feat: Add the abstract DataStore class

lib/sdk.js

@@ -88,3 +88,58 @@ export.PatSDK = class PatSDK {
   }
 }
 
+/**
+ * An abstract implementation of the required data storage API.
+ *
+ * @abstract
+ */
+export.DataStore = class DataStore {
+  constructor() {
+    if (new.target === DataStore) {
+      throw new TypeError('DataStore is abstract and must be extended')
+    }
+  }
+
+  /**
+   * List all of the keys currently in the delegate storage provider.
+   *
+   * @returns {Promise<String>}
+   */
+  getKeys() {
+    throw new TypeError('"getKeys" must be implemented by the extending class')
+  }
+
+  /**
+   * Store the `value` alongside the given `key` inside the delegate storage provider.
+   *
+   * @param {String} key
+   * @param {String} value
+   *
+   * @returns {Promise<None>}
+   */
+  setItem(key, value) {
+    throw new TypeError('"setItem" must be implemented by the extending class')
+  }
+
+  /**
+   * Retrieve the data assigned to the given `key` from the delegate storage provider.
+   *
+   * @param {String} key
+   *
+   * @returns {Promise<String>}
+   */
+  getItem(key) {
+    throw new TypeError('"getItem" must be implemented by the extending class')
+  }
+
+  /**
+   * Remove the data at the `key` provided from the delegate storage provider.
+   *
+   * @param {String} key
+   *
+   * @returns {Promise<None>}
+   */
+  removeItem(key) {
+    throw new TypeError('"removeItem" must be implemented by the extending class')
+  }
+}