| 1 | class LazyPromise {
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| 2 | constructor(func, params) {
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| 3 | this._func = func;
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| 4 | this._params = params;
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| 5 | this._promise = undefined; // not call `func(...params)` immediately
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| 6 | }
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| 7 |
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| 8 | async then(resolve, reject) {
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| 9 | this._promise = this._promise || this._func(...this._params);
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| 10 |
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| 11 | try {
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| 12 | resolve(await this._promise);
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| 13 | } catch (e) {
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| 14 | reject(e);
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| 15 | }
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| 16 | }
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| 17 | }
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| 18 |
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| 19 | module.exports = LazyPromise;
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