reactive_graph/signal/
subscriber_traits.rs

1//! Traits to reduce the boilerplate when implementing the [`ReactiveNode`], [`Source`], and
2//! [`ToAnySource`] traits for signal types.
3//!
4//! These traits can be automatically derived for any type that
5//! 1) is a root node in the reactive graph, with no sources (i.e., a signal, not a memo)
6//! 2) contains an `Arc<RwLock<SubscriberSet>>`
7//!
8//! This makes it easy to implement a variety of different signal primitives, as long as they share
9//! these characteristics.
10
11use crate::{
12    graph::{
13        AnySource, AnySubscriber, ReactiveNode, Source, SubscriberSet,
14        ToAnySource,
15    },
16    traits::{DefinedAt, IsDisposed},
17    unwrap_signal,
18};
19use or_poisoned::OrPoisoned;
20use std::{
21    borrow::Borrow,
22    sync::{Arc, RwLock, Weak},
23};
24
25pub(crate) trait AsSubscriberSet {
26    type Output: Borrow<RwLock<SubscriberSet>>;
27
28    fn as_subscriber_set(&self) -> Option<Self::Output>;
29}
30
31impl<'a> AsSubscriberSet for &'a RwLock<SubscriberSet> {
32    type Output = &'a RwLock<SubscriberSet>;
33
34    #[inline(always)]
35    fn as_subscriber_set(&self) -> Option<Self::Output> {
36        Some(self)
37    }
38}
39
40impl DefinedAt for RwLock<SubscriberSet> {
41    fn defined_at(&self) -> Option<&'static std::panic::Location<'static>> {
42        None
43    }
44}
45
46// Implement reactive types for RwLock<SubscriberSet>
47// This is used so that Weak<RwLock<SubscriberSet>> is a Weak<dyn ReactiveNode> and Weak<dyn
48// Source>
49impl<T: AsSubscriberSet + DefinedAt> ReactiveNode for T {
50    fn mark_dirty(&self) {
51        self.mark_subscribers_check();
52    }
53
54    fn mark_check(&self) {}
55
56    fn mark_subscribers_check(&self) {
57        if let Some(inner) = self.as_subscriber_set() {
58            let subs = inner.borrow().read().unwrap().clone();
59            for sub in subs {
60                sub.mark_dirty();
61            }
62        }
63    }
64
65    fn update_if_necessary(&self) -> bool {
66        // a signal will always mark its dependents Dirty when it runs, so they know
67        // that they may have changed and need to check themselves at least
68        //
69        // however, it's always possible that *another* signal or memo has triggered any
70        // given effect/memo, and so this signal should *not* say that it is dirty, as it
71        // may also be checked but has not changed
72        false
73    }
74}
75
76impl<T: AsSubscriberSet + DefinedAt> Source for T {
77    fn clear_subscribers(&self) {
78        if let Some(inner) = self.as_subscriber_set() {
79            inner.borrow().write().unwrap().take();
80        }
81    }
82
83    fn add_subscriber(&self, subscriber: AnySubscriber) {
84        if let Some(inner) = self.as_subscriber_set() {
85            inner.borrow().write().unwrap().subscribe(subscriber)
86        }
87    }
88
89    fn remove_subscriber(&self, subscriber: &AnySubscriber) {
90        if let Some(inner) = self.as_subscriber_set() {
91            inner.borrow().write().unwrap().unsubscribe(subscriber)
92        }
93    }
94}
95
96impl<T: AsSubscriberSet + DefinedAt + IsDisposed> ToAnySource for T
97where
98    T::Output: Borrow<Arc<RwLock<SubscriberSet>>>,
99{
100    #[track_caller]
101    fn to_any_source(&self) -> AnySource {
102        self.as_subscriber_set()
103            .map(|subs| {
104                let subs = subs.borrow();
105                AnySource(
106                    Arc::as_ptr(subs) as usize,
107                    Arc::downgrade(subs) as Weak<dyn Source + Send + Sync>,
108                    #[cfg(any(debug_assertions, leptos_debuginfo))]
109                    self.defined_at().expect("no DefinedAt in debug mode"),
110                )
111            })
112            .unwrap_or_else(unwrap_signal!(self))
113    }
114}
115
116impl ReactiveNode for RwLock<SubscriberSet> {
117    fn mark_dirty(&self) {
118        self.mark_subscribers_check();
119    }
120
121    fn mark_check(&self) {}
122
123    fn mark_subscribers_check(&self) {
124        let subs = self.write().unwrap().take();
125        for sub in subs {
126            sub.mark_dirty();
127        }
128    }
129
130    fn update_if_necessary(&self) -> bool {
131        // a signal will always mark its dependents Dirty when it runs, so they know
132        // that they may have changed and need to check themselves at least
133        //
134        // however, it's always possible that *another* signal or memo has triggered any
135        // given effect/memo, and so this signal should *not* say that it is dirty, as it
136        // may also be checked but has not changed
137        false
138    }
139}
140
141impl Source for RwLock<SubscriberSet> {
142    fn clear_subscribers(&self) {
143        self.write().or_poisoned().take();
144    }
145
146    fn add_subscriber(&self, subscriber: AnySubscriber) {
147        self.write().or_poisoned().subscribe(subscriber)
148    }
149
150    fn remove_subscriber(&self, subscriber: &AnySubscriber) {
151        self.write().or_poisoned().unsubscribe(subscriber)
152    }
153}
reactive_graph/signal/subscriber_traits.rs

reactive_graph/signal/
subscriber_traits.rs
