1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Numeric traits and functions for the built-in numeric types.
13 #![stable(feature = "rust1", since = "1.0.0")]
14 #![allow(missing_docs)]
16 use self::wrapping::OverflowingOps;
19 use cmp::{Eq, PartialOrd};
24 use option::Option::{self, Some, None};
25 use result::Result::{self, Ok, Err};
26 use str::{FromStr, StrExt};
29 /// Provides intentionally-wrapped arithmetic on `T`.
31 /// Operations like `+` on `u32` values is intended to never overflow,
32 /// and in some debug configurations overflow is detected and results
33 /// in a panic. While most arithmetic falls into this category, some
34 /// code explicitly expects and relies upon modular arithmetic (e.g.,
37 /// Wrapping arithmetic can be achieved either through methods like
38 /// `wrapping_add`, or through the `Wrapping<T>` type, which says that
39 /// all standard arithmetic operations on the underlying value are
40 /// intended to have wrapping semantics.
41 #[stable(feature = "rust1", since = "1.0.0")]
42 #[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug)]
43 pub struct Wrapping<T>(#[stable(feature = "rust1", since = "1.0.0")] pub T);
48 /// Types that have a "zero" value.
50 /// This trait is intended for use in conjunction with `Add`, as an identity:
51 /// `x + T::zero() == x`.
52 #[unstable(feature = "zero_one",
53 reason = "unsure of placement, wants to use associated constants")]
55 /// The "zero" (usually, additive identity) for this type.
59 /// Types that have a "one" value.
61 /// This trait is intended for use in conjunction with `Mul`, as an identity:
62 /// `x * T::one() == x`.
63 #[unstable(feature = "zero_one",
64 reason = "unsure of placement, wants to use associated constants")]
66 /// The "one" (usually, multiplicative identity) for this type.
70 macro_rules! zero_one_impl {
74 fn zero() -> Self { 0 }
78 fn one() -> Self { 1 }
82 zero_one_impl! { u8 u16 u32 u64 usize i8 i16 i32 i64 isize }
84 macro_rules! zero_one_impl_float {
88 fn zero() -> Self { 0.0 }
92 fn one() -> Self { 1.0 }
96 zero_one_impl_float! { f32 f64 }
98 macro_rules! checked_op {
99 ($U:ty, $op:path, $x:expr, $y:expr) => {{
100 let (result, overflowed) = unsafe { $op($x as $U, $y as $U) };
101 if overflowed { None } else { Some(result as Self) }
105 /// Swapping a single byte is a no-op. This is marked as `unsafe` for
106 /// consistency with the other `bswap` intrinsics.
107 unsafe fn bswap8(x: u8) -> u8 { x }
109 // `Int` + `SignedInt` implemented for signed integers
110 macro_rules! int_impl {
111 ($ActualT:ty, $UnsignedT:ty, $BITS:expr,
112 $add_with_overflow:path,
113 $sub_with_overflow:path,
114 $mul_with_overflow:path) => {
115 /// Returns the smallest value that can be represented by this integer type.
116 #[stable(feature = "rust1", since = "1.0.0")]
118 pub fn min_value() -> Self {
119 (-1 as Self) << ($BITS - 1)
122 /// Returns the largest value that can be represented by this integer type.
123 #[stable(feature = "rust1", since = "1.0.0")]
125 pub fn max_value() -> Self {
126 let min = Self::min_value(); !min
129 /// Converts a string slice in a given base to an integer.
131 /// Leading and trailing whitespace represent an error.
136 /// assert_eq!(u32::from_str_radix("A", 16), Ok(10));
138 #[stable(feature = "rust1", since = "1.0.0")]
140 pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
141 from_str_radix(src, radix)
144 /// Returns the number of ones in the binary representation of `self`.
149 /// let n = 0b01001100u8;
151 /// assert_eq!(n.count_ones(), 3);
153 #[stable(feature = "rust1", since = "1.0.0")]
155 pub fn count_ones(self) -> u32 { (self as $UnsignedT).count_ones() }
157 /// Returns the number of zeros in the binary representation of `self`.
162 /// let n = 0b01001100u8;
164 /// assert_eq!(n.count_zeros(), 5);
166 #[stable(feature = "rust1", since = "1.0.0")]
168 pub fn count_zeros(self) -> u32 {
172 /// Returns the number of leading zeros in the binary representation
178 /// let n = 0b0101000u16;
180 /// assert_eq!(n.leading_zeros(), 10);
182 #[stable(feature = "rust1", since = "1.0.0")]
184 pub fn leading_zeros(self) -> u32 {
185 (self as $UnsignedT).leading_zeros()
188 /// Returns the number of trailing zeros in the binary representation
194 /// let n = 0b0101000u16;
196 /// assert_eq!(n.trailing_zeros(), 3);
198 #[stable(feature = "rust1", since = "1.0.0")]
200 pub fn trailing_zeros(self) -> u32 {
201 (self as $UnsignedT).trailing_zeros()
204 /// Shifts the bits to the left by a specified amount, `n`,
205 /// wrapping the truncated bits to the end of the resulting integer.
210 /// let n = 0x0123456789ABCDEFu64;
211 /// let m = 0x3456789ABCDEF012u64;
213 /// assert_eq!(n.rotate_left(12), m);
215 #[stable(feature = "rust1", since = "1.0.0")]
217 pub fn rotate_left(self, n: u32) -> Self {
218 (self as $UnsignedT).rotate_left(n) as Self
221 /// Shifts the bits to the right by a specified amount, `n`,
222 /// wrapping the truncated bits to the beginning of the resulting
228 /// let n = 0x0123456789ABCDEFu64;
229 /// let m = 0xDEF0123456789ABCu64;
231 /// assert_eq!(n.rotate_right(12), m);
233 #[stable(feature = "rust1", since = "1.0.0")]
235 pub fn rotate_right(self, n: u32) -> Self {
236 (self as $UnsignedT).rotate_right(n) as Self
239 /// Reverses the byte order of the integer.
244 /// let n = 0x0123456789ABCDEFu64;
245 /// let m = 0xEFCDAB8967452301u64;
247 /// assert_eq!(n.swap_bytes(), m);
249 #[stable(feature = "rust1", since = "1.0.0")]
251 pub fn swap_bytes(self) -> Self {
252 (self as $UnsignedT).swap_bytes() as Self
255 /// Converts an integer from big endian to the target's endianness.
257 /// On big endian this is a no-op. On little endian the bytes are
263 /// let n = 0x0123456789ABCDEFu64;
265 /// if cfg!(target_endian = "big") {
266 /// assert_eq!(u64::from_be(n), n)
268 /// assert_eq!(u64::from_be(n), n.swap_bytes())
271 #[stable(feature = "rust1", since = "1.0.0")]
273 pub fn from_be(x: Self) -> Self {
274 if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
277 /// Converts an integer from little endian to the target's endianness.
279 /// On little endian this is a no-op. On big endian the bytes are
285 /// let n = 0x0123456789ABCDEFu64;
287 /// if cfg!(target_endian = "little") {
288 /// assert_eq!(u64::from_le(n), n)
290 /// assert_eq!(u64::from_le(n), n.swap_bytes())
293 #[stable(feature = "rust1", since = "1.0.0")]
295 pub fn from_le(x: Self) -> Self {
296 if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
299 /// Converts `self` to big endian from the target's endianness.
301 /// On big endian this is a no-op. On little endian the bytes are
307 /// let n = 0x0123456789ABCDEFu64;
309 /// if cfg!(target_endian = "big") {
310 /// assert_eq!(n.to_be(), n)
312 /// assert_eq!(n.to_be(), n.swap_bytes())
315 #[stable(feature = "rust1", since = "1.0.0")]
317 pub fn to_be(self) -> Self { // or not to be?
318 if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
321 /// Converts `self` to little endian from the target's endianness.
323 /// On little endian this is a no-op. On big endian the bytes are
329 /// let n = 0x0123456789ABCDEFu64;
331 /// if cfg!(target_endian = "little") {
332 /// assert_eq!(n.to_le(), n)
334 /// assert_eq!(n.to_le(), n.swap_bytes())
337 #[stable(feature = "rust1", since = "1.0.0")]
339 pub fn to_le(self) -> Self {
340 if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
343 /// Checked integer addition. Computes `self + other`, returning `None`
344 /// if overflow occurred.
349 /// assert_eq!(5u16.checked_add(65530), Some(65535));
350 /// assert_eq!(6u16.checked_add(65530), None);
352 #[stable(feature = "rust1", since = "1.0.0")]
354 pub fn checked_add(self, other: Self) -> Option<Self> {
355 checked_op!($ActualT, $add_with_overflow, self, other)
358 /// Checked integer subtraction. Computes `self - other`, returning
359 /// `None` if underflow occurred.
364 /// assert_eq!((-127i8).checked_sub(1), Some(-128));
365 /// assert_eq!((-128i8).checked_sub(1), None);
367 #[stable(feature = "rust1", since = "1.0.0")]
369 pub fn checked_sub(self, other: Self) -> Option<Self> {
370 checked_op!($ActualT, $sub_with_overflow, self, other)
373 /// Checked integer multiplication. Computes `self * other`, returning
374 /// `None` if underflow or overflow occurred.
379 /// assert_eq!(5u8.checked_mul(51), Some(255));
380 /// assert_eq!(5u8.checked_mul(52), None);
382 #[stable(feature = "rust1", since = "1.0.0")]
384 pub fn checked_mul(self, other: Self) -> Option<Self> {
385 checked_op!($ActualT, $mul_with_overflow, self, other)
388 /// Checked integer division. Computes `self / other`, returning `None`
389 /// if `other == 0` or the operation results in underflow or overflow.
394 /// assert_eq!((-127i8).checked_div(-1), Some(127));
395 /// assert_eq!((-128i8).checked_div(-1), None);
396 /// assert_eq!((1i8).checked_div(0), None);
398 #[stable(feature = "rust1", since = "1.0.0")]
400 pub fn checked_div(self, v: Self) -> Option<Self> {
403 -1 if self == Self::min_value()
409 /// Saturating integer addition. Computes `self + other`, saturating at
410 /// the numeric bounds instead of overflowing.
411 #[stable(feature = "rust1", since = "1.0.0")]
413 pub fn saturating_add(self, other: Self) -> Self {
414 match self.checked_add(other) {
416 None if other >= Self::zero() => Self::max_value(),
417 None => Self::min_value(),
421 /// Saturating integer subtraction. Computes `self - other`, saturating
422 /// at the numeric bounds instead of overflowing.
423 #[stable(feature = "rust1", since = "1.0.0")]
425 pub fn saturating_sub(self, other: Self) -> Self {
426 match self.checked_sub(other) {
428 None if other >= Self::zero() => Self::min_value(),
429 None => Self::max_value(),
433 /// Wrapping (modular) addition. Computes `self + other`,
434 /// wrapping around at the boundary of the type.
435 #[stable(feature = "rust1", since = "1.0.0")]
437 pub fn wrapping_add(self, rhs: Self) -> Self {
439 intrinsics::overflowing_add(self, rhs)
443 /// Wrapping (modular) subtraction. Computes `self - other`,
444 /// wrapping around at the boundary of the type.
445 #[stable(feature = "rust1", since = "1.0.0")]
447 pub fn wrapping_sub(self, rhs: Self) -> Self {
449 intrinsics::overflowing_sub(self, rhs)
453 /// Wrapping (modular) multiplication. Computes `self *
454 /// other`, wrapping around at the boundary of the type.
455 #[stable(feature = "rust1", since = "1.0.0")]
457 pub fn wrapping_mul(self, rhs: Self) -> Self {
459 intrinsics::overflowing_mul(self, rhs)
463 /// Wrapping (modular) division. Computes `self / other`,
464 /// wrapping around at the boundary of the type.
466 /// The only case where such wrapping can occur is when one
467 /// divides `MIN / -1` on a signed type (where `MIN` is the
468 /// negative minimal value for the type); this is equivalent
469 /// to `-MIN`, a positive value that is too large to represent
470 /// in the type. In such a case, this function returns `MIN`
472 #[stable(feature = "num_wrapping", since = "1.2.0")]
474 pub fn wrapping_div(self, rhs: Self) -> Self {
475 self.overflowing_div(rhs).0
478 /// Wrapping (modular) remainder. Computes `self % other`,
479 /// wrapping around at the boundary of the type.
481 /// Such wrap-around never actually occurs mathematically;
482 /// implementation artifacts make `x % y` illegal for `MIN /
483 /// -1` on a signed type illegal (where `MIN` is the negative
484 /// minimal value). In such a case, this function returns `0`.
485 #[stable(feature = "num_wrapping", since = "1.2.0")]
487 pub fn wrapping_rem(self, rhs: Self) -> Self {
488 self.overflowing_rem(rhs).0
491 /// Wrapping (modular) negation. Computes `-self`,
492 /// wrapping around at the boundary of the type.
494 /// The only case where such wrapping can occur is when one
495 /// negates `MIN` on a signed type (where `MIN` is the
496 /// negative minimal value for the type); this is a positive
497 /// value that is too large to represent in the type. In such
498 /// a case, this function returns `MIN` itself.
499 #[stable(feature = "num_wrapping", since = "1.2.0")]
501 pub fn wrapping_neg(self) -> Self {
502 self.overflowing_neg().0
505 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
506 /// where `mask` removes any high-order bits of `rhs` that
507 /// would cause the shift to exceed the bitwidth of the type.
508 #[stable(feature = "num_wrapping", since = "1.2.0")]
510 pub fn wrapping_shl(self, rhs: u32) -> Self {
511 self.overflowing_shl(rhs).0
514 /// Panic-free bitwise shift-left; yields `self >> mask(rhs)`,
515 /// where `mask` removes any high-order bits of `rhs` that
516 /// would cause the shift to exceed the bitwidth of the type.
517 #[stable(feature = "num_wrapping", since = "1.2.0")]
519 pub fn wrapping_shr(self, rhs: u32) -> Self {
520 self.overflowing_shr(rhs).0
523 /// Raises self to the power of `exp`, using exponentiation by squaring.
528 /// let x: i32 = 2; // or any other integer type
530 /// assert_eq!(x.pow(4), 16);
532 #[stable(feature = "rust1", since = "1.0.0")]
534 pub fn pow(self, mut exp: u32) -> Self {
536 let mut acc = Self::one();
538 let mut prev_base = self;
539 let mut base_oflo = false;
543 // ensure overflow occurs in the same manner it
544 // would have otherwise (i.e. signal any exception
545 // it would have otherwise).
546 acc = acc * (prev_base * prev_base);
552 let (new_base, new_base_oflo) = base.overflowing_mul(base);
554 base_oflo = new_base_oflo;
560 /// Computes the absolute value of `self`.
562 /// # Overflow behavior
564 /// The absolute value of `i32::min_value()` cannot be represented as an
565 /// `i32`, and attempting to calculate it will cause an overflow. This
566 /// means that code in debug mode will trigger a panic on this case and
567 /// optimized code will return `i32::min_value()` without a panic.
568 #[stable(feature = "rust1", since = "1.0.0")]
570 pub fn abs(self) -> Self {
571 if self.is_negative() {
572 // Note that the #[inline] above means that the overflow
573 // semantics of this negation depend on the crate we're being
581 /// Returns a number representing sign of `self`.
583 /// - `0` if the number is zero
584 /// - `1` if the number is positive
585 /// - `-1` if the number is negative
586 #[stable(feature = "rust1", since = "1.0.0")]
588 pub fn signum(self) -> Self {
596 /// Returns `true` if `self` is positive and `false` if the number
597 /// is zero or negative.
598 #[stable(feature = "rust1", since = "1.0.0")]
600 pub fn is_positive(self) -> bool { self > 0 }
602 /// Returns `true` if `self` is negative and `false` if the number
603 /// is zero or positive.
604 #[stable(feature = "rust1", since = "1.0.0")]
606 pub fn is_negative(self) -> bool { self < 0 }
612 int_impl! { i8, u8, 8,
613 intrinsics::i8_add_with_overflow,
614 intrinsics::i8_sub_with_overflow,
615 intrinsics::i8_mul_with_overflow }
620 int_impl! { i16, u16, 16,
621 intrinsics::i16_add_with_overflow,
622 intrinsics::i16_sub_with_overflow,
623 intrinsics::i16_mul_with_overflow }
628 int_impl! { i32, u32, 32,
629 intrinsics::i32_add_with_overflow,
630 intrinsics::i32_sub_with_overflow,
631 intrinsics::i32_mul_with_overflow }
636 int_impl! { i64, u64, 64,
637 intrinsics::i64_add_with_overflow,
638 intrinsics::i64_sub_with_overflow,
639 intrinsics::i64_mul_with_overflow }
642 #[cfg(target_pointer_width = "32")]
645 int_impl! { i32, u32, 32,
646 intrinsics::i32_add_with_overflow,
647 intrinsics::i32_sub_with_overflow,
648 intrinsics::i32_mul_with_overflow }
651 #[cfg(target_pointer_width = "64")]
654 int_impl! { i64, u64, 64,
655 intrinsics::i64_add_with_overflow,
656 intrinsics::i64_sub_with_overflow,
657 intrinsics::i64_mul_with_overflow }
660 // `Int` + `UnsignedInt` implemented for signed integers
661 macro_rules! uint_impl {
662 ($ActualT:ty, $BITS:expr,
667 $add_with_overflow:path,
668 $sub_with_overflow:path,
669 $mul_with_overflow:path) => {
670 /// Returns the smallest value that can be represented by this integer type.
671 #[stable(feature = "rust1", since = "1.0.0")]
673 pub fn min_value() -> Self { 0 }
675 /// Returns the largest value that can be represented by this integer type.
676 #[stable(feature = "rust1", since = "1.0.0")]
678 pub fn max_value() -> Self { !0 }
680 /// Converts a string slice in a given base to an integer.
682 /// Leading and trailing whitespace represent an error.
686 /// * src - A string slice
687 /// * radix - The base to use. Must lie in the range [2 .. 36]
691 /// `Err(ParseIntError)` if the string did not represent a valid number.
692 /// Otherwise, `Ok(n)` where `n` is the integer represented by `src`.
693 #[stable(feature = "rust1", since = "1.0.0")]
695 pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
696 from_str_radix(src, radix)
699 /// Returns the number of ones in the binary representation of `self`.
704 /// let n = 0b01001100u8;
706 /// assert_eq!(n.count_ones(), 3);
708 #[stable(feature = "rust1", since = "1.0.0")]
710 pub fn count_ones(self) -> u32 {
711 unsafe { $ctpop(self as $ActualT) as u32 }
714 /// Returns the number of zeros in the binary representation of `self`.
719 /// let n = 0b01001100u8;
721 /// assert_eq!(n.count_zeros(), 5);
723 #[stable(feature = "rust1", since = "1.0.0")]
725 pub fn count_zeros(self) -> u32 {
729 /// Returns the number of leading zeros in the binary representation
735 /// let n = 0b0101000u16;
737 /// assert_eq!(n.leading_zeros(), 10);
739 #[stable(feature = "rust1", since = "1.0.0")]
741 pub fn leading_zeros(self) -> u32 {
742 unsafe { $ctlz(self as $ActualT) as u32 }
745 /// Returns the number of trailing zeros in the binary representation
751 /// let n = 0b0101000u16;
753 /// assert_eq!(n.trailing_zeros(), 3);
755 #[stable(feature = "rust1", since = "1.0.0")]
757 pub fn trailing_zeros(self) -> u32 {
758 // As of LLVM 3.6 the codegen for the zero-safe cttz8 intrinsic
759 // emits two conditional moves on x86_64. By promoting the value to
760 // u16 and setting bit 8, we get better code without any conditional
762 // FIXME: There's a LLVM patch (http://reviews.llvm.org/D9284)
763 // pending, remove this workaround once LLVM generates better code
767 intrinsics::cttz16(self as u16 | 0x100) as u32
769 $cttz(self as $ActualT) as u32
774 /// Shifts the bits to the left by a specified amount, `n`,
775 /// wrapping the truncated bits to the end of the resulting integer.
780 /// let n = 0x0123456789ABCDEFu64;
781 /// let m = 0x3456789ABCDEF012u64;
783 /// assert_eq!(n.rotate_left(12), m);
785 #[stable(feature = "rust1", since = "1.0.0")]
787 pub fn rotate_left(self, n: u32) -> Self {
788 // Protect against undefined behaviour for over-long bit shifts
790 (self << n) | (self >> (($BITS - n) % $BITS))
793 /// Shifts the bits to the right by a specified amount, `n`,
794 /// wrapping the truncated bits to the beginning of the resulting
800 /// let n = 0x0123456789ABCDEFu64;
801 /// let m = 0xDEF0123456789ABCu64;
803 /// assert_eq!(n.rotate_right(12), m);
805 #[stable(feature = "rust1", since = "1.0.0")]
807 pub fn rotate_right(self, n: u32) -> Self {
808 // Protect against undefined behaviour for over-long bit shifts
810 (self >> n) | (self << (($BITS - n) % $BITS))
813 /// Reverses the byte order of the integer.
818 /// let n = 0x0123456789ABCDEFu64;
819 /// let m = 0xEFCDAB8967452301u64;
821 /// assert_eq!(n.swap_bytes(), m);
823 #[stable(feature = "rust1", since = "1.0.0")]
825 pub fn swap_bytes(self) -> Self {
826 unsafe { $bswap(self as $ActualT) as Self }
829 /// Converts an integer from big endian to the target's endianness.
831 /// On big endian this is a no-op. On little endian the bytes are
837 /// let n = 0x0123456789ABCDEFu64;
839 /// if cfg!(target_endian = "big") {
840 /// assert_eq!(u64::from_be(n), n)
842 /// assert_eq!(u64::from_be(n), n.swap_bytes())
845 #[stable(feature = "rust1", since = "1.0.0")]
847 pub fn from_be(x: Self) -> Self {
848 if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
851 /// Converts an integer from little endian to the target's endianness.
853 /// On little endian this is a no-op. On big endian the bytes are
859 /// let n = 0x0123456789ABCDEFu64;
861 /// if cfg!(target_endian = "little") {
862 /// assert_eq!(u64::from_le(n), n)
864 /// assert_eq!(u64::from_le(n), n.swap_bytes())
867 #[stable(feature = "rust1", since = "1.0.0")]
869 pub fn from_le(x: Self) -> Self {
870 if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
873 /// Converts `self` to big endian from the target's endianness.
875 /// On big endian this is a no-op. On little endian the bytes are
881 /// let n = 0x0123456789ABCDEFu64;
883 /// if cfg!(target_endian = "big") {
884 /// assert_eq!(n.to_be(), n)
886 /// assert_eq!(n.to_be(), n.swap_bytes())
889 #[stable(feature = "rust1", since = "1.0.0")]
891 pub fn to_be(self) -> Self { // or not to be?
892 if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
895 /// Converts `self` to little endian from the target's endianness.
897 /// On little endian this is a no-op. On big endian the bytes are
903 /// let n = 0x0123456789ABCDEFu64;
905 /// if cfg!(target_endian = "little") {
906 /// assert_eq!(n.to_le(), n)
908 /// assert_eq!(n.to_le(), n.swap_bytes())
911 #[stable(feature = "rust1", since = "1.0.0")]
913 pub fn to_le(self) -> Self {
914 if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
917 /// Checked integer addition. Computes `self + other`, returning `None`
918 /// if overflow occurred.
923 /// assert_eq!(5u16.checked_add(65530), Some(65535));
924 /// assert_eq!(6u16.checked_add(65530), None);
926 #[stable(feature = "rust1", since = "1.0.0")]
928 pub fn checked_add(self, other: Self) -> Option<Self> {
929 checked_op!($ActualT, $add_with_overflow, self, other)
932 /// Checked integer subtraction. Computes `self - other`, returning
933 /// `None` if underflow occurred.
938 /// assert_eq!((-127i8).checked_sub(1), Some(-128));
939 /// assert_eq!((-128i8).checked_sub(1), None);
941 #[stable(feature = "rust1", since = "1.0.0")]
943 pub fn checked_sub(self, other: Self) -> Option<Self> {
944 checked_op!($ActualT, $sub_with_overflow, self, other)
947 /// Checked integer multiplication. Computes `self * other`, returning
948 /// `None` if underflow or overflow occurred.
953 /// assert_eq!(5u8.checked_mul(51), Some(255));
954 /// assert_eq!(5u8.checked_mul(52), None);
956 #[stable(feature = "rust1", since = "1.0.0")]
958 pub fn checked_mul(self, other: Self) -> Option<Self> {
959 checked_op!($ActualT, $mul_with_overflow, self, other)
962 /// Checked integer division. Computes `self / other`, returning `None`
963 /// if `other == 0` or the operation results in underflow or overflow.
968 /// assert_eq!((-127i8).checked_div(-1), Some(127));
969 /// assert_eq!((-128i8).checked_div(-1), None);
970 /// assert_eq!((1i8).checked_div(0), None);
972 #[stable(feature = "rust1", since = "1.0.0")]
974 pub fn checked_div(self, v: Self) -> Option<Self> {
981 /// Saturating integer addition. Computes `self + other`, saturating at
982 /// the numeric bounds instead of overflowing.
983 #[stable(feature = "rust1", since = "1.0.0")]
985 pub fn saturating_add(self, other: Self) -> Self {
986 match self.checked_add(other) {
988 None if other >= Self::zero() => Self::max_value(),
989 None => Self::min_value(),
993 /// Saturating integer subtraction. Computes `self - other`, saturating
994 /// at the numeric bounds instead of overflowing.
995 #[stable(feature = "rust1", since = "1.0.0")]
997 pub fn saturating_sub(self, other: Self) -> Self {
998 match self.checked_sub(other) {
1000 None if other >= Self::zero() => Self::min_value(),
1001 None => Self::max_value(),
1005 /// Wrapping (modular) addition. Computes `self + other`,
1006 /// wrapping around at the boundary of the type.
1007 #[stable(feature = "rust1", since = "1.0.0")]
1009 pub fn wrapping_add(self, rhs: Self) -> Self {
1011 intrinsics::overflowing_add(self, rhs)
1015 /// Wrapping (modular) subtraction. Computes `self - other`,
1016 /// wrapping around at the boundary of the type.
1017 #[stable(feature = "rust1", since = "1.0.0")]
1019 pub fn wrapping_sub(self, rhs: Self) -> Self {
1021 intrinsics::overflowing_sub(self, rhs)
1025 /// Wrapping (modular) multiplication. Computes `self *
1026 /// other`, wrapping around at the boundary of the type.
1027 #[stable(feature = "rust1", since = "1.0.0")]
1029 pub fn wrapping_mul(self, rhs: Self) -> Self {
1031 intrinsics::overflowing_mul(self, rhs)
1035 /// Wrapping (modular) division. Computes `self / other`,
1036 /// wrapping around at the boundary of the type.
1038 /// The only case where such wrapping can occur is when one
1039 /// divides `MIN / -1` on a signed type (where `MIN` is the
1040 /// negative minimal value for the type); this is equivalent
1041 /// to `-MIN`, a positive value that is too large to represent
1042 /// in the type. In such a case, this function returns `MIN`
1044 #[stable(feature = "num_wrapping", since = "1.2.0")]
1046 pub fn wrapping_div(self, rhs: Self) -> Self {
1047 self.overflowing_div(rhs).0
1050 /// Wrapping (modular) remainder. Computes `self % other`,
1051 /// wrapping around at the boundary of the type.
1053 /// Such wrap-around never actually occurs mathematically;
1054 /// implementation artifacts make `x % y` illegal for `MIN /
1055 /// -1` on a signed type illegal (where `MIN` is the negative
1056 /// minimal value). In such a case, this function returns `0`.
1057 #[stable(feature = "num_wrapping", since = "1.2.0")]
1059 pub fn wrapping_rem(self, rhs: Self) -> Self {
1060 self.overflowing_rem(rhs).0
1063 /// Wrapping (modular) negation. Computes `-self`,
1064 /// wrapping around at the boundary of the type.
1066 /// The only case where such wrapping can occur is when one
1067 /// negates `MIN` on a signed type (where `MIN` is the
1068 /// negative minimal value for the type); this is a positive
1069 /// value that is too large to represent in the type. In such
1070 /// a case, this function returns `MIN` itself.
1071 #[stable(feature = "num_wrapping", since = "1.2.0")]
1073 pub fn wrapping_neg(self) -> Self {
1074 self.overflowing_neg().0
1077 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
1078 /// where `mask` removes any high-order bits of `rhs` that
1079 /// would cause the shift to exceed the bitwidth of the type.
1080 #[stable(feature = "num_wrapping", since = "1.2.0")]
1082 pub fn wrapping_shl(self, rhs: u32) -> Self {
1083 self.overflowing_shl(rhs).0
1086 /// Panic-free bitwise shift-left; yields `self >> mask(rhs)`,
1087 /// where `mask` removes any high-order bits of `rhs` that
1088 /// would cause the shift to exceed the bitwidth of the type.
1089 #[stable(feature = "num_wrapping", since = "1.2.0")]
1091 pub fn wrapping_shr(self, rhs: u32) -> Self {
1092 self.overflowing_shr(rhs).0
1095 /// Raises self to the power of `exp`, using exponentiation by squaring.
1100 /// assert_eq!(2i32.pow(4), 16);
1102 #[stable(feature = "rust1", since = "1.0.0")]
1104 pub fn pow(self, mut exp: u32) -> Self {
1105 let mut base = self;
1106 let mut acc = Self::one();
1108 let mut prev_base = self;
1109 let mut base_oflo = false;
1113 // ensure overflow occurs in the same manner it
1114 // would have otherwise (i.e. signal any exception
1115 // it would have otherwise).
1116 acc = acc * (prev_base * prev_base);
1122 let (new_base, new_base_oflo) = base.overflowing_mul(base);
1124 base_oflo = new_base_oflo;
1130 /// Returns `true` if and only if `self == 2^k` for some `k`.
1131 #[stable(feature = "rust1", since = "1.0.0")]
1133 pub fn is_power_of_two(self) -> bool {
1134 (self.wrapping_sub(Self::one())) & self == Self::zero() &&
1135 !(self == Self::zero())
1138 /// Returns the smallest power of two greater than or equal to `self`.
1139 /// Unspecified behavior on overflow.
1140 #[stable(feature = "rust1", since = "1.0.0")]
1142 pub fn next_power_of_two(self) -> Self {
1143 let bits = size_of::<Self>() * 8;
1144 let one: Self = Self::one();
1145 one << ((bits - self.wrapping_sub(one).leading_zeros() as usize) % bits)
1148 /// Returns the smallest power of two greater than or equal to `n`. If
1149 /// the next power of two is greater than the type's maximum value,
1150 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
1151 #[stable(feature = "rust1", since = "1.0.0")]
1152 pub fn checked_next_power_of_two(self) -> Option<Self> {
1153 let npot = self.next_power_of_two();
1170 intrinsics::u8_add_with_overflow,
1171 intrinsics::u8_sub_with_overflow,
1172 intrinsics::u8_mul_with_overflow }
1177 uint_impl! { u16, 16,
1178 intrinsics::ctpop16,
1181 intrinsics::bswap16,
1182 intrinsics::u16_add_with_overflow,
1183 intrinsics::u16_sub_with_overflow,
1184 intrinsics::u16_mul_with_overflow }
1189 uint_impl! { u32, 32,
1190 intrinsics::ctpop32,
1193 intrinsics::bswap32,
1194 intrinsics::u32_add_with_overflow,
1195 intrinsics::u32_sub_with_overflow,
1196 intrinsics::u32_mul_with_overflow }
1202 uint_impl! { u64, 64,
1203 intrinsics::ctpop64,
1206 intrinsics::bswap64,
1207 intrinsics::u64_add_with_overflow,
1208 intrinsics::u64_sub_with_overflow,
1209 intrinsics::u64_mul_with_overflow }
1212 #[cfg(target_pointer_width = "32")]
1215 uint_impl! { u32, 32,
1216 intrinsics::ctpop32,
1219 intrinsics::bswap32,
1220 intrinsics::u32_add_with_overflow,
1221 intrinsics::u32_sub_with_overflow,
1222 intrinsics::u32_mul_with_overflow }
1225 #[cfg(target_pointer_width = "64")]
1228 uint_impl! { u64, 64,
1229 intrinsics::ctpop64,
1232 intrinsics::bswap64,
1233 intrinsics::u64_add_with_overflow,
1234 intrinsics::u64_sub_with_overflow,
1235 intrinsics::u64_mul_with_overflow }
1238 /// Used for representing the classification of floating point numbers
1239 #[derive(Copy, Clone, PartialEq, Debug)]
1240 #[stable(feature = "rust1", since = "1.0.0")]
1241 pub enum FpCategory {
1242 /// "Not a Number", often obtained by dividing by zero
1243 #[stable(feature = "rust1", since = "1.0.0")]
1246 /// Positive or negative infinity
1247 #[stable(feature = "rust1", since = "1.0.0")]
1250 /// Positive or negative zero
1251 #[stable(feature = "rust1", since = "1.0.0")]
1254 /// De-normalized floating point representation (less precise than `Normal`)
1255 #[stable(feature = "rust1", since = "1.0.0")]
1258 /// A regular floating point number
1259 #[stable(feature = "rust1", since = "1.0.0")]
1263 /// A built-in floating point number.
1265 #[unstable(feature = "core_float",
1266 reason = "stable interface is via `impl f{32,64}` in later crates")]
1268 /// Returns the NaN value.
1270 /// Returns the infinite value.
1271 fn infinity() -> Self;
1272 /// Returns the negative infinite value.
1273 fn neg_infinity() -> Self;
1275 fn neg_zero() -> Self;
1280 /// Parses the string `s` with the radix `r` as a float.
1281 fn from_str_radix(s: &str, r: u32) -> Result<Self, ParseFloatError>;
1283 /// Returns true if this value is NaN and false otherwise.
1284 fn is_nan(self) -> bool;
1285 /// Returns true if this value is positive infinity or negative infinity and
1286 /// false otherwise.
1287 fn is_infinite(self) -> bool;
1288 /// Returns true if this number is neither infinite nor NaN.
1289 fn is_finite(self) -> bool;
1290 /// Returns true if this number is neither zero, infinite, denormal, or NaN.
1291 fn is_normal(self) -> bool;
1292 /// Returns the category that this number falls into.
1293 fn classify(self) -> FpCategory;
1295 /// Returns the mantissa, exponent and sign as integers, respectively.
1296 fn integer_decode(self) -> (u64, i16, i8);
1298 /// Return the largest integer less than or equal to a number.
1299 fn floor(self) -> Self;
1300 /// Return the smallest integer greater than or equal to a number.
1301 fn ceil(self) -> Self;
1302 /// Return the nearest integer to a number. Round half-way cases away from
1304 fn round(self) -> Self;
1305 /// Return the integer part of a number.
1306 fn trunc(self) -> Self;
1307 /// Return the fractional part of a number.
1308 fn fract(self) -> Self;
1310 /// Computes the absolute value of `self`. Returns `Float::nan()` if the
1311 /// number is `Float::nan()`.
1312 fn abs(self) -> Self;
1313 /// Returns a number that represents the sign of `self`.
1315 /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
1316 /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
1317 /// - `Float::nan()` if the number is `Float::nan()`
1318 fn signum(self) -> Self;
1319 /// Returns `true` if `self` is positive, including `+0.0` and
1320 /// `Float::infinity()`.
1321 fn is_positive(self) -> bool;
1322 /// Returns `true` if `self` is negative, including `-0.0` and
1323 /// `Float::neg_infinity()`.
1324 fn is_negative(self) -> bool;
1326 /// Fused multiply-add. Computes `(self * a) + b` with only one rounding
1327 /// error. This produces a more accurate result with better performance than
1328 /// a separate multiplication operation followed by an add.
1329 fn mul_add(self, a: Self, b: Self) -> Self;
1330 /// Take the reciprocal (inverse) of a number, `1/x`.
1331 fn recip(self) -> Self;
1333 /// Raise a number to an integer power.
1335 /// Using this function is generally faster than using `powf`
1336 fn powi(self, n: i32) -> Self;
1337 /// Raise a number to a floating point power.
1338 fn powf(self, n: Self) -> Self;
1340 /// Take the square root of a number.
1342 /// Returns NaN if `self` is a negative number.
1343 fn sqrt(self) -> Self;
1344 /// Take the reciprocal (inverse) square root of a number, `1/sqrt(x)`.
1345 fn rsqrt(self) -> Self;
1347 /// Returns `e^(self)`, (the exponential function).
1348 fn exp(self) -> Self;
1349 /// Returns 2 raised to the power of the number, `2^(self)`.
1350 fn exp2(self) -> Self;
1351 /// Returns the natural logarithm of the number.
1352 fn ln(self) -> Self;
1353 /// Returns the logarithm of the number with respect to an arbitrary base.
1354 fn log(self, base: Self) -> Self;
1355 /// Returns the base 2 logarithm of the number.
1356 fn log2(self) -> Self;
1357 /// Returns the base 10 logarithm of the number.
1358 fn log10(self) -> Self;
1360 /// Convert radians to degrees.
1361 fn to_degrees(self) -> Self;
1362 /// Convert degrees to radians.
1363 fn to_radians(self) -> Self;
1366 macro_rules! from_str_float_impl {
1368 #[stable(feature = "rust1", since = "1.0.0")]
1369 impl FromStr for $t {
1370 type Err = ParseFloatError;
1372 /// Converts a string in base 10 to a float.
1373 /// Accepts an optional decimal exponent.
1375 /// This function accepts strings such as
1379 /// * '2.5E10', or equivalently, '2.5e10'
1381 /// * '.' (understood as 0)
1383 /// * '.5', or, equivalently, '0.5'
1384 /// * 'inf', '-inf', 'NaN'
1386 /// Leading and trailing whitespace represent an error.
1390 /// * src - A string
1394 /// `Err(ParseFloatError)` if the string did not represent a valid
1395 /// number. Otherwise, `Ok(n)` where `n` is the floating-point
1396 /// number represented by `src`.
1398 #[allow(deprecated)]
1399 fn from_str(src: &str) -> Result<Self, ParseFloatError> {
1400 Self::from_str_radix(src, 10)
1405 from_str_float_impl!(f32);
1406 from_str_float_impl!(f64);
1408 macro_rules! from_str_radix_int_impl {
1410 #[stable(feature = "rust1", since = "1.0.0")]
1411 #[allow(deprecated)]
1412 impl FromStr for $t {
1413 type Err = ParseIntError;
1414 fn from_str(src: &str) -> Result<Self, ParseIntError> {
1415 from_str_radix(src, 10)
1420 from_str_radix_int_impl! { isize i8 i16 i32 i64 usize u8 u16 u32 u64 }
1423 trait FromStrRadixHelper: PartialOrd + Copy {
1424 fn min_value() -> Self;
1425 fn from_u32(u: u32) -> Self;
1426 fn checked_mul(&self, other: u32) -> Option<Self>;
1427 fn checked_sub(&self, other: u32) -> Option<Self>;
1428 fn checked_add(&self, other: u32) -> Option<Self>;
1432 ($($t:ty)*) => ($(impl FromStrRadixHelper for $t {
1433 fn min_value() -> Self { Self::min_value() }
1434 fn from_u32(u: u32) -> Self { u as Self }
1435 fn checked_mul(&self, other: u32) -> Option<Self> {
1436 Self::checked_mul(*self, other as Self)
1438 fn checked_sub(&self, other: u32) -> Option<Self> {
1439 Self::checked_sub(*self, other as Self)
1441 fn checked_add(&self, other: u32) -> Option<Self> {
1442 Self::checked_add(*self, other as Self)
1446 doit! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
1448 fn from_str_radix<T: FromStrRadixHelper>(src: &str, radix: u32)
1449 -> Result<T, ParseIntError> {
1450 use self::IntErrorKind::*;
1451 use self::ParseIntError as PIE;
1453 assert!(radix >= 2 && radix <= 36,
1454 "from_str_radix_int: must lie in the range `[2, 36]` - found {}",
1458 return Err(PIE { kind: Empty });
1461 let is_signed_ty = T::from_u32(0) > T::min_value();
1463 // all valid digits are ascii, so we will just iterate over the utf8 bytes
1464 // and cast them to chars. .to_digit() will safely return None for anything
1465 // other than a valid ascii digit for a the given radix, including the first-byte
1466 // of multi-byte sequences
1467 let src = src.as_bytes();
1469 match (src[0], &src[1..]) {
1470 (b'-', digits) if digits.is_empty() => Err(PIE { kind: Empty }),
1471 (b'-', digits) if is_signed_ty => {
1472 // The number is negative
1473 let mut result = T::from_u32(0);
1475 let x = match (c as char).to_digit(radix) {
1477 None => return Err(PIE { kind: InvalidDigit }),
1479 result = match result.checked_mul(radix) {
1480 Some(result) => result,
1481 None => return Err(PIE { kind: Underflow }),
1483 result = match result.checked_sub(x) {
1484 Some(result) => result,
1485 None => return Err(PIE { kind: Underflow }),
1491 // The number is signed
1492 let mut result = match (c as char).to_digit(radix) {
1493 Some(x) => T::from_u32(x),
1494 None => return Err(PIE { kind: InvalidDigit }),
1497 let x = match (c as char).to_digit(radix) {
1499 None => return Err(PIE { kind: InvalidDigit }),
1501 result = match result.checked_mul(radix) {
1502 Some(result) => result,
1503 None => return Err(PIE { kind: Overflow }),
1505 result = match result.checked_add(x) {
1506 Some(result) => result,
1507 None => return Err(PIE { kind: Overflow }),
1515 /// An error which can be returned when parsing an integer.
1516 #[derive(Debug, Clone, PartialEq)]
1517 #[stable(feature = "rust1", since = "1.0.0")]
1518 pub struct ParseIntError { kind: IntErrorKind }
1520 #[derive(Debug, Clone, PartialEq)]
1528 impl ParseIntError {
1529 #[unstable(feature = "int_error_internals",
1530 reason = "available through Error trait and this method should \
1531 not be exposed publicly")]
1533 pub fn __description(&self) -> &str {
1535 IntErrorKind::Empty => "cannot parse integer from empty string",
1536 IntErrorKind::InvalidDigit => "invalid digit found in string",
1537 IntErrorKind::Overflow => "number too large to fit in target type",
1538 IntErrorKind::Underflow => "number too small to fit in target type",
1543 #[stable(feature = "rust1", since = "1.0.0")]
1544 impl fmt::Display for ParseIntError {
1545 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1546 self.__description().fmt(f)
1550 /// An error which can be returned when parsing a float.
1551 #[derive(Debug, Clone, PartialEq)]
1552 #[stable(feature = "rust1", since = "1.0.0")]
1553 pub struct ParseFloatError {
1555 #[unstable(feature = "float_error_internals",
1556 reason = "should not be exposed publicly")]
1557 pub __kind: FloatErrorKind
1560 #[derive(Debug, Clone, PartialEq)]
1561 #[unstable(feature = "float_error_internals",
1562 reason = "should not be exposed publicly")]
1564 pub enum FloatErrorKind {
1569 impl ParseFloatError {
1571 pub fn __description(&self) -> &str {
1573 FloatErrorKind::Empty => "cannot parse float from empty string",
1574 FloatErrorKind::Invalid => "invalid float literal",
1579 #[stable(feature = "rust1", since = "1.0.0")]
1580 impl fmt::Display for ParseFloatError {
1581 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1582 self.__description().fmt(f)