ROS Parser

A Python parser for ROS message definitions and Foxglove message path syntax.

Installation

uv add ros-parser

Parsers

• ros1_msg: Parses ROS1 message definition files (.msg)
• ros2_msg: Parses ROS2 message definition files (.msg)
• message_path: Parses Foxglove message path syntax for data access and filtering

Usage

Parsing ROS2 Messages

from ros_parser import ros2_msg

definition = ros2_msg.parse_message_string("""
float64 x
float64 y
float64 z
""")

for field in definition.fields:
    print(f"{field.name}: {field.type}")

Parsing ROS1 Messages

from ros_parser import ros1_msg

definition = ros1_msg.parse_message_string("""
Header header
float64 x
float64 y
float64 z
""")

for field in definition.fields:
    print(f"{field.name}: {field.type}")

Parsing Schema with Dependencies

from ros_parser import parse_schema_to_definitions

# Parse a full schema including embedded type definitions
definitions = parse_schema_to_definitions(
    "geometry_msgs/msg/Pose",
    schema_data
)

Regenerating Standalone Parsers

The project uses Lark to generate standalone parsers from grammar files. If you modify any .lark grammar file, regenerate the parsers:

uv run _generate_standalone.py \
  src/ros_parser/ros1_msg/grammar.lark \
  src/ros_parser/ros2_msg/grammar.lark \
  src/ros_parser/message_path/grammar.lark \
  --output-dir src/ros_parser \
  --lexer contextual

For more details on the message path syntax, see src/ros_parser/message_path/README.md.