dioxus_signals/
set_compare.rs

1use crate::{write::WritableExt, ReadableExt};
2use std::hash::Hash;
3
4use dioxus_core::ReactiveContext;
5use futures_util::StreamExt;
6use generational_box::{Storage, UnsyncStorage};
7
8use crate::{CopyValue, ReadSignal, Signal, SignalData};
9use rustc_hash::FxHashMap;
10
11/// An object that can efficiently compare a value to a set of values.
12pub struct SetCompare<R, S: 'static = UnsyncStorage> {
13    subscribers: CopyValue<FxHashMap<R, Signal<bool, S>>>,
14}
15
16impl<R: Eq + Hash + 'static> SetCompare<R> {
17    /// Creates a new [`SetCompare`] which efficiently tracks when a value changes to check if it is equal to a set of values.
18    ///
19    /// Generally, you shouldn't need to use this hook. Instead you can use [`crate::Memo`]. If you have many values that you need to compare to a single value, this hook will change updates from O(n) to O(1) where n is the number of values you are comparing to.
20    #[track_caller]
21    pub fn new(f: impl FnMut() -> R + 'static) -> SetCompare<R> {
22        Self::new_maybe_sync(f)
23    }
24}
25
26impl<R: Eq + Hash + 'static, S: Storage<SignalData<bool>> + 'static> SetCompare<R, S> {
27    /// Creates a new [`SetCompare`] that may be `Sync + Send` which efficiently tracks when a value changes to check if it is equal to a set of values.
28    ///
29    /// Generally, you shouldn't need to use this hook. Instead you can use [`crate::Memo`]. If you have many values that you need to compare to a single value, this hook will change updates from O(n) to O(1) where n is the number of values you are comparing to.
30    #[track_caller]
31    pub fn new_maybe_sync(mut f: impl FnMut() -> R + 'static) -> SetCompare<R, S> {
32        let subscribers: CopyValue<FxHashMap<R, Signal<bool, S>>> =
33            CopyValue::new(FxHashMap::default());
34        let mut previous = CopyValue::new(None);
35
36        let mut recompute = move || {
37            let subscribers = subscribers.read();
38            let mut previous = previous.write();
39
40            if let Some(previous) = previous.take() {
41                if let Some(mut value) = subscribers.get(&previous).cloned() {
42                    *value.write() = false;
43                }
44            }
45
46            let current = f();
47
48            if let Some(mut value) = subscribers.get(&current).cloned() {
49                *value.write() = true;
50            }
51
52            *previous = Some(current);
53        };
54        let (rc, mut changed) = ReactiveContext::new();
55        dioxus_core::spawn(async move {
56            loop {
57                // Recompute the value
58                rc.reset_and_run_in(&mut recompute);
59
60                // Wait for context to change
61                let _ = changed.next().await;
62            }
63        });
64
65        SetCompare { subscribers }
66    }
67}
68
69impl<R: Eq + Hash + 'static> SetCompare<R> {
70    /// Returns a signal which is true when the value is equal to the value passed to this function.
71    pub fn equal(&mut self, value: R) -> ReadSignal<bool> {
72        let subscribers = self.subscribers.write();
73
74        match subscribers.get(&value) {
75            Some(&signal) => signal.into(),
76            None => {
77                drop(subscribers);
78                let mut subscribers = self.subscribers.write();
79                let signal = Signal::new_maybe_sync(false);
80                subscribers.insert(value, signal);
81                signal.into()
82            }
83        }
84    }
85}
86
87impl<R, S: Storage<SignalData<bool>>> PartialEq for SetCompare<R, S> {
88    fn eq(&self, other: &Self) -> bool {
89        self.subscribers == other.subscribers
90    }
91}
92
93impl<R, S: Storage<SignalData<bool>>> Clone for SetCompare<R, S> {
94    fn clone(&self) -> Self {
95        *self
96    }
97}
98
99impl<R, S: Storage<SignalData<bool>>> Copy for SetCompare<R, S> {}
dioxus_signals/set_compare.rs

dioxus_signals/
set_compare.rs
