rx_rust/operators/conditional_boolean/
skip_while.rs

1use crate::utils::types::MaybeSend;
2use crate::{
3    observable::{Observable, Subscription},
4    observer::{Flow, Observer, Termination},
5};
6use educe::Educe;
7
8/// Discards items emitted by an Observable until a specified condition becomes false.
9/// See <https://reactivex.io/documentation/operators/skipwhile.html>
10///
11/// # Examples
12/// ```rust
13/// use rx_rust::{
14///     observable::ObservableExt,
15///     observer::Termination,
16///     operators::{
17///         conditional_boolean::skip_while::SkipWhile,
18///         creating::from_iter::FromIter,
19///     },
20/// };
21///
22/// let mut values = Vec::new();
23/// let mut terminations = Vec::new();
24///
25/// let observable = SkipWhile::new(FromIter::new(vec![1, 2, 3, 4]), |value| *value < 3);
26/// observable.subscribe_with_callback(
27///     |value| values.push(value),
28///     |termination| terminations.push(termination),
29/// );
30///
31/// assert_eq!(values, vec![3, 4]);
32/// assert_eq!(terminations, vec![Termination::Completed]);
33/// ```
34#[derive(Educe)]
35#[educe(Debug, Clone)]
36pub struct SkipWhile<OE, F> {
37    source: OE,
38    callback: F,
39}
40
41impl<OE, F> SkipWhile<OE, F> {
42    pub fn new<'or, T, E>(source: OE, callback: F) -> Self
43    where
44        OE: Observable<'or, T, E>,
45        F: FnMut(&T) -> bool,
46    {
47        Self { source, callback }
48    }
49}
50
51impl<'or, T, E, OE, F> Observable<'or, T, E> for SkipWhile<OE, F>
52where
53    OE: Observable<'or, T, E>,
54    F: FnMut(&T) -> bool + MaybeSend + 'or,
55{
56    type D = OE::D;
57
58    fn subscribe(self, observer: impl Observer<T, E> + MaybeSend + 'or) -> Subscription<Self::D> {
59        let observer = SkipWhileObserver {
60            observer,
61            callback: self.callback,
62            skip: true,
63        };
64        self.source.subscribe(observer)
65    }
66}
67
68struct SkipWhileObserver<OR, F> {
69    observer: OR,
70    callback: F,
71    skip: bool,
72}
73
74impl<T, E, OR, F> Observer<T, E> for SkipWhileObserver<OR, F>
75where
76    OR: Observer<T, E>,
77    F: FnMut(&T) -> bool,
78{
79    fn on_next(&mut self, value: T) -> Flow {
80        if !self.skip {
81            self.observer.on_next(value)
82        } else {
83            self.skip = (self.callback)(&value);
84            if !self.skip {
85                self.observer.on_next(value)
86            } else {
87                Flow::Continue
88            }
89        }
90    }
91
92    fn on_termination(self, termination: Termination<E>) {
93        self.observer.on_termination(termination)
94    }
95}
rx_rust/operators/conditional_boolean/skip_while.rs

rx_rust/operators/conditional_boolean/
skip_while.rs
