added a cacheFunction

README.md

@@ -30,6 +30,10 @@ const value = cache.get('myKey');
 // Remove a value from the cache
 cache.del('myKey');
 
+// cache a function
+const sum = (...nums: number[]) => nums.reduce((total, curr) => total + curr, 0);
+const result = cache.cacheFunction('sum', sum, [1, 2, 3]); // 6 (cached)
+
 // Retrieve all key-value pairs from the cache
 const allItems = cache.getAll();
 

src/index.ts

@@ -30,6 +30,33 @@ class Mmry<T> {
     this.cache.set(key, cacheItem);
   }
 
+  /**
+   * Caches the return value of a function based on its parameters.
+   * @param key The key associated with the cached value.
+   * @param func The function to be cached.
+   * @param params The parameters of the function.
+   * @param ttlString The TTL string in the format "<amount> <unit>", e.g., "5 minutes", "5234 seconds".
+   * @returns The cached value if available, otherwise the return value of the function.
+   */
+  public cacheFunction<U extends (...args: any[]) => any>(
+    key: string,
+    func: U,
+    params: Parameters<U>,
+    ttlString?: string
+  ): T {
+    const cacheKey = key + JSON.stringify(params);
+    const cachedValue = this.get(cacheKey);
+
+    if (cachedValue) {
+      return cachedValue;
+    }
+
+    const funcReturnValue = func(...params);
+    this.put(cacheKey, funcReturnValue, ttlString);
+
+    return funcReturnValue;
+  }
+
   /**
    * Retrieves a value from the cache.
    * @param key The key associated with the value.

test/index.test.ts

@@ -133,4 +133,19 @@ describe('Mmry', () => {
     const result = cache.getAll();
     expect(result).toEqual({ key1: 'value1', key2: 'value2' });
   });
+
+  it('should set a function to be cached and return its return value', () => {
+    const sum = (...nums: number[]) => nums.reduce((total, curr) => total + curr, 0);
+    let result = cache.cacheFunction('sum', sum, [1, 2, 3]);
+    expect(result).toBe(6);
+    result = cache.cacheFunction('sum', sum, [3, 4, 5]);
+    expect(result).toBe(12);
+  });
+
+  it('Make sure that the function is caching the function and not duplicating', () => {
+    const test = (firstName: string, lastName: string) => ({firstName, lastName});
+    let result1 = cache.cacheFunction('test', test, ['foo', 'bar']);
+    let result2 = cache.cacheFunction('test', test, ['foo', 'bar']);
+    expect(result1).toBe(result2);
+  });
 });