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"""
Support for using numpy with rospy messages.

For tutorials, see U{http://www.ros.org/wiki/rospy_tutorials/Tutorials/numpy}

Listener example::
    from rospy.numpy_msg import numpy_msg

    rospy.init_node('mynode')
    rospy.Subscriber("mytopic", numpy_msg(TopicType)

Publisher example::

    from rospy.numpy_msg import numpy_msg
    import numpy
    
    pub = rospy.Publisher('mytopic', numpy_msg(TopicType), queue_size=10)
    rospy.init_node('mynode')
    a = numpy.array([1.0, 2.1, 3.2, 4.3, 5.4, 6.5], dtype=numpy.float32)
    pub.publish(a)
"""

import numpy

# TODO: we will need to generate a new type structure with
# little-endian specified and then pass that type structure into the
# *_numpy calls.

def _serialize_numpy(self, buff):
    """
    wrapper for factory-generated class that passes numpy module into serialize
    """
    # pass in numpy module reference to prevent import in auto-generated code
    return self.serialize_numpy(buff, numpy)

def _deserialize_numpy(self, str):
    """
    wrapper for factory-generated class that passes numpy module into deserialize    
    """
    # pass in numpy module reference to prevent import in auto-generated code
    return self.deserialize_numpy(str, numpy)
    
_numpy_msg_types = {}
## Use this function to generate message instances using numpy array
## types for numerical arrays. 
## @msg_type Message class: call this functioning on the message type that you pass
## into a Publisher or Subscriber call. 
## @returns Message class
def numpy_msg(msg_type):
    if msg_type in _numpy_msg_types:
        return _numpy_msg_types[msg_type]

    classdict = { '__slots__': msg_type.__slots__, '_slot_types': msg_type._slot_types,
                  '_md5sum': msg_type._md5sum, '_type': msg_type._type,
                  '_has_header': msg_type._has_header, '_full_text': msg_type._full_text,
                  'serialize': _serialize_numpy, 'deserialize': _deserialize_numpy,
                  'serialize_numpy': msg_type.serialize_numpy,
                  'deserialize_numpy': msg_type.deserialize_numpy
                  }

    # create the numpy message type
    msg_type_name = "Numpy_%s"%msg_type._type.replace('/', '__')
    numpy_type = type(msg_type_name,(msg_type,),classdict)
    _numpy_msg_types[msg_type] = numpy_type
    return numpy_type
