another_rxrust/operators/
scan.rs

1use crate::internals::{function_wrapper::*, stream_controller::*};
2use crate::prelude::*;
3use std::sync::{Arc, RwLock};
4
5#[derive(Clone)]
6pub struct Scan<'a, Item>
7where
8  Item: Clone + Send + Sync,
9{
10  reduce_f: FunctionWrapper<'a, (Item, Item), Item>,
11}
12
13impl<'a, Item> Scan<'a, Item>
14where
15  Item: Clone + Send + Sync,
16{
17  pub fn new<F>(f: F) -> Scan<'a, Item>
18  where
19    F: Fn((Item, Item)) -> Item + Send + Sync + 'a,
20  {
21    Scan { reduce_f: FunctionWrapper::new(f) }
22  }
23  pub fn execute(&self, source: Observable<'a, Item>) -> Observable<'a, Item> {
24    let f = self.reduce_f.clone();
25
26    Observable::<Item>::create(move |s| {
27      let f = f.clone();
28      let result = Arc::new(RwLock::new(None::<Item>));
29
30      let sctl = StreamController::new(s);
31      let sctl_next = sctl.clone();
32      let sctl_error = sctl.clone();
33      let sctl_complete = sctl.clone();
34
35      let result_next = Arc::clone(&result);
36
37      source.inner_subscribe(sctl.new_observer(
38        move |_, x| {
39          {
40            let mut r = result_next.write().unwrap();
41            if let Some(xx) = &*r {
42              *r = Some(f.call((xx.clone(), x)));
43            } else {
44              *r = Some(x);
45            }
46          }
47          if let Some(x) = &*result_next.read().unwrap() {
48            sctl_next.sink_next(x.clone());
49          }
50        },
51        move |_, e| {
52          sctl_error.sink_error(e);
53        },
54        move |serial| {
55          sctl_complete.sink_complete(&serial);
56        },
57      ));
58    })
59  }
60}
61
62impl<'a, Item> Observable<'a, Item>
63where
64  Item: Clone + Send + Sync,
65{
66  pub fn scan<F>(&self, f: F) -> Observable<'a, Item>
67  where
68    F: Fn((Item, Item)) -> Item + Send + Sync + 'a,
69  {
70    Scan::new(f).execute(self.clone())
71  }
72}
73
74#[cfg(test)]
75mod test {
76  use crate::prelude::*;
77
78  #[test]
79  fn basic() {
80    observables::range(1, 10).scan(|(a, b)| a + b).subscribe(
81      print_next_fmt!("{}"),
82      print_error!(),
83      print_complete!(),
84    );
85  }
86
87  #[test]
88  fn string() {
89    observables::from_iter(
90      ["a".to_owned(), "b".to_owned(), "c".to_owned()].into_iter(),
91    )
92    .scan(|(a, b)| format!("{} - {}", a, b))
93    .subscribe(
94      print_next_fmt!("{}"),
95      print_error!(),
96      print_complete!(),
97    );
98  }
99
100  #[test]
101  fn single() {
102    observables::just(1).scan(|(a, b)| a + b).subscribe(
103      print_next_fmt!("{}"),
104      print_error!(),
105      print_complete!(),
106    );
107  }
108
109  #[test]
110  fn empty() {
111    observables::empty::<i32>().scan(|(a, b)| a + b).subscribe(
112      print_next_fmt!("{}"),
113      print_error!(),
114      print_complete!(),
115    );
116  }
117
118  #[test]
119  fn error() {
120    Observable::create(|s| {
121      s.next(1);
122      s.error(RxError::from_error("ERR!"))
123    })
124    .scan(|(a, b)| a + b)
125    .subscribe(
126      print_next_fmt!("{}"),
127      print_error_as!(&str),
128      print_complete!(),
129    );
130  }
131}
another_rxrust/operators/scan.rs

another_rxrust/operators/
scan.rs
