rxrust 0.4.0

A Rust implementation of Reactive Extensions.
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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179

use crate::ops::SharedOp;
use crate::prelude::*;
/// Emits only the first `count` values emitted by the source Observable.
///
/// `take` returns an Observable that emits only the first `count` values
/// emitted by the source Observable. If the source emits fewer than `count`
/// values then all of its values are emitted. After that, it completes,
/// regardless if the source completes.
///
/// # Example
/// Take the first 5 seconds of an infinite 1-second interval Observable
///
/// ```
/// # use rxrust::{
///   ops::{Take}, prelude::*,
/// };
///
/// observable::from_iter!(0..10).take(5).subscribe(|v| println!("{}", v));
///

/// // print logs:
/// // 0
/// // 1
/// // 2
/// // 3
/// // 4
/// ```
///
pub trait Take {
  fn take(self, count: u32) -> TakeOp<Self>
  where
    Self: Sized,
  {
    TakeOp {
      source: self,
      count,
    }
  }
}

impl<O> Take for O {}

pub struct TakeOp<S> {
  source: S,
  count: u32,
}

impl<S> IntoShared for TakeOp<S>
where
  S: IntoShared,
{
  type Shared = SharedOp<TakeOp<S::Shared>>;
  fn to_shared(self) -> Self::Shared {
    SharedOp(TakeOp {
      source: self.source.to_shared(),
      count: self.count,
    })
  }
}

impl<Item, Err, O, U, S> RawSubscribable<Item, Err, Subscriber<O, U>>
  for TakeOp<S>
where
  S: RawSubscribable<Item, Err, Subscriber<TakeObserver<O, U>, U>>,
  U: SubscriptionLike + Clone + 'static,
{
  type Unsub = S::Unsub;
  fn raw_subscribe(self, subscriber: Subscriber<O, U>) -> Self::Unsub {
    let subscriber = Subscriber {
      observer: TakeObserver {
        observer: subscriber.observer,
        subscription: subscriber.subscription.clone(),
        count: self.count,
        hits: 0,
      },
      subscription: subscriber.subscription,
    };
    self.source.raw_subscribe(subscriber)
  }
}

pub struct TakeObserver<O, S> {
  observer: O,
  subscription: S,
  count: u32,
  hits: u32,
}

impl<S, ST> IntoShared for TakeObserver<S, ST>
where
  S: IntoShared,
  ST: IntoShared,
{
  type Shared = TakeObserver<S::Shared, ST::Shared>;
  fn to_shared(self) -> Self::Shared {
    TakeObserver {
      observer: self.observer.to_shared(),
      subscription: self.subscription.to_shared(),
      count: self.count,
      hits: self.hits,
    }
  }
}

impl<S, ST, Item, Err> Observer<Item, Err> for TakeObserver<S, ST>
where
  S: Observer<Item, Err>,
  ST: SubscriptionLike,
{
  fn next(&mut self, value: &Item) {
    if self.hits < self.count {
      self.hits += 1;
      self.observer.next(value);
      if self.hits == self.count {
        self.complete();
        self.subscription.unsubscribe();
      }
    }
  }
  #[inline(always)]
  fn error(&mut self, err: &Err) { self.observer.error(err); }
  #[inline(always)]
  fn complete(&mut self) { self.observer.complete(); }
}

impl<S> Fork for TakeOp<S>
where
  S: Fork,
{
  type Output = TakeOp<S::Output>;
  fn fork(&self) -> Self::Output {
    TakeOp {
      source: self.source.fork(),
      count: self.count,
    }
  }
}

#[cfg(test)]
mod test {
  use super::Take;
  use crate::prelude::*;

  #[test]
  fn base_function() {
    let mut completed = false;
    let mut next_count = 0;

    observable::from_iter!(0..100)
      .take(5)
      .subscribe_complete(|_| next_count += 1, || completed = true);

    assert_eq!(next_count, 5);
    assert_eq!(completed, true);
  }

  #[test]
  fn take_support_fork() {
    let mut nc1 = 0;
    let mut nc2 = 0;
    let take5 = observable::from_iter!(0..100).take(5);
    let f1 = take5.fork();
    let f2 = take5.fork();
    f1.take(5).fork().subscribe(|_| nc1 += 1);
    f2.take(5).fork().subscribe(|_| nc2 += 1);

    assert_eq!(nc1, 5);
    assert_eq!(nc2, 5);
  }

  #[test]
  fn into_shared() {
    observable::from_iter!(0..100)
      .take(5)
      .take(5)
      .to_shared()
      .subscribe(|_| {});
  }
}