🚧 progress: Import existing sources and tests from js-itertools.

Author: make-github-pseudonymous-again

src/reversed.js

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+/**
+ * Yields elements of the input iterable in reverse order.
+ *
+ * @param {Iterable} iterable - The input iterable.
+ * @returns {Iterator} - The input iterable, reversed.
+ */
+export default function* reversed(iterable) {
+	const buffer = [];
+
+	for (const item of iterable) {
+		buffer.push(item);
+	}
+
+	// Caching length is believed to be faster
+
+	let jz = buffer.length;
+
+	for (; jz; --jz) {
+		yield buffer.pop();
+	}
+}

test/src/reversed.js

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+import test from 'ava';
+
+import {list, reversed} from '../../../src/index.js';
+
+test('reversed', (t) => {
+	const x = function (A, B) {
+		t.deepEqual(list(reversed(A)), B);
+		t.deepEqual(list(reversed(B)), A);
+	};
+
+	x([], []);
+	x([1], [1]);
+	x([1, 2, 3], [3, 2, 1]);
+	x([1, 2, 3, 4, 5, 6], [6, 5, 4, 3, 2, 1]);
+	x([1, 2, 3, 4, 5, 6, 7, 8, 9], [9, 8, 7, 6, 5, 4, 3, 2, 1]);
+});