diff --git a/engine/lib/Dictionary.ts b/engine/lib/Dictionary.ts
new file mode 100644
index 0000000..0fc0e2d
--- /dev/null
+++ b/engine/lib/Dictionary.ts
@@ -0,0 +1,90 @@
+export type Dictionary<K, V> = {
+	entries: Array<[K, V]>;
+	indices: Map<K, number>;
+	isIterating: boolean;
+	deleteQueue: Array<K>;
+	setQueue: Array<[K, V]>;
+};
+
+export function createDictionary<K, V>(): Dictionary<K, V> {
+	return {
+		entries: [],
+		indices: new Map(),
+		isIterating: false,
+		deleteQueue: [],
+		setQueue: [],
+	};
+}
+
+export function deleteEntry<K, V>(dict: Dictionary<K, V>, key: K): void {
+	const index = dict.indices.get(key);
+	if (index === undefined) {
+		return;
+	}
+
+	const last = dict.entries.length - 1;
+	if (index !== last) {
+		dict.entries[index] = dict.entries[last];
+		dict.indices.set(dict.entries[index][0], index);
+	}
+
+	dict.entries.pop();
+	dict.indices.delete(key);
+}
+
+export function deleteEntrySave<K, V>(dict: Dictionary<K, V>, key: K): void {
+	if (dict.isIterating) {
+		dict.deleteQueue.push();
+	} else {
+		deleteEntry(dict, key);
+	}
+}
+
+export function setEntry<K, V>(
+	dict: Dictionary<K, V>,
+	[key, value]: [K, V],
+): void {
+	const index = dict.indices.get(key);
+	if (index === undefined) {
+		dict.entries.push([key, value]);
+		dict.indices.set(key, dict.entries.length);
+	} else {
+		dict.entries[index][1] = value;
+	}
+}
+
+export function setEntrySave<K, V>(
+	dict: Dictionary<K, V>,
+	key: K,
+	value: V,
+): void {
+	if (dict.isIterating) {
+		dict.setQueue.push([key, value]);
+	} else {
+		setEntry(dict, [key, value]);
+	}
+}
+
+export function getEntry<K, V>(dict: Dictionary<K, V>, key: K): V | undefined {
+	const index = dict.indices.get(key);
+	return index === undefined ? undefined : dict.entries[index][1];
+}
+
+export function forEntry<K, V>(
+	dict: Dictionary<K, V>,
+	callback: (value: V, key: K, index: number) => void,
+): void {
+	dict.isIterating = true;
+	for (let i = 0; i < dict.entries.length; i++) {
+		callback(dict.entries[i][1], dict.entries[i][0], i);
+	}
+	dict.isIterating = false;
+
+	while (dict.deleteQueue.length > 0) {
+		deleteEntry(dict, dict.deleteQueue.pop()!);
+	}
+
+	while (dict.setQueue.length > 0) {
+		setEntry(dict, dict.setQueue.pop()!);
+	}
+}