33 lines
790 B
JavaScript
33 lines
790 B
JavaScript
export default class HintKeyProducer {
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constructor(charset) {
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if (charset.length === 0) {
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throw new TypeError('charset is empty');
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}
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this.charset = charset;
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this.counter = [];
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}
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produce() {
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this.increment();
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return this.counter.map(x => this.charset[x]).join('');
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}
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increment() {
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let max = this.charset.length - 1;
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if (this.counter.every(x => x === max)) {
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this.counter = new Array(this.counter.length + 1).fill(0);
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return;
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}
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this.counter.reverse();
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let len = this.charset.length;
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let num = this.counter.reduce((x, y, index) => x + y * len ** index) + 1;
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for (let i = 0; i < this.counter.length; ++i) {
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this.counter[i] = num % len;
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num = ~~(num / len);
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}
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this.counter.reverse();
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}
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}
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