decision_state.py

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#!/usr/bin/env python

import rospy
from flexbe_core import EventState, Logger
from rospy.exceptions import ROSInterruptException

'''
Created on 11.06.2013

@author: Philipp Schillinger
'''

class DecisionState(EventState):
        '''
        Evaluates a condition function in order to return one of the specified outcomes.
        This state can be used if the further control flow of the behavior depends on an advanced condition.

        -- outcomes     string[]        A list containing all possible outcomes of this state
        -- conditions   function        Implements the condition check and returns one of the available outcomes.
                                                                Has to expect one parameter which will be set to input_value.

        ># input_value  object          Input to the condition function.

        '''


        def __init__(self, outcomes, conditions):
                '''
                Constructor
                '''
                super(DecisionState, self).__init__(outcomes=outcomes,
                                                                                        input_keys=['input_value'])
                
                self._conditions = conditions
                self._my_outcomes = outcomes
                
                
        def execute(self, userdata):
                '''
                Execute this state
                '''
                
                if self._conditions is not None:
                        outcome = DecisionState._loopback_name
                        try:
                                outcome = str(self._conditions(userdata.input_value))
                        except Exception as e:
                                Logger.logwarn('Passed no function as predicate!\n%s' % str(e))
                                outcome = DecisionState._loopback_name
                        if outcome is not None:
                                return outcome
                        
        
        def on_enter(self, userdata):
                try:
                        rospy.sleep(0.2) # TODO: check why this has been added
                except ROSInterruptException:
                        rospy.logwarn('Skipped sleep.')