-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathindex.js
217 lines (185 loc) · 4.04 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
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
const isFunction = val => typeof val === 'function';
const globalRef = {
current: null,
};
const createContext = () => ({ children: [], cache: new WeakMap() });
const registerInCurrentContext = subj => {
if (globalRef.current === null) return;
globalRef.current.children.push(subj);
};
const inGlobalContext = (nextGlobal, cb) => {
const prev = globalRef.current;
globalRef.current = nextGlobal;
const result = cb();
globalRef.current = prev;
return result;
};
const S = init => {
let value,
callbacks = [],
producer;
if (isFunction(init)) {
producer = init;
} else {
value = init;
}
const setValue = v => {
if (producer) {
value = producer(v);
} else {
value = v;
}
};
const resolve = () => {
result.age++;
result.author = globalRef.current;
const cbs = callbacks.slice();
callbacks = [];
cbs.forEach(fn => fn(value));
}
const result = v => {
if (isFunction(v)) {
const cb = v;
return v => {
const handled = cb(v);
setValue(handled);
resolve();
return;
};
}
if (v !== undefined) {
// Setter
setValue(v);
resolve();
return;
}
// Getter
return value;
};
result.age = value !== undefined ? 1 : 0;
result.then = resolve => {
const next = S(resolve);
registerInCurrentContext(next);
const origCancel = next.cancel;
next.cancel = cb => {
if (cb !== undefined) {
origCancel(cb);
return;
}
result.cancel(next);
}
callbacks.push(next);
return next;
};
result.cancel = cb => {
if (cb !== undefined) {
callbacks = callbacks.filter(v => v !== cb);
return;
}
callbacks = [];
};
return result;
};
////
const effect = cb => {
const context = createContext();
const sig = S();
registerInCurrentContext(sig);
const onCancel = inGlobalContext(context, () => cb(sig));
const origCancel = sig.cancel;
sig.cancel = cb => {
if (cb !== undefined) {
origCancel(cb);
return;
}
if (onCancel) onCancel();
context.children.forEach(child => {
if (child.cancel) child.cancel();
});
origCancel();
};
return sig;
};
////
const take = source => {
return {
then: cb => {
const cache = globalRef.current.cache;
if (cache.has(source)) {
const lastAge = cache.get(source);
if (source.age > lastAge && source.author !== globalRef.current) {
cache.set(source, source.age);
cb(source());
return;
}
}
source.then(v => {
cache.set(source, source.age);
cb(v);
});
}
}
}
const read = source => {
const cache = globalRef.current.cache;
cache.set(source, source.age);
return source();
}
const loop = makeGen => {
const sig = S();
const context = createContext();
let gen,
running,
cancelled = false;
registerInCurrentContext(sig);
const startOver = () => {
context.children.forEach(child => {
if (child.cancel) child.cancel();
});
context.children = [];
gen = inGlobalContext(context, () => makeGen());
resolve();
};
const onGettingSignal = (value, resolve) => {
return inGlobalContext(context, () => {
if (value.then) {
value.then(resolve);
return value;
}
})
};
const resolve = v => {
if (cancelled) return;
const result = inGlobalContext(context, () => gen.next(v));
if (result.done) {
if (result.value !== undefined) {
sig(result.value);
return;
}
startOver();
return;
}
running = onGettingSignal(result.value, resolve);
};
const origCancel = sig.cancel;
sig.cancel = cb => {
if (cb !== undefined) {
origCancel(cb);
return;
}
cancelled = true;
if (running && running.cancel) running.cancel(resolve);
context.children.forEach(child => {
if (child.cancel) child.cancel();
});
};
startOver();
return sig;
};
module.exports = {
S,
effect,
take,
loop,
read,
};