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use integer::Integer;
use malachite_base::num::conversion::traits::{CheckedFrom, ConvertibleFrom, RoundingFrom};
use malachite_base::rounding_modes::RoundingMode;
macro_rules! float_impls {
($f: ident) => {
impl<'a> RoundingFrom<&'a Integer> for $f {
/// Converts an [`Integer`] to a primitive float according to a specified
/// [`RoundingMode`](malachite_base::rounding_modes::RoundingMode).
///
/// - If the rounding mode is `Floor` the largest float less than or equal to the
/// [`Integer`] is returned. If the [`Integer`] is greater than the maximum finite
/// float, then the maximum finite float is returned. If it is smaller than the
/// minimum finite float, then negative infinity is returned.
/// - If the rounding mode is `Ceiling`, the smallest float greater than or equal to
/// the [`Integer`] is returned. If the [`Integer`] is greater than the maximum
/// finite float, then positive infinity is returned. If it is smaller than the
/// minimum finite float, then the minimum finite float is returned.
/// - If the rounding mode is `Down`, then the rounding proceeds as with `Floor` if the
/// [`Integer`] is non-negative and as with `Ceiling` if the [`Integer`] is negative.
/// - If the rounding mode is `Up`, then the rounding proceeds as with `Ceiling` if the
/// [`Integer`] is non-negative and as with `Floor` if the [`Integer`] is negative.
/// - If the rounding mode is `Nearest`, then the nearest float is returned. If the
/// [`Integer`] is exactly between two floats, the float with the zero
/// least-significant bit in its representation is selected. If the [`Integer`] is
/// greater than the maximum finite float, then the maximum finite float is returned.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.significant_bits()`.
///
/// # Panics
/// Panics if the rounding mode is `Exact` and `value` cannot be represented exactly.
///
/// # Examples
/// See [here](super::primitive_float_from_integer#rounding_from).
fn rounding_from(value: &'a Integer, rm: RoundingMode) -> $f {
if value.sign {
$f::rounding_from(&value.abs, rm)
} else {
-$f::rounding_from(&value.abs, -rm)
}
}
}
impl<'a> From<&'a Integer> for $f {
/// Converts an [`Integer`] to a primitive float.
///
/// If there are two nearest floats, the one whose least-significant bit is zero is
/// chosen. If the [`Integer`] is larger than the maximum finite float, then the result
/// is the maximum finite float.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.significant_bits()`.
///
/// # Examples
/// See [here](super::primitive_float_from_integer#from).
fn from(value: &'a Integer) -> $f {
let abs = $f::from(&value.abs);
if value.sign {
abs
} else {
-abs
}
}
}
impl<'a> CheckedFrom<&'a Integer> for $f {
/// Converts an [`Integer`] to a primitive float.
///
/// If the input isn't exactly equal to some float, `None` is returned.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.significant_bits()`.
///
/// # Examples
/// See [here](super::primitive_float_from_integer#checked_from).
fn checked_from(value: &'a Integer) -> Option<$f> {
$f::checked_from(&value.abs).map(|f| if value.sign { f } else { -f })
}
}
impl<'a> ConvertibleFrom<&'a Integer> for $f {
/// Determines whether an [`Integer`] can be exactly converted to a primitive float.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(1)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.significant_bits()`.
///
/// # Examples
/// See [here](super::primitive_float_from_integer#convertible_from).
fn convertible_from(value: &'a Integer) -> bool {
$f::convertible_from(&value.abs)
}
}
};
}
apply_to_primitive_floats!(float_impls);