Merge #55

55: Add derive macro for num_traits::Signed r=cuviper a=tdelabro



Co-authored-by: Timothée Delabrouille <timothee.delabrouille@gmail.com>
Co-authored-by: Josh Stone <cuviper@gmail.com>

src/lib.rs

@@ -952,3 +952,61 @@ pub fn float(input: TokenStream) -> TokenStream {
 
     import.wrap("Float", name, impl_).into()
 }
+
+/// Derives [`num_traits::Signed`][signed] for newtypes.  The inner type must already implement
+/// `Signed`.
+///
+/// [signed]: https://docs.rs/num-traits/0.2/num_traits/sign/trait.Signed.html
+#[proc_macro_derive(Signed, attributes(num_traits))]
+pub fn signed(input: TokenStream) -> TokenStream {
+    let ast = parse!(input as syn::DeriveInput);
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+
+    let import = NumTraits::new(&ast);
+
+    let impl_ = quote! {
+        impl #import::Signed for #name {
+            #[inline]
+            fn abs(&self) -> Self {
+                #name(<#inner_ty as #import::Signed>::abs(&self.0))
+            }
+            #[inline]
+            fn abs_sub(&self, other: &Self) -> Self {
+                #name(<#inner_ty as #import::Signed>::abs_sub(&self.0, &other.0))
+            }
+            #[inline]
+            fn signum(&self) -> Self {
+                #name(<#inner_ty as #import::Signed>::signum(&self.0))
+            }
+            #[inline]
+            fn is_positive(&self) -> bool {
+                <#inner_ty as #import::Signed>::is_positive(&self.0)
+            }
+            #[inline]
+            fn is_negative(&self) -> bool {
+                <#inner_ty as #import::Signed>::is_negative(&self.0)
+            }
+        }
+    };
+
+    import.wrap("Signed", &name, impl_).into()
+}
+
+/// Derives [`num_traits::Unsigned`][unsigned].  The inner type must already implement
+/// `Unsigned`.
+///
+/// [unsigned]: https://docs.rs/num/latest/num/traits/trait.Unsigned.html
+#[proc_macro_derive(Unsigned, attributes(num_traits))]
+pub fn unsigned(input: TokenStream) -> TokenStream {
+    let ast = parse!(input as syn::DeriveInput);
+    let name = &ast.ident;
+
+    let import = NumTraits::new(&ast);
+
+    let impl_ = quote! {
+        impl #import::Unsigned for #name {}
+    };
+
+    import.wrap("Unsigned", &name, impl_).into()
+}

tests/newtype.rs

@@ -2,9 +2,22 @@ extern crate num as num_renamed;
 #[macro_use]
 extern crate num_derive;
 
-use crate::num_renamed::{Float, FromPrimitive, Num, NumCast, One, ToPrimitive, Zero};
+use crate::num_renamed::{
+    Float, FromPrimitive, Num, NumCast, One, Signed, ToPrimitive, Unsigned, Zero,
+};
 use std::ops::Neg;
 
+#[derive(PartialEq, Zero, One, NumOps, Num, Unsigned)]
+struct MyNum(u32);
+
+#[test]
+fn test_derive_unsigned_works() {
+    fn do_nothing_on_unsigned(_input: impl Unsigned) {}
+
+    let x = MyNum(42);
+    do_nothing_on_unsigned(x);
+}
+
 #[derive(
     Debug,
     Clone,
@@ -19,6 +32,7 @@ use std::ops::Neg;
     Zero,
     Num,
     Float,
+    Signed,
 )]
 struct MyFloat(f64);
 
@@ -87,3 +101,8 @@ fn test_num() {
 fn test_float() {
     assert_eq!(MyFloat(4.0).log(MyFloat(2.0)), MyFloat(2.0));
 }
+
+#[test]
+fn test_signed() {
+    assert!(MyFloat(-2.0).is_negative())
+}