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</pre><pre class="rust"><code><span class="kw">use </span>core::num::Wrapping;
<span class="kw">use </span>core::ops::Neg;
<span class="kw">use </span><span class="kw">crate</span>::float::FloatCore;
<span class="kw">use </span><span class="kw">crate</span>::Num;
<span class="doccomment">/// Useful functions for signed numbers (i.e. numbers that can be negative).
</span><span class="kw">pub trait </span>Signed: Sized + Num + Neg<Output = <span class="self">Self</span>> {
<span class="doccomment">/// Computes the absolute value.
///
/// For `f32` and `f64`, `NaN` will be returned if the number is `NaN`.
///
/// For signed integers, `::MIN` will be returned if the number is `::MIN`.
</span><span class="kw">fn </span>abs(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self</span>;
<span class="doccomment">/// The positive difference of two numbers.
///
/// Returns `zero` if the number is less than or equal to `other`, otherwise the difference
/// between `self` and `other` is returned.
</span><span class="kw">fn </span>abs_sub(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> <span class="self">Self</span>;
<span class="doccomment">/// Returns the sign of the number.
///
/// For `f32` and `f64`:
///
/// * `1.0` if the number is positive, `+0.0` or `INFINITY`
/// * `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
/// * `NaN` if the number is `NaN`
///
/// For signed integers:
///
/// * `0` if the number is zero
/// * `1` if the number is positive
/// * `-1` if the number is negative
</span><span class="kw">fn </span>signum(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self</span>;
<span class="doccomment">/// Returns true if the number is positive and false if the number is zero or negative.
</span><span class="kw">fn </span>is_positive(<span class="kw-2">&</span><span class="self">self</span>) -> bool;
<span class="doccomment">/// Returns true if the number is negative and false if the number is zero or positive.
</span><span class="kw">fn </span>is_negative(<span class="kw-2">&</span><span class="self">self</span>) -> bool;
}
<span class="macro">macro_rules! </span>signed_impl {
($(<span class="macro-nonterminal">$t</span>:ty)<span class="kw-2">*</span>) => ($(
<span class="kw">impl </span>Signed <span class="kw">for </span><span class="macro-nonterminal">$t </span>{
<span class="attr">#[inline]
</span><span class="kw">fn </span>abs(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="macro-nonterminal">$t </span>{
<span class="kw">if </span><span class="self">self</span>.is_negative() { -<span class="kw-2">*</span><span class="self">self </span>} <span class="kw">else </span>{ <span class="kw-2">*</span><span class="self">self </span>}
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>abs_sub(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="macro-nonterminal">$t</span>) -> <span class="macro-nonterminal">$t </span>{
<span class="kw">if </span><span class="kw-2">*</span><span class="self">self </span><= <span class="kw-2">*</span>other { <span class="number">0 </span>} <span class="kw">else </span>{ <span class="kw-2">*</span><span class="self">self </span>- <span class="kw-2">*</span>other }
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>signum(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="macro-nonterminal">$t </span>{
<span class="kw">match </span><span class="kw-2">*</span><span class="self">self </span>{
n <span class="kw">if </span>n > <span class="number">0 </span>=> <span class="number">1</span>,
<span class="number">0 </span>=> <span class="number">0</span>,
<span class="kw">_ </span>=> -<span class="number">1</span>,
}
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>is_positive(<span class="kw-2">&</span><span class="self">self</span>) -> bool { <span class="kw-2">*</span><span class="self">self </span>> <span class="number">0 </span>}
<span class="attr">#[inline]
</span><span class="kw">fn </span>is_negative(<span class="kw-2">&</span><span class="self">self</span>) -> bool { <span class="kw-2">*</span><span class="self">self </span>< <span class="number">0 </span>}
}
)<span class="kw-2">*</span>)
}
<span class="macro">signed_impl!</span>(isize i8 i16 i32 i64 i128);
<span class="kw">impl</span><T: Signed> Signed <span class="kw">for </span>Wrapping<T>
<span class="kw">where
</span>Wrapping<T>: Num + Neg<Output = Wrapping<T>>,
{
<span class="attr">#[inline]
</span><span class="kw">fn </span>abs(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{
Wrapping(<span class="self">self</span>.<span class="number">0</span>.abs())
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>abs_sub(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> <span class="self">Self </span>{
Wrapping(<span class="self">self</span>.<span class="number">0</span>.abs_sub(<span class="kw-2">&</span>other.<span class="number">0</span>))
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>signum(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{
Wrapping(<span class="self">self</span>.<span class="number">0</span>.signum())
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>is_positive(<span class="kw-2">&</span><span class="self">self</span>) -> bool {
<span class="self">self</span>.<span class="number">0</span>.is_positive()
}
<span class="attr">#[inline]
</span><span class="kw">fn </span>is_negative(<span class="kw-2">&</span><span class="self">self</span>) -> bool {
<span class="self">self</span>.<span class="number">0</span>.is_negative()
}
}
<span class="macro">macro_rules! </span>signed_float_impl {
(<span class="macro-nonterminal">$t</span>:ty) => {
<span class="kw">impl </span>Signed <span class="kw">for </span><span class="macro-nonterminal">$t </span>{
<span class="doccomment">/// Computes the absolute value. Returns `NAN` if the number is `NAN`.
</span><span class="attr">#[inline]
</span><span class="kw">fn </span>abs(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="macro-nonterminal">$t </span>{
FloatCore::abs(<span class="kw-2">*</span><span class="self">self</span>)
}
<span class="doccomment">/// The positive difference of two numbers. Returns `0.0` if the number is
/// less than or equal to `other`, otherwise the difference between`self`
/// and `other` is returned.
</span><span class="attr">#[inline]
</span><span class="kw">fn </span>abs_sub(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="macro-nonterminal">$t</span>) -> <span class="macro-nonterminal">$t </span>{
<span class="kw">if </span><span class="kw-2">*</span><span class="self">self </span><= <span class="kw-2">*</span>other {
<span class="number">0.
</span>} <span class="kw">else </span>{
<span class="kw-2">*</span><span class="self">self </span>- <span class="kw-2">*</span>other
}
}
<span class="doccomment">/// # Returns
///
/// - `1.0` if the number is positive, `+0.0` or `INFINITY`
/// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
/// - `NAN` if the number is NaN
</span><span class="attr">#[inline]
</span><span class="kw">fn </span>signum(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="macro-nonterminal">$t </span>{
FloatCore::signum(<span class="kw-2">*</span><span class="self">self</span>)
}
<span class="doccomment">/// Returns `true` if the number is positive, including `+0.0` and `INFINITY`
</span><span class="attr">#[inline]
</span><span class="kw">fn </span>is_positive(<span class="kw-2">&</span><span class="self">self</span>) -> bool {
FloatCore::is_sign_positive(<span class="kw-2">*</span><span class="self">self</span>)
}
<span class="doccomment">/// Returns `true` if the number is negative, including `-0.0` and `NEG_INFINITY`
</span><span class="attr">#[inline]
</span><span class="kw">fn </span>is_negative(<span class="kw-2">&</span><span class="self">self</span>) -> bool {
FloatCore::is_sign_negative(<span class="kw-2">*</span><span class="self">self</span>)
}
}
};
}
<span class="macro">signed_float_impl!</span>(f32);
<span class="macro">signed_float_impl!</span>(f64);
<span class="doccomment">/// Computes the absolute value.
///
/// For `f32` and `f64`, `NaN` will be returned if the number is `NaN`
///
/// For signed integers, `::MIN` will be returned if the number is `::MIN`.
</span><span class="attr">#[inline(always)]
</span><span class="kw">pub fn </span>abs<T: Signed>(value: T) -> T {
value.abs()
}
<span class="doccomment">/// The positive difference of two numbers.
///
/// Returns zero if `x` is less than or equal to `y`, otherwise the difference
/// between `x` and `y` is returned.
</span><span class="attr">#[inline(always)]
</span><span class="kw">pub fn </span>abs_sub<T: Signed>(x: T, y: T) -> T {
x.abs_sub(<span class="kw-2">&</span>y)
}
<span class="doccomment">/// Returns the sign of the number.
///
/// For `f32` and `f64`:
///
/// * `1.0` if the number is positive, `+0.0` or `INFINITY`
/// * `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
/// * `NaN` if the number is `NaN`
///
/// For signed integers:
///
/// * `0` if the number is zero
/// * `1` if the number is positive
/// * `-1` if the number is negative
</span><span class="attr">#[inline(always)]
</span><span class="kw">pub fn </span>signum<T: Signed>(value: T) -> T {
value.signum()
}
<span class="doccomment">/// A trait for values which cannot be negative
</span><span class="kw">pub trait </span>Unsigned: Num {}
<span class="macro">macro_rules! </span>empty_trait_impl {
(<span class="macro-nonterminal">$name</span>:ident <span class="kw">for </span>$(<span class="macro-nonterminal">$t</span>:ty)<span class="kw-2">*</span>) => ($(
<span class="kw">impl </span><span class="macro-nonterminal">$name </span><span class="kw">for </span><span class="macro-nonterminal">$t </span>{}
)<span class="kw-2">*</span>)
}
<span class="macro">empty_trait_impl!</span>(Unsigned <span class="kw">for </span>usize u8 u16 u32 u64 u128);
<span class="kw">impl</span><T: Unsigned> Unsigned <span class="kw">for </span>Wrapping<T> <span class="kw">where </span>Wrapping<T>: Num {}
<span class="attr">#[test]
</span><span class="kw">fn </span>unsigned_wrapping_is_unsigned() {
<span class="kw">fn </span>require_unsigned<T: Unsigned>(<span class="kw">_</span>: <span class="kw-2">&</span>T) {}
require_unsigned(<span class="kw-2">&</span>Wrapping(<span class="number">42_u32</span>));
}
<span class="attr">#[test]
</span><span class="kw">fn </span>signed_wrapping_is_signed() {
<span class="kw">fn </span>require_signed<T: Signed>(<span class="kw">_</span>: <span class="kw-2">&</span>T) {}
require_signed(<span class="kw-2">&</span>Wrapping(-<span class="number">42</span>));
}
</code></pre></div>
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