1 files changed, 106 insertions, 0 deletions
diff --git a/dom/manifest/ValueExtractor.jsm b/dom/manifest/ValueExtractor.jsm
new file mode 100644
index 0000000000..a122467ec1
--- /dev/null
+++ b/dom/manifest/ValueExtractor.jsm
@@ -0,0 +1,106 @@
+/* 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 errors.
+ */
+"use strict";
+
+class ValueExtractor {
+  constructor(errors, aBundle) {
+    this.errors = errors;
+    this.domBundle = aBundle;
+  }
+
+  /**
+   * @param options
+   *        The 'spec' object.
+   * @note  This function takes a 'spec' object and destructures it to extract
+   *        a value. If the value is of the wrong type, it warns the developer
+   *        and returns undefined.
+   *        expectedType: 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.
+   *        throwTypeError: boolean, throw a TypeError if the type is incorrect.
+   *        trim: boolean, if the value should be trimmed (used by string type).
+   */
+  extractValue(options) {
+    const {
+      expectedType,
+      object,
+      objectName,
+      property,
+      throwTypeError,
+      trim,
+    } = options;
+    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") {
+        const warn = this.domBundle.formatStringFromName(
+          "ManifestInvalidType",
+          [objectName, property, expectedType]
+        );
+        this.errors.push({ warn });
+        if (throwTypeError) {
+          throw new TypeError(warn);
+        }
+      }
+      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);
+    let color;
+    if (InspectorUtils.isValidCSSColor(value)) {
+      const rgba = InspectorUtils.colorToRGBA(value);
+      color =
+        "#" +
+        rgba.r.toString(16).padStart(2, "0") +
+        rgba.g.toString(16).padStart(2, "0") +
+        rgba.b.toString(16).padStart(2, "0") +
+        Math.round(rgba.a * 255)
+          .toString(16)
+          .padStart(2, "0");
+    } else if (value) {
+      const warn = this.domBundle.formatStringFromName(
+        "ManifestInvalidCSSColor",
+        [spec.property, value]
+      );
+      this.errors.push({ warn });
+    }
+    return color;
+  }
+
+  extractLanguageValue(spec) {
+    let langTag;
+    const value = this.extractValue(spec);
+    if (value !== undefined) {
+      try {
+        langTag = Intl.getCanonicalLocales(value)[0];
+      } catch (err) {
+        const warn = this.domBundle.formatStringFromName(
+          "ManifestLangIsInvalid",
+          [spec.property, value]
+        );
+        this.errors.push({ warn });
+      }
+    }
+    return langTag;
+  }
+}
+
+const EXPORTED_SYMBOLS = ["ValueExtractor"];