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Diffstat (limited to 'library/std/src/num.rs')
| -rw-r--r-- | library/std/src/num.rs | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/library/std/src/num.rs b/library/std/src/num.rs new file mode 100644 index 00000000000..b496c16a749 --- /dev/null +++ b/library/std/src/num.rs @@ -0,0 +1,297 @@ +//! 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; + + #[test] + fn test_saturating_add_uint() { + assert_eq!(3_usize.saturating_add(5_usize), 8_usize); + assert_eq!(3_usize.saturating_add(usize::MAX - 1), usize::MAX); + assert_eq!(usize::MAX.saturating_add(usize::MAX), usize::MAX); + assert_eq!((usize::MAX - 2).saturating_add(1), usize::MAX - 1); + } + + #[test] + fn test_saturating_sub_uint() { + 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!((usize::MAX - 1).saturating_sub(usize::MAX), 0); + } + + #[test] + fn test_saturating_add_int() { + assert_eq!(3i32.saturating_add(5), 8); + assert_eq!(3isize.saturating_add(isize::MAX - 1), isize::MAX); + assert_eq!(isize::MAX.saturating_add(isize::MAX), isize::MAX); + assert_eq!((isize::MAX - 2).saturating_add(1), isize::MAX - 1); + assert_eq!(3i32.saturating_add(-5), -2); + assert_eq!(isize::MIN.saturating_add(-1), isize::MIN); + assert_eq!((-2isize).saturating_add(-isize::MAX), isize::MIN); + } + + #[test] + fn test_saturating_sub_int() { + assert_eq!(3i32.saturating_sub(5), -2); + assert_eq!(isize::MIN.saturating_sub(1), isize::MIN); + assert_eq!((-2isize).saturating_sub(isize::MAX), isize::MIN); + assert_eq!(3i32.saturating_sub(-5), 8); + assert_eq!(3isize.saturating_sub(-(isize::MAX - 1)), isize::MAX); + assert_eq!(isize::MAX.saturating_sub(-isize::MAX), isize::MAX); + assert_eq!((isize::MAX - 2).saturating_sub(-1), isize::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)); + }); + } +} |