has_node_params.py

# Copyright (c) 2021 PAL Robotics S.L.
#
# 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.
 
import launch
import yaml
 
 
class HasNodeParams(launch.Substitution):  # type: ignore[misc]
    """
    Substitution that checks if a param file contains parameters for a node.
 
    Used in launch system
    """
 
    def __init__(
        self, source_file: launch.SomeSubstitutionsType, node_name: str
    ) -> None:
        super().__init__()
        """
    Construct the substitution
 
    :param: source_file the parameter YAML file
    :param: node_name the name of the node to check
    """
 
        # import here to avoid loop
        from launch.utilities import normalize_to_list_of_substitutions
 
        self.__source_file: list[launch.Substitution] = \
            normalize_to_list_of_substitutions(source_file)
        self.__node_name__node_name = node_name
 
    @property
    def name(self) -> list[launch.Substitution]:
        """Getter for name."""
        return self.__source_file
 
    def describe(self) -> str:
        """Return a description of this substitution as a string."""
        return ''
 
    def perform(self, context: launch.LaunchContext) -> str:
        yaml_filename = launch.utilities.perform_substitutions(context, self.namename)
        data = yaml.safe_load(open(yaml_filename))
 
        if self.__node_name__node_name in data.keys():
            return 'True'
        return 'False'