1 files changed, 65 insertions, 0 deletions
diff --git a/dom/manifest/ValueExtractor.jsm b/dom/manifest/ValueExtractor.jsm
new file mode 100644
index 000000000..f3dd25905
--- /dev/null
+++ b/dom/manifest/ValueExtractor.jsm
@@ -0,0 +1,65 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+/*
+ * Helper functions extract values from manifest members
+ * and reports conformance violations.
+ */
+/*globals Components*/
+'use strict';
+const {
+  classes: Cc,
+  interfaces: Ci
+} = Components;
+
+function ValueExtractor(aConsole, aBundle) {
+  this.console = aConsole;
+  this.domBundle = aBundle;
+}
+
+ValueExtractor.prototype = {
+  // This function takes a 'spec' object and destructures
+  // it to extract a value. If the value is of th wrong type, it
+  // warns the developer and returns undefined.
+  //  expectType: is the type of a JS primitive (string, number, etc.)
+  //  object: is the object from which to extract the value.
+  //  objectName: string used to construct the developer warning.
+  //  property: the name of the property being extracted.
+  //  trim: boolean, if the value should be trimmed (used by string type).
+  extractValue({expectedType, object, objectName, property, trim}) {
+    const value = object[property];
+    const isArray = Array.isArray(value);
+    // We need to special-case "array", as it's not a JS primitive.
+    const type = (isArray) ? 'array' : typeof value;
+    if (type !== expectedType) {
+      if (type !== 'undefined') {
+        this.console.warn(this.domBundle.formatStringFromName("ManifestInvalidType",
+                                                              [objectName, property, expectedType],
+                                                              3));
+      }
+      return undefined;
+    }
+    // Trim string and returned undefined if the empty string.
+    const shouldTrim = expectedType === 'string' && value && trim;
+    if (shouldTrim) {
+      return value.trim() || undefined;
+    }
+    return value;
+  },
+  extractColorValue(spec) {
+    const value = this.extractValue(spec);
+    const DOMUtils = Cc['@mozilla.org/inspector/dom-utils;1']
+      .getService(Ci.inIDOMUtils);
+    let color;
+    if (DOMUtils.isValidCSSColor(value)) {
+      color = value;
+    } else if (value) {
+      this.console.warn(this.domBundle.formatStringFromName("ManifestInvalidCSSColor",
+                                                            [spec.property, value],
+                                                            2));
+    }
+    return color;
+  }
+};
+this.ValueExtractor = ValueExtractor; // jshint ignore:line
+this.EXPORTED_SYMBOLS = ['ValueExtractor']; // jshint ignore:line