.
///
/// # Panics
/// Panics if the [`Rational`] is not an integer and `rm` is `Exact`, or if the [`Rational`] is
/// less than zero and `rm` is not `Down`, `Ceiling`, or `Nearest`.
///
/// # Examples
/// ```
/// use malachite_base::num::conversion::traits::RoundingFrom;
/// use malachite_base::rounding_modes::RoundingMode;
/// use malachite_nz::natural::Natural;
/// use malachite_q::Rational;
///
/// assert_eq!(Natural::rounding_from(&Rational::from(123), RoundingMode::Exact), 123);
///
/// assert_eq!(Natural::rounding_from(&Rational::from_signeds(22, 7), RoundingMode::Floor), 3);
/// assert_eq!(Natural::rounding_from(&Rational::from_signeds(22, 7), RoundingMode::Down), 3);
/// assert_eq!(
/// Natural::rounding_from(&Rational::from_signeds(22, 7), RoundingMode::Ceiling),
/// 4
/// );
/// assert_eq!(Natural::rounding_from(&Rational::from_signeds(22, 7), RoundingMode::Up), 4);
/// assert_eq!(
/// Natural::rounding_from(&Rational::from_signeds(22, 7), RoundingMode::Nearest),
/// 3
/// );
///
/// assert_eq!(Natural::rounding_from(&Rational::from(-123), RoundingMode::Down), 0);
/// assert_eq!(Natural::rounding_from(&Rational::from(-123), RoundingMode::Ceiling), 0);
/// assert_eq!(Natural::rounding_from(&Rational::from(-123), RoundingMode::Nearest), 0);
/// ```
fn rounding_from(x: &Rational, rm: RoundingMode) -> Natural {
if x.sign {
(&x.numerator).div_round(&x.denominator, rm)
} else if rm == RoundingMode::Down
|| rm == RoundingMode::Ceiling
|| rm == RoundingMode::Nearest
{
Natural::ZERO
} else {
panic!(
"Cannot round negative Rational to Natural using RoundingMode {}",
rm
);
}
}
}