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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

//! Order floating point numbers, into this ordering:
//!
//!    NaN | -Infinity | x < 0 | -0 | +0 | x > 0 | +Infinity | NaN

/* Adapted from https://github.com/notriddle/rust-float-ord revision e995165f
 * maintained by Michael Howell <michael@notriddle.com>
 * licensed under MIT / Apache-2.0 licenses
 * 
 * This version drops any dependency on rand.
 * Caution: Don't pull the version from crates.io
 * before making sure rand is optional.
 */

extern crate core;

use crate::float_ord::core::cmp::{Eq, Ord, Ordering, PartialEq, PartialOrd};
use crate::float_ord::core::hash::{Hash, Hasher};
use crate::float_ord::core::mem::transmute;

/// A wrapper for floats, that implements total equality and ordering
/// and hashing.
#[derive(Clone, Copy)]
pub struct FloatOrd<T>(pub T);

macro_rules! float_ord_impl {
    ($f:ident, $i:ident, $n:expr) => {
        impl FloatOrd<$f> {
            fn convert(self) -> $i {
                let u = unsafe { transmute::<$f, $i>(self.0) };
                let bit = 1 << ($n - 1);
                if u & bit == 0 {
                    u | bit
                } else {
                    !u
                }
            }
        }
        impl PartialEq for FloatOrd<$f> {
            fn eq(&self, other: &Self) -> bool {
                self.convert() == other.convert()
            }
        }
        impl Eq for FloatOrd<$f> {}
        impl PartialOrd for FloatOrd<$f> {
            fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
                self.convert().partial_cmp(&other.convert())
            }
        }
        impl Ord for FloatOrd<$f> {
            fn cmp(&self, other: &Self) -> Ordering {
                self.convert().cmp(&other.convert())
            }
        }
        impl Hash for FloatOrd<$f> {
            fn hash<H: Hasher>(&self, state: &mut H) {
                self.convert().hash(state);
            }
        }
    }
}

float_ord_impl!(f32, u32, 32);
float_ord_impl!(f64, u64, 64);

/// Sort a slice of floats.
///
/// # Allocation behavior
///
/// This routine uses a quicksort implementation that does not heap allocate.
///
/// # Example
///
/// ```
/// use rs::float_ord;
/// let mut v = [-5.0, 4.0, 1.0, -3.0, 2.0];
///
/// float_ord::sort(&mut v);
/// assert!(v == [-5.0, -3.0, 1.0, 2.0, 4.0]);
/// ```
#[allow(dead_code)]
pub fn sort<T>(v: &mut [T]) where FloatOrd<T>: Ord {
    let v_: &mut [FloatOrd<T>] = unsafe { transmute(v) };
    v_.sort_unstable();
}

#[cfg(test)]
mod tests {
    extern crate std;

    use self::std::collections::hash_map::DefaultHasher;
    use self::std::hash::{Hash, Hasher};
    use super::FloatOrd;

    #[test]
    fn test_ord() {
        assert!(FloatOrd(1.0f64) < FloatOrd(2.0f64));
        assert!(FloatOrd(2.0f32) > FloatOrd(1.0f32));
        assert!(FloatOrd(1.0f64) == FloatOrd(1.0f64));
        assert!(FloatOrd(1.0f32) == FloatOrd(1.0f32));
        assert!(FloatOrd(0.0f64) > FloatOrd(-0.0f64));
        assert!(FloatOrd(0.0f32) > FloatOrd(-0.0f32));
        assert!(FloatOrd(crate::float_ord::core::f64::NAN) == FloatOrd(crate::float_ord::core::f64::NAN));
        assert!(FloatOrd(crate::float_ord::core::f32::NAN) == FloatOrd(crate::float_ord::core::f32::NAN));
        assert!(FloatOrd(-crate::float_ord::core::f64::NAN) < FloatOrd(crate::float_ord::core::f64::NAN));
        assert!(FloatOrd(-crate::float_ord::core::f32::NAN) < FloatOrd(crate::float_ord::core::f32::NAN));
        assert!(FloatOrd(-crate::float_ord::core::f64::INFINITY) < FloatOrd(crate::float_ord::core::f64::INFINITY));
        assert!(FloatOrd(-crate::float_ord::core::f32::INFINITY) < FloatOrd(crate::float_ord::core::f32::INFINITY));
        assert!(FloatOrd(crate::float_ord::core::f64::INFINITY) < FloatOrd(crate::float_ord::core::f64::NAN));
        assert!(FloatOrd(crate::float_ord::core::f32::INFINITY) < FloatOrd(crate::float_ord::core::f32::NAN));
        assert!(FloatOrd(-crate::float_ord::core::f64::NAN) < FloatOrd(crate::float_ord::core::f64::INFINITY));
        assert!(FloatOrd(-crate::float_ord::core::f32::NAN) < FloatOrd(crate::float_ord::core::f32::INFINITY));
    }

    fn hash<F: Hash>(f: F) -> u64 {
        let mut hasher = DefaultHasher::new();
        f.hash(&mut hasher);
        hasher.finish()
    }

    #[test]
    fn test_hash() {
        assert_ne!(hash(FloatOrd(0.0f64)), hash(FloatOrd(-0.0f64)));
        assert_ne!(hash(FloatOrd(0.0f32)), hash(FloatOrd(-0.0f32)));
        assert_eq!(hash(FloatOrd(-0.0f64)), hash(FloatOrd(-0.0f64)));
        assert_eq!(hash(FloatOrd(0.0f32)), hash(FloatOrd(0.0f32)));
        assert_ne!(hash(FloatOrd(crate::float_ord::core::f64::NAN)), hash(FloatOrd(-crate::float_ord::core::f64::NAN)));
        assert_ne!(hash(FloatOrd(crate::float_ord::core::f32::NAN)), hash(FloatOrd(-crate::float_ord::core::f32::NAN)));
        assert_eq!(hash(FloatOrd(crate::float_ord::core::f64::NAN)), hash(FloatOrd(crate::float_ord::core::f64::NAN)));
        assert_eq!(hash(FloatOrd(-crate::float_ord::core::f32::NAN)), hash(FloatOrd(-crate::float_ord::core::f32::NAN)));
    }

    #[test]
    fn test_sort_nan() {
        let nan = crate::float_ord::core::f64::NAN;
        let mut v = [-1.0, 5.0, 0.0, -0.0, nan, 1.5, nan, 3.7];
        super::sort(&mut v);
        assert!(v[0] == -1.0);
        assert!(v[1] == 0.0 && v[1].is_sign_negative());
        assert!(v[2] == 0.0 && !v[2].is_sign_negative());
        assert!(v[3] == 1.5);
        assert!(v[4] == 3.7);
        assert!(v[5] == 5.0);
        assert!(v[6].is_nan());
        assert!(v[7].is_nan());
    }
}