1 files changed, 107 insertions, 0 deletions
diff --git a/toolkit/components/xulstore/new/XULStore.jsm b/toolkit/components/xulstore/new/XULStore.jsm
new file mode 100644
index 0000000000..16108eeb8b
--- /dev/null
+++ b/toolkit/components/xulstore/new/XULStore.jsm
@@ -0,0 +1,107 @@
+/* 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";
+
+// This JS module wraps the nsIXULStore XPCOM service with useful abstractions.
+// In particular, it wraps the enumerators returned by getIDsEnumerator()
+// and getAttributeEnumerator() in JS objects that implement the iterable
+// protocol.  It also implements the persist() method.  JS consumers should use
+// this module rather than accessing nsIXULStore directly.
+
+const EXPORTED_SYMBOLS = ["XULStore", "getXULStore"];
+
+// Services.xulStore loads this module and returns its `XULStore` symbol
+// when this implementation of XULStore is enabled, so using it here
+// would loop infinitely.  But the mozilla/use-services rule is a good
+// requiremnt for every other consumer of XULStore.
+// eslint-disable-next-line mozilla/use-services
+const xulStore = Cc["@mozilla.org/xul/xulstore;1"].getService(Ci.nsIXULStore);
+
+// Enables logging.
+const debugMode = false;
+
+// Internal function for logging debug messages to the Error Console window
+function log(message) {
+  if (!debugMode) {
+    return;
+  }
+  console.log("XULStore: " + message);
+}
+
+const XULStore = {
+  setValue: xulStore.setValue,
+  hasValue: xulStore.hasValue,
+  getValue: xulStore.getValue,
+  removeValue: xulStore.removeValue,
+  removeDocument: xulStore.removeDocument,
+
+  /**
+   * Sets a value for a specified node's attribute, except in
+   * the case below:
+   * If the value is empty and if calling `hasValue` with the node's
+   * document and ID and `attr` would return true, then the
+   * value instead gets removed from the store (see Bug 1476680).
+   *
+   * @param node - DOM node
+   * @param attr - attribute to store
+   */
+  persist(node, attr) {
+    if (!node.id) {
+      throw new Error("Node without ID passed into persist()");
+    }
+
+    const uri = node.ownerDocument.documentURI;
+    const value = node.getAttribute(attr);
+
+    if (node.localName == "window") {
+      log("Persisting attributes to windows is handled by AppWindow.");
+      return;
+    }
+
+    // See Bug 1476680 - we could drop the `hasValue` check so that
+    // any time there's an empty attribute it gets removed from the
+    // store. Since this is copying behavior from document.persist,
+    // callers would need to be updated with that change.
+    if (!value && xulStore.hasValue(uri, node.id, attr)) {
+      xulStore.removeValue(uri, node.id, attr);
+    } else {
+      xulStore.setValue(uri, node.id, attr, value);
+    }
+  },
+
+  getIDsEnumerator(docURI) {
+    return new XULStoreEnumerator(xulStore.getIDsEnumerator(docURI));
+  },
+
+  getAttributeEnumerator(docURI, id) {
+    return new XULStoreEnumerator(xulStore.getAttributeEnumerator(docURI, id));
+  },
+};
+
+class XULStoreEnumerator {
+  constructor(enumerator) {
+    this.enumerator = enumerator;
+  }
+
+  hasMore() {
+    return this.enumerator.hasMore();
+  }
+
+  getNext() {
+    return this.enumerator.getNext();
+  }
+
+  *[Symbol.iterator]() {
+    while (this.enumerator.hasMore()) {
+      yield this.enumerator.getNext();
+    }
+  }
+}
+
+// Only here for the sake of component registration, which requires a
+// callable function.
+function getXULStore() {
+  return XULStore;
+}