rx_rust/operators/combining/
zip.rs

1use crate::safe_lock_option_observer;
2use crate::utils::types::{Mutable, MutableHelper, NecessarySendSync, Shared};
3use crate::{
4    disposable::subscription::Subscription,
5    observable::Observable,
6    observer::{Observer, Termination},
7    utils::unsub_after_termination::subscribe_unsub_after_termination,
8};
9use educe::Educe;
10use std::collections::VecDeque;
11
12/// Combines the emissions of multiple Observables together via a specified function and emits single items for each combination based on the sequence of their emissions.
13/// See <https://reactivex.io/documentation/operators/zip.html>
14///
15/// # Examples
16/// ```rust
17/// use rx_rust::{
18///     observable::observable_ext::ObservableExt,
19///     observer::Termination,
20///     operators::{
21///         combining::zip::Zip,
22///         creating::from_iter::FromIter,
23///     },
24/// };
25///
26/// let mut values = Vec::new();
27/// let mut terminations = Vec::new();
28///
29/// let observable = Zip::new(
30///     FromIter::new(vec![1, 2]),
31///     FromIter::new(vec![10, 20]),
32/// );
33/// observable.subscribe_with_callback(
34///     |value| values.push(value),
35///     |termination| terminations.push(termination),
36/// );
37///
38/// assert_eq!(values, vec![(1, 10), (2, 20)]);
39/// assert_eq!(terminations, vec![Termination::Completed]);
40/// ```
41#[derive(Educe)]
42#[educe(Debug, Clone)]
43pub struct Zip<OE1, OE2> {
44    source_1: OE1,
45    source_2: OE2,
46}
47
48impl<OE1, OE2> Zip<OE1, OE2> {
49    pub fn new<'or, 'sub, T1, T2, E>(source_1: OE1, source_2: OE2) -> Self
50    where
51        OE1: Observable<'or, 'sub, T1, E>,
52        OE2: Observable<'or, 'sub, T2, E>,
53    {
54        Self { source_1, source_2 }
55    }
56}
57
58impl<'or, 'sub, T1, T2, E, OE1, OE2> Observable<'or, 'sub, (T1, T2), E> for Zip<OE1, OE2>
59where
60    T1: NecessarySendSync + 'or,
61    T2: NecessarySendSync + 'or,
62    OE1: Observable<'or, 'sub, T1, E>,
63    OE2: Observable<'or, 'sub, T2, E>,
64    'sub: 'or,
65{
66    fn subscribe(
67        self,
68        observer: impl Observer<(T1, T2), E> + NecessarySendSync + 'or,
69    ) -> Subscription<'sub> {
70        subscribe_unsub_after_termination(observer, |observer| {
71            let observer = Shared::new(Mutable::new(Some(observer)));
72            let buffer = Shared::new(Mutable::new(ZipObserverBufferState::None));
73            let observer_1 = ZipObserver1 {
74                observer: observer.clone(),
75                buffer: buffer.clone(),
76            };
77            let observer_2 = ZipObserver2 { observer, buffer };
78            let subscription_1 = self.source_1.subscribe(observer_1);
79            let subscription_2 = self.source_2.subscribe(observer_2);
80            subscription_1 + subscription_2
81        })
82    }
83}
84
85enum ZipObserverBufferState<T1, T2> {
86    None,
87    One {
88        buffer: VecDeque<T1>,
89        is_completed: bool,
90    },
91    Two {
92        buffer: VecDeque<T2>,
93        is_completed: bool,
94    },
95}
96
97struct ZipObserver1<T1, T2, OR> {
98    observer: Shared<Mutable<Option<OR>>>,
99    buffer: Shared<Mutable<ZipObserverBufferState<T1, T2>>>,
100}
101
102impl<T1, T2, E, OR> Observer<T1, E> for ZipObserver1<T1, T2, OR>
103where
104    OR: Observer<(T1, T2), E>,
105{
106    fn on_next(&mut self, value: T1) {
107        self.buffer.lock_mut(|mut lock| match &mut *lock {
108            ZipObserverBufferState::None => {
109                *lock = ZipObserverBufferState::One {
110                    buffer: VecDeque::from([value]),
111                    is_completed: false,
112                };
113            }
114            ZipObserverBufferState::One { buffer: items, .. } => {
115                items.push_back(value);
116            }
117            ZipObserverBufferState::Two {
118                buffer: items,
119                is_completed,
120            } => {
121                let item = items.pop_front().unwrap();
122                let should_complete;
123                if items.is_empty() {
124                    should_complete = *is_completed;
125                    *lock = ZipObserverBufferState::None;
126                } else {
127                    should_complete = false;
128                }
129                drop(lock);
130                if should_complete {
131                    safe_lock_option_observer!(on_next_and_termination: self.observer, (value, item), Termination::Completed);
132                } else {
133                    safe_lock_option_observer!(on_next: self.observer, (value, item));
134                }
135            }
136        });
137    }
138
139    fn on_termination(self, termination: Termination<E>) {
140        let should_terminate = match termination {
141            Termination::Completed => self.buffer.lock_mut(|mut lock| match &mut *lock {
142                ZipObserverBufferState::None => true,
143                ZipObserverBufferState::One { is_completed, .. } => {
144                    *is_completed = true;
145                    false
146                }
147                ZipObserverBufferState::Two { .. } => true,
148            }),
149            Termination::Error(_) => true,
150        };
151        if should_terminate {
152            safe_lock_option_observer!(on_termination: self.observer, termination);
153        }
154    }
155}
156
157struct ZipObserver2<T1, T2, OR> {
158    observer: Shared<Mutable<Option<OR>>>,
159    buffer: Shared<Mutable<ZipObserverBufferState<T1, T2>>>,
160}
161
162impl<T1, T2, E, OR> Observer<T2, E> for ZipObserver2<T1, T2, OR>
163where
164    OR: Observer<(T1, T2), E>,
165{
166    fn on_next(&mut self, value: T2) {
167        self.buffer.lock_mut(|mut lock| match &mut *lock {
168            ZipObserverBufferState::None => {
169                *lock = ZipObserverBufferState::Two {
170                    buffer: VecDeque::from([value]),
171                    is_completed: false,
172                };
173            }
174            ZipObserverBufferState::One {
175                buffer: items,
176                is_completed,
177            } => {
178                let item = items.pop_front().unwrap();
179                let should_complete;
180                if items.is_empty() {
181                    should_complete = *is_completed;
182                    *lock = ZipObserverBufferState::None;
183                } else {
184                    should_complete = false;
185                }
186                drop(lock);
187                if should_complete {
188                    safe_lock_option_observer!(on_next_and_termination: self.observer, (item, value), Termination::Completed);
189                } else {
190                    safe_lock_option_observer!(on_next: self.observer, (item, value));
191                }
192            }
193            ZipObserverBufferState::Two { buffer: items, .. } => {
194                items.push_back(value);
195            }
196        });
197    }
198
199    fn on_termination(self, termination: Termination<E>) {
200        let should_terminate = match termination {
201            Termination::Completed => self.buffer.lock_mut(|mut lock| match &mut *lock {
202                ZipObserverBufferState::None => true,
203                ZipObserverBufferState::One { .. } => true,
204                ZipObserverBufferState::Two { is_completed, .. } => {
205                    *is_completed = true;
206                    false
207                }
208            }),
209            Termination::Error(_) => true,
210        };
211        if should_terminate {
212            safe_lock_option_observer!(on_termination: self.observer, termination);
213        }
214    }
215}
rx_rust/operators/combining/zip.rs

rx_rust/operators/combining/
zip.rs
