1 files changed, 131 insertions, 0 deletions
diff --git a/common/storage_light.js b/common/storage_light.js
new file mode 100644
index 0000000..246e5eb
--- /dev/null
+++ b/common/storage_light.js
@@ -0,0 +1,131 @@
+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Storage manager, lighter than the previous one.
+ *
+ * Copyright (C) 2021 Wojtek Kosior
+ * Redistribution terms are gathered in the `copyright' file.
+ */
+
+/*
+ * IMPORTS_START
+ * IMPORT TYPE_PREFIX
+ * IMPORT raw_storage
+ * IMPORT is_mozilla
+ * IMPORT observables
+ * IMPORTS_END
+ */
+
+const reg_spec = new Set(["\\", "[", "]", "(", ")", "{", "}", ".", "*", "+"]);
+const escape_reg_special = c => reg_spec.has(c) ? "\\" + c : c;
+
+function make_regex(name)
+{
+    return new RegExp(`^${name.split("").map(escape_reg_special).join("")}\$`);
+}
+
+const listeners_by_callback = new Map();
+
+function listen(callback, prefix, name)
+{
+    let by_prefix = listeners_by_callback.get(callback);
+    if (!by_prefix) {
+	by_prefix = new Map();
+	listeners_by_callback.set(callback, by_prefix);
+    }
+
+    let by_name = by_prefix.get(prefix);
+    if (!by_name) {
+	by_name = new Map();
+	by_prefix.set(prefix, by_name);
+    }
+
+    let name_reg = by_name.get(name);
+    if (!name_reg) {
+	name_reg = name.test ? name : make_regex(name);
+	by_name.set(name, name_reg);
+    }
+}
+
+function no_listen(callback, prefix, name)
+{
+    const by_prefix = listeners_by_callback.get(callback);
+    if (!by_prefix)
+	return;
+
+    const by_name = by_prefix.get(prefix);
+    if (!by_name)
+	return;
+
+    const name_reg = by_name.get(name);
+    if (!name_reg)
+	return;
+
+    by_name.delete(name);
+
+    if (by_name.size === 0)
+	by_prefix.delete(prefix);
+
+    if (by_prefix.size === 0)
+	listeners_by_callback.delete(callback);
+}
+
+function storage_change_callback(changes, area)
+{
+    if (is_mozilla && area !== "local")
+    {console.log("area", area);return;}
+
+    for (const item of Object.keys(changes)) {
+	for (const [callback, by_prefix] of listeners_by_callback.entries()) {
+	    const by_name = by_prefix.get(item[0]);
+	    if (!by_name)
+		continue;
+
+	    for (const reg of by_name.values()) {
+		if (!reg.test(item.substring(1)))
+		    continue;
+
+		try {
+		    callback(item, changes[item]);
+		} catch(e) {
+		    console.error(e);
+		}
+	    }
+	}
+    }
+}
+
+raw_storage.listen(storage_change_callback);
+
+
+const created_observables = new Map();
+
+async function observe(prefix, name)
+{
+    const observable = observables.make();
+    const callback = (it, ch) => observables.set(observable, ch.newValue);
+    listen(callback, prefix, name);
+    created_observables.set(observable, [callback, prefix, name]);
+    observables.silent_set(observable, await raw_storage.get(prefix + name));
+
+    return observable;
+}
+
+const observe_var = name => observe(TYPE_PREFIX.VAR, name);
+
+function no_observe(observable)
+{
+    no_listen(...created_observables.get(observable) || []);
+    created_observables.delete(observable);
+}
+
+const light_storage = {};
+Object.assign(light_storage, raw_storage);
+Object.assign(light_storage,
+	      {listen, no_listen, observe, observe_var, no_observe});
+
+/*
+ * EXPORTS_START
+ * EXPORT light_storage
+ * EXPORTS_END
+ */