unit-intervals 0.1.0

Constrained f32/f64 wrapper types for normalized [0, 1] and [-1, 1] values.
Documentation 
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
147
148
149
150
151

use std::string::ToString;

use unit_intervals::UnitInterval;

#[test]
fn f32_constructor_accepts_unit_interval() {
    let default_width: UnitInterval = UnitInterval::new(0.5).unwrap();

    assert_eq!(default_width.get(), 0.5);
    assert_eq!(UnitInterval::<f32>::new(0.0).map(|u| u.get()), Some(0.0));
    assert_eq!(UnitInterval::<f32>::new(0.5).map(|u| u.get()), Some(0.5));
    assert_eq!(UnitInterval::<f32>::new(1.0).map(|u| u.get()), Some(1.0));
    assert_eq!(UnitInterval::<f32>::new(-0.1), None);
    assert_eq!(UnitInterval::<f32>::new(1.1), None);
}

#[test]
fn f64_constructor_accepts_unit_interval() {
    assert_eq!(UnitInterval::<f64>::new(0.0).map(|u| u.get()), Some(0.0));
    assert_eq!(UnitInterval::<f64>::new(0.5).map(|u| u.get()), Some(0.5));
    assert_eq!(UnitInterval::<f64>::new(1.0).map(|u| u.get()), Some(1.0));
    assert_eq!(UnitInterval::<f64>::new(-0.1), None);
    assert_eq!(UnitInterval::<f64>::new(1.1), None);
}

#[test]
fn constructors_reject_nan() {
    assert_eq!(UnitInterval::<f32>::new(f32::NAN), None);
    assert_eq!(UnitInterval::<f64>::new(f64::NAN), None);
}

#[test]
fn saturating_clamps_for_both_float_widths() {
    assert_eq!(UnitInterval::<f32>::saturating(-0.1).get(), 0.0);
    assert_eq!(UnitInterval::<f32>::saturating(1.1).get(), 1.0);
    assert_eq!(UnitInterval::<f32>::saturating(f32::NAN).get(), 0.0);
    assert_eq!(UnitInterval::<f64>::saturating(-0.1).get(), 0.0);
    assert_eq!(UnitInterval::<f64>::saturating(1.1).get(), 1.0);
    assert_eq!(UnitInterval::<f64>::saturating(f64::NAN).get(), 0.0);
}

#[test]
fn constants_and_basic_helpers_work() {
    assert_eq!(UnitInterval::<f32>::default(), UnitInterval::<f32>::ZERO);
    assert_eq!(UnitInterval::<f32>::ZERO.get(), 0.0);
    assert_eq!(UnitInterval::<f32>::HALF.get(), 0.5);
    assert_eq!(UnitInterval::<f32>::ONE.get(), 1.0);
    assert!(UnitInterval::<f32>::contains(0.5));
    assert!(!UnitInterval::<f32>::contains(1.5));
    assert!(UnitInterval::<f32>::ZERO.is_zero());
    assert!(UnitInterval::<f32>::ONE.is_one());
    assert_eq!(UnitInterval::new(0.25).unwrap().complement().get(), 0.75);
}

#[test]
fn standard_conversions_are_available() {
    let from_result = UnitInterval::<f32>::try_from(0.5).unwrap();
    let as_f64_interval = UnitInterval::<f64>::from(from_result);
    let as_f32_interval = UnitInterval::<f32>::from(as_f64_interval);

    assert_eq!(from_result.get(), 0.5);
    assert_eq!(
        UnitInterval::<f32>::try_from(1.5).unwrap_err().to_string(),
        "value is outside the unit interval"
    );
    assert_eq!(as_f64_interval.get(), 0.5);
    assert_eq!(as_f32_interval.get(), 0.5);
}

#[test]
fn comparison_helpers_preserve_unit_interval() {
    let low = UnitInterval::new(0.25).unwrap();
    let high = UnitInterval::new(0.75).unwrap();

    assert_eq!(low.min(high), low);
    assert_eq!(low.max(high), high);
    assert_eq!(low.midpoint(high).get(), 0.5);
    assert_eq!(low.distance_to(high).get(), 0.5);
}

#[test]
fn checked_arithmetic_rejects_out_of_range_results() {
    let low = UnitInterval::new(0.25).unwrap();
    let high = UnitInterval::new(0.75).unwrap();

    assert_eq!(low.checked_add(low).map(|u| u.get()), Some(0.5));
    assert_eq!(high.checked_add(high), None);
    assert_eq!(high.checked_sub(low).map(|u| u.get()), Some(0.5));
    assert_eq!(low.checked_sub(high), None);
    assert_eq!(low.checked_div(high).map(|u| u.get()), Some(1.0 / 3.0));
    assert_eq!(high.checked_div(low), None);
    assert_eq!(low.checked_scale(2.0).map(|u| u.get()), Some(0.5));
    assert_eq!(high.checked_scale(2.0), None);
}

#[test]
fn saturating_arithmetic_clamps_out_of_range_results() {
    let low = UnitInterval::new(0.25).unwrap();
    let high = UnitInterval::new(0.75).unwrap();

    assert_eq!(high.saturating_add(high).get(), 1.0);
    assert_eq!(low.saturating_sub(high).get(), 0.0);
    assert_eq!(high.saturating_div(low).get(), 1.0);
    assert_eq!(low.saturating_scale(-1.0).get(), 0.0);
    assert_eq!(high.saturating_scale(2.0).get(), 1.0);
}

#[test]
fn multiplication_and_lerp_are_convenient() {
    let low = UnitInterval::new(0.25).unwrap();
    let high = UnitInterval::new(0.75).unwrap();

    assert_eq!((low * high).get(), 0.1875);
    assert_eq!(UnitInterval::<f32>::HALF.lerp(10.0, 20.0), 15.0);
}

#[test]
fn unconstrained_arithmetic_returns_backing_float() {
    let low = UnitInterval::<f32>::new(0.25).unwrap();
    let high = UnitInterval::<f32>::new(0.75).unwrap();

    let sum: f32 = low + high;
    let difference: f32 = low - high;
    let product: UnitInterval<f32> = low * high;
    let scaled: f32 = low * 4.0;
    let reverse_scaled: f32 = 4.0 * low;
    let quotient: f32 = high / low;
    let remainder: f32 = high % low;
    let negated: f32 = -low;

    assert_eq!(sum, 1.0);
    assert_eq!(difference, -0.5);
    assert_eq!(product.get(), 0.1875);
    assert_eq!(scaled, 1.0);
    assert_eq!(reverse_scaled, 1.0);
    assert_eq!(quotient, 3.0);
    assert_eq!(remainder, 0.0);
    assert_eq!(negated, -0.25);
}

#[test]
fn comparisons_work_against_backing_float() {
    let half = UnitInterval::<f32>::HALF;

    assert_eq!(half, 0.5);
    assert_eq!(0.5, half);
    assert!(half < 0.75);
    assert!(0.25 < half);
    assert!(half >= 0.5);
    assert!(0.5 <= half);
}