str0m 0.6.3

WebRTC library in Sans-IO style
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
152
153
154
155

use std::{
    ops::{Add, AddAssign, Sub, SubAssign},
    time::{Duration, Instant},
};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]

/// This is created to ease the modeling of values that represent a moment
/// that is far in the future or in the past, yet allowing PartialEq, Ord, Add,
/// "transparently".
//
// Before doing this, a workaround like Optional<Instant> was considered,
// but it would not clarify whether the absence of a value would be considered
// as a distant past or distant future and it would have to be handled on a
// case-by-case basis.
pub(crate) enum SuperInstant {
    DistantPast,
    Value { instant: Instant },
    DistantFuture,
}

impl SuperInstant {
    #[cfg(test)]
    pub fn now() -> Self {
        Self::Value {
            instant: Instant::now(),
        }
    }

    pub fn is_finite(&self) -> bool {
        matches!(self, Self::Value { .. })
    }

    pub fn is_not_finite(&self) -> bool {
        !self.is_finite()
    }

    pub fn as_instant(&self) -> Option<Instant> {
        match self {
            Self::DistantPast | Self::DistantFuture => None,
            Self::Value { instant } => Some(*instant),
        }
    }
}

impl PartialOrd for SuperInstant {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        match (self, other) {
            (Self::DistantPast, Self::DistantPast) => Some(std::cmp::Ordering::Equal),
            (Self::DistantPast, _) => Some(std::cmp::Ordering::Less),
            (_, Self::DistantPast) => Some(std::cmp::Ordering::Greater),
            (Self::DistantFuture, Self::DistantFuture) => Some(std::cmp::Ordering::Equal),
            (Self::DistantFuture, _) => Some(std::cmp::Ordering::Greater),
            (_, Self::DistantFuture) => Some(std::cmp::Ordering::Less),
            (Self::Value { instant: a }, Self::Value { instant: b }) => a.partial_cmp(b),
        }
    }
}

impl Sub<Duration> for SuperInstant {
    type Output = Self;

    fn sub(self, rhs: Duration) -> Self::Output {
        match self {
            Self::DistantPast => Self::DistantPast,
            Self::DistantFuture => Self::DistantFuture,
            Self::Value { instant } => Self::Value {
                instant: instant - rhs,
            },
        }
    }
}

impl SubAssign<Duration> for SuperInstant {
    fn sub_assign(&mut self, rhs: Duration) {
        match self {
            Self::DistantPast => {}
            Self::DistantFuture => {}
            Self::Value { instant } => *instant -= rhs,
        }
    }
}

impl AddAssign<Duration> for SuperInstant {
    fn add_assign(&mut self, rhs: Duration) {
        match self {
            Self::DistantPast => {}
            Self::DistantFuture => {}
            Self::Value { instant } => *instant += rhs,
        }
    }
}

impl Add<Duration> for SuperInstant {
    type Output = Self;

    fn add(self, rhs: Duration) -> Self::Output {
        match self {
            Self::DistantPast => Self::DistantPast,
            Self::DistantFuture => Self::DistantFuture,
            Self::Value { instant } => Self::Value {
                instant: instant + rhs,
            },
        }
    }
}

impl From<Instant> for SuperInstant {
    fn from(instant: Instant) -> Self {
        Self::Value { instant }
    }
}

#[cfg(test)]
mod test {
    use std::time::Duration;

    use crate::packet::bwe::super_instant::SuperInstant;

    #[test]
    fn test() {
        let mut past = SuperInstant::DistantPast;
        let mut future = SuperInstant::DistantFuture;
        let now = SuperInstant::now();
        assert!(past < now);
        assert!(now > past);

        assert!(now < future);
        assert!(future > now);

        assert!(past < future);
        assert!(future > past);

        assert!(now == now);
        assert!(past == past);
        assert!(future == future);

        assert!(now != past);
        assert!(now != future);
        assert!(future != past);

        assert!(past - Duration::from_secs(1) == past);
        past -= Duration::from_secs(1);
        assert!(past == past);
        past += Duration::from_secs(1);
        assert!(past == past);

        assert!(future + Duration::from_secs(1) == future);
        assert!(future - Duration::from_secs(1) == future);
        future -= Duration::from_secs(1);
        assert!(future == future);
        future += Duration::from_secs(1);
        assert!(future == future);
    }
}