| //! Additional functionality for numerics. |
| //! |
| //! This module provides some extra types that are useful when doing numerical |
| //! work. See the individual documentation for each piece for more information. |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| #![allow(missing_docs)] |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::num::Wrapping; |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::num::{FpCategory, ParseFloatError, ParseIntError, TryFromIntError}; |
| |
| #[stable(feature = "signed_nonzero", since = "1.34.0")] |
| pub use core::num::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize}; |
| #[stable(feature = "nonzero", since = "1.28.0")] |
| pub use core::num::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize}; |
| |
| #[unstable( |
| feature = "int_error_matching", |
| reason = "it can be useful to match errors when making error messages \ |
| for integer parsing", |
| issue = "22639" |
| )] |
| pub use core::num::IntErrorKind; |
| |
| #[cfg(test)] |
| use crate::fmt; |
| #[cfg(test)] |
| use crate::ops::{Add, Div, Mul, Rem, Sub}; |
| |
| /// Helper function for testing numeric operations |
| #[cfg(test)] |
| pub fn test_num<T>(ten: T, two: T) |
| where |
| T: PartialEq |
| + Add<Output = T> |
| + Sub<Output = T> |
| + Mul<Output = T> |
| + Div<Output = T> |
| + Rem<Output = T> |
| + fmt::Debug |
| + Copy, |
| { |
| assert_eq!(ten.add(two), ten + two); |
| assert_eq!(ten.sub(two), ten - two); |
| assert_eq!(ten.mul(two), ten * two); |
| assert_eq!(ten.div(two), ten / two); |
| assert_eq!(ten.rem(two), ten % two); |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use crate::ops::Mul; |
| use crate::u16; |
| use crate::u32; |
| use crate::u64; |
| use crate::u8; |
| use crate::usize; |
| |
| #[test] |
| fn test_saturating_add_uint() { |
| use crate::usize::MAX; |
| assert_eq!(3_usize.saturating_add(5_usize), 8_usize); |
| assert_eq!(3_usize.saturating_add(MAX - 1), MAX); |
| assert_eq!(MAX.saturating_add(MAX), MAX); |
| assert_eq!((MAX - 2).saturating_add(1), MAX - 1); |
| } |
| |
| #[test] |
| fn test_saturating_sub_uint() { |
| use crate::usize::MAX; |
| assert_eq!(5_usize.saturating_sub(3_usize), 2_usize); |
| assert_eq!(3_usize.saturating_sub(5_usize), 0_usize); |
| assert_eq!(0_usize.saturating_sub(1_usize), 0_usize); |
| assert_eq!((MAX - 1).saturating_sub(MAX), 0); |
| } |
| |
| #[test] |
| fn test_saturating_add_int() { |
| use crate::isize::{MAX, MIN}; |
| assert_eq!(3i32.saturating_add(5), 8); |
| assert_eq!(3isize.saturating_add(MAX - 1), MAX); |
| assert_eq!(MAX.saturating_add(MAX), MAX); |
| assert_eq!((MAX - 2).saturating_add(1), MAX - 1); |
| assert_eq!(3i32.saturating_add(-5), -2); |
| assert_eq!(MIN.saturating_add(-1), MIN); |
| assert_eq!((-2isize).saturating_add(-MAX), MIN); |
| } |
| |
| #[test] |
| fn test_saturating_sub_int() { |
| use crate::isize::{MAX, MIN}; |
| assert_eq!(3i32.saturating_sub(5), -2); |
| assert_eq!(MIN.saturating_sub(1), MIN); |
| assert_eq!((-2isize).saturating_sub(MAX), MIN); |
| assert_eq!(3i32.saturating_sub(-5), 8); |
| assert_eq!(3isize.saturating_sub(-(MAX - 1)), MAX); |
| assert_eq!(MAX.saturating_sub(-MAX), MAX); |
| assert_eq!((MAX - 2).saturating_sub(-1), MAX - 1); |
| } |
| |
| #[test] |
| fn test_checked_add() { |
| let five_less = usize::MAX - 5; |
| assert_eq!(five_less.checked_add(0), Some(usize::MAX - 5)); |
| assert_eq!(five_less.checked_add(1), Some(usize::MAX - 4)); |
| assert_eq!(five_less.checked_add(2), Some(usize::MAX - 3)); |
| assert_eq!(five_less.checked_add(3), Some(usize::MAX - 2)); |
| assert_eq!(five_less.checked_add(4), Some(usize::MAX - 1)); |
| assert_eq!(five_less.checked_add(5), Some(usize::MAX)); |
| assert_eq!(five_less.checked_add(6), None); |
| assert_eq!(five_less.checked_add(7), None); |
| } |
| |
| #[test] |
| fn test_checked_sub() { |
| assert_eq!(5_usize.checked_sub(0), Some(5)); |
| assert_eq!(5_usize.checked_sub(1), Some(4)); |
| assert_eq!(5_usize.checked_sub(2), Some(3)); |
| assert_eq!(5_usize.checked_sub(3), Some(2)); |
| assert_eq!(5_usize.checked_sub(4), Some(1)); |
| assert_eq!(5_usize.checked_sub(5), Some(0)); |
| assert_eq!(5_usize.checked_sub(6), None); |
| assert_eq!(5_usize.checked_sub(7), None); |
| } |
| |
| #[test] |
| fn test_checked_mul() { |
| let third = usize::MAX / 3; |
| assert_eq!(third.checked_mul(0), Some(0)); |
| assert_eq!(third.checked_mul(1), Some(third)); |
| assert_eq!(third.checked_mul(2), Some(third * 2)); |
| assert_eq!(third.checked_mul(3), Some(third * 3)); |
| assert_eq!(third.checked_mul(4), None); |
| } |
| |
| macro_rules! test_is_power_of_two { |
| ($test_name:ident, $T:ident) => { |
| fn $test_name() { |
| #![test] |
| assert_eq!((0 as $T).is_power_of_two(), false); |
| assert_eq!((1 as $T).is_power_of_two(), true); |
| assert_eq!((2 as $T).is_power_of_two(), true); |
| assert_eq!((3 as $T).is_power_of_two(), false); |
| assert_eq!((4 as $T).is_power_of_two(), true); |
| assert_eq!((5 as $T).is_power_of_two(), false); |
| assert_eq!(($T::MAX / 2 + 1).is_power_of_two(), true); |
| } |
| }; |
| } |
| |
| test_is_power_of_two! { test_is_power_of_two_u8, u8 } |
| test_is_power_of_two! { test_is_power_of_two_u16, u16 } |
| test_is_power_of_two! { test_is_power_of_two_u32, u32 } |
| test_is_power_of_two! { test_is_power_of_two_u64, u64 } |
| test_is_power_of_two! { test_is_power_of_two_uint, usize } |
| |
| macro_rules! test_next_power_of_two { |
| ($test_name:ident, $T:ident) => { |
| fn $test_name() { |
| #![test] |
| assert_eq!((0 as $T).next_power_of_two(), 1); |
| let mut next_power = 1; |
| for i in 1 as $T..40 { |
| assert_eq!(i.next_power_of_two(), next_power); |
| if i == next_power { |
| next_power *= 2 |
| } |
| } |
| } |
| }; |
| } |
| |
| test_next_power_of_two! { test_next_power_of_two_u8, u8 } |
| test_next_power_of_two! { test_next_power_of_two_u16, u16 } |
| test_next_power_of_two! { test_next_power_of_two_u32, u32 } |
| test_next_power_of_two! { test_next_power_of_two_u64, u64 } |
| test_next_power_of_two! { test_next_power_of_two_uint, usize } |
| |
| macro_rules! test_checked_next_power_of_two { |
| ($test_name:ident, $T:ident) => { |
| fn $test_name() { |
| #![test] |
| assert_eq!((0 as $T).checked_next_power_of_two(), Some(1)); |
| let smax = $T::MAX >> 1; |
| assert_eq!(smax.checked_next_power_of_two(), Some(smax + 1)); |
| assert_eq!((smax + 1).checked_next_power_of_two(), Some(smax + 1)); |
| assert_eq!((smax + 2).checked_next_power_of_two(), None); |
| assert_eq!(($T::MAX - 1).checked_next_power_of_two(), None); |
| assert_eq!($T::MAX.checked_next_power_of_two(), None); |
| let mut next_power = 1; |
| for i in 1 as $T..40 { |
| assert_eq!(i.checked_next_power_of_two(), Some(next_power)); |
| if i == next_power { |
| next_power *= 2 |
| } |
| } |
| } |
| }; |
| } |
| |
| test_checked_next_power_of_two! { test_checked_next_power_of_two_u8, u8 } |
| test_checked_next_power_of_two! { test_checked_next_power_of_two_u16, u16 } |
| test_checked_next_power_of_two! { test_checked_next_power_of_two_u32, u32 } |
| test_checked_next_power_of_two! { test_checked_next_power_of_two_u64, u64 } |
| test_checked_next_power_of_two! { test_checked_next_power_of_two_uint, usize } |
| |
| #[test] |
| fn test_pow() { |
| fn naive_pow<T: Mul<Output = T> + Copy>(one: T, base: T, exp: usize) -> T { |
| (0..exp).fold(one, |acc, _| acc * base) |
| } |
| macro_rules! assert_pow { |
| (($num:expr, $exp:expr) => $expected:expr) => {{ |
| let result = $num.pow($exp); |
| assert_eq!(result, $expected); |
| assert_eq!(result, naive_pow(1, $num, $exp)); |
| }}; |
| } |
| assert_pow!((3u32, 0 ) => 1); |
| assert_pow!((5u32, 1 ) => 5); |
| assert_pow!((-4i32, 2 ) => 16); |
| assert_pow!((8u32, 3 ) => 512); |
| assert_pow!((2u64, 50) => 1125899906842624); |
| } |
| |
| #[test] |
| fn test_uint_to_str_overflow() { |
| let mut u8_val: u8 = 255; |
| assert_eq!(u8_val.to_string(), "255"); |
| |
| u8_val = u8_val.wrapping_add(1); |
| assert_eq!(u8_val.to_string(), "0"); |
| |
| let mut u16_val: u16 = 65_535; |
| assert_eq!(u16_val.to_string(), "65535"); |
| |
| u16_val = u16_val.wrapping_add(1); |
| assert_eq!(u16_val.to_string(), "0"); |
| |
| let mut u32_val: u32 = 4_294_967_295; |
| assert_eq!(u32_val.to_string(), "4294967295"); |
| |
| u32_val = u32_val.wrapping_add(1); |
| assert_eq!(u32_val.to_string(), "0"); |
| |
| let mut u64_val: u64 = 18_446_744_073_709_551_615; |
| assert_eq!(u64_val.to_string(), "18446744073709551615"); |
| |
| u64_val = u64_val.wrapping_add(1); |
| assert_eq!(u64_val.to_string(), "0"); |
| } |
| |
| fn from_str<T: crate::str::FromStr>(t: &str) -> Option<T> { |
| crate::str::FromStr::from_str(t).ok() |
| } |
| |
| #[test] |
| fn test_uint_from_str_overflow() { |
| let mut u8_val: u8 = 255; |
| assert_eq!(from_str::<u8>("255"), Some(u8_val)); |
| assert_eq!(from_str::<u8>("256"), None); |
| |
| u8_val = u8_val.wrapping_add(1); |
| assert_eq!(from_str::<u8>("0"), Some(u8_val)); |
| assert_eq!(from_str::<u8>("-1"), None); |
| |
| let mut u16_val: u16 = 65_535; |
| assert_eq!(from_str::<u16>("65535"), Some(u16_val)); |
| assert_eq!(from_str::<u16>("65536"), None); |
| |
| u16_val = u16_val.wrapping_add(1); |
| assert_eq!(from_str::<u16>("0"), Some(u16_val)); |
| assert_eq!(from_str::<u16>("-1"), None); |
| |
| let mut u32_val: u32 = 4_294_967_295; |
| assert_eq!(from_str::<u32>("4294967295"), Some(u32_val)); |
| assert_eq!(from_str::<u32>("4294967296"), None); |
| |
| u32_val = u32_val.wrapping_add(1); |
| assert_eq!(from_str::<u32>("0"), Some(u32_val)); |
| assert_eq!(from_str::<u32>("-1"), None); |
| |
| let mut u64_val: u64 = 18_446_744_073_709_551_615; |
| assert_eq!(from_str::<u64>("18446744073709551615"), Some(u64_val)); |
| assert_eq!(from_str::<u64>("18446744073709551616"), None); |
| |
| u64_val = u64_val.wrapping_add(1); |
| assert_eq!(from_str::<u64>("0"), Some(u64_val)); |
| assert_eq!(from_str::<u64>("-1"), None); |
| } |
| } |
| |
| #[cfg(test)] |
| mod bench { |
| use test::Bencher; |
| |
| #[bench] |
| fn bench_pow_function(b: &mut Bencher) { |
| let v = (0..1024).collect::<Vec<u32>>(); |
| b.iter(|| { |
| v.iter().fold(0u32, |old, new| old.pow(*new as u32)); |
| }); |
| } |
| } |
