check_condition_state.py

Go to the documentation of this file.

#!/usr/bin/env python

import rospy
from flexbe_core import EventState, Logger

'''
Created on 02/24/2015

@author: Philipp Schillinger
'''

class CheckConditionState(EventState):
        '''
        Checks if the given condition is true and returns the corresponding outcome.
        This state can be used if the further control flow of the behavior depends on a simple condition.
        
        -- predicate    function        The condition whose truth value will be evaluated.
                                                                Has to expect one parameter which will be set to input_value and return a boolean.

        ># input_value  object          Input to the predicate function.

        <= true                                         Returned if the condition evaluates to True
        <= false                                        Returned if the condition evaluates to False
        
        '''


        def __init__(self, predicate):
                '''Constructor'''
                super(CheckConditionState, self).__init__(outcomes=['true', 'false'],
                                                                                                        input_keys=['input_value'])
                
                self._predicate = predicate
                self._outcome = 'false'
                
                
        def execute(self, userdata):
                '''Execute this state'''

                return self._outcome
                
        
        def on_enter(self, userdata):
                try:
                        self._outcome = 'true' if self._predicate(userdata.input_value) else 'false'
                except Exception as e:
                        Logger.logwarn('Failed to execute condition function!\n%s' % str(e))