From d42dadca04bd2c40cfe836b3f2bbe0ffbf176eda Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <koszko@koszko.org>
Date: Fri, 23 Jul 2021 17:32:31 +0200
Subject: extract observables implementation from storage.js

---
 common/observable.js | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 common/observable.js

(limited to 'common')

diff --git a/common/observable.js b/common/observable.js
new file mode 100644
index 0000000..1fb0b0a
--- /dev/null
+++ b/common/observable.js
@@ -0,0 +1,36 @@
+/**
+ * part of Hachette
+ * Facilitate listening to events
+ *
+ * Copyright (C) 2021 Wojtek Kosior
+ * Redistribution terms are gathered in the `copyright' file.
+ */
+
+function make()
+{
+    return new Set();
+}
+
+function subscribe(observable, cb)
+{
+    observable.add(cb);
+}
+
+function unsubscribe(observable, cb)
+{
+    observable.delete(cb);
+}
+
+function broadcast(observable, event)
+{
+    for (const callback of observable)
+	callback(event);
+}
+
+const observables = {make, subscribe, unsubscribe, broadcast};
+
+/*
+ * EXPORTS_START
+ * EXPORT observables
+ * EXPORTS_END
+ */
-- 
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