make publisher be able to take-in a plain JavaScript object as messag…

index.js

@@ -25,6 +25,7 @@ const path = require('path');
 const QoS = require('./lib/qos.js');
 const rclnodejs = require('bindings')('rclnodejs');
 const validator = require('./lib/validator.js');
+const util = require('./lib/utility.js');
 
 function inherits(target, source) {
   let properties = Object.getOwnPropertyNames(source.prototype);
@@ -224,7 +225,9 @@ let rcl = {
    */
   expandTopicName(topicName, nodeName, nodeNamespace) {
     return rclnodejs.expandTopicName(topicName, nodeName, nodeNamespace);
-  }
+  },
+
+  util: util,
 };
 
 module.exports = rcl;

lib/message_translator.js

@@ -0,0 +1,109 @@
+// Copyright (c) 2017 Intel Corporation. All rights reserved.
+//
+// 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.
+
+'use strict';
+
+const debug = require('debug')('rclnodejs:message_translator');
+
+/* eslint-disable max-depth */
+function copyMsgObject(msg, obj) {
+  if (typeof obj === 'object') {
+    for (let i in obj) {
+      if (typeof msg[i] !== 'undefined') {
+        const type = typeof obj[i];
+        if (type === 'string' || type === 'number' || type === 'boolean') {
+          // A primitive-type value
+          msg[i] = obj[i];
+        } else if (Array.isArray(obj[i])) {  // TODO(Kenny): deal with TypedArray
+          // It's an array
+          if (typeof obj[i][0] === 'object') {
+            // It's an array of objects: converting to ROS message objects
+
+            // 1. Extract the element-type first
+            const t = new MessageTranslator(msg[i].classType.elementType);
+            // 2. Build the array by translate every elements
+            let msgArray = [];
+            obj[i].forEach((o) => {
+              msgArray.push(t.toROSMessage(o));
+            });
+            // 3. Assign
+            msg[i].fill(msgArray);
+          } else {
+            // It's an array of primitive-type elements
+            msg[i] = obj[i];
+          }
+        } else {
+          // Proceed further of this object
+          copyMsgObject(msg[i], obj[i]);  // TODO(Kenny): deal with TypedArray
+        }
+      } else {
+        // Extra fields in obj (but not in msg)
+      }
+    } // for
+  }
+}
+/* eslint-enable max-depth */
+
+class MessageTranslator {
+  constructor(typeClass) {
+    this._typeClass = typeClass;
+  }
+
+  static toPlainObject(message) {
+    // TODO(Kenny): deal with primitive-type array (convert to TypedArray)
+
+    if (message.isROSArray) {
+      // It's a ROS message array
+      //  Note: there won't be any JavaScript array in message
+      let array = [];
+      const data = message.data;
+      data.forEach((e) => {
+        // Translate every elements
+        array.push(MessageTranslator.toPlainObject(e));
+      });
+      return array;
+      // eslint-disable-next-line no-else-return
+    } else {
+      // It's a ROS message
+      const def = message.classType.ROSMessageDef;
+      let obj = {};
+      for (let i in def.fields) {
+        const name = def.fields[i].name;
+        if (def.fields[i].type.isPrimitiveType) {
+          // Direct assignment
+          obj[name] = message[name];
+        } else {
+          // Proceed further
+          obj[name] = MessageTranslator.toPlainObject(message[name]);
+        }
+      }
+      return obj;
+    }
+  }
+
+  toROSMessage(obj) {
+    let msg = new this._typeClass();
+    const type = typeof obj;
+    if (type === 'string' || type === 'number' || type === 'boolean') {
+      msg.data = obj;
+    } else if (type === 'object') {
+      copyMsgObject(msg, obj);
+    }
+    return msg;
+  }
+}
+
+module.exports = {
+  MessageTranslator: MessageTranslator
+};

lib/publisher.js

@@ -17,6 +17,7 @@
 const rclnodejs = require('bindings')('rclnodejs');
 const debug = require('debug')('rclnodejs:publisher');
 const Entity = require('./entity.js');
+const {MessageTranslator} = require('./message_translator.js');
 
 /**
  * @class - Class representing a Publisher in ROS
@@ -27,6 +28,7 @@ class Publisher extends Entity {
   constructor(handle, nodeHandle, typeClass, topic, qos) {
     super(handle, typeClass, qos);
     this._topic = topic;
+    this.translator = new MessageTranslator(typeClass);
   }
 
   /**
@@ -42,12 +44,15 @@ class Publisher extends Entity {
    * @return {undefined}
    */
   publish(message) {
-    // TODO(minggang): Support to convert a plain JavaScript value/object to a ROS message,
-    // thus we can invoke this function like: publisher.publish('hello world').
-    let rclMessage = message;
-    if (!(message instanceof this._typeClass)) {
-      rclMessage = new this._typeClass();
-      rclMessage.data = message;
+    let rclMessage;
+    if (message instanceof this._typeClass) {
+      rclMessage = message;
+    } else {
+      // Use translator to enable call by plain object/number/string argument
+      //  e.g. publisher.publish(3.14);
+      //       publisher.publish('The quick brown fox...');
+      //       publisher.publish({linear: {x: 0, y: 1, z: 2}, ...});
+      rclMessage = this.translator.toROSMessage(message);
     }
 
     let rawRosMessage = rclMessage.serialize();

lib/utility.js

@@ -0,0 +1,62 @@
+// Copyright (c) 2017 Intel Corporation. All rights reserved.
+//
+// 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.
+
+'use strict';
+
+/* eslint-disable max-depth */
+function deepEqual(msg, obj) {
+  if (typeof obj !== 'object') {
+    return msg === obj;
+  }
+
+  for (let i in obj) {
+    const m = msg[i];
+    const o = obj[i];
+
+    if (typeof m === 'undefined') {
+      return false;
+    }
+
+    const t = typeof o;
+    if (t === 'string' || t === 'number' || t === 'boolean') {
+      // A primitive value
+      if (m !== o) {
+        return false;
+      }
+    } else if (m.isROSArray) {
+      // An array of message objects
+      if (!Array.isArray(o)) return false;
+
+      const data = m.data;
+      for (let j in data) {
+        if (!deepEqual(data[j], o[j])) {
+          return false;
+        }
+      }
+    } else {
+      // A regular message object
+      const equal = deepEqual(m, o);
+      if (!equal) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+/* eslint-enable max-depth */
+
+module.exports = {
+  deepEqual: deepEqual,
+};

rosidl_gen/templates/message.dot

@@ -18,6 +18,7 @@ let arrayWrapper = it.spec.msgName + 'ArrayWrapper';
 let refObjectType = it.spec.msgName + 'RefStruct';
 let refObjectArrayType = it.spec.msgName + 'RefStructArray';
 let refArrayType = it.spec.msgName + 'RefArray';
+const compactMsgDefJSON = JSON.stringify(JSON.parse(it.json));
 
 if (it.spec.fields.length === 0) {
   /* Following rosidl_generator_c style, put a bool member named '_dummy' */
@@ -326,6 +327,14 @@ class {{=objectWrapper}} {
     {{?}}
     {{~}}
   }
+
+  get classType() {
+    return {{=objectWrapper}};
+  }
+
+  static get ROSMessageDef() {
+    return {{=compactMsgDefJSON}};
+  }
 }
 
 // Define the wrapper of array class.
@@ -445,6 +454,18 @@ class {{=arrayWrapper}} {
       {{=objectWrapper}}.freeStruct(refObjectArray[index]);
     }
   }
+
+  static get elementType() {
+    return {{=objectWrapper}};
+  }
+
+  get isROSArray() {
+    return true;
+  }
+
+  get classType() {
+    return {{=arrayWrapper}};
+  }
 }
 
 {{? it.spec.constants != undefined && it.spec.constants.length}}

test/publisher_array_setup.js

@@ -48,7 +48,7 @@ rclnodejs.init().then(function() {
     node.destroy();
     rclnodejs.shutdown();
     process.exit(0);
-  });  
+  });
 }).catch(function(err) {
   console.log(err);
 });