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use std::ops::Neg;
use std::{f32, f64};
use Num;
pub trait Signed: Sized + Num + Neg<Output = Self> {
fn abs(&self) -> Self;
fn abs_sub(&self, other: &Self) -> Self;
fn signum(&self) -> Self;
fn is_positive(&self) -> bool;
fn is_negative(&self) -> bool;
}
macro_rules! signed_impl {
($($t:ty)*) => ($(
impl Signed for $t {
#[inline]
fn abs(&self) -> $t {
if self.is_negative() { -*self } else { *self }
}
#[inline]
fn abs_sub(&self, other: &$t) -> $t {
if *self <= *other { 0 } else { *self - *other }
}
#[inline]
fn signum(&self) -> $t {
match *self {
n if n > 0 => 1,
0 => 0,
_ => -1,
}
}
#[inline]
fn is_positive(&self) -> bool { *self > 0 }
#[inline]
fn is_negative(&self) -> bool { *self < 0 }
}
)*)
}
signed_impl!(isize i8 i16 i32 i64);
macro_rules! signed_float_impl {
($t:ty, $nan:expr, $inf:expr, $neg_inf:expr) => {
impl Signed for $t {
#[inline]
fn abs(&self) -> $t {
<$t>::abs(*self)
}
#[inline]
fn abs_sub(&self, other: &$t) -> $t {
<$t>::abs_sub(*self, *other)
}
#[inline]
fn signum(&self) -> $t {
<$t>::signum(*self)
}
#[inline]
fn is_positive(&self) -> bool { *self > 0.0 || (1.0 / *self) == $inf }
#[inline]
fn is_negative(&self) -> bool { *self < 0.0 || (1.0 / *self) == $neg_inf }
}
}
}
signed_float_impl!(f32, f32::NAN, f32::INFINITY, f32::NEG_INFINITY);
signed_float_impl!(f64, f64::NAN, f64::INFINITY, f64::NEG_INFINITY);
pub trait Unsigned: Num {}
macro_rules! empty_trait_impl {
($name:ident for $($t:ty)*) => ($(
impl $name for $t {}
)*)
}
empty_trait_impl!(Unsigned for usize u8 u16 u32 u64);