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.
 
from typing import List
from typing import Text
 
import yaml
import launch
 
import sys # delete this
 
class HasNodeParams(launch.Substitution):
  """
  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: Text) -> None:
    super().__init__()
    """
    Construct the substitution
 
    :param: source_file the parameter YAML file
    :param: node_name the name of the node to check
    """
 
    from launch.utilities import normalize_to_list_of_substitutions  # import here to avoid loop
    self.__source_file__source_file = 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__source_file
 
  def describe(self) -> Text:
    """Return a description of this substitution as a string."""
    return ''
 
  def perform(self, context: launch.LaunchContext) -> Text:
    yaml_filename = launch.utilities.perform_substitutions(context, self.namename)
    data = yaml.safe_load(open(yaml_filename, 'r'))
 
    if self.__node_name__node_name in data.keys():
        return "True"
    return "False"