[Time Conductor] Add DateAggregator

Add DateAggregator, to allow composite services to expose
different ways of parsing/formatting dates.
nasa/openmctweb#182.

platform/commonUI/general/src/services/DateAggregator.js

@@ -0,0 +1,116 @@
+/*****************************************************************************
+ * Open MCT Web, Copyright (c) 2014-2015, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT Web is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT Web includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+/*global define*/
+
+define([
+
+], function (
+) {
+    "use strict";
+
+    /**
+     * Formats dates for display and parses dates from user input,
+     * varying by a chosen time system.
+     *
+     * Time systems are typically domain keys from telemetry metadata.
+     * If omitted/left undefined, the time system is presumed to be UTC time,
+     * with its numeric interpretation being milliseconds since the
+     * start of 1970.
+     *
+     * @interface DateService
+     */
+
+    /**
+     * Check if the provided text can be parsed into a numeric
+     * representation of a time in the specified time system.
+     * @method validate
+     * @memberof DateService#
+     * @param {string} text the text to validate
+     * @param {string} [key] a key identifying the time system
+     * @returns {boolean} true if the text can be parsed
+     */
+
+    /**
+     * Parse the provided into a numeric representation of a time
+     * in the specified time system.
+     *
+     * Behavior of this method for invalid text is undefined; use
+     * the `validate` method to check for validity first.
+     *
+     * @method parse
+     * @memberof DateService#
+     * @param {string} text the text to parse
+     * @param {string} [key] a key identifying the time system
+     * @returns {number} a numeric representation of the date/time
+     */
+
+    /**
+     * Format the provided numeric representation of a time
+     * into a human-readable string appropriate for that time system.
+     *
+     * If the time system is not recognized, the return value will be
+     * `undefined`.
+     *
+     * @method format
+     * @memberof DateService#
+     * @param {number} value the time value to format
+     * @param {string} [key] a key identifying the time system
+     * @returns {string} a human-readable representation of the date/time
+     */
+
+    /**
+     * Composites multiple DateService implementations such that
+     * they can be used as one.
+     * @memberof platform/commonUI/general
+     * @constructor
+     */
+    function DateAggregator(dateProviders) {
+        this.dateProviders = dateProviders;
+    }
+
+    DateAggregator.prototype.validate = function (text, key) {
+        return this.dateProviders.some(function (provider) {
+            return provider.validate(text, key);
+        });
+    };
+
+    DateAggregator.prototype.format = function (value, key) {
+        var i, text;
+        for (i = 0; i < this.dateProviders.length; i += 1) {
+            text = this.dateProviders[i].format(value, key);
+            if (text !== undefined) {
+                return text;
+            }
+        }
+    };
+
+    DateAggregator.prototype.parse = function (text, key) {
+        var i;
+        for (i = 0; i < this.dateProviders.length; i += 1) {
+            if (this.dateProviders[i].validate(text, key)) {
+                return this.dateProviders[i].parse(text, key);
+            }
+        }
+    };
+
+    return DateAggregator;
+});