34 lines
872 B
JavaScript
34 lines
872 B
JavaScript
function length(array) {
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return array.length | 0;
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}
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function empty(length) {
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return !(length > 0);
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}
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function arrayify(values) {
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return typeof values !== "object" || "length" in values ? values : Array.from(values);
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}
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function reducer(reduce) {
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return values => reduce(...values);
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}
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export default function cross(...values) {
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const reduce = typeof values[values.length - 1] === "function" && reducer(values.pop());
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values = values.map(arrayify);
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const lengths = values.map(length);
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const j = values.length - 1;
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const index = new Array(j + 1).fill(0);
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const product = [];
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if (j < 0 || lengths.some(empty)) return product;
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while (true) {
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product.push(index.map((j, i) => values[i][j]));
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let i = j;
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while (++index[i] === lengths[i]) {
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if (i === 0) return reduce ? product.map(reduce) : product;
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index[i--] = 0;
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}
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}
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}
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