/
index.js
199 lines (189 loc) · 5.3 KB
/
index.js
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
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
import {
run_all,
subscribe,
noop,
safe_not_equal,
is_function,
get_store_value
} from '../internal/index.js';
const subscriber_queue = [];
/**
* Creates a `Readable` store that allows reading by subscription.
*
* https://svelte.dev/docs/svelte-store#readable
* @template T
* @param {T} [value] initial value
* @param {import('./public.js').StartStopNotifier<T>} [start]
* @returns {import('./public.js').Readable<T>}
*/
export function readable(value, start) {
return {
subscribe: writable(value, start).subscribe
};
}
/**
* Create a `Writable` store that allows both updating and reading by subscription.
*
* https://svelte.dev/docs/svelte-store#writable
* @template T
* @param {T} [value] initial value
* @param {import('./public.js').StartStopNotifier<T>} [start]
* @returns {import('./public.js').Writable<T>}
*/
export function writable(value, start = noop) {
/** @type {import('./public.js').Unsubscriber} */
let stop;
/** @type {Set<import('./private.js').SubscribeInvalidateTuple<T>>} */
const subscribers = new Set();
/** @param {T} new_value
* @returns {void}
*/
function set(new_value) {
if (safe_not_equal(value, new_value)) {
value = new_value;
if (stop) {
// store is ready
const run_queue = !subscriber_queue.length;
for (const subscriber of subscribers) {
subscriber[1]();
subscriber_queue.push(subscriber, value);
}
if (run_queue) {
for (let i = 0; i < subscriber_queue.length; i += 2) {
subscriber_queue[i][0](subscriber_queue[i + 1]);
}
subscriber_queue.length = 0;
}
}
}
}
/**
* @param {import('./public.js').Updater<T>} fn
* @returns {void}
*/
function update(fn) {
set(fn(value));
}
/**
* @param {import('./public.js').Subscriber<T>} run
* @param {import('./private.js').Invalidator<T>} [invalidate]
* @returns {import('./public.js').Unsubscriber}
*/
function subscribe(run, invalidate = noop) {
/** @type {import('./private.js').SubscribeInvalidateTuple<T>} */
const subscriber = [run, invalidate];
subscribers.add(subscriber);
if (subscribers.size === 1) {
stop = start(set, update) || noop;
}
run(value);
return () => {
subscribers.delete(subscriber);
if (subscribers.size === 0 && stop) {
stop();
stop = null;
}
};
}
return { set, update, subscribe };
}
/**
* Derived value store by synchronizing one or more readable stores and
* applying an aggregation function over its input values.
*
* https://svelte.dev/docs/svelte-store#derived
* @template {import('./private.js').Stores} S
* @template T
* @overload
* @param {S} stores - input stores
* @param {(values: import('./private.js').StoresValues<S>, set: (value: T) => void, update: (fn: import('./public.js').Updater<T>) => void) => import('./public.js').Unsubscriber | void} fn - function callback that aggregates the values
* @param {T} [initial_value] - initial value
* @returns {import('./public.js').Readable<T>}
*/
/**
* Derived value store by synchronizing one or more readable stores and
* applying an aggregation function over its input values.
*
* https://svelte.dev/docs/svelte-store#derived
* @template {import('./private.js').Stores} S
* @template T
* @overload
* @param {S} stores - input stores
* @param {(values: import('./private.js').StoresValues<S>) => T} fn - function callback that aggregates the values
* @param {T} [initial_value] - initial value
* @returns {import('./public.js').Readable<T>}
*/
/**
* @template {import('./private.js').Stores} S
* @template T
* @param {S} stores
* @param {Function} fn
* @param {T} [initial_value]
* @returns {import('./public.js').Readable<T>}
*/
export function derived(stores, fn, initial_value) {
const single = !Array.isArray(stores);
/** @type {Array<import('./public.js').Readable<any>>} */
const stores_array = single ? [stores] : stores;
if (!stores_array.every(Boolean)) {
throw new Error('derived() expects stores as input, got a falsy value');
}
const auto = fn.length < 2;
return readable(initial_value, (set, update) => {
let started = false;
const values = [];
let pending = 0;
let cleanup = noop;
const sync = () => {
if (pending) {
return;
}
cleanup();
const result = fn(single ? values[0] : values, set, update);
if (auto) {
set(result);
} else {
cleanup = is_function(result) ? result : noop;
}
};
const unsubscribers = stores_array.map((store, i) =>
subscribe(
store,
(value) => {
values[i] = value;
pending &= ~(1 << i);
if (started) {
sync();
}
},
() => {
pending |= 1 << i;
}
)
);
started = true;
sync();
return function stop() {
run_all(unsubscribers);
cleanup();
// We need to set this to false because callbacks can still happen despite having unsubscribed:
// Callbacks might already be placed in the queue which doesn't know it should no longer
// invoke this derived store.
started = false;
};
});
}
/**
* Takes a store and returns a new one derived from the old one that is readable.
*
* https://svelte.dev/docs/svelte-store#readonly
* @template T
* @param {import('./public.js').Readable<T>} store - store to make readonly
* @returns {import('./public.js').Readable<T>}
*/
export function readonly(store) {
return {
subscribe: store.subscribe.bind(store)
};
}
export { get_store_value as get };