Source: lib/subscription.js

  1. // Copyright (c) 2017 Intel Corporation. All rights reserved.
  2. //
  3. // Licensed under the Apache License, Version 2.0 (the "License");
  4. // you may not use this file except in compliance with the License.
  5. // You may obtain a copy of the License at
  6. //
  7. //     http://www.apache.org/licenses/LICENSE-2.0
  8. //
  9. // Unless required by applicable law or agreed to in writing, software
  10. // distributed under the License is distributed on an "AS IS" BASIS,
  11. // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12. // See the License for the specific language governing permissions and
  13. // limitations under the License.
  15. 'use strict';
  17. const rclnodejs = require('bindings')('rclnodejs');
  18. const Entity = require('./entity.js');
  19. const debug = require('debug')('rclnodejs:subscription');
  21. /**
  22.  * @class - Class representing a ROS 2 Subscription
  23.  * @hideconstructor
  24.  * Includes support for content-filtering topics beginning with the
  25.  * ROS Humble release. To learn more about content-filtering
  26.  * @see {@link Node#options}
  27.  * @see {@link Node#createSubscription}
  28.  * @see {@link https://www.omg.org/spec/DDS/1.4/PDF|DDS 1.4 specification, Annex B}
  29.  */
  31. class Subscription extends Entity {
  32.   constructor(handle, typeClass, topic, options, callback) {
  33.     super(handle, typeClass, options);
  34.     this._topic = topic;
  35.     this._callback = callback;
  36.     this._isRaw = options.isRaw || false;
  37.   }
  39.   processResponse(msg) {
  40.     debug(`Message of topic ${this._topic} received.`);
  41.     if (this._isRaw) {
  42.       this._callback(msg);
  43.     } else {
  44.       this._callback(msg.toPlainObject(this.typedArrayEnabled));
  45.     }
  46.   }
  48.   static createSubscription(nodeHandle, typeClass, topic, options, callback) {
  49.     let type = typeClass.type();
  51.     // convert contentFilter.parameters to a string[]
  52.     if (options.contentFilter && options.contentFilter.parameters) {
  53.       options.contentFilter.parameters = options.contentFilter.parameters.map(
  54.         (param) => param.toString()
  55.       );
  56.     }
  58.     let handle = rclnodejs.createSubscription(
  59.       nodeHandle,
  60.       type.pkgName,
  61.       type.subFolder,
  62.       type.interfaceName,
  63.       topic,
  64.       options
  65.     );
  66.     return new Subscription(handle, typeClass, topic, options, callback);
  67.   }
  69.   /**
  70.    * @type {string}
  71.    */
  72.   get topic() {
  73.     return this._topic;
  74.   }
  76.   /**
  77.    * @type {boolean}
  78.    */
  79.   get isRaw() {
  80.     return this._isRaw;
  81.   }
  83.   /**
  84.    * Test if the RMW supports content-filtered topics and that this subscription
  85.    * has an active wellformed content-filter.
  86.    * @returns {boolean} True if content-filtering will be applied; otherwise false.
  87.    */
  88.   hasContentFilter() {
  89.     return rclnodejs.hasContentFilter(this.handle);
  90.   }
  92.   /**
  93.    * If the RMW supports content-filtered topics set this subscription's content-filter.
  94.    * @param {object} contentFilter - The content-filter description.
  95.    * @param {string} contentFilter.expression - Specifies the criteria to select messages of interest.
  96.    *  It is similar to the WHERE part of an SQL clause. Clear the current contentFilter if
  97.    *  the expression is undefined or an empty string.
  98.    * @param {object[]}  [contentFilter.parameters=undefined] - Array of objects that give values to
  99.    *  the ‘parameters’ (i.e., "%n" tokens) in the filter_expression. The number of supplied parameters must
  100.    *  fit with the requested values in the filter_expression (i.e., the number of %n tokens). default: undefined.
  101.    * @returns {boolean} - True if successful; false otherwise
  102.    * @see {@link https://www.omg.org/spec/DDS/1.4/PDF|DDS 1.4 specification, Annex B}
  103.    */
  104.   setContentFilter(contentFilter) {
  105.     return contentFilter?.expression
  106.       ? rclnodejs.setContentFilter(this.handle, contentFilter)
  107.       : this.clearContentFilter();
  108.   }
  110.   /**
  111.    * Clear the current content-filter. No filtering is to be applied.
  112.    * @returns {boolean} - True if successful; false otherwise
  113.    */
  114.   clearContentFilter() {
  115.     return this.hasContentFilter()
  116.       ? rclnodejs.clearContentFilter(this.handle)
  117.       : true;
  118.   }
  119. }
  121. module.exports = Subscription;