1 files changed, 54 insertions, 0 deletions
diff --git a/devtools/client/shared/redux/middleware/promise.js b/devtools/client/shared/redux/middleware/promise.js
new file mode 100644
index 000000000..237e41eef
--- /dev/null
+++ b/devtools/client/shared/redux/middleware/promise.js
@@ -0,0 +1,54 @@
+/* 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 uuidgen = require("sdk/util/uuid").uuid;
+const defer = require("devtools/shared/defer");
+const {
+  entries, toObject, executeSoon
+} = require("devtools/shared/DevToolsUtils");
+const PROMISE = exports.PROMISE = "@@dispatch/promise";
+
+function promiseMiddleware({ dispatch, getState }) {
+  return next => action => {
+    if (!(PROMISE in action)) {
+      return next(action);
+    }
+
+    const promiseInst = action[PROMISE];
+    const seqId = uuidgen().toString();
+
+    // Create a new action that doesn't have the promise field and has
+    // the `seqId` field that represents the sequence id
+    action = Object.assign(
+      toObject(entries(action).filter(pair => pair[0] !== PROMISE)), { seqId }
+    );
+
+    dispatch(Object.assign({}, action, { status: "start" }));
+
+    // Return the promise so action creators can still compose if they
+    // want to.
+    const deferred = defer();
+    promiseInst.then(value => {
+      executeSoon(() => {
+        dispatch(Object.assign({}, action, {
+          status: "done",
+          value: value
+        }));
+        deferred.resolve(value);
+      });
+    }, error => {
+      executeSoon(() => {
+        dispatch(Object.assign({}, action, {
+          status: "error",
+          error: error.message || error
+        }));
+        deferred.reject(error);
+      });
+    });
+    return deferred.promise;
+  };
+}
+
+exports.promise = promiseMiddleware;