react_rs_core/
signal.rs

1use std::cell::RefCell;
2use std::rc::Rc;
3
4use crate::effect::flush_effects;
5use crate::runtime::RUNTIME;
6
7type SubscriberId = usize;
8
9struct SignalInner<T> {
10    value: T,
11    subscribers: Vec<SubscriberId>,
12    version: u64,
13}
14
15pub struct ReadSignal<T> {
16    inner: Rc<RefCell<SignalInner<T>>>,
17}
18
19impl<T> Clone for ReadSignal<T> {
20    fn clone(&self) -> Self {
21        Self {
22            inner: self.inner.clone(),
23        }
24    }
25}
26
27pub struct WriteSignal<T> {
28    inner: Rc<RefCell<SignalInner<T>>>,
29}
30
31impl<T> Clone for WriteSignal<T> {
32    fn clone(&self) -> Self {
33        Self {
34            inner: self.inner.clone(),
35        }
36    }
37}
38
39/// Creates a reactive signal with the given initial value. Returns a (read, write) pair.
40pub fn create_signal<T>(value: T) -> (ReadSignal<T>, WriteSignal<T>) {
41    let inner = Rc::new(RefCell::new(SignalInner {
42        value,
43        subscribers: Vec::new(),
44        version: 0,
45    }));
46
47    (
48        ReadSignal {
49            inner: inner.clone(),
50        },
51        WriteSignal { inner },
52    )
53}
54
55impl<T: Clone> ReadSignal<T> {
56    /// Reads the current value. Subscribes the current effect to this signal.
57    pub fn get(&self) -> T {
58        self.track();
59        self.inner.borrow().value.clone()
60    }
61
62    pub fn with<R>(&self, f: impl FnOnce(&T) -> R) -> R {
63        self.track();
64        f(&self.inner.borrow().value)
65    }
66
67    pub fn get_untracked(&self) -> T {
68        self.inner.borrow().value.clone()
69    }
70
71    fn track(&self) {
72        RUNTIME.with(|rt| {
73            if let Some(effect_id) = rt.borrow().current_effect() {
74                let mut inner = self.inner.borrow_mut();
75                if !inner.subscribers.contains(&effect_id) {
76                    inner.subscribers.push(effect_id);
77                }
78            }
79        });
80    }
81}
82
83impl<T> WriteSignal<T> {
84    /// Replaces the signal value and notifies subscribers.
85    pub fn set(&self, value: T) {
86        {
87            let mut inner = self.inner.borrow_mut();
88            inner.value = value;
89            inner.version += 1;
90        }
91        self.notify_subscribers();
92    }
93
94    pub fn update(&self, f: impl FnOnce(&mut T)) {
95        {
96            let mut inner = self.inner.borrow_mut();
97            f(&mut inner.value);
98            inner.version += 1;
99        }
100        self.notify_subscribers();
101    }
102
103    fn notify_subscribers(&self) {
104        let inner = self.inner.borrow();
105        let should_flush = RUNTIME.with(|rt| {
106            let mut rt = rt.borrow_mut();
107            for &subscriber_id in &inner.subscribers {
108                rt.schedule_effect(subscriber_id);
109            }
110            !rt.is_batching()
111        });
112        drop(inner);
113
114        if should_flush {
115            flush_effects();
116        }
117    }
118}
119
120#[cfg(test)]
121mod tests {
122    use super::*;
123
124    #[test]
125    fn test_signal_read_write() {
126        let (read, write) = create_signal(0);
127        assert_eq!(read.get_untracked(), 0);
128        write.set(5);
129        assert_eq!(read.get_untracked(), 5);
130    }
131
132    #[test]
133    fn test_signal_update() {
134        let (read, write) = create_signal(vec![1, 2]);
135        write.update(|v| v.push(3));
136        assert_eq!(read.get_untracked(), vec![1, 2, 3]);
137    }
138
139    #[test]
140    fn test_signal_with() {
141        let (read, _write) = create_signal(String::from("hello"));
142        let len = read.with(|s| s.len());
143        assert_eq!(len, 5);
144    }
145}
react_rs_core/signal.rs

react_rs_core/
signal.rs
