translator from LaunchConfiguration to YML

src/rosdiscover/ros2_translator/arch.py

@@ -0,0 +1,68 @@
+from typing import Any, Dict, List
+import argparse
+import json
+from launch import LaunchDescription, LaunchDescriptionEntity
+from launch.launch_context import LaunchContext
+from launch.launch_description_sources import PythonLaunchDescriptionSource
+from launch.actions import IncludeLaunchDescription
+from launch_ros.actions import Node
+NodeDescription = Dict[str, Any]
+
+
+class NodeDescriptionExtractor:
+    def __init__(self) -> None:
+        self.__unnamed_nodes = 0
+
+    def _node_to_description(self, node: Node) -> NodeDescription:
+        # Note: The code directly accesses variables since there are no getters for
+        # these specific variables in launch.
+        # This code might break with changed implementations of launch
+        output: NodeDescription = {}
+        if node._Node__node_name:
+            name_entry = node._Node__node_name
+            output['name'] = node._Node__node_name
+        else:
+            name_entry = f'unknown{self.__unnamed_nodes}'
+            self.__unnamed_nodes += 1
+            output['name'] = name_entry
+        if node._Node__node_namespace:
+            output['namespace'] = node._Node__node_namespace
+        if node._Node__node_executable:
+            output['executable'] = node._Node__node_executable
+        if node._Node__package:
+            output['package'] = node._Node__package
+        return output
+
+    def _extract_descriptions(self,
+                              entity: LaunchDescriptionEntity,
+                              context: LaunchContext
+                              ) -> List[NodeDescription]:
+        descriptions: List[NodeDescription] = []
+        if isinstance(entity, LaunchDescription) or isinstance(entity, IncludeLaunchDescription):  # noqa
+            for sub_entity in entity.visit(context):
+                descriptions += self._extract_descriptions(sub_entity, context)
+        elif isinstance(entity, Node):
+            descriptions = [self._node_to_description(entity)]
+        else:
+            print(f'UNKNOWN ENTITY: {type(entity)}')
+        return descriptions
+
+    def extract(self, filename: str) -> List[NodeDescription]:
+        context = LaunchContext()
+        launch_description_source = \
+            PythonLaunchDescriptionSource(args.launchfile)
+        launch_description = LaunchDescription([
+            IncludeLaunchDescription(launch_description_source)
+        ])
+        return self._extract_descriptions(launch_description, context)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Find nodes')
+    parser.add_argument('launchfile', type=str)
+    parser.add_argument('--output', type=str, default='arch.json')
+    args = parser.parse_args()
+    extractor = NodeDescriptionExtractor()
+    output = extractor.extract(args.launchfile)
+    with open(args.output, 'w') as f:
+        f.write(json.dumps(output, indent=2))