Create providers/decorators.js

providers/decorators.js

@@ -0,0 +1,113 @@
+module.exports = {
+	singleton,
+	debounce,
+	cache,
+	throttle,
+	memoize,
+	retry,
+};
+
+/**
+ * @template T
+ * @param {T} fn
+ * @returns {T}
+ */
+function singleton(fn) {
+	let called = false;
+	return (...args) => {
+		if (called) return;
+		called = true;
+		return fn(...args);
+	};
+}
+
+/**
+ * @template T
+ * @param {T} fn
+ * @param {number} delay
+ * @returns {T}
+ */
+function debounce(fn, delay) {
+	let timeout;
+	return (...args) => {
+		clearTimeout(timeout);
+		timeout = setTimeout(() => fn(...args), delay);
+	};
+}
+
+/**
+ * @template T
+ * @param {T} fn
+ * @returns {T}
+ */
+function cache(fn) {
+	let lastArgs;
+	let lastResult;
+	return (...args) => {
+		if (
+			args.length !== lastArgs?.length ||
+			args.some((arg, i) => arg !== lastArgs[i])
+		) {
+			lastArgs = args;
+			lastResult = fn(...args);
+		}
+		return lastResult;
+	};
+}
+
+/*
+  the following are currently unused, but potentially useful in the future
+*/
+
+/**
+ * @template T
+ * @param {T} fn
+ * @param {number} delay
+ * @returns {T}
+ */
+function throttle(fn, delay) {
+	let timeout;
+	return (...args) => {
+		if (timeout) return;
+		timeout = setTimeout(() => {
+			timeout = undefined;
+			fn(...args);
+		}, delay);
+	};
+}
+
+/**
+ * @template T
+ * @param {T} fn
+ * @returns {T}
+ */
+function memoize(fn) {
+	const cache = new Map();
+	return (...args) => {
+		const key = JSON.stringify(args);
+		if (!cache.has(key)) {
+			cache.set(key, fn(...args));
+		}
+		return cache.get(key);
+	};
+}
+
+/**
+ * @template T
+ * @param {T} fn
+ * @returns {T}
+ */
+function retry(fn, { retries = 3, delay = 1000 } = {}) {
+	return (...args) => {
+		try {
+			return fn(...args);
+		} catch (e) {
+			if (retries > 0) {
+				retries--;
+				setTimeout(() => retry(fn, { retries, delay })(...args), delay);
+			} else {
+				throw e;
+			}
+		}
+	};
+}