/
callback.ts
56 lines (51 loc) · 1.5 KB
/
callback.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
/*
* Copyright The OpenTelemetry Authors
*
* 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
*
* https://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 { Deferred } from './promise';
/**
* Bind the callback and only invoke the callback once regardless how many times `BindOnceFuture.call` is invoked.
*/
export class BindOnceFuture<
R,
This = unknown,
T extends (this: This, ...args: unknown[]) => R = () => R,
> {
private _isCalled = false;
private _deferred = new Deferred<R>();
constructor(
private _callback: T,
private _that: This
) {}
get isCalled() {
return this._isCalled;
}
get promise() {
return this._deferred.promise;
}
call(...args: Parameters<T>): Promise<R> {
if (!this._isCalled) {
this._isCalled = true;
try {
Promise.resolve(this._callback.call(this._that, ...args)).then(
val => this._deferred.resolve(val),
err => this._deferred.reject(err)
);
} catch (err) {
this._deferred.reject(err);
}
}
return this._deferred.promise;
}
}