diff options
Diffstat (limited to 'library/core/src/num/nonzero.rs')
| -rw-r--r-- | library/core/src/num/nonzero.rs | 67 |
1 files changed, 49 insertions, 18 deletions
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs index 74a325b89d4..38a1c42d9e8 100644 --- a/library/core/src/num/nonzero.rs +++ b/library/core/src/num/nonzero.rs @@ -493,6 +493,43 @@ macro_rules! nonzero_unsigned_operations { pub const fn ilog10(self) -> u32 { super::int_log10::$Int(self.0) } + + /// Calculates the middle point of `self` and `rhs`. + /// + /// `midpoint(a, b)` is `(a + b) >> 1` as if it were performed in a + /// sufficiently-large signed integral type. This implies that the result is + /// always rounded towards negative infinity and that no overflow will ever occur. + /// + /// # Examples + /// + /// ``` + /// #![feature(num_midpoint)] + #[doc = concat!("# use std::num::", stringify!($Ty), ";")] + /// + /// # fn main() { test().unwrap(); } + /// # fn test() -> Option<()> { + #[doc = concat!("let one = ", stringify!($Ty), "::new(1)?;")] + #[doc = concat!("let two = ", stringify!($Ty), "::new(2)?;")] + #[doc = concat!("let four = ", stringify!($Ty), "::new(4)?;")] + /// + /// assert_eq!(one.midpoint(four), two); + /// assert_eq!(four.midpoint(one), two); + /// # Some(()) + /// # } + /// ``` + #[unstable(feature = "num_midpoint", issue = "110840")] + #[rustc_const_unstable(feature = "const_num_midpoint", issue = "110840")] + #[rustc_allow_const_fn_unstable(const_num_midpoint)] + #[must_use = "this returns the result of the operation, \ + without modifying the original"] + #[inline] + pub const fn midpoint(self, rhs: Self) -> Self { + // SAFETY: The only way to get `0` with midpoint is to have two opposite or + // near opposite numbers: (-5, 5), (0, 1), (0, 0) which is impossible because + // of the unsignedness of this number and also because $Ty is guaranteed to + // never being 0. + unsafe { $Ty::new_unchecked(self.get().midpoint(rhs.get())) } + } } )+ } @@ -719,8 +756,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -734,7 +769,8 @@ macro_rules! nonzero_signed_operations { /// ``` #[must_use] #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn is_positive(self) -> bool { self.get().is_positive() } @@ -745,8 +781,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -760,7 +794,8 @@ macro_rules! nonzero_signed_operations { /// ``` #[must_use] #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn is_negative(self) -> bool { self.get().is_negative() } @@ -770,8 +805,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -786,7 +819,8 @@ macro_rules! nonzero_signed_operations { /// # } /// ``` #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn checked_neg(self) -> Option<$Ty> { if let Some(result) = self.get().checked_neg() { // SAFETY: negation of nonzero cannot yield zero values. @@ -803,8 +837,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -819,7 +851,8 @@ macro_rules! nonzero_signed_operations { /// # } /// ``` #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn overflowing_neg(self) -> ($Ty, bool) { let (result, overflow) = self.get().overflowing_neg(); // SAFETY: negation of nonzero cannot yield zero values. @@ -832,8 +865,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -853,7 +884,8 @@ macro_rules! nonzero_signed_operations { /// # } /// ``` #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn saturating_neg(self) -> $Ty { if let Some(result) = self.checked_neg() { return result; @@ -870,8 +902,6 @@ macro_rules! nonzero_signed_operations { /// # Example /// /// ``` - /// #![feature(nonzero_negation_ops)] - /// #[doc = concat!("# use std::num::", stringify!($Ty), ";")] /// # fn main() { test().unwrap(); } /// # fn test() -> Option<()> { @@ -886,7 +916,8 @@ macro_rules! nonzero_signed_operations { /// # } /// ``` #[inline] - #[unstable(feature = "nonzero_negation_ops", issue = "102443")] + #[stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] + #[rustc_const_stable(feature = "nonzero_negation_ops", since = "CURRENT_RUSTC_VERSION")] pub const fn wrapping_neg(self) -> $Ty { let result = self.get().wrapping_neg(); // SAFETY: negation of nonzero cannot yield zero values. |