1 files changed, 57 insertions, 0 deletions
diff --git a/devtools/client/shared/async-store-helper.js b/devtools/client/shared/async-store-helper.js
new file mode 100644
index 0000000000..0919a07b98
--- /dev/null
+++ b/devtools/client/shared/async-store-helper.js
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+"use strict";
+
+const asyncStorage = require("resource://devtools/shared/async-storage.js");
+
+/*
+ * asyncStoreHelper wraps asyncStorage so that it is easy to define project
+ * specific properties. It is similar to PrefsHelper.
+ *
+ * e.g.
+ *   const asyncStore = asyncStoreHelper("r", {a: "_a"})
+ *   asyncStore.a         // => asyncStorage.getItem("r._a")
+ *   asyncStore.a = 2     // => asyncStorage.setItem("r._a", 2)
+ */
+function asyncStoreHelper(root, mappings) {
+  let store = {};
+
+  function getMappingKey(key) {
+    return Array.isArray(mappings[key]) ? mappings[key][0] : mappings[key];
+  }
+
+  function getMappingDefaultValue(key) {
+    return Array.isArray(mappings[key]) ? mappings[key][1] : null;
+  }
+
+  Object.keys(mappings).map(key =>
+    Object.defineProperty(store, key, {
+      async get() {
+        const value = await asyncStorage.getItem(
+          `${root}.${getMappingKey(key)}`
+        );
+        return value || getMappingDefaultValue(key);
+      },
+      set(value) {
+        asyncStorage.setItem(`${root}.${getMappingKey(key)}`, value);
+      },
+    })
+  );
+
+  store = new Proxy(store, {
+    set(target, property, value, receiver) {
+      if (!mappings.hasOwnProperty(property)) {
+        throw new Error(`AsyncStore: ${property} is not defined in mappings`);
+      }
+
+      Reflect.set(...arguments);
+      return true;
+    },
+  });
+
+  return store;
+}
+
+module.exports = asyncStoreHelper;