1 files changed, 67 insertions, 0 deletions
diff --git a/devtools/client/fronts/property-iterator.js b/devtools/client/fronts/property-iterator.js
new file mode 100644
index 0000000000..dcbdf3e22e
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+++ b/devtools/client/fronts/property-iterator.js
@@ -0,0 +1,67 @@
+/* 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 {
+  FrontClassWithSpec,
+  registerFront,
+} = require("devtools/shared/protocol");
+const {
+  propertyIteratorSpec,
+} = require("devtools/shared/specs/property-iterator");
+const {
+  getAdHocFrontOrPrimitiveGrip,
+} = require("devtools/client/fronts/object");
+
+/**
+ * A PropertyIteratorFront provides a way to access to property names and
+ * values of an object efficiently, slice by slice.
+ * Note that the properties can be sorted in the backend,
+ * this is controled while creating the PropertyIteratorFront
+ * from ObjectFront.enumProperties.
+ */
+class PropertyIteratorFront extends FrontClassWithSpec(propertyIteratorSpec) {
+  form(data) {
+    this.actorID = data.actor;
+    this.count = data.count;
+  }
+
+  async slice(start, count) {
+    const result = await super.slice({ start, count });
+    return this._onResult(result);
+  }
+
+  async all() {
+    const result = await super.all();
+    return this._onResult(result);
+  }
+
+  _onResult(result) {
+    if (!result.ownProperties) {
+      return result;
+    }
+
+    // The result packet can have multiple properties that hold grips which we may need
+    // to turn into fronts.
+    const gripKeys = ["value", "getterValue", "get", "set"];
+
+    Object.entries(result.ownProperties).forEach(([key, descriptor]) => {
+      if (descriptor) {
+        for (const gripKey of gripKeys) {
+          if (descriptor.hasOwnProperty(gripKey)) {
+            result.ownProperties[key][gripKey] = getAdHocFrontOrPrimitiveGrip(
+              descriptor[gripKey],
+              this
+            );
+          }
+        }
+      }
+    });
+    return result;
+  }
+}
+
+exports.PropertyIteratorFront = PropertyIteratorFront;
+registerFront(PropertyIteratorFront);