| 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 |
2x
2x
282979x
282979x
282979x
282979x
282979x
282979x
282979x
282979x
282949x
282949x
282949x
79765x
30x
30x
30x
14x
2x
6946x
186730x
186730x
186730x
186730x
106951x
106935x
16x
79779x
79779x
79765x
79779x
14x
15036x
15036x
15036x
2x
179794x
179794x
179783x
50793x
128990x
11x
2x
186700x
179765x
6935x
2x
30x
29x
1x
2x
181524x
181524x
2x
16x
16x
2x
17565x
9608x
9608x
2x
2x
| /**
* Copyright 2017 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { fail } from '../util/assert';
export type FulfilledHandler<T, R> =
| ((result: T) => R | PersistencePromise<R>)
| null;
export type RejectedHandler<R> =
| ((reason: Error) => R | PersistencePromise<R>)
| null;
export type Resolver<T> = (value?: T) => void;
export type Rejector = (error: Error) => void;
/**
* PersistencePromise<> is essentially a re-implementation of Promise<> except
* it has a .next() method instead of .then() and .next() and .catch() callbacks
* are executed synchronously when a PersistencePromise resolves rather than
* asynchronously (Promise<> implementations use setImmediate() or similar).
*
* This is necessary to interoperate with IndexedDB which will automatically
* commit transactions if control is returned to the event loop without
* synchronously initiating another operation on the transaction.
*
* NOTE: .then() and .catch() only allow a single consumer, unlike normal
* Promises.
*/
export class PersistencePromise<T> {
// NOTE: next/catchCallback will always point to our own wrapper functions,
// not the user's raw next() or catch() callbacks.
// tslint:disable-next-line:no-any Accept any result type for the next call in the Promise chain.
private nextCallback: FulfilledHandler<T, any> = null;
// tslint:disable-next-line:no-any Accept any result type for the error handler.
private catchCallback: RejectedHandler<any> = null;
// When the operation resolves, we'll set result or error and mark isDone.
private result: T | undefined = undefined;
private error: Error | undefined = undefined;
private isDone = false;
// Set to true when .then() or .catch() are called and prevents additional
// chaining.
private callbackAttached = false;
constructor(callback: (resolve: Resolver<T>, reject: Rejector) => void) {
callback(
value => {
this.isDone = true;
this.result = value;
if (this.nextCallback) {
// value should be defined unless T is Void, but we can't express
// that in the type system.
this.nextCallback(value!);
}
},
error => {
this.isDone = true;
this.error = error;
if (this.catchCallback) {
this.catchCallback(error);
}
}
);
}
catch<R>(
fn: (error: Error) => R | PersistencePromise<R>
): PersistencePromise<R> {
return this.next(undefined, fn);
}
next<R>(
nextFn?: FulfilledHandler<T, R>,
catchFn?: RejectedHandler<R>
): PersistencePromise<R> {
Iif (this.callbackAttached) {
fail('Called next() or catch() twice for PersistencePromise');
}
this.callbackAttached = true;
if (this.isDone) {
if (!this.error) {
return this.wrapSuccess(nextFn, this.result!);
} else {
return this.wrapFailure(catchFn, this.error);
}
} else {
return new PersistencePromise<R>((resolve, reject) => {
this.nextCallback = (value: T) => {
this.wrapSuccess(nextFn, value).next(resolve, reject);
};
this.catchCallback = (error: Error) => {
this.wrapFailure(catchFn, error).next(resolve, reject);
};
});
}
}
toPromise(): Promise<T> {
return new Promise((resolve, reject) => {
this.next(resolve, reject);
});
}
private wrapUserFunction<R>(
fn: () => R | PersistencePromise<R>
): PersistencePromise<R> {
try {
const result = fn();
if (result instanceof PersistencePromise) {
return result;
} else {
return PersistencePromise.resolve(result);
}
} catch (e) {
return PersistencePromise.reject<R>(e);
}
}
private wrapSuccess<R>(
nextFn: FulfilledHandler<T, R> | undefined,
value: T
): PersistencePromise<R> {
if (nextFn) {
return this.wrapUserFunction(() => nextFn(value));
} else {
// If there's no nextFn, then R must be the same as T but we
// can't express that in the type system.
// tslint:disable-next-line:no-any
return PersistencePromise.resolve<R>(value as any);
}
}
private wrapFailure<R>(
catchFn: RejectedHandler<R> | undefined,
error: Error
): PersistencePromise<R> {
if (catchFn) {
return this.wrapUserFunction(() => catchFn(error));
} else {
return PersistencePromise.reject<R>(error);
}
}
static resolve(): PersistencePromise<void>;
static resolve<R>(result: R): PersistencePromise<R>;
static resolve<R>(result?: R): PersistencePromise<R | void> {
return new PersistencePromise<R>((resolve, reject) => {
resolve(result);
});
}
static reject<R>(error: Error): PersistencePromise<R> {
return new PersistencePromise<R>((resolve, reject) => {
reject(error);
});
}
static waitFor(
// tslint:disable-next-line:no-any Accept all Promise types in waitFor().
all: Array<PersistencePromise<any>>
): PersistencePromise<void> {
return all.reduce((promise, nextPromise, idx) => {
return promise.next(() => {
return nextPromise;
});
}, PersistencePromise.resolve());
}
static map<R>(all: Array<PersistencePromise<R>>): PersistencePromise<R[]> {
const results: R[] = [];
let first = true;
// initial is ignored, so we can cheat on the type.
// tslint:disable-next-line:no-any
const initial = PersistencePromise.resolve<R>(null as any);
return all
.reduce((promise, nextPromise) => {
return promise.next(result => {
if (!first) {
results.push(result);
}
first = false;
return nextPromise;
});
}, initial)
.next(result => {
results.push(result);
return results;
});
}
}
|