handlers.py

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#! /usr/bin/env python
# -*- coding: utf-8 -*-
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#            ROBOTICS™
#
#
#  Copyright © 2012 Clearpath Robotics, Inc. 
#  All Rights Reserved
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# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
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#       notice, this list of conditions and the following disclaimer.
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#       documentation and/or other materials provided with the distribution.
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#       names of its contributors may be used to endorse or promote products
#       derived from this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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import translator
import rospy

from applanix_msgs.msg import Ack


class Handler:
  def handle(self, data):
    raise NotImplementedError


class NullHandler(Handler):
  def handle(self, data):
    pass


class GroupHandler(Handler):
  def __init__(self, name, data_class, listener):
    self.publisher = rospy.Publisher(name, data_class, subscriber_listener=listener)
    self.message = self.publisher.data_class()

  def handle(self, buff):
    self.message.translator().deserialize(buff)
    self.publisher.publish(self.message)


class MessageHandler(Handler):
  def __init__(self, name, data_class, all_msgs):
    self.name = name
    if data_class.in_all_msgs:
      self.message = getattr(all_msgs, name) 
    else:
      self.message = data_class()

    # Keep a reference to the all_msgs aggregate message.
    self.all_msgs = all_msgs

  def handle(self, buff):
    self.message.translator().deserialize(buff)
    self.all_msgs.last_changed = rospy.get_rostime()


class AckHandler(Handler):
  def __init__(self):
    self.message = Ack()

  def handle(self, buff):
    self.message.translator().deserialize(buff)