text: # Copyright 2019 Google LLC.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  """Basic interface for wrapping a primitive."""
  
  from __future__ import absolute_import
  from __future__ import division
  # Placeholder for import for type annotations
  from __future__ import print_function
  
  import abc
  from typing import Generic, Type, TypeVar
  # Special imports
  import six
  
  from tink.core import _primitive_set
  
  
  B = TypeVar('B')
  P = TypeVar('P')
  
  
  @six.add_metaclass(abc.ABCMeta)
  class PrimitiveWrapper(Generic[B, P]):
    """Basic interface for wrapping a primitive.
  
    A PrimitiveSet can be wrapped by a single primitive in order to fulfill a
    cryptographic task. This is done by the PrimitiveWrapper. Whenever a new
    primitive type is added to Tink, the user should define a new PrimitiveWrapper
    and register it by calling registry.registerPrimitiveWrapper().
  
    The primitive of type B is wrapped into a primitive of type P. In most cases,
    B and P are the same.
    """
  
    @abc.abstractmethod
    def wrap(self, pset: _primitive_set.PrimitiveSet) -> P:
      """Wraps a PrimitiveSet and returns a single primitive instance."""
      raise NotImplementedError()
  
    @abc.abstractmethod
    def primitive_class(self) -> Type[P]:
      """Returns the class of the primitive produced by the wrapper."""
      raise NotImplementedError()
  
    def input_primitive_class(self) -> Type[B]:
      """Returns the class of the primitive that gets wrapped."""
      raise NotImplementedError()
  