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"""A simple wrapper around enum types to expose utility functions.

Instances are created as properties with the same name as the enum they wrap
on proto classes.  For usage, see:
  reflection_test.py
"""

__author__ = 'rabsatt@google.com (Kevin Rabsatt)'


class EnumTypeWrapper(object):
  """A utility for finding the names of enum values."""

  DESCRIPTOR = None

  def __init__(self, enum_type):
    """Inits EnumTypeWrapper with an EnumDescriptor."""
    self._enum_type = enum_type
    self.DESCRIPTOR = enum_type

  def Name(self, number):
    """Returns a string containing the name of an enum value."""
    if number in self._enum_type.values_by_number:
      return self._enum_type.values_by_number[number].name
    raise ValueError('Enum %s has no name defined for value %d' % (
        self._enum_type.name, number))

  def Value(self, name):
    """Returns the value corresponding to the given enum name."""
    if name in self._enum_type.values_by_name:
      return self._enum_type.values_by_name[name].number
    raise ValueError('Enum %s has no value defined for name %s' % (
        self._enum_type.name, name))

  def keys(self):
    """Return a list of the string names in the enum.

    These are returned in the order they were defined in the .proto file.
    """

    return [value_descriptor.name
            for value_descriptor in self._enum_type.values]

  def values(self):
    """Return a list of the integer values in the enum.

    These are returned in the order they were defined in the .proto file.
    """

    return [value_descriptor.number
            for value_descriptor in self._enum_type.values]

  def items(self):
    """Return a list of the (name, value) pairs of the enum.

    These are returned in the order they were defined in the .proto file.
    """
    return [(value_descriptor.name, value_descriptor.number)
            for value_descriptor in self._enum_type.values]

  def __getattr__(self, name):
    """Returns the value corresponding to the given enum name."""
    if name in self._enum_type.values_by_name:
      return self._enum_type.values_by_name[name].number
    raise AttributeError
