58 lines
1.6 KiB
JavaScript
58 lines
1.6 KiB
JavaScript
'use strict';
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const isIterable = (obj) => Symbol.iterator in obj;
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const hasIterableEntries = (value) => (
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// HACK: avoid checking entries type
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"entries" in value
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);
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const compareEntries = (valueA, valueB) => {
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const mapA = valueA instanceof Map ? valueA : new Map(valueA.entries());
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const mapB = valueB instanceof Map ? valueB : new Map(valueB.entries());
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if (mapA.size !== mapB.size) {
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return false;
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}
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for (const [key, value] of mapA) {
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if (!mapB.has(key) || !Object.is(value, mapB.get(key))) {
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return false;
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}
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}
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return true;
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};
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const compareIterables = (valueA, valueB) => {
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const iteratorA = valueA[Symbol.iterator]();
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const iteratorB = valueB[Symbol.iterator]();
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let nextA = iteratorA.next();
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let nextB = iteratorB.next();
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while (!nextA.done && !nextB.done) {
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if (!Object.is(nextA.value, nextB.value)) {
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return false;
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}
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nextA = iteratorA.next();
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nextB = iteratorB.next();
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}
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return !!nextA.done && !!nextB.done;
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};
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function shallow(valueA, valueB) {
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if (Object.is(valueA, valueB)) {
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return true;
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}
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if (typeof valueA !== "object" || valueA === null || typeof valueB !== "object" || valueB === null) {
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return false;
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}
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if (Object.getPrototypeOf(valueA) !== Object.getPrototypeOf(valueB)) {
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return false;
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}
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if (isIterable(valueA) && isIterable(valueB)) {
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if (hasIterableEntries(valueA) && hasIterableEntries(valueB)) {
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return compareEntries(valueA, valueB);
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}
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return compareIterables(valueA, valueB);
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}
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return compareEntries(
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{ entries: () => Object.entries(valueA) },
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{ entries: () => Object.entries(valueB) }
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);
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}
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exports.shallow = shallow;
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