[rustc.git] / src / libstd / num.rs

//! 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::{FpCategory, ParseIntError, ParseFloatError, TryFromIntError};
#[stable(feature = "rust1", since = "1.0.0")]
pub use core::num::Wrapping;

#[stable(feature = "nonzero", since = "1.28.0")]
pub use core::num::{NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize};

#[cfg(test)] use fmt;
#[cfg(test)] use ops::{Add, Sub, Mul, Div, Rem};

/// 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 u8;
    use u16;
    use u32;
    use u64;
    use usize;
    use ops::Mul;

    #[test]
    fn test_saturating_add_uint() {
        use 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 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 isize::{MIN,MAX};
        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 isize::{MIN,MAX};
        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: ::str::FromStr>(t: &str) -> Option<T> {
        ::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 {
    extern crate test;
    use self::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));});
    }
}
Commit	Line	Data
7453a54e	1	//! Additional functionality for numerics.
1a4d82fc	2	//!
7453a54e SL	3	//! This module provides some extra types that are useful when doing numerical
7453a54e SL	4	//! work. See the individual documentation for each piece for more information.
1a4d82fc	5
85aaf69f	6	#![stable(feature = "rust1", since = "1.0.0")]
1a4d82fc JJ	7	#![allow(missing_docs)]
1a4d82fc JJ	8
92a42be0	9	#[stable(feature = "rust1", since = "1.0.0")]
a7813a04	10	pub use core::num::{FpCategory, ParseIntError, ParseFloatError, TryFromIntError};
92a42be0	11	#[stable(feature = "rust1", since = "1.0.0")]
54a0048b	12	pub use core::num::Wrapping;
1a4d82fc	13
94b46f34 XL	14	#[stable(feature = "nonzero", since = "1.28.0")]
94b46f34 XL	15	pub use core::num::{NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize};
0531ce1d	16
d9579d0f	17	#[cfg(test)] use fmt;
d9579d0f	18	#[cfg(test)] use ops::{Add, Sub, Mul, Div, Rem};
1a4d82fc JJ	19
	20	/// Helper function for testing numeric operations
	21	#[cfg(test)]
	22	pub fn test_num<T>(ten: T, two: T) where
9346a6ac	23	T: PartialEq
1a4d82fc JJ	24	+ Add<Output=T> + Sub<Output=T>
1a4d82fc JJ	25	+ Mul<Output=T> + Div<Output=T>
9346a6ac	26	+ Rem<Output=T> + fmt::Debug
1a4d82fc JJ	27	+ Copy
1a4d82fc JJ	28	{
1a4d82fc JJ	29	assert_eq!(ten.add(two), ten + two);
	30	assert_eq!(ten.sub(two), ten - two);
	31	assert_eq!(ten.mul(two), ten * two);
	32	assert_eq!(ten.div(two), ten / two);
	33	assert_eq!(ten.rem(two), ten % two);
	34	}
	35
	36	#[cfg(test)]
	37	mod tests {
1a4d82fc JJ	38	use u8;
	39	use u16;
	40	use u32;
	41	use u64;
c34b1796	42	use usize;
9346a6ac	43	use ops::Mul;
1a4d82fc JJ	44
	45	#[test]
	46	fn test_saturating_add_uint() {
c34b1796	47	use usize::MAX;
85aaf69f SL	48	assert_eq!(3_usize.saturating_add(5_usize), 8_usize);
85aaf69f SL	49	assert_eq!(3_usize.saturating_add(MAX-1), MAX);
1a4d82fc JJ	50	assert_eq!(MAX.saturating_add(MAX), MAX);
	51	assert_eq!((MAX-2).saturating_add(1), MAX-1);
	52	}
	53
	54	#[test]
	55	fn test_saturating_sub_uint() {
c34b1796	56	use usize::MAX;
85aaf69f SL	57	assert_eq!(5_usize.saturating_sub(3_usize), 2_usize);
	58	assert_eq!(3_usize.saturating_sub(5_usize), 0_usize);
	59	assert_eq!(0_usize.saturating_sub(1_usize), 0_usize);
1a4d82fc JJ	60	assert_eq!((MAX-1).saturating_sub(MAX), 0);
	61	}
	62
	63	#[test]
	64	fn test_saturating_add_int() {
c34b1796	65	use isize::{MIN,MAX};
9346a6ac AL	66	assert_eq!(3i32.saturating_add(5), 8);
9346a6ac AL	67	assert_eq!(3isize.saturating_add(MAX-1), MAX);
1a4d82fc JJ	68	assert_eq!(MAX.saturating_add(MAX), MAX);
1a4d82fc JJ	69	assert_eq!((MAX-2).saturating_add(1), MAX-1);
9346a6ac	70	assert_eq!(3i32.saturating_add(-5), -2);
85aaf69f	71	assert_eq!(MIN.saturating_add(-1), MIN);
9346a6ac	72	assert_eq!((-2isize).saturating_add(-MAX), MIN);
1a4d82fc JJ	73	}
	74
	75	#[test]
	76	fn test_saturating_sub_int() {
c34b1796	77	use isize::{MIN,MAX};
9346a6ac	78	assert_eq!(3i32.saturating_sub(5), -2);
85aaf69f	79	assert_eq!(MIN.saturating_sub(1), MIN);
9346a6ac AL	80	assert_eq!((-2isize).saturating_sub(MAX), MIN);
	81	assert_eq!(3i32.saturating_sub(-5), 8);
	82	assert_eq!(3isize.saturating_sub(-(MAX-1)), MAX);
1a4d82fc JJ	83	assert_eq!(MAX.saturating_sub(-MAX), MAX);
	84	assert_eq!((MAX-2).saturating_sub(-1), MAX-1);
	85	}
	86
	87	#[test]
	88	fn test_checked_add() {
c34b1796 AL	89	let five_less = usize::MAX - 5;
	90	assert_eq!(five_less.checked_add(0), Some(usize::MAX - 5));
	91	assert_eq!(five_less.checked_add(1), Some(usize::MAX - 4));
	92	assert_eq!(five_less.checked_add(2), Some(usize::MAX - 3));
	93	assert_eq!(five_less.checked_add(3), Some(usize::MAX - 2));
	94	assert_eq!(five_less.checked_add(4), Some(usize::MAX - 1));
	95	assert_eq!(five_less.checked_add(5), Some(usize::MAX));
1a4d82fc JJ	96	assert_eq!(five_less.checked_add(6), None);
	97	assert_eq!(five_less.checked_add(7), None);
	98	}
	99
	100	#[test]
	101	fn test_checked_sub() {
85aaf69f SL	102	assert_eq!(5_usize.checked_sub(0), Some(5));
	103	assert_eq!(5_usize.checked_sub(1), Some(4));
	104	assert_eq!(5_usize.checked_sub(2), Some(3));
	105	assert_eq!(5_usize.checked_sub(3), Some(2));
	106	assert_eq!(5_usize.checked_sub(4), Some(1));
	107	assert_eq!(5_usize.checked_sub(5), Some(0));
	108	assert_eq!(5_usize.checked_sub(6), None);
	109	assert_eq!(5_usize.checked_sub(7), None);
1a4d82fc JJ	110	}
	111
	112	#[test]
	113	fn test_checked_mul() {
c34b1796	114	let third = usize::MAX / 3;
1a4d82fc JJ	115	assert_eq!(third.checked_mul(0), Some(0));
	116	assert_eq!(third.checked_mul(1), Some(third));
	117	assert_eq!(third.checked_mul(2), Some(third * 2));
	118	assert_eq!(third.checked_mul(3), Some(third * 3));
	119	assert_eq!(third.checked_mul(4), None);
	120	}
	121
	122	macro_rules! test_is_power_of_two {
	123	($test_name:ident, $T:ident) => (
	124	fn $test_name() {
	125	#![test]
	126	assert_eq!((0 as $T).is_power_of_two(), false);
	127	assert_eq!((1 as $T).is_power_of_two(), true);
	128	assert_eq!((2 as $T).is_power_of_two(), true);
	129	assert_eq!((3 as $T).is_power_of_two(), false);
	130	assert_eq!((4 as $T).is_power_of_two(), true);
	131	assert_eq!((5 as $T).is_power_of_two(), false);
c34b1796	132	assert_eq!(($T::MAX / 2 + 1).is_power_of_two(), true);
1a4d82fc JJ	133	}
	134	)
	135	}
	136
	137	test_is_power_of_two!{ test_is_power_of_two_u8, u8 }
	138	test_is_power_of_two!{ test_is_power_of_two_u16, u16 }
	139	test_is_power_of_two!{ test_is_power_of_two_u32, u32 }
	140	test_is_power_of_two!{ test_is_power_of_two_u64, u64 }
c34b1796	141	test_is_power_of_two!{ test_is_power_of_two_uint, usize }
1a4d82fc JJ	142
	143	macro_rules! test_next_power_of_two {
	144	($test_name:ident, $T:ident) => (
	145	fn $test_name() {
	146	#![test]
	147	assert_eq!((0 as $T).next_power_of_two(), 1);
	148	let mut next_power = 1;
c34b1796	149	for i in 1 as $T..40 {
1a4d82fc JJ	150	assert_eq!(i.next_power_of_two(), next_power);
	151	if i == next_power { next_power *= 2 }
	152	}
	153	}
	154	)
	155	}
	156
	157	test_next_power_of_two! { test_next_power_of_two_u8, u8 }
	158	test_next_power_of_two! { test_next_power_of_two_u16, u16 }
	159	test_next_power_of_two! { test_next_power_of_two_u32, u32 }
	160	test_next_power_of_two! { test_next_power_of_two_u64, u64 }
c34b1796	161	test_next_power_of_two! { test_next_power_of_two_uint, usize }
1a4d82fc JJ	162
	163	macro_rules! test_checked_next_power_of_two {
	164	($test_name:ident, $T:ident) => (
	165	fn $test_name() {
	166	#![test]
	167	assert_eq!((0 as $T).checked_next_power_of_two(), Some(1));
041b39d2 XL	168	let smax = $T::MAX >> 1;
	169	assert_eq!(smax.checked_next_power_of_two(), Some(smax+1));
	170	assert_eq!((smax + 1).checked_next_power_of_two(), Some(smax + 1));
	171	assert_eq!((smax + 2).checked_next_power_of_two(), None);
1a4d82fc JJ	172	assert_eq!(($T::MAX - 1).checked_next_power_of_two(), None);
	173	assert_eq!($T::MAX.checked_next_power_of_two(), None);
	174	let mut next_power = 1;
c34b1796	175	for i in 1 as $T..40 {
1a4d82fc JJ	176	assert_eq!(i.checked_next_power_of_two(), Some(next_power));
	177	if i == next_power { next_power *= 2 }
	178	}
	179	}
	180	)
	181	}
	182
	183	test_checked_next_power_of_two! { test_checked_next_power_of_two_u8, u8 }
	184	test_checked_next_power_of_two! { test_checked_next_power_of_two_u16, u16 }
	185	test_checked_next_power_of_two! { test_checked_next_power_of_two_u32, u32 }
	186	test_checked_next_power_of_two! { test_checked_next_power_of_two_u64, u64 }
c34b1796	187	test_checked_next_power_of_two! { test_checked_next_power_of_two_uint, usize }
1a4d82fc	188
1a4d82fc JJ	189	#[test]
1a4d82fc JJ	190	fn test_pow() {
3157f602	191	fn naive_pow<T: Mul<Output=T> + Copy>(one: T, base: T, exp: usize) -> T {
85aaf69f	192	(0..exp).fold(one, \|acc, _\| acc * base)
1a4d82fc JJ	193	}
	194	macro_rules! assert_pow {
	195	(($num:expr, $exp:expr) => $expected:expr) => {{
	196	let result = $num.pow($exp);
	197	assert_eq!(result, $expected);
3157f602	198	assert_eq!(result, naive_pow(1, $num, $exp));
1a4d82fc JJ	199	}}
1a4d82fc JJ	200	}
9346a6ac AL	201	assert_pow!((3u32, 0 ) => 1);
	202	assert_pow!((5u32, 1 ) => 5);
	203	assert_pow!((-4i32, 2 ) => 16);
	204	assert_pow!((8u32, 3 ) => 512);
	205	assert_pow!((2u64, 50) => 1125899906842624);
1a4d82fc	206	}
c34b1796 AL	207
	208	#[test]
	209	fn test_uint_to_str_overflow() {
	210	let mut u8_val: u8 = 255;
	211	assert_eq!(u8_val.to_string(), "255");
	212
	213	u8_val = u8_val.wrapping_add(1);
	214	assert_eq!(u8_val.to_string(), "0");
	215
	216	let mut u16_val: u16 = 65_535;
	217	assert_eq!(u16_val.to_string(), "65535");
	218
	219	u16_val = u16_val.wrapping_add(1);
	220	assert_eq!(u16_val.to_string(), "0");
	221
	222	let mut u32_val: u32 = 4_294_967_295;
	223	assert_eq!(u32_val.to_string(), "4294967295");
	224
	225	u32_val = u32_val.wrapping_add(1);
	226	assert_eq!(u32_val.to_string(), "0");
	227
	228	let mut u64_val: u64 = 18_446_744_073_709_551_615;
	229	assert_eq!(u64_val.to_string(), "18446744073709551615");
	230
	231	u64_val = u64_val.wrapping_add(1);
	232	assert_eq!(u64_val.to_string(), "0");
	233	}
	234
	235	fn from_str<T: ::str::FromStr>(t: &str) -> Option<T> {
	236	::str::FromStr::from_str(t).ok()
	237	}
	238
	239	#[test]
	240	fn test_uint_from_str_overflow() {
	241	let mut u8_val: u8 = 255;
	242	assert_eq!(from_str::<u8>("255"), Some(u8_val));
	243	assert_eq!(from_str::<u8>("256"), None);
	244
	245	u8_val = u8_val.wrapping_add(1);
	246	assert_eq!(from_str::<u8>("0"), Some(u8_val));
	247	assert_eq!(from_str::<u8>("-1"), None);
	248
	249	let mut u16_val: u16 = 65_535;
	250	assert_eq!(from_str::<u16>("65535"), Some(u16_val));
	251	assert_eq!(from_str::<u16>("65536"), None);
	252
	253	u16_val = u16_val.wrapping_add(1);
	254	assert_eq!(from_str::<u16>("0"), Some(u16_val));
	255	assert_eq!(from_str::<u16>("-1"), None);
	256
	257	let mut u32_val: u32 = 4_294_967_295;
	258	assert_eq!(from_str::<u32>("4294967295"), Some(u32_val));
	259	assert_eq!(from_str::<u32>("4294967296"), None);
	260
	261	u32_val = u32_val.wrapping_add(1);
	262	assert_eq!(from_str::<u32>("0"), Some(u32_val));
	263	assert_eq!(from_str::<u32>("-1"), None);
	264
	265	let mut u64_val: u64 = 18_446_744_073_709_551_615;
	266	assert_eq!(from_str::<u64>("18446744073709551615"), Some(u64_val));
	267	assert_eq!(from_str::<u64>("18446744073709551616"), None);
	268
	269	u64_val = u64_val.wrapping_add(1);
	270	assert_eq!(from_str::<u64>("0"), Some(u64_val));
271	assert_eq!(from_str::<u64>("-1"), None);
272	}
1a4d82fc JJ	273	}
	274
	275
	276	#[cfg(test)]
	277	mod bench {
	278	extern crate test;
	279	use self::test::Bencher;
1a4d82fc JJ	280
	281	#[bench]
	282	fn bench_pow_function(b: &mut Bencher) {
9346a6ac AL	283	let v = (0..1024).collect::<Vec<u32>>();
9346a6ac AL	284	b.iter(\|\| {v.iter().fold(0u32, \|old, new\| old.pow(*new as u32));});
1a4d82fc JJ	285	}
1a4d82fc JJ	286	}