npm package: @lichtblick/rosmsg
Description: Parser for ROS and ROS 2 .msg definitions
Author: Lichtblick
Latest version: 1.0.0

# @lichtblick/rosmsg

> _ROS1 and ROS2 message definition parser_

[![npm version](https://img.shields.io/npm/v/@lichtblick/rosmsg.svg?style=flat)](https://www.npmjs.com/package/@lichtblick/rosmsg)

## Introduction

[The Robot Operating System (ROS)](https://www.ros.org/) defines a simplified message description language for describing data types. This library parses those message definitions and can round trip them back into a canonical string format suitable for checksum generation. The parsed definitions are useful for serialization or deserialization when paired with other libraries.

This library supports both [ROS1](http://wiki.ros.org/msg) and [ROS 2](https://docs.ros.org/en/galactic/Concepts/About-ROS-Interfaces.html) message definitions.

## ROS 1 Definition Usage

```Typescript
import { parse, stringify } from "@lichtblick/rosmsg";

const definitionStr = `# geometry_msgs/Pose
geometry_msgs/Point position
geometry_msgs/Quaternion orientation

===
MSG: geometry_msgs/Point
float64 x
float64 y
float64 z

===
MSG: geometry_msgs/Quaternion
float64 x
float64 y
float64 z
float64 w`;

const messageDefinition = parse(definitionStr);

// print the parsed message definition structure
console.log(JSON.stringify(messageDefinition, null, 2));
```

Prints:

```JSON
[
  {
    "definitions": [
      {
        "type": "geometry_msgs/Point",
        "isArray": false,
        "name": "position",
        "isComplex": true
      },
      {
        "type": "geometry_msgs/Quaternion",
        "isArray": false,
        "name": "orientation",
        "isComplex": true
      }
    ]
  },
  {
    "name": "geometry_msgs/Point",
    "definitions": [
      {
        "type": "float64",
        "isArray": false,
        "name": "x",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "y",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "z",
        "isComplex": false
      }
    ]
  },
  {
    "name": "geometry_msgs/Quaternion",
    "definitions": [
      {
        "type": "float64",
        "isArray": false,
        "name": "x",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "y",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "z",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "w",
        "isComplex": false
      }
    ]
  }
]
```

## ROS 2 Definition Usage

```Typescript
import { parse, stringify } from "@lichtblick/rosmsg";

const definitionStr = `# geometry_msgs/msg/Pose
geometry_msgs/msg/Point position
geometry_msgs/msg/Quaternion orientation

===
MSG: geometry_msgs/msg/Point
float64 x
float64 y
float64 z

===
MSG: geometry_msgs/msg/Quaternion
float64 x
float64 y
float64 z
float64 w`;

const messageDefinition = parse(definitionStr, {ros2: true});

// stringify(messageDefinition) will return a canonical string, similar to
// _definitionStr_
// print the parsed message definition structure
console.log(JSON.stringify(messageDefinition, null, 2));
```

Prints:

```JSON
[
  {
    "definitions": [
      {
        "type": "geometry_msgs/msg/Point",
        "isArray": false,
        "name": "position",
        "isComplex": true
      },
      {
        "type": "geometry_msgs/msg/Quaternion",
        "isArray": false,
        "name": "orientation",
        "isComplex": true
      }
    ]
  },
  {
    "name": "geometry_msgs/msg/Point",
    "definitions": [
      {
        "type": "float64",
        "isArray": false,
        "name": "x",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "y",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "z",
        "isComplex": false
      }
    ]
  },
  {
    "name": "geometry_msgs/msg/Quaternion",
    "definitions": [
      {
        "type": "float64",
        "isArray": false,
        "name": "x",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "y",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "z",
        "isComplex": false
      },
      {
        "type": "float64",
        "isArray": false,
        "name": "w",
        "isComplex": false
      }
    ]
  }
]
```

## ROS 2 IDL Support

See (`@lichtblick/ros2idl-parser`)[https://github.com/lichtblick-suite/omgidl/packages/ros2idl-parser] for our implementation of `ros2idl` schema support.

## License

@lichtblick/rosmsg is licensed under the [MIT License](https://opensource.org/licenses/MIT).

## Releasing

1. Run `yarn version --[major|minor|patch]` to bump version
2. Run `git push && git push --tags` to push new tag
3. GitHub Actions will take care of the rest