Auto merge of #286 - yoanlcq:missing-impls-for-wrapping, r=cuviper

impl remaining num-traits for std::num::Wrapping<T>

This is a (late) follow-up for [https://github.com/rust-num/num/pull/279](https://github.com/rust-num/num/pull/279) since I realized that implementing `Num` for `Wrapping<T>` was merely half of the work.

This PR makes `Wrapping<T>` implement the remaining appropriate traits, granting it the ability to really be used a complete substitute for its primitive integer counterparts.
Some benefits are :
- Less refactoring for users using `num`'s traits replacing some primitives by their `Wrapping` counterpart (same for the opposite);
- Since `Wrapping<T>` is from `std`, nobody except us can `impl` our traits for it, so people don't have to create their own.

Author: homu

traits/src/bounds.rs

@@ -1,6 +1,7 @@
 use std::{usize, u8, u16, u32, u64};
 use std::{isize, i8, i16, i32, i64};
 use std::{f32, f64};
+use std::num::Wrapping;
 
 /// Numbers which have upper and lower bounds
 pub trait Bounded {
@@ -35,6 +36,11 @@ bounded_impl!(i16,   i16::MIN,   i16::MAX);
 bounded_impl!(i32,   i32::MIN,   i32::MAX);
 bounded_impl!(i64,   i64::MIN,   i64::MAX);
 
+impl<T: Bounded> Bounded for Wrapping<T> {
+    fn min_value() -> Self { Wrapping(T::min_value()) }
+    fn max_value() -> Self { Wrapping(T::max_value()) }
+}
+
 bounded_impl!(f32, f32::MIN, f32::MAX);
 
 macro_rules! for_each_tuple_ {
@@ -69,3 +75,25 @@ macro_rules! bounded_tuple {
 
 for_each_tuple!(bounded_tuple);
 bounded_impl!(f64, f64::MIN, f64::MAX);
+
+
+macro_rules! test_wrapping_bounded {
+    ($($t:ty)+) => {
+        $(
+            assert_eq!(Wrapping::<$t>::min_value().0, <$t>::min_value());
+            assert_eq!(Wrapping::<$t>::max_value().0, <$t>::max_value());
+        )+   
+    };
+}
+
+#[test]
+fn wrapping_bounded() {
+    test_wrapping_bounded!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
+}
+
+#[test]
+fn wrapping_is_bounded() {
+    fn require_bounded<T: Bounded>(_: &T) {}
+    require_bounded(&Wrapping(42_u32));
+    require_bounded(&Wrapping(-42));
+}

traits/src/cast.rs

@@ -1,4 +1,5 @@
 use std::mem::size_of;
+use std::num::Wrapping;
 
 use identities::Zero;
 use bounds::Bounded;
@@ -385,6 +386,17 @@ impl_from_primitive!(u64,   to_u64);
 impl_from_primitive!(f32,   to_f32);
 impl_from_primitive!(f64,   to_f64);
 
+
+impl<T: ToPrimitive> ToPrimitive for Wrapping<T> {
+    fn to_i64(&self) -> Option<i64> { self.0.to_i64() }
+    fn to_u64(&self) -> Option<u64> { self.0.to_u64() }
+}
+impl<T: FromPrimitive> FromPrimitive for Wrapping<T> {
+    fn from_u64(n: u64) -> Option<Self> { T::from_u64(n).map(Wrapping) }
+    fn from_i64(n: i64) -> Option<Self> { T::from_i64(n).map(Wrapping) }
+}
+
+
 /// Cast from one machine scalar to another.
 ///
 /// # Examples
@@ -434,6 +446,11 @@ impl_num_cast!(isize, to_isize);
 impl_num_cast!(f32,   to_f32);
 impl_num_cast!(f64,   to_f64);
 
+impl<T: NumCast> NumCast for Wrapping<T> {
+    fn from<U: ToPrimitive>(n: U) -> Option<Self> {
+        T::from(n).map(Wrapping)
+    }
+}
 
 #[test]
 fn to_primitive_float() {
@@ -448,3 +465,47 @@ fn to_primitive_float() {
     assert_eq!((f64::NEG_INFINITY).to_f32(), Some(f32::NEG_INFINITY));
     assert!((f64::NAN).to_f32().map_or(false, |f| f.is_nan()));
 }
+
+macro_rules! test_wrapping_to_primitive {
+    ($($t:ty)+) => {
+        $({
+            let i: $t = 0;
+            let w = Wrapping(i);
+            assert_eq!(i.to_u8(),    w.to_u8());
+            assert_eq!(i.to_u16(),   w.to_u16());
+            assert_eq!(i.to_u32(),   w.to_u32());
+            assert_eq!(i.to_u64(),   w.to_u64());
+            assert_eq!(i.to_usize(), w.to_usize());
+            assert_eq!(i.to_i8(),    w.to_i8());
+            assert_eq!(i.to_i16(),   w.to_i16());
+            assert_eq!(i.to_i32(),   w.to_i32());
+            assert_eq!(i.to_i64(),   w.to_i64());
+            assert_eq!(i.to_isize(), w.to_isize());
+            assert_eq!(i.to_f32(),   w.to_f32());
+            assert_eq!(i.to_f64(),   w.to_f64());
+        })+   
+    };
+}
+
+#[test]
+fn wrapping_to_primitive() {
+    test_wrapping_to_primitive!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
+}
+
+#[test]
+fn wrapping_is_toprimitive() {
+    fn require_toprimitive<T: ToPrimitive>(_: &T) {}
+    require_toprimitive(&Wrapping(42));
+}
+
+#[test]
+fn wrapping_is_fromprimitive() {
+    fn require_fromprimitive<T: FromPrimitive>(_: &T) {}
+    require_fromprimitive(&Wrapping(42));
+}
+
+#[test]
+fn wrapping_is_numcast() {
+    fn require_numcast<T: NumCast>(_: &T) {}
+    require_numcast(&Wrapping(42));
+}

traits/src/identities.rs

@@ -118,3 +118,31 @@ impl<T: One> One for Wrapping<T> where Wrapping<T>: Mul<Output=Wrapping<T>> {
 
 /// Returns the multiplicative identity, `1`.
 #[inline(always)] pub fn one<T: One>() -> T { One::one() }
+
+
+macro_rules! test_wrapping_identities {
+    ($($t:ty)+) => {
+        $(
+            assert_eq!(zero::<$t>(), zero::<Wrapping<$t>>().0);
+            assert_eq!(one::<$t>(), one::<Wrapping<$t>>().0);
+            assert_eq!((0 as $t).is_zero(), Wrapping(0 as $t).is_zero());
+            assert_eq!((1 as $t).is_zero(), Wrapping(1 as $t).is_zero());
+        )+   
+    };
+}
+
+#[test]
+fn wrapping_identities() {
+    test_wrapping_identities!(isize i8 i16 i32 i64 usize u8 u16 u32 u64);
+}
+
+#[test]
+fn wrapping_is_zero() {
+    fn require_zero<T: Zero>(_: &T) {}
+    require_zero(&Wrapping(42));
+}
+#[test]
+fn wrapping_is_one() {
+    fn require_one<T: One>(_: &T) {}
+    require_one(&Wrapping(42));
+}

traits/src/lib.rs

@@ -294,3 +294,24 @@ fn from_str_radix_unwrap() {
     let f: f32 = Num::from_str_radix("0.0", 10).unwrap();
     assert_eq!(f, 0.0);
 }
+
+macro_rules! test_wrapping_from_str_radix {
+    ($($t:ty)+) => {
+        $(
+            for &(s, r) in &[("42", 10), ("42", 2), ("-13.0", 10), ("foo", 10)] {
+                let w = Wrapping::<$t>::from_str_radix(s, r).map(|w| w.0);
+                assert_eq!(w, <$t as Num>::from_str_radix(s, r));
+            } 
+        )+   
+    };
+}
+#[test]
+fn wrapping_is_num() {
+    fn require_num<T: Num>(_: &T) {}
+    require_num(&Wrapping(42_u32));
+    require_num(&Wrapping(-42));
+}
+#[test]
+fn wrapping_from_str_radix() {
+    test_wrapping_from_str_radix!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
+}

traits/src/ops/checked.rs

@@ -89,3 +89,4 @@ checked_impl!(CheckedDiv, checked_div, i16);
 checked_impl!(CheckedDiv, checked_div, i32);
 checked_impl!(CheckedDiv, checked_div, i64);
 checked_impl!(CheckedDiv, checked_div, isize);
+

traits/src/ops/wrapping.rs

@@ -1,4 +1,5 @@
 use std::ops::{Add, Sub, Mul};
+use std::num::Wrapping;
 
 macro_rules! wrapping_impl {
     ($trait_name:ident, $method:ident, $t:ty) => {
@@ -76,6 +77,23 @@ wrapping_impl!(WrappingMul, wrapping_mul, i32);
 wrapping_impl!(WrappingMul, wrapping_mul, i64);
 wrapping_impl!(WrappingMul, wrapping_mul, isize);
 
+// Well this is a bit funny, but all the more appropriate.
+impl<T: WrappingAdd> WrappingAdd for Wrapping<T> where Wrapping<T>: Add<Output = Wrapping<T>> {
+    fn wrapping_add(&self, v: &Self) -> Self {
+        Wrapping(self.0.wrapping_add(&v.0))
+    }
+}
+impl<T: WrappingSub> WrappingSub for Wrapping<T> where Wrapping<T>: Sub<Output = Wrapping<T>> {
+    fn wrapping_sub(&self, v: &Self) -> Self {
+        Wrapping(self.0.wrapping_sub(&v.0))
+    }
+}
+impl<T: WrappingMul> WrappingMul for Wrapping<T> where Wrapping<T>: Mul<Output = Wrapping<T>> {
+    fn wrapping_mul(&self, v: &Self) -> Self {
+        Wrapping(self.0.wrapping_mul(&v.0))
+    }
+}
+
 
 #[test]
 fn test_wrapping_traits() {
@@ -85,4 +103,25 @@ fn test_wrapping_traits() {
     assert_eq!(wrapping_add(255, 1), 0u8);
     assert_eq!(wrapping_sub(0, 1), 255u8);
     assert_eq!(wrapping_mul(255, 2), 254u8);
+    assert_eq!(wrapping_add(255, 1), (Wrapping(255u8) + Wrapping(1u8)).0);
+    assert_eq!(wrapping_sub(0, 1), (Wrapping(0u8) - Wrapping(1u8)).0);
+    assert_eq!(wrapping_mul(255, 2), (Wrapping(255u8) * Wrapping(2u8)).0);
+}
+
+#[test]
+fn wrapping_is_wrappingadd() {
+    fn require_wrappingadd<T: WrappingAdd>(_: &T) {}
+    require_wrappingadd(&Wrapping(42));
+}
+
+#[test]
+fn wrapping_is_wrappingsub() {
+    fn require_wrappingsub<T: WrappingSub>(_: &T) {}
+    require_wrappingsub(&Wrapping(42));
+}
+
+#[test]
+fn wrapping_is_wrappingmul() {
+    fn require_wrappingmul<T: WrappingMul>(_: &T) {}
+    require_wrappingmul(&Wrapping(42));
 }

traits/src/sign.rs

@@ -1,5 +1,6 @@
 use std::ops::Neg;
 use std::{f32, f64};
+use std::num::Wrapping;
 
 use Num;
 
@@ -73,6 +74,30 @@ macro_rules! signed_impl {
 
 signed_impl!(isize i8 i16 i32 i64);
 
+impl<T: Signed> Signed for Wrapping<T> where Wrapping<T>: Num + Neg<Output=Wrapping<T>>
+{
+    #[inline]
+    fn abs(&self) -> Self {
+        Wrapping(self.0.abs())
+    }
+
+    #[inline]
+    fn abs_sub(&self, other: &Self) -> Self {
+        Wrapping(self.0.abs_sub(&other.0))
+    }
+
+    #[inline]
+    fn signum(&self) -> Self {
+        Wrapping(self.0.signum())
+    }
+
+    #[inline]
+    fn is_positive(&self) -> bool { self.0.is_positive() }
+
+    #[inline]
+    fn is_negative(&self) -> bool { self.0.is_negative() }
+}
+
 macro_rules! signed_float_impl {
     ($t:ty, $nan:expr, $inf:expr, $neg_inf:expr) => {
         impl Signed for $t {
@@ -159,3 +184,21 @@ macro_rules! empty_trait_impl {
 }
 
 empty_trait_impl!(Unsigned for usize u8 u16 u32 u64);
+
+impl<T: Unsigned> Unsigned for Wrapping<T> where Wrapping<T>: Num {}
+
+#[test]
+fn unsigned_wrapping_is_unsigned() {
+    fn require_unsigned<T: Unsigned>(_: &T) {}
+    require_unsigned(&Wrapping(42_u32));
+}
+/*
+// Commenting this out since it doesn't compile on Rust 1.8,
+// because on this version Wrapping doesn't implement Neg and therefore can't
+// implement Signed.
+#[test]
+fn signed_wrapping_is_signed() {
+    fn require_signed<T: Signed>(_: &T) {}
+    require_signed(&Wrapping(-42));
+}
+*/