forked from reduxjs/react-redux
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Subscription.ts
184 lines (153 loc) · 3.93 KB
/
Subscription.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
import { getBatch } from './batch'
// encapsulates the subscription logic for connecting a component to the redux store, as
// well as nesting subscriptions of descendant components, so that we can ensure the
// ancestor components re-render before descendants
type VoidFunc = () => void
type Listener = {
callback: VoidFunc
next: Listener | null
prev: Listener | null
}
function createListenerCollection() {
const batch = getBatch()
let first: Listener | null = null
let last: Listener | null = null
return {
clear() {
first = null
last = null
},
notify() {
batch(() => {
let listener = first
while (listener) {
listener.callback()
listener = listener.next
}
})
},
get() {
let listeners: Listener[] = []
let listener = first
while (listener) {
listeners.push(listener)
listener = listener.next
}
return listeners
},
subscribe(callback: () => void) {
let isSubscribed = true
let listener: Listener = (last = {
callback,
next: null,
prev: last,
})
if (listener.prev) {
listener.prev.next = listener
} else {
first = listener
}
return function unsubscribe() {
if (!isSubscribed || first === null) return
isSubscribed = false
if (listener.next) {
listener.next.prev = listener.prev
} else {
last = listener.prev
}
if (listener.prev) {
listener.prev.next = listener.next
} else {
first = listener.next
}
}
},
}
}
type ListenerCollection = ReturnType<typeof createListenerCollection>
export interface Subscription {
addNestedSub: (listener: VoidFunc) => VoidFunc
notifyNestedSubs: VoidFunc
handleChangeWrapper: VoidFunc
isSubscribed: () => boolean
onStateChange?: VoidFunc | null
trySubscribe: VoidFunc
tryUnsubscribe: VoidFunc
getListeners: () => ListenerCollection
}
const nullListeners = {
notify() {},
get: () => [],
} as unknown as ListenerCollection
export function createSubscription(store: any, parentSub?: Subscription) {
let unsubscribe: VoidFunc | undefined
let listeners: ListenerCollection = nullListeners
// Reasons to keep the subscription active
let subscriptionsAmount = 0
// Is this specific subscription subscribed (or only nested ones?)
let selfSubscribed = false
function addNestedSub(listener: () => void) {
trySubscribe()
const cleanupListener = listeners.subscribe(listener)
// cleanup nested sub
let removed = false
return () => {
if (!removed) {
removed = true
cleanupListener()
tryUnsubscribe()
}
}
}
function notifyNestedSubs() {
listeners.notify()
}
function handleChangeWrapper() {
if (subscription.onStateChange) {
subscription.onStateChange()
}
}
function isSubscribed() {
return selfSubscribed
}
function trySubscribe() {
subscriptionsAmount++
if (!unsubscribe) {
unsubscribe = parentSub
? parentSub.addNestedSub(handleChangeWrapper)
: store.subscribe(handleChangeWrapper)
listeners = createListenerCollection()
}
}
function tryUnsubscribe() {
subscriptionsAmount--
if (unsubscribe && subscriptionsAmount === 0) {
unsubscribe()
unsubscribe = undefined
listeners.clear()
listeners = nullListeners
}
}
function trySubscribeSelf() {
if (!selfSubscribed) {
selfSubscribed = true
trySubscribe()
}
}
function tryUnsubscribeSelf() {
if (selfSubscribed) {
selfSubscribed = false
tryUnsubscribe()
}
}
const subscription: Subscription = {
addNestedSub,
notifyNestedSubs,
handleChangeWrapper,
isSubscribed,
trySubscribe: trySubscribeSelf,
tryUnsubscribe: tryUnsubscribeSelf,
getListeners: () => listeners,
}
return subscription
}