Skip to content

Commit

Permalink
Rollup merge of rust-lang#87601 - a1phyr:feature_uint_add_signed, r=k…
Browse files Browse the repository at this point in the history 
…ennytm

Add functions to add unsigned and signed integers

This PR adds methods to unsigned integers to add signed integers with good overflow semantics under `#![feature(mixed_integer_ops)]`.

The added API is:

```rust
// `uX` is `u8`, `u16`, `u32`, `u64`,`u128`, `usize`
impl uX {
    pub const fn checked_add_signed(self, iX) -> Option<Self>;
    pub const fn overflowing_add_signed(self, iX) -> (Self, bool);
    pub const fn saturating_add_signed(self, iX) -> Self;
    pub const fn wrapping_add_signed(self, iX) -> Self;
}

impl iX {
    pub const fn checked_add_unsigned(self, uX) -> Option<Self>;
    pub const fn overflowing_add_unsigned(self, uX) -> (Self, bool);
    pub const fn saturating_add_unsigned(self, uX) -> Self;
    pub const fn wrapping_add_unsigned(self, uX) -> Self;

    pub const fn checked_sub_unsigned(self, uX) -> Option<Self>;
    pub const fn overflowing_sub_unsigned(self, uX) -> (Self, bool);
    pub const fn saturating_sub_unsigned(self, uX) -> Self;
    pub const fn wrapping_sub_unsigned(self, uX) -> Self;
}
```

Maybe it would be interesting to also have `add_signed` that panics in debug and wraps in release ?
  • Loading branch information
@Manishearth
Manishearth committed Oct 6, 2021
2 parents 98a5a98 + 47edde1 commit 0c78e9d
Show file tree
Hide file tree
Showing 6 changed files with 304 additions and 15 deletions.
1 change: 1 addition & 0 deletions library/core/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -142,6 +142,7 @@
#![feature(link_llvm_intrinsics)]
#![feature(llvm_asm)]
#![feature(min_specialization)]
#![feature(mixed_integer_ops)]
#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
#![feature(negative_impls)]
#![feature(never_type)]
Expand Down
192 changes: 192 additions & 0 deletions library/core/src/num/int_macros.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -433,6 +433,28 @@ macro_rules! int_impl {
unsafe { intrinsics::unchecked_add(self, rhs) }
}

/// Checked addition with an unsigned integer. Computes `self + rhs`,
/// returning `None` if overflow occurred.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_unsigned(2), Some(3));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_unsigned(3), None);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn checked_add_unsigned(self, rhs: $UnsignedT) -> Option<Self> {
let (a, b) = self.overflowing_add_unsigned(rhs);
if unlikely!(b) {None} else {Some(a)}
}

/// Checked integer subtraction. Computes `self - rhs`, returning `None` if
/// overflow occurred.
///
Expand Down Expand Up @@ -479,6 +501,28 @@ macro_rules! int_impl {
unsafe { intrinsics::unchecked_sub(self, rhs) }
}

/// Checked subtraction with an unsigned integer. Computes `self - rhs`,
/// returning `None` if overflow occurred.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_unsigned(2), Some(-1));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MIN + 2).checked_sub_unsigned(3), None);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn checked_sub_unsigned(self, rhs: $UnsignedT) -> Option<Self> {
let (a, b) = self.overflowing_sub_unsigned(rhs);
if unlikely!(b) {None} else {Some(a)}
}

/// Checked integer multiplication. Computes `self * rhs`, returning `None` if
/// overflow occurred.
///
Expand Down Expand Up @@ -826,6 +870,32 @@ macro_rules! int_impl {
intrinsics::saturating_add(self, rhs)
}

/// Saturating addition with an unsigned integer. Computes `self + rhs`,
/// saturating at the numeric bounds instead of overflowing.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_unsigned(2), 3);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add_unsigned(100), ", stringify!($SelfT), "::MAX);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn saturating_add_unsigned(self, rhs: $UnsignedT) -> Self {
// Overflow can only happen at the upper bound
// We cannot use `unwrap_or` here because it is not `const`
match self.checked_add_unsigned(rhs) {
Some(x) => x,
None => Self::MAX,
}
}

/// Saturating integer subtraction. Computes `self - rhs`, saturating at the
/// numeric bounds instead of overflowing.
///
Expand All @@ -847,6 +917,32 @@ macro_rules! int_impl {
intrinsics::saturating_sub(self, rhs)
}

/// Saturating subtraction with an unsigned integer. Computes `self - rhs`,
/// saturating at the numeric bounds instead of overflowing.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub_unsigned(127), -27);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.saturating_sub_unsigned(100), ", stringify!($SelfT), "::MIN);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn saturating_sub_unsigned(self, rhs: $UnsignedT) -> Self {
// Overflow can only happen at the lower bound
// We cannot use `unwrap_or` here because it is not `const`
match self.checked_sub_unsigned(rhs) {
Some(x) => x,
None => Self::MIN,
}
}

/// Saturating integer negation. Computes `-self`, returning `MAX` if `self == MIN`
/// instead of overflowing.
///
Expand Down Expand Up @@ -1002,6 +1098,27 @@ macro_rules! int_impl {
intrinsics::wrapping_add(self, rhs)
}

/// Wrapping (modular) addition with an unsigned integer. Computes
/// `self + rhs`, wrapping around at the boundary of the type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_add_unsigned(27), 127);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_add_unsigned(2), ", stringify!($SelfT), "::MIN + 1);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline(always)]
pub const fn wrapping_add_unsigned(self, rhs: $UnsignedT) -> Self {
self.wrapping_add(rhs as Self)
}

/// Wrapping (modular) subtraction. Computes `self - rhs`, wrapping around at the
/// boundary of the type.
///
Expand All @@ -1022,6 +1139,27 @@ macro_rules! int_impl {
intrinsics::wrapping_sub(self, rhs)
}

/// Wrapping (modular) subtraction with an unsigned integer. Computes
/// `self - rhs`, wrapping around at the boundary of the type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(0", stringify!($SelfT), ".wrapping_sub_unsigned(127), -127);")]
#[doc = concat!("assert_eq!((-2", stringify!($SelfT), ").wrapping_sub_unsigned(", stringify!($UnsignedT), "::MAX), -1);")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline(always)]
pub const fn wrapping_sub_unsigned(self, rhs: $UnsignedT) -> Self {
self.wrapping_sub(rhs as Self)
}

/// Wrapping (modular) multiplication. Computes `self * rhs`, wrapping around at
/// the boundary of the type.
///
Expand Down Expand Up @@ -1372,6 +1510,33 @@ macro_rules! int_impl {
(sum as $SelfT, carry)
}

/// Calculates `self` + `rhs` with an unsigned `rhs`
///
/// Returns a tuple of the addition along with a boolean indicating
/// whether an arithmetic overflow would occur. If an overflow would
/// have occurred then the wrapped value is returned.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_unsigned(2), (3, false));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MIN).overflowing_add_unsigned(", stringify!($UnsignedT), "::MAX), (", stringify!($SelfT), "::MAX, false));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_unsigned(3), (", stringify!($SelfT), "::MIN, true));")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn overflowing_add_unsigned(self, rhs: $UnsignedT) -> (Self, bool) {
let rhs = rhs as Self;
let (res, overflowed) = self.overflowing_add(rhs);
(res, overflowed ^ (rhs < 0))
}

/// Calculates `self` - `rhs`
///
/// Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow
Expand Down Expand Up @@ -1423,6 +1588,33 @@ macro_rules! int_impl {
(sum as $SelfT, borrow)
}

/// Calculates `self` - `rhs` with an unsigned `rhs`
///
/// Returns a tuple of the subtraction along with a boolean indicating
/// whether an arithmetic overflow would occur. If an overflow would
/// have occurred then the wrapped value is returned.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(mixed_integer_ops)]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_unsigned(2), (-1, false));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).overflowing_sub_unsigned(", stringify!($UnsignedT), "::MAX), (", stringify!($SelfT), "::MIN, false));")]
#[doc = concat!("assert_eq!((", stringify!($SelfT), "::MIN + 2).overflowing_sub_unsigned(3), (", stringify!($SelfT), "::MAX, true));")]
/// ```
#[unstable(feature = "mixed_integer_ops", issue = "87840")]
#[rustc_const_unstable(feature = "mixed_integer_ops", issue = "87840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn overflowing_sub_unsigned(self, rhs: $UnsignedT) -> (Self, bool) {
let rhs = rhs as Self;
let (res, overflowed) = self.overflowing_sub(rhs);
(res, overflowed ^ (rhs < 0))
}

/// Calculates the multiplication of `self` and `rhs`.
///
/// Returns a tuple of the multiplication along with a boolean indicating whether an arithmetic overflow
Expand Down
16 changes: 8 additions & 8 deletions library/core/src/num/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -245,7 +245,7 @@ const ASCII_CASE_MASK: u8 = 0b0010_0000;
#[lang = "u8"]
impl u8 {
widening_impl! { u8, u16, 8 }
uint_impl! { u8, u8, 8, 255, 2, "0x82", "0xa", "0x12", "0x12", "0x48", "[0x12]",
uint_impl! { u8, u8, i8, 8, 255, 2, "0x82", "0xa", "0x12", "0x12", "0x48", "[0x12]",
"[0x12]", "", "" }

/// Checks if the value is within the ASCII range.
Expand Down Expand Up @@ -779,21 +779,21 @@ impl u8 {
#[lang = "u16"]
impl u16 {
widening_impl! { u16, u32, 16 }
uint_impl! { u16, u16, 16, 65535, 4, "0xa003", "0x3a", "0x1234", "0x3412", "0x2c48",
uint_impl! { u16, u16, i16, 16, 65535, 4, "0xa003", "0x3a", "0x1234", "0x3412", "0x2c48",
"[0x34, 0x12]", "[0x12, 0x34]", "", "" }
}

#[lang = "u32"]
impl u32 {
widening_impl! { u32, u64, 32 }
uint_impl! { u32, u32, 32, 4294967295, 8, "0x10000b3", "0xb301", "0x12345678",
uint_impl! { u32, u32, i32, 32, 4294967295, 8, "0x10000b3", "0xb301", "0x12345678",
"0x78563412", "0x1e6a2c48", "[0x78, 0x56, 0x34, 0x12]", "[0x12, 0x34, 0x56, 0x78]", "", "" }
}

#[lang = "u64"]
impl u64 {
widening_impl! { u64, u128, 64 }
uint_impl! { u64, u64, 64, 18446744073709551615, 12, "0xaa00000000006e1", "0x6e10aa",
uint_impl! { u64, u64, i64, 64, 18446744073709551615, 12, "0xaa00000000006e1", "0x6e10aa",
"0x1234567890123456", "0x5634129078563412", "0x6a2c48091e6a2c48",
"[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
"[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
Expand All @@ -802,7 +802,7 @@ impl u64 {

#[lang = "u128"]
impl u128 {
uint_impl! { u128, u128, 128, 340282366920938463463374607431768211455, 16,
uint_impl! { u128, u128, i128, 128, 340282366920938463463374607431768211455, 16,
"0x13f40000000000000000000000004f76", "0x4f7613f4", "0x12345678901234567890123456789012",
"0x12907856341290785634129078563412", "0x48091e6a2c48091e6a2c48091e6a2c48",
"[0x12, 0x90, 0x78, 0x56, 0x34, 0x12, 0x90, 0x78, \
Expand All @@ -816,15 +816,15 @@ impl u128 {
#[lang = "usize"]
impl usize {
widening_impl! { usize, u32, 16 }
uint_impl! { usize, u16, 16, 65535, 4, "0xa003", "0x3a", "0x1234", "0x3412", "0x2c48",
uint_impl! { usize, u16, isize, 16, 65535, 4, "0xa003", "0x3a", "0x1234", "0x3412", "0x2c48",
"[0x34, 0x12]", "[0x12, 0x34]",
usize_isize_to_xe_bytes_doc!(), usize_isize_from_xe_bytes_doc!() }
}
#[cfg(target_pointer_width = "32")]
#[lang = "usize"]
impl usize {
widening_impl! { usize, u64, 32 }
uint_impl! { usize, u32, 32, 4294967295, 8, "0x10000b3", "0xb301", "0x12345678",
uint_impl! { usize, u32, isize, 32, 4294967295, 8, "0x10000b3", "0xb301", "0x12345678",
"0x78563412", "0x1e6a2c48", "[0x78, 0x56, 0x34, 0x12]", "[0x12, 0x34, 0x56, 0x78]",
usize_isize_to_xe_bytes_doc!(), usize_isize_from_xe_bytes_doc!() }
}
Expand All @@ -833,7 +833,7 @@ impl usize {
#[lang = "usize"]
impl usize {
widening_impl! { usize, u128, 64 }
uint_impl! { usize, u64, 64, 18446744073709551615, 12, "0xaa00000000006e1", "0x6e10aa",
uint_impl! { usize, u64, isize, 64, 18446744073709551615, 12, "0xaa00000000006e1", "0x6e10aa",
"0x1234567890123456", "0x5634129078563412", "0x6a2c48091e6a2c48",
"[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
"[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
Expand Down
Loading

0 comments on commit 0c78e9d

Please sign in to comment.