fmt::DisplayInt abstraction obsolete with better macro

Author: pascaldekloe

library/core/src/fmt/num.rs

@@ -2,35 +2,8 @@
 
 use crate::mem::MaybeUninit;
 use crate::num::fmt as numfmt;
-use crate::ops::{Div, Rem, Sub};
 use crate::{fmt, ptr, slice, str};
 
-#[doc(hidden)]
-trait DisplayInt:
-    PartialEq + PartialOrd + Div<Output = Self> + Rem<Output = Self> + Sub<Output = Self> + Copy
-{
-    #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-    fn to_u32(&self) -> u32;
-    fn to_u64(&self) -> u64;
-    fn to_u128(&self) -> u128;
-}
-
-macro_rules! impl_int {
-    ($($t:ident)*) => (
-        $(impl DisplayInt for $t {
-            #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-            fn to_u32(&self) -> u32 { *self as u32 }
-            fn to_u64(&self) -> u64 { *self as u64 }
-            fn to_u128(&self) -> u128 { *self as u128 }
-        })*
-    )
-}
-
-impl_int! {
-    i8 i16 i32 i64 i128 isize
-    u8 u16 u32 u64 u128 usize
-}
-
 // Formatting of integers with a non-decimal radix.
 macro_rules! radix_integer {
     (fmt::$Trait:ident for $Signed:ident and $Unsigned:ident, $prefix:expr, $dig_tab:expr) => {
@@ -142,47 +115,47 @@ static DEC_DIGITS_LUT: &[u8; 200] = b"\
       8081828384858687888990919293949596979899";
 
 macro_rules! impl_Display {
-    ($($signed:ident, $unsigned:ident,)* ; as $u:ident via $conv_fn:ident named $gen_name:ident) => {
+    ($($Signed:ident, $Unsigned:ident),* ; as $T:ident into $fmt_fn:ident) => {
 
         $(
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::Display for $unsigned {
+        impl fmt::Display for $Unsigned {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 #[cfg(not(feature = "optimize_for_size"))]
                 {
-                    const MAX_DEC_N: usize = $unsigned::MAX.ilog10() as usize + 1;
-                    // Buffer decimals for $unsigned with right alignment.
+                    const MAX_DEC_N: usize = $Unsigned::MAX.ilog10() as usize + 1;
+                    // Buffer decimals for self with right alignment.
                     let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
 
                     f.pad_integral(true, "", self._fmt(&mut buf))
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    $gen_name(self.$conv_fn(), true, f)
+                    $fmt_fn(self as $T, true, f)
                 }
             }
         }
 
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::Display for $signed {
+        impl fmt::Display for $Signed {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 #[cfg(not(feature = "optimize_for_size"))]
                 {
-                    const MAX_DEC_N: usize = $unsigned::MAX.ilog10() as usize + 1;
-                    // Buffer decimals for $unsigned with right alignment.
+                    const MAX_DEC_N: usize = $Unsigned::MAX.ilog10() as usize + 1;
+                    // Buffer decimals for self with right alignment.
                     let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
 
                     f.pad_integral(*self >= 0, "", self.unsigned_abs()._fmt(&mut buf))
                 }
                 #[cfg(feature = "optimize_for_size")]
                 {
-                    return $gen_name(self.unsigned_abs().$conv_fn(), *self >= 0, f);
+                    return $fmt_fn(self.unsigned_abs() as $T, *self >= 0, f);
                 }
             }
         }
 
         #[cfg(not(feature = "optimize_for_size"))]
-        impl $unsigned {
+        impl $Unsigned {
             #[doc(hidden)]
             #[unstable(
                 feature = "fmt_internals",
@@ -264,8 +237,8 @@ macro_rules! impl_Display {
         })*
 
         #[cfg(feature = "optimize_for_size")]
-        fn $gen_name(mut n: $u, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-            const MAX_DEC_N: usize = $u::MAX.ilog10() as usize + 1;
+        fn $fmt_fn(mut n: $T, is_nonnegative: bool, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            const MAX_DEC_N: usize = $T::MAX.ilog10() as usize + 1;
             let mut buf = [MaybeUninit::<u8>::uninit(); MAX_DEC_N];
             let mut curr = MAX_DEC_N;
             let buf_ptr = MaybeUninit::slice_as_mut_ptr(&mut buf);
@@ -298,9 +271,9 @@ macro_rules! impl_Display {
 }
 
 macro_rules! impl_Exp {
-    ($($t:ident),* as $u:ident via $conv_fn:ident named $name:ident) => {
-        fn $name(
-            mut n: $u,
+    ($($Signed:ident, $Unsigned:ident),* ; as $T:ident into $fmt_fn:ident) => {
+        fn $fmt_fn(
+            mut n: $T,
             is_nonnegative: bool,
             upper: bool,
             f: &mut fmt::Formatter<'_>
@@ -434,32 +407,41 @@ macro_rules! impl_Exp {
 
         $(
             #[stable(feature = "integer_exp_format", since = "1.42.0")]
-            impl fmt::LowerExp for $t {
-                #[allow(unused_comparisons)]
+            impl fmt::LowerExp for $Signed {
                 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                     let is_nonnegative = *self >= 0;
                     let n = if is_nonnegative {
-                        self.$conv_fn()
+                        *self as $T
                     } else {
-                        // convert the negative num to positive by summing 1 to its 2s complement
-                        (!self.$conv_fn()).wrapping_add(1)
+                        self.unsigned_abs() as $T
                     };
-                    $name(n, is_nonnegative, false, f)
+                    $fmt_fn(n, is_nonnegative, false, f)
+                }
+            }
+            #[stable(feature = "integer_exp_format", since = "1.42.0")]
+            impl fmt::LowerExp for $Unsigned {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    $fmt_fn(*self as $T, true, false, f)
                 }
             })*
+
         $(
             #[stable(feature = "integer_exp_format", since = "1.42.0")]
-            impl fmt::UpperExp for $t {
-                #[allow(unused_comparisons)]
+            impl fmt::UpperExp for $Signed {
                 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                     let is_nonnegative = *self >= 0;
                     let n = if is_nonnegative {
-                        self.$conv_fn()
+                        *self as $T
                     } else {
-                        // convert the negative num to positive by summing 1 to its 2s complement
-                        (!self.$conv_fn()).wrapping_add(1)
+                        self.unsigned_abs() as $T
                     };
-                    $name(n, is_nonnegative, true, f)
+                    $fmt_fn(n, is_nonnegative, true, f)
+                }
+            }
+            #[stable(feature = "integer_exp_format", since = "1.42.0")]
+            impl fmt::UpperExp for $Unsigned {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    $fmt_fn(*self as $T, true, true, f)
                 }
             })*
     };
@@ -475,37 +457,20 @@ impl_Debug! {
 #[cfg(any(target_pointer_width = "64", target_arch = "wasm32"))]
 mod imp {
     use super::*;
-    impl_Display!(
-        i8, u8,
-        i16, u16,
-        i32, u32,
-        i64, u64,
-        isize, usize,
-        ; as u64 via to_u64 named fmt_u64
-    );
-    impl_Exp!(
-        i8, u8, i16, u16, i32, u32, i64, u64, usize, isize
-            as u64 via to_u64 named exp_u64
-    );
+    impl_Display!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into fmt_u64);
+    impl_Exp!(i8, u8, i16, u16, i32, u32, i64, u64, isize, usize; as u64 into exp_u64);
 }
 
 #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
 mod imp {
     use super::*;
-    impl_Display!(
-        i8, u8,
-        i16, u16,
-        i32, u32,
-        isize, usize,
-        ; as u32 via to_u32 named fmt_u32);
-    impl_Display!(
-        i64, u64,
-        ; as u64 via to_u64 named fmt_u64);
-
-    impl_Exp!(i8, u8, i16, u16, i32, u32, isize, usize as u32 via to_u32 named exp_u32);
-    impl_Exp!(i64, u64 as u64 via to_u64 named exp_u64);
+    impl_Display!(i8, u8, i16, u16, i32, u32, isize, usize; as u32 into fmt_u32);
+    impl_Display!(i64, u64, ; as u64 into fmt_u64);
+
+    impl_Exp!(i8, u8, i16, u16, i32, u32, isize, usize; as u32 into exp_u32);
+    impl_Exp!(i64, u64; as u64 into exp_u64);
 }
-impl_Exp!(i128, u128 as u128 via to_u128 named exp_u128);
+impl_Exp!(i128, u128; as u128 into exp_u128);
 
 const U128_MAX_DEC_N: usize = u128::MAX.ilog10() as usize + 1;