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};
22 use marker::{Copy, Sized};
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);
49 /// Types that have a "zero" value.
51 /// This trait is intended for use in conjunction with `Add`, as an identity:
52 /// `x + T::zero() == x`.
53 #[unstable(feature = "zero_one",
54 reason = "unsure of placement, wants to use associated constants",
57 /// The "zero" (usually, additive identity) for this type.
61 /// Types that have a "one" value.
63 /// This trait is intended for use in conjunction with `Mul`, as an identity:
64 /// `x * T::one() == x`.
65 #[unstable(feature = "zero_one",
66 reason = "unsure of placement, wants to use associated constants",
69 /// The "one" (usually, multiplicative identity) for this type.
73 macro_rules! zero_one_impl {
77 fn zero() -> Self { 0 }
81 fn one() -> Self { 1 }
85 zero_one_impl! { u8 u16 u32 u64 usize i8 i16 i32 i64 isize }
87 macro_rules! zero_one_impl_float {
91 fn zero() -> Self { 0.0 }
95 fn one() -> Self { 1.0 }
99 zero_one_impl_float! { f32 f64 }
101 macro_rules! checked_op {
102 ($U:ty, $op:path, $x:expr, $y:expr) => {{
103 let (result, overflowed) = unsafe { $op($x as $U, $y as $U) };
104 if overflowed { None } else { Some(result as Self) }
108 /// Swapping a single byte is a no-op. This is marked as `unsafe` for
109 /// consistency with the other `bswap` intrinsics.
110 unsafe fn bswap8(x: u8) -> u8 { x }
112 // `Int` + `SignedInt` implemented for signed integers
113 macro_rules! int_impl {
114 ($ActualT:ty, $UnsignedT:ty, $BITS:expr,
115 $add_with_overflow:path,
116 $sub_with_overflow:path,
117 $mul_with_overflow:path) => {
118 /// Returns the smallest value that can be represented by this integer type.
119 #[stable(feature = "rust1", since = "1.0.0")]
121 pub fn min_value() -> Self {
122 (-1 as Self) << ($BITS - 1)
125 /// Returns the largest value that can be represented by this integer type.
126 #[stable(feature = "rust1", since = "1.0.0")]
128 pub fn max_value() -> Self {
129 let min = Self::min_value(); !min
132 /// Converts a string slice in a given base to an integer.
134 /// Leading and trailing whitespace represent an error.
139 /// assert_eq!(u32::from_str_radix("A", 16), Ok(10));
141 #[stable(feature = "rust1", since = "1.0.0")]
142 pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
143 from_str_radix(src, radix)
146 /// Returns the number of ones in the binary representation of `self`.
151 /// let n = 0b01001100u8;
153 /// assert_eq!(n.count_ones(), 3);
155 #[stable(feature = "rust1", since = "1.0.0")]
157 pub fn count_ones(self) -> u32 { (self as $UnsignedT).count_ones() }
159 /// Returns the number of zeros in the binary representation of `self`.
164 /// let n = 0b01001100u8;
166 /// assert_eq!(n.count_zeros(), 5);
168 #[stable(feature = "rust1", since = "1.0.0")]
170 pub fn count_zeros(self) -> u32 {
174 /// Returns the number of leading zeros in the binary representation
180 /// let n = 0b0101000u16;
182 /// assert_eq!(n.leading_zeros(), 10);
184 #[stable(feature = "rust1", since = "1.0.0")]
186 pub fn leading_zeros(self) -> u32 {
187 (self as $UnsignedT).leading_zeros()
190 /// Returns the number of trailing zeros in the binary representation
196 /// let n = 0b0101000u16;
198 /// assert_eq!(n.trailing_zeros(), 3);
200 #[stable(feature = "rust1", since = "1.0.0")]
202 pub fn trailing_zeros(self) -> u32 {
203 (self as $UnsignedT).trailing_zeros()
206 /// Shifts the bits to the left by a specified amount, `n`,
207 /// wrapping the truncated bits to the end of the resulting integer.
212 /// let n = 0x0123456789ABCDEFu64;
213 /// let m = 0x3456789ABCDEF012u64;
215 /// assert_eq!(n.rotate_left(12), m);
217 #[stable(feature = "rust1", since = "1.0.0")]
219 pub fn rotate_left(self, n: u32) -> Self {
220 (self as $UnsignedT).rotate_left(n) as Self
223 /// Shifts the bits to the right by a specified amount, `n`,
224 /// wrapping the truncated bits to the beginning of the resulting
230 /// let n = 0x0123456789ABCDEFu64;
231 /// let m = 0xDEF0123456789ABCu64;
233 /// assert_eq!(n.rotate_right(12), m);
235 #[stable(feature = "rust1", since = "1.0.0")]
237 pub fn rotate_right(self, n: u32) -> Self {
238 (self as $UnsignedT).rotate_right(n) as Self
241 /// Reverses the byte order of the integer.
246 /// let n = 0x0123456789ABCDEFu64;
247 /// let m = 0xEFCDAB8967452301u64;
249 /// assert_eq!(n.swap_bytes(), m);
251 #[stable(feature = "rust1", since = "1.0.0")]
253 pub fn swap_bytes(self) -> Self {
254 (self as $UnsignedT).swap_bytes() as Self
257 /// Converts an integer from big endian to the target's endianness.
259 /// On big endian this is a no-op. On little endian the bytes are
265 /// let n = 0x0123456789ABCDEFu64;
267 /// if cfg!(target_endian = "big") {
268 /// assert_eq!(u64::from_be(n), n)
270 /// assert_eq!(u64::from_be(n), n.swap_bytes())
273 #[stable(feature = "rust1", since = "1.0.0")]
275 pub fn from_be(x: Self) -> Self {
276 if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
279 /// Converts an integer from little endian to the target's endianness.
281 /// On little endian this is a no-op. On big endian the bytes are
287 /// let n = 0x0123456789ABCDEFu64;
289 /// if cfg!(target_endian = "little") {
290 /// assert_eq!(u64::from_le(n), n)
292 /// assert_eq!(u64::from_le(n), n.swap_bytes())
295 #[stable(feature = "rust1", since = "1.0.0")]
297 pub fn from_le(x: Self) -> Self {
298 if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
301 /// Converts `self` to big endian from the target's endianness.
303 /// On big endian this is a no-op. On little endian the bytes are
309 /// let n = 0x0123456789ABCDEFu64;
311 /// if cfg!(target_endian = "big") {
312 /// assert_eq!(n.to_be(), n)
314 /// assert_eq!(n.to_be(), n.swap_bytes())
317 #[stable(feature = "rust1", since = "1.0.0")]
319 pub fn to_be(self) -> Self { // or not to be?
320 if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
323 /// Converts `self` to little endian from the target's endianness.
325 /// On little endian this is a no-op. On big endian the bytes are
331 /// let n = 0x0123456789ABCDEFu64;
333 /// if cfg!(target_endian = "little") {
334 /// assert_eq!(n.to_le(), n)
336 /// assert_eq!(n.to_le(), n.swap_bytes())
339 #[stable(feature = "rust1", since = "1.0.0")]
341 pub fn to_le(self) -> Self {
342 if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
345 /// Checked integer addition. Computes `self + other`, returning `None`
346 /// if overflow occurred.
351 /// assert_eq!(5u16.checked_add(65530), Some(65535));
352 /// assert_eq!(6u16.checked_add(65530), None);
354 #[stable(feature = "rust1", since = "1.0.0")]
356 pub fn checked_add(self, other: Self) -> Option<Self> {
357 checked_op!($ActualT, $add_with_overflow, self, other)
360 /// Checked integer subtraction. Computes `self - other`, returning
361 /// `None` if underflow occurred.
366 /// assert_eq!((-127i8).checked_sub(1), Some(-128));
367 /// assert_eq!((-128i8).checked_sub(1), None);
369 #[stable(feature = "rust1", since = "1.0.0")]
371 pub fn checked_sub(self, other: Self) -> Option<Self> {
372 checked_op!($ActualT, $sub_with_overflow, self, other)
375 /// Checked integer multiplication. Computes `self * other`, returning
376 /// `None` if underflow or overflow occurred.
381 /// assert_eq!(5u8.checked_mul(51), Some(255));
382 /// assert_eq!(5u8.checked_mul(52), None);
384 #[stable(feature = "rust1", since = "1.0.0")]
386 pub fn checked_mul(self, other: Self) -> Option<Self> {
387 checked_op!($ActualT, $mul_with_overflow, self, other)
390 /// Checked integer division. Computes `self / other`, returning `None`
391 /// if `other == 0` or the operation results in underflow or overflow.
396 /// assert_eq!((-127i8).checked_div(-1), Some(127));
397 /// assert_eq!((-128i8).checked_div(-1), None);
398 /// assert_eq!((1i8).checked_div(0), None);
400 #[stable(feature = "rust1", since = "1.0.0")]
402 pub fn checked_div(self, v: Self) -> Option<Self> {
405 -1 if self == Self::min_value()
411 /// Saturating integer addition. Computes `self + other`, saturating at
412 /// the numeric bounds instead of overflowing.
413 #[stable(feature = "rust1", since = "1.0.0")]
415 pub fn saturating_add(self, other: Self) -> Self {
416 match self.checked_add(other) {
418 None if other >= Self::zero() => Self::max_value(),
419 None => Self::min_value(),
423 /// Saturating integer subtraction. Computes `self - other`, saturating
424 /// at the numeric bounds instead of overflowing.
425 #[stable(feature = "rust1", since = "1.0.0")]
427 pub fn saturating_sub(self, other: Self) -> Self {
428 match self.checked_sub(other) {
430 None if other >= Self::zero() => Self::min_value(),
431 None => Self::max_value(),
435 /// Wrapping (modular) addition. Computes `self + other`,
436 /// wrapping around at the boundary of the type.
437 #[stable(feature = "rust1", since = "1.0.0")]
439 pub fn wrapping_add(self, rhs: Self) -> Self {
441 intrinsics::overflowing_add(self, rhs)
445 /// Wrapping (modular) subtraction. Computes `self - other`,
446 /// wrapping around at the boundary of the type.
447 #[stable(feature = "rust1", since = "1.0.0")]
449 pub fn wrapping_sub(self, rhs: Self) -> Self {
451 intrinsics::overflowing_sub(self, rhs)
455 /// Wrapping (modular) multiplication. Computes `self *
456 /// other`, wrapping around at the boundary of the type.
457 #[stable(feature = "rust1", since = "1.0.0")]
459 pub fn wrapping_mul(self, rhs: Self) -> Self {
461 intrinsics::overflowing_mul(self, rhs)
465 /// Wrapping (modular) division. Computes `self / other`,
466 /// wrapping around at the boundary of the type.
468 /// The only case where such wrapping can occur is when one
469 /// divides `MIN / -1` on a signed type (where `MIN` is the
470 /// negative minimal value for the type); this is equivalent
471 /// to `-MIN`, a positive value that is too large to represent
472 /// in the type. In such a case, this function returns `MIN`
474 #[stable(feature = "num_wrapping", since = "1.2.0")]
476 pub fn wrapping_div(self, rhs: Self) -> Self {
477 self.overflowing_div(rhs).0
480 /// Wrapping (modular) remainder. Computes `self % other`,
481 /// wrapping around at the boundary of the type.
483 /// Such wrap-around never actually occurs mathematically;
484 /// implementation artifacts make `x % y` invalid for `MIN /
485 /// -1` on a signed type (where `MIN` is the negative
486 /// minimal value). In such a case, this function returns `0`.
487 #[stable(feature = "num_wrapping", since = "1.2.0")]
489 pub fn wrapping_rem(self, rhs: Self) -> Self {
490 self.overflowing_rem(rhs).0
493 /// Wrapping (modular) negation. Computes `-self`,
494 /// wrapping around at the boundary of the type.
496 /// The only case where such wrapping can occur is when one
497 /// negates `MIN` on a signed type (where `MIN` is the
498 /// negative minimal value for the type); this is a positive
499 /// value that is too large to represent in the type. In such
500 /// a case, this function returns `MIN` itself.
501 #[stable(feature = "num_wrapping", since = "1.2.0")]
503 pub fn wrapping_neg(self) -> Self {
504 self.overflowing_neg().0
507 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
508 /// where `mask` removes any high-order bits of `rhs` that
509 /// would cause the shift to exceed the bitwidth of the type.
510 #[stable(feature = "num_wrapping", since = "1.2.0")]
512 pub fn wrapping_shl(self, rhs: u32) -> Self {
513 self.overflowing_shl(rhs).0
516 /// Panic-free bitwise shift-left; yields `self >> mask(rhs)`,
517 /// where `mask` removes any high-order bits of `rhs` that
518 /// would cause the shift to exceed the bitwidth of the type.
519 #[stable(feature = "num_wrapping", since = "1.2.0")]
521 pub fn wrapping_shr(self, rhs: u32) -> Self {
522 self.overflowing_shr(rhs).0
525 /// Raises self to the power of `exp`, using exponentiation by squaring.
530 /// let x: i32 = 2; // or any other integer type
532 /// assert_eq!(x.pow(4), 16);
534 #[stable(feature = "rust1", since = "1.0.0")]
536 pub fn pow(self, mut exp: u32) -> Self {
538 let mut acc = Self::one();
540 let mut prev_base = self;
541 let mut base_oflo = false;
545 // ensure overflow occurs in the same manner it
546 // would have otherwise (i.e. signal any exception
547 // it would have otherwise).
548 acc = acc * (prev_base * prev_base);
554 let (new_base, new_base_oflo) = base.overflowing_mul(base);
556 base_oflo = new_base_oflo;
562 /// Computes the absolute value of `self`.
564 /// # Overflow behavior
566 /// The absolute value of `i32::min_value()` cannot be represented as an
567 /// `i32`, and attempting to calculate it will cause an overflow. This
568 /// means that code in debug mode will trigger a panic on this case and
569 /// optimized code will return `i32::min_value()` without a panic.
570 #[stable(feature = "rust1", since = "1.0.0")]
572 pub fn abs(self) -> Self {
573 if self.is_negative() {
574 // Note that the #[inline] above means that the overflow
575 // semantics of this negation depend on the crate we're being
583 /// Returns a number representing sign of `self`.
585 /// - `0` if the number is zero
586 /// - `1` if the number is positive
587 /// - `-1` if the number is negative
588 #[stable(feature = "rust1", since = "1.0.0")]
590 pub fn signum(self) -> Self {
598 /// Returns `true` if `self` is positive and `false` if the number
599 /// is zero or negative.
600 #[stable(feature = "rust1", since = "1.0.0")]
602 pub fn is_positive(self) -> bool { self > 0 }
604 /// Returns `true` if `self` is negative and `false` if the number
605 /// is zero or positive.
606 #[stable(feature = "rust1", since = "1.0.0")]
608 pub fn is_negative(self) -> bool { self < 0 }
614 int_impl! { i8, u8, 8,
615 intrinsics::i8_add_with_overflow,
616 intrinsics::i8_sub_with_overflow,
617 intrinsics::i8_mul_with_overflow }
622 int_impl! { i16, u16, 16,
623 intrinsics::i16_add_with_overflow,
624 intrinsics::i16_sub_with_overflow,
625 intrinsics::i16_mul_with_overflow }
630 int_impl! { i32, u32, 32,
631 intrinsics::i32_add_with_overflow,
632 intrinsics::i32_sub_with_overflow,
633 intrinsics::i32_mul_with_overflow }
638 int_impl! { i64, u64, 64,
639 intrinsics::i64_add_with_overflow,
640 intrinsics::i64_sub_with_overflow,
641 intrinsics::i64_mul_with_overflow }
644 #[cfg(target_pointer_width = "32")]
647 int_impl! { i32, u32, 32,
648 intrinsics::i32_add_with_overflow,
649 intrinsics::i32_sub_with_overflow,
650 intrinsics::i32_mul_with_overflow }
653 #[cfg(target_pointer_width = "64")]
656 int_impl! { i64, u64, 64,
657 intrinsics::i64_add_with_overflow,
658 intrinsics::i64_sub_with_overflow,
659 intrinsics::i64_mul_with_overflow }
662 // `Int` + `UnsignedInt` implemented for signed integers
663 macro_rules! uint_impl {
664 ($ActualT:ty, $BITS:expr,
669 $add_with_overflow:path,
670 $sub_with_overflow:path,
671 $mul_with_overflow:path) => {
672 /// Returns the smallest value that can be represented by this integer type.
673 #[stable(feature = "rust1", since = "1.0.0")]
675 pub fn min_value() -> Self { 0 }
677 /// Returns the largest value that can be represented by this integer type.
678 #[stable(feature = "rust1", since = "1.0.0")]
680 pub fn max_value() -> Self { !0 }
682 /// Converts a string slice in a given base to an integer.
684 /// Leading and trailing whitespace represent an error.
688 /// * src - A string slice
689 /// * radix - The base to use. Must lie in the range [2 .. 36]
693 /// `Err(ParseIntError)` if the string did not represent a valid number.
694 /// Otherwise, `Ok(n)` where `n` is the integer represented by `src`.
695 #[stable(feature = "rust1", since = "1.0.0")]
696 pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
697 from_str_radix(src, radix)
700 /// Returns the number of ones in the binary representation of `self`.
705 /// let n = 0b01001100u8;
707 /// assert_eq!(n.count_ones(), 3);
709 #[stable(feature = "rust1", since = "1.0.0")]
711 pub fn count_ones(self) -> u32 {
712 unsafe { $ctpop(self as $ActualT) as u32 }
715 /// Returns the number of zeros in the binary representation of `self`.
720 /// let n = 0b01001100u8;
722 /// assert_eq!(n.count_zeros(), 5);
724 #[stable(feature = "rust1", since = "1.0.0")]
726 pub fn count_zeros(self) -> u32 {
730 /// Returns the number of leading zeros in the binary representation
736 /// let n = 0b0101000u16;
738 /// assert_eq!(n.leading_zeros(), 10);
740 #[stable(feature = "rust1", since = "1.0.0")]
742 pub fn leading_zeros(self) -> u32 {
743 unsafe { $ctlz(self as $ActualT) as u32 }
746 /// Returns the number of trailing zeros in the binary representation
752 /// let n = 0b0101000u16;
754 /// assert_eq!(n.trailing_zeros(), 3);
756 #[stable(feature = "rust1", since = "1.0.0")]
758 pub fn trailing_zeros(self) -> u32 {
759 // As of LLVM 3.6 the codegen for the zero-safe cttz8 intrinsic
760 // emits two conditional moves on x86_64. By promoting the value to
761 // u16 and setting bit 8, we get better code without any conditional
763 // FIXME: There's a LLVM patch (http://reviews.llvm.org/D9284)
764 // pending, remove this workaround once LLVM generates better code
768 intrinsics::cttz16(self as u16 | 0x100) as u32
770 $cttz(self as $ActualT) as u32
775 /// Shifts the bits to the left by a specified amount, `n`,
776 /// wrapping the truncated bits to the end of the resulting integer.
781 /// let n = 0x0123456789ABCDEFu64;
782 /// let m = 0x3456789ABCDEF012u64;
784 /// assert_eq!(n.rotate_left(12), m);
786 #[stable(feature = "rust1", since = "1.0.0")]
788 pub fn rotate_left(self, n: u32) -> Self {
789 // Protect against undefined behaviour for over-long bit shifts
791 (self << n) | (self >> (($BITS - n) % $BITS))
794 /// Shifts the bits to the right by a specified amount, `n`,
795 /// wrapping the truncated bits to the beginning of the resulting
801 /// let n = 0x0123456789ABCDEFu64;
802 /// let m = 0xDEF0123456789ABCu64;
804 /// assert_eq!(n.rotate_right(12), m);
806 #[stable(feature = "rust1", since = "1.0.0")]
808 pub fn rotate_right(self, n: u32) -> Self {
809 // Protect against undefined behaviour for over-long bit shifts
811 (self >> n) | (self << (($BITS - n) % $BITS))
814 /// Reverses the byte order of the integer.
819 /// let n = 0x0123456789ABCDEFu64;
820 /// let m = 0xEFCDAB8967452301u64;
822 /// assert_eq!(n.swap_bytes(), m);
824 #[stable(feature = "rust1", since = "1.0.0")]
826 pub fn swap_bytes(self) -> Self {
827 unsafe { $bswap(self as $ActualT) as Self }
830 /// Converts an integer from big endian to the target's endianness.
832 /// On big endian this is a no-op. On little endian the bytes are
838 /// let n = 0x0123456789ABCDEFu64;
840 /// if cfg!(target_endian = "big") {
841 /// assert_eq!(u64::from_be(n), n)
843 /// assert_eq!(u64::from_be(n), n.swap_bytes())
846 #[stable(feature = "rust1", since = "1.0.0")]
848 pub fn from_be(x: Self) -> Self {
849 if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
852 /// Converts an integer from little endian to the target's endianness.
854 /// On little endian this is a no-op. On big endian the bytes are
860 /// let n = 0x0123456789ABCDEFu64;
862 /// if cfg!(target_endian = "little") {
863 /// assert_eq!(u64::from_le(n), n)
865 /// assert_eq!(u64::from_le(n), n.swap_bytes())
868 #[stable(feature = "rust1", since = "1.0.0")]
870 pub fn from_le(x: Self) -> Self {
871 if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
874 /// Converts `self` to big endian from the target's endianness.
876 /// On big endian this is a no-op. On little endian the bytes are
882 /// let n = 0x0123456789ABCDEFu64;
884 /// if cfg!(target_endian = "big") {
885 /// assert_eq!(n.to_be(), n)
887 /// assert_eq!(n.to_be(), n.swap_bytes())
890 #[stable(feature = "rust1", since = "1.0.0")]
892 pub fn to_be(self) -> Self { // or not to be?
893 if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
896 /// Converts `self` to little endian from the target's endianness.
898 /// On little endian this is a no-op. On big endian the bytes are
904 /// let n = 0x0123456789ABCDEFu64;
906 /// if cfg!(target_endian = "little") {
907 /// assert_eq!(n.to_le(), n)
909 /// assert_eq!(n.to_le(), n.swap_bytes())
912 #[stable(feature = "rust1", since = "1.0.0")]
914 pub fn to_le(self) -> Self {
915 if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
918 /// Checked integer addition. Computes `self + other`, returning `None`
919 /// if overflow occurred.
924 /// assert_eq!(5u16.checked_add(65530), Some(65535));
925 /// assert_eq!(6u16.checked_add(65530), None);
927 #[stable(feature = "rust1", since = "1.0.0")]
929 pub fn checked_add(self, other: Self) -> Option<Self> {
930 checked_op!($ActualT, $add_with_overflow, self, other)
933 /// Checked integer subtraction. Computes `self - other`, returning
934 /// `None` if underflow occurred.
939 /// assert_eq!((-127i8).checked_sub(1), Some(-128));
940 /// assert_eq!((-128i8).checked_sub(1), None);
942 #[stable(feature = "rust1", since = "1.0.0")]
944 pub fn checked_sub(self, other: Self) -> Option<Self> {
945 checked_op!($ActualT, $sub_with_overflow, self, other)
948 /// Checked integer multiplication. Computes `self * other`, returning
949 /// `None` if underflow or overflow occurred.
954 /// assert_eq!(5u8.checked_mul(51), Some(255));
955 /// assert_eq!(5u8.checked_mul(52), None);
957 #[stable(feature = "rust1", since = "1.0.0")]
959 pub fn checked_mul(self, other: Self) -> Option<Self> {
960 checked_op!($ActualT, $mul_with_overflow, self, other)
963 /// Checked integer division. Computes `self / other`, returning `None`
964 /// if `other == 0` or the operation results in underflow or overflow.
969 /// assert_eq!((-127i8).checked_div(-1), Some(127));
970 /// assert_eq!((-128i8).checked_div(-1), None);
971 /// assert_eq!((1i8).checked_div(0), None);
973 #[stable(feature = "rust1", since = "1.0.0")]
975 pub fn checked_div(self, v: Self) -> Option<Self> {
982 /// Saturating integer addition. Computes `self + other`, saturating at
983 /// the numeric bounds instead of overflowing.
984 #[stable(feature = "rust1", since = "1.0.0")]
986 pub fn saturating_add(self, other: Self) -> Self {
987 match self.checked_add(other) {
989 None if other >= Self::zero() => Self::max_value(),
990 None => Self::min_value(),
994 /// Saturating integer subtraction. Computes `self - other`, saturating
995 /// at the numeric bounds instead of overflowing.
996 #[stable(feature = "rust1", since = "1.0.0")]
998 pub fn saturating_sub(self, other: Self) -> Self {
999 match self.checked_sub(other) {
1001 None if other >= Self::zero() => Self::min_value(),
1002 None => Self::max_value(),
1006 /// Wrapping (modular) addition. Computes `self + other`,
1007 /// wrapping around at the boundary of the type.
1008 #[stable(feature = "rust1", since = "1.0.0")]
1010 pub fn wrapping_add(self, rhs: Self) -> Self {
1012 intrinsics::overflowing_add(self, rhs)
1016 /// Wrapping (modular) subtraction. Computes `self - other`,
1017 /// wrapping around at the boundary of the type.
1018 #[stable(feature = "rust1", since = "1.0.0")]
1020 pub fn wrapping_sub(self, rhs: Self) -> Self {
1022 intrinsics::overflowing_sub(self, rhs)
1026 /// Wrapping (modular) multiplication. Computes `self *
1027 /// other`, wrapping around at the boundary of the type.
1028 #[stable(feature = "rust1", since = "1.0.0")]
1030 pub fn wrapping_mul(self, rhs: Self) -> Self {
1032 intrinsics::overflowing_mul(self, rhs)
1036 /// Wrapping (modular) division. Computes `self / other`,
1037 /// wrapping around at the boundary of the type.
1039 /// The only case where such wrapping can occur is when one
1040 /// divides `MIN / -1` on a signed type (where `MIN` is the
1041 /// negative minimal value for the type); this is equivalent
1042 /// to `-MIN`, a positive value that is too large to represent
1043 /// in the type. In such a case, this function returns `MIN`
1045 #[stable(feature = "num_wrapping", since = "1.2.0")]
1047 pub fn wrapping_div(self, rhs: Self) -> Self {
1048 self.overflowing_div(rhs).0
1051 /// Wrapping (modular) remainder. Computes `self % other`,
1052 /// wrapping around at the boundary of the type.
1054 /// Such wrap-around never actually occurs mathematically;
1055 /// implementation artifacts make `x % y` invalid for `MIN /
1056 /// -1` on a signed type (where `MIN` is the negative
1057 /// minimal value). In such a case, this function returns `0`.
1058 #[stable(feature = "num_wrapping", since = "1.2.0")]
1060 pub fn wrapping_rem(self, rhs: Self) -> Self {
1061 self.overflowing_rem(rhs).0
1064 /// Wrapping (modular) negation. Computes `-self`,
1065 /// wrapping around at the boundary of the type.
1067 /// The only case where such wrapping can occur is when one
1068 /// negates `MIN` on a signed type (where `MIN` is the
1069 /// negative minimal value for the type); this is a positive
1070 /// value that is too large to represent in the type. In such
1071 /// a case, this function returns `MIN` itself.
1072 #[stable(feature = "num_wrapping", since = "1.2.0")]
1074 pub fn wrapping_neg(self) -> Self {
1075 self.overflowing_neg().0
1078 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
1079 /// where `mask` removes any high-order bits of `rhs` that
1080 /// would cause the shift to exceed the bitwidth of the type.
1081 #[stable(feature = "num_wrapping", since = "1.2.0")]
1083 pub fn wrapping_shl(self, rhs: u32) -> Self {
1084 self.overflowing_shl(rhs).0
1087 /// Panic-free bitwise shift-left; yields `self >> mask(rhs)`,
1088 /// where `mask` removes any high-order bits of `rhs` that
1089 /// would cause the shift to exceed the bitwidth of the type.
1090 #[stable(feature = "num_wrapping", since = "1.2.0")]
1092 pub fn wrapping_shr(self, rhs: u32) -> Self {
1093 self.overflowing_shr(rhs).0
1096 /// Raises self to the power of `exp`, using exponentiation by squaring.
1101 /// assert_eq!(2i32.pow(4), 16);
1103 #[stable(feature = "rust1", since = "1.0.0")]
1105 pub fn pow(self, mut exp: u32) -> Self {
1106 let mut base = self;
1107 let mut acc = Self::one();
1109 let mut prev_base = self;
1110 let mut base_oflo = false;
1114 // ensure overflow occurs in the same manner it
1115 // would have otherwise (i.e. signal any exception
1116 // it would have otherwise).
1117 acc = acc * (prev_base * prev_base);
1123 let (new_base, new_base_oflo) = base.overflowing_mul(base);
1125 base_oflo = new_base_oflo;
1131 /// Returns `true` if and only if `self == 2^k` for some `k`.
1132 #[stable(feature = "rust1", since = "1.0.0")]
1134 pub fn is_power_of_two(self) -> bool {
1135 (self.wrapping_sub(Self::one())) & self == Self::zero() &&
1136 !(self == Self::zero())
1139 /// Returns the smallest power of two greater than or equal to `self`.
1140 /// Unspecified behavior on overflow.
1141 #[stable(feature = "rust1", since = "1.0.0")]
1143 pub fn next_power_of_two(self) -> Self {
1144 let bits = size_of::<Self>() * 8;
1145 let one: Self = Self::one();
1146 one << ((bits - self.wrapping_sub(one).leading_zeros() as usize) % bits)
1149 /// Returns the smallest power of two greater than or equal to `n`. If
1150 /// the next power of two is greater than the type's maximum value,
1151 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
1152 #[stable(feature = "rust1", since = "1.0.0")]
1153 pub fn checked_next_power_of_two(self) -> Option<Self> {
1154 let npot = self.next_power_of_two();
1171 intrinsics::u8_add_with_overflow,
1172 intrinsics::u8_sub_with_overflow,
1173 intrinsics::u8_mul_with_overflow }
1178 uint_impl! { u16, 16,
1179 intrinsics::ctpop16,
1182 intrinsics::bswap16,
1183 intrinsics::u16_add_with_overflow,
1184 intrinsics::u16_sub_with_overflow,
1185 intrinsics::u16_mul_with_overflow }
1190 uint_impl! { u32, 32,
1191 intrinsics::ctpop32,
1194 intrinsics::bswap32,
1195 intrinsics::u32_add_with_overflow,
1196 intrinsics::u32_sub_with_overflow,
1197 intrinsics::u32_mul_with_overflow }
1203 uint_impl! { u64, 64,
1204 intrinsics::ctpop64,
1207 intrinsics::bswap64,
1208 intrinsics::u64_add_with_overflow,
1209 intrinsics::u64_sub_with_overflow,
1210 intrinsics::u64_mul_with_overflow }
1213 #[cfg(target_pointer_width = "32")]
1216 uint_impl! { u32, 32,
1217 intrinsics::ctpop32,
1220 intrinsics::bswap32,
1221 intrinsics::u32_add_with_overflow,
1222 intrinsics::u32_sub_with_overflow,
1223 intrinsics::u32_mul_with_overflow }
1226 #[cfg(target_pointer_width = "64")]
1229 uint_impl! { u64, 64,
1230 intrinsics::ctpop64,
1233 intrinsics::bswap64,
1234 intrinsics::u64_add_with_overflow,
1235 intrinsics::u64_sub_with_overflow,
1236 intrinsics::u64_mul_with_overflow }
1239 /// Used for representing the classification of floating point numbers
1240 #[derive(Copy, Clone, PartialEq, Debug)]
1241 #[stable(feature = "rust1", since = "1.0.0")]
1242 pub enum FpCategory {
1243 /// "Not a Number", often obtained by dividing by zero
1244 #[stable(feature = "rust1", since = "1.0.0")]
1247 /// Positive or negative infinity
1248 #[stable(feature = "rust1", since = "1.0.0")]
1251 /// Positive or negative zero
1252 #[stable(feature = "rust1", since = "1.0.0")]
1255 /// De-normalized floating point representation (less precise than `Normal`)
1256 #[stable(feature = "rust1", since = "1.0.0")]
1259 /// A regular floating point number
1260 #[stable(feature = "rust1", since = "1.0.0")]
1264 /// A built-in floating point number.
1266 #[unstable(feature = "core_float",
1267 reason = "stable interface is via `impl f{32,64}` in later crates",
1269 pub trait Float: Sized {
1270 /// Returns the NaN value.
1272 /// Returns the infinite value.
1273 fn infinity() -> Self;
1274 /// Returns the negative infinite value.
1275 fn neg_infinity() -> Self;
1277 fn neg_zero() -> Self;
1282 /// Parses the string `s` with the radix `r` as a float.
1283 fn from_str_radix(s: &str, r: u32) -> Result<Self, ParseFloatError>;
1285 /// Returns true if this value is NaN and false otherwise.
1286 fn is_nan(self) -> bool;
1287 /// Returns true if this value is positive infinity or negative infinity and
1288 /// false otherwise.
1289 fn is_infinite(self) -> bool;
1290 /// Returns true if this number is neither infinite nor NaN.
1291 fn is_finite(self) -> bool;
1292 /// Returns true if this number is neither zero, infinite, denormal, or NaN.
1293 fn is_normal(self) -> bool;
1294 /// Returns the category that this number falls into.
1295 fn classify(self) -> FpCategory;
1297 /// Returns the mantissa, exponent and sign as integers, respectively.
1298 fn integer_decode(self) -> (u64, i16, i8);
1300 /// Computes the absolute value of `self`. Returns `Float::nan()` if the
1301 /// number is `Float::nan()`.
1302 fn abs(self) -> Self;
1303 /// Returns a number that represents the sign of `self`.
1305 /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
1306 /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
1307 /// - `Float::nan()` if the number is `Float::nan()`
1308 fn signum(self) -> Self;
1309 /// Returns `true` if `self` is positive, including `+0.0` and
1310 /// `Float::infinity()`.
1311 fn is_positive(self) -> bool;
1312 /// Returns `true` if `self` is negative, including `-0.0` and
1313 /// `Float::neg_infinity()`.
1314 fn is_negative(self) -> bool;
1316 /// Take the reciprocal (inverse) of a number, `1/x`.
1317 fn recip(self) -> Self;
1319 /// Raise a number to an integer power.
1321 /// Using this function is generally faster than using `powf`
1322 fn powi(self, n: i32) -> Self;
1324 /// Convert radians to degrees.
1325 fn to_degrees(self) -> Self;
1326 /// Convert degrees to radians.
1327 fn to_radians(self) -> Self;
1330 macro_rules! from_str_float_impl {
1331 ($t:ty, $func:ident) => {
1332 #[stable(feature = "rust1", since = "1.0.0")]
1333 impl FromStr for $t {
1334 type Err = ParseFloatError;
1336 /// Converts a string in base 10 to a float.
1337 /// Accepts an optional decimal exponent.
1339 /// This function accepts strings such as
1343 /// * '2.5E10', or equivalently, '2.5e10'
1345 /// * '.' (understood as 0)
1347 /// * '.5', or, equivalently, '0.5'
1348 /// * 'inf', '-inf', 'NaN'
1350 /// Leading and trailing whitespace represent an error.
1354 /// * src - A string
1358 /// `Err(ParseFloatError)` if the string did not represent a valid
1359 /// number. Otherwise, `Ok(n)` where `n` is the floating-point
1360 /// number represented by `src`.
1362 fn from_str(src: &str) -> Result<Self, ParseFloatError> {
1368 from_str_float_impl!(f32, to_f32);
1369 from_str_float_impl!(f64, to_f64);
1371 macro_rules! from_str_radix_int_impl {
1373 #[stable(feature = "rust1", since = "1.0.0")]
1374 impl FromStr for $t {
1375 type Err = ParseIntError;
1376 fn from_str(src: &str) -> Result<Self, ParseIntError> {
1377 from_str_radix(src, 10)
1382 from_str_radix_int_impl! { isize i8 i16 i32 i64 usize u8 u16 u32 u64 }
1385 trait FromStrRadixHelper: PartialOrd + Copy {
1386 fn min_value() -> Self;
1387 fn from_u32(u: u32) -> Self;
1388 fn checked_mul(&self, other: u32) -> Option<Self>;
1389 fn checked_sub(&self, other: u32) -> Option<Self>;
1390 fn checked_add(&self, other: u32) -> Option<Self>;
1394 ($($t:ty)*) => ($(impl FromStrRadixHelper for $t {
1395 fn min_value() -> Self { Self::min_value() }
1396 fn from_u32(u: u32) -> Self { u as Self }
1397 fn checked_mul(&self, other: u32) -> Option<Self> {
1398 Self::checked_mul(*self, other as Self)
1400 fn checked_sub(&self, other: u32) -> Option<Self> {
1401 Self::checked_sub(*self, other as Self)
1403 fn checked_add(&self, other: u32) -> Option<Self> {
1404 Self::checked_add(*self, other as Self)
1408 doit! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }
1410 fn from_str_radix<T: FromStrRadixHelper>(src: &str, radix: u32)
1411 -> Result<T, ParseIntError> {
1412 use self::IntErrorKind::*;
1413 use self::ParseIntError as PIE;
1415 assert!(radix >= 2 && radix <= 36,
1416 "from_str_radix_int: must lie in the range `[2, 36]` - found {}",
1420 return Err(PIE { kind: Empty });
1423 let is_signed_ty = T::from_u32(0) > T::min_value();
1425 // all valid digits are ascii, so we will just iterate over the utf8 bytes
1426 // and cast them to chars. .to_digit() will safely return None for anything
1427 // other than a valid ascii digit for a the given radix, including the first-byte
1428 // of multi-byte sequences
1429 let src = src.as_bytes();
1431 match (src[0], &src[1..]) {
1432 (b'-', digits) if digits.is_empty() => Err(PIE { kind: Empty }),
1433 (b'-', digits) if is_signed_ty => {
1434 // The number is negative
1435 let mut result = T::from_u32(0);
1437 let x = match (c as char).to_digit(radix) {
1439 None => return Err(PIE { kind: InvalidDigit }),
1441 result = match result.checked_mul(radix) {
1442 Some(result) => result,
1443 None => return Err(PIE { kind: Underflow }),
1445 result = match result.checked_sub(x) {
1446 Some(result) => result,
1447 None => return Err(PIE { kind: Underflow }),
1453 // The number is signed
1454 let mut result = match (c as char).to_digit(radix) {
1455 Some(x) => T::from_u32(x),
1456 None => return Err(PIE { kind: InvalidDigit }),
1459 let x = match (c as char).to_digit(radix) {
1461 None => return Err(PIE { kind: InvalidDigit }),
1463 result = match result.checked_mul(radix) {
1464 Some(result) => result,
1465 None => return Err(PIE { kind: Overflow }),
1467 result = match result.checked_add(x) {
1468 Some(result) => result,
1469 None => return Err(PIE { kind: Overflow }),
1477 /// An error which can be returned when parsing an integer.
1478 #[derive(Debug, Clone, PartialEq)]
1479 #[stable(feature = "rust1", since = "1.0.0")]
1480 pub struct ParseIntError { kind: IntErrorKind }
1482 #[derive(Debug, Clone, PartialEq)]
1490 impl ParseIntError {
1491 #[unstable(feature = "int_error_internals",
1492 reason = "available through Error trait and this method should \
1493 not be exposed publicly",
1496 pub fn __description(&self) -> &str {
1498 IntErrorKind::Empty => "cannot parse integer from empty string",
1499 IntErrorKind::InvalidDigit => "invalid digit found in string",
1500 IntErrorKind::Overflow => "number too large to fit in target type",
1501 IntErrorKind::Underflow => "number too small to fit in target type",
1506 #[stable(feature = "rust1", since = "1.0.0")]
1507 impl fmt::Display for ParseIntError {
1508 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1509 self.__description().fmt(f)
1513 /// An error which can be returned when parsing a float.
1514 #[derive(Debug, Clone, PartialEq)]
1515 #[stable(feature = "rust1", since = "1.0.0")]
1516 pub struct ParseFloatError {
1518 #[unstable(feature = "float_error_internals",
1519 reason = "should not be exposed publicly",
1521 pub __kind: FloatErrorKind
1524 #[derive(Debug, Clone, PartialEq)]
1525 #[unstable(feature = "float_error_internals",
1526 reason = "should not be exposed publicly",
1529 pub enum FloatErrorKind {
1534 impl ParseFloatError {
1536 pub fn __description(&self) -> &str {
1538 FloatErrorKind::Empty => "cannot parse float from empty string",
1539 FloatErrorKind::Invalid => "invalid float literal",
1544 #[stable(feature = "rust1", since = "1.0.0")]
1545 impl fmt::Display for ParseFloatError {
1546 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1547 self.__description().fmt(f)