1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

use num::arithmetic::traits::{Parity, Pow, PowAssign};
use num::conversion::traits::ExactFrom;

macro_rules! impl_pow_unsigned {
    ($t:ident) => {
        impl Pow<u64> for $t {
            type Output = $t;

            /// This is a wrapper over the `pow` functions in the standard library, for example
            /// [this one](u32::pow).
            #[inline]
            fn pow(self, exp: u64) -> $t {
                if exp == 0 {
                    1
                } else if self < 2 {
                    self
                } else {
                    self.pow(u32::exact_from(exp))
                }
            }
        }
    };
}
apply_to_unsigneds!(impl_pow_unsigned);

macro_rules! impl_pow_signed {
    ($t:ident) => {
        impl Pow<u64> for $t {
            type Output = $t;

            /// This is a wrapper over the `pow` functions in the standard library, for example
            /// [this one](i32::pow).
            #[inline]
            fn pow(self, exp: u64) -> $t {
                if exp == 0 {
                    1
                } else if self == 0 || self == 1 {
                    self
                } else if self == -1 {
                    if exp.even() {
                        1
                    } else {
                        -1
                    }
                } else {
                    self.pow(u32::exact_from(exp))
                }
            }
        }
    };
}
apply_to_signeds!(impl_pow_signed);

macro_rules! impl_pow_primitive_int {
    ($t:ident) => {
        impl PowAssign<u64> for $t {
            /// Raises a number to a power, in place.
            ///
            /// # Worst-case complexity
            /// $T(n) = O(n)$
            ///
            /// $M(n) = O(1)$
            ///
            /// where $T$ is time, $M$ is additional memory, and $n$ is `exp.significant_bits()`.
            ///
            /// # Examples
            /// See [here](super::pow#pow_assign).
            #[inline]
            fn pow_assign(&mut self, exp: u64) {
                *self = Pow::pow(*self, exp);
            }
        }
    };
}
apply_to_primitive_ints!(impl_pow_primitive_int);

macro_rules! impl_pow_primitive_float {
    ($t:ident) => {
        impl Pow<i64> for $t {
            type Output = $t;

            /// This is a wrapper over the `powi` functions in the standard library, for example
            /// [this one](f32::powi).
            #[inline]
            fn pow(self, exp: i64) -> $t {
                self.powi(i32::exact_from(exp))
            }
        }

        impl PowAssign<i64> for $t {
            /// Raises a number to a power, in place.
            ///
            /// # Worst-case complexity
            /// Constant time and additional memory.
            ///
            /// # Examples
            /// See [here](super::pow#pow_assign).
            #[inline]
            fn pow_assign(&mut self, exp: i64) {
                *self = self.powi(i32::exact_from(exp));
            }
        }

        impl Pow<$t> for $t {
            type Output = $t;

            /// This is a wrapper over the `powf` functions in the standard library, for example
            /// [this one](f32::powf).
            #[inline]
            fn pow(self, exp: $t) -> $t {
                self.powf(exp)
            }
        }

        impl PowAssign<$t> for $t {
            /// Raises a number to a power, in place.
            ///
            /// # Worst-case complexity
            /// Constant time and additional memory.
            ///
            /// # Examples
            /// See [here](super::pow#pow_assign).
            #[inline]
            fn pow_assign(&mut self, exp: $t) {
                *self = self.powf(exp);
            }
        }
    };
}
apply_to_primitive_floats!(impl_pow_primitive_float);