+page.svelte

<script lang="js">
	import { range } from './range';

	let numCacheEntries = 4;
	let valuesQueued = '1,2,3,4,5,6,7,6,8,5,9';
	let oldestEntry = 0;

	$: lruMatrix = makeLruMatrix(numCacheEntries);
	/** @type {string[]} */
	$: cacheEntries = new Array(numCacheEntries);

	/** @param size {number}
	 *  @returns {number[][]}
	 */
	function makeLruMatrix(size) {
		const matrix = new Array(size - 1);
		for (let i = 0; i < size - 1; i++) {
			const row = new Array(size).fill(null);
			for (let j = i + 1; j < size; j++) {
				row[j] = 1;
			}
			matrix[i] = row;
		}
		return matrix;
	}

	function handleAccessNextValueClick() {
		const rawValues = valuesQueued.trim();
		if (rawValues.length === 0) {
			return;
		}

		const [valueToAccess, ...rest] = rawValues
			.split(',')
			.map((v) => v.trim())
			.filter((v) => v.length !== 0);

		accessEntry(valueToAccess);
		valuesQueued = rest.join(',');
	}

	/** @param value {string} */
	function accessEntry(value) {
		if (!isEntryInCache(value)) {
			const oldestIndex = findOldestEntryIndex();
			cacheEntries[oldestIndex] = value;
		}
		markIndexAsNewest(cacheEntries.indexOf(value));
	}

	/** @param value {string} */
	function isEntryInCache(value) {
		return cacheEntries.some((ce) => ce === value);
	}

	function findOldestEntryIndex() {
		for (let possibleIndex = 0; possibleIndex < numCacheEntries; possibleIndex++) {
			let isNotOldestIndex = false;
			// Check that every thing on top of us is 0 (they are younger):
			for (let i = 0; i < possibleIndex; i++) {
				if (lruMatrix[i][possibleIndex] !== 0) {
					isNotOldestIndex = true;
					break;
				}
			}
			if (isNotOldestIndex) continue;

			// Check that everything to the right of us is 1 (we are older):
			for (let j = possibleIndex + 1; j < numCacheEntries; j++) {
				if (lruMatrix[possibleIndex][j] !== 1) {