text: # Copyright (c) 2021, NVIDIA CORPORATION.  All rights reserved.
  #
  # 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.
  
  from nemo_text_processing.inverse_text_normalization.vi.graph_utils import NEMO_NOT_QUOTE, GraphFst, delete_space
  
  try:
      import pynini
      from pynini.lib import pynutil
  
      PYNINI_AVAILABLE = True
  except (ModuleNotFoundError, ImportError):
      PYNINI_AVAILABLE = False
  
  
  class ElectronicFst(GraphFst):
      """
      Finite state transducer for verbalizing electronic
          e.g. tokens { electronic { username: "cdf1" domain: "abc.edu" } } -> cdf1@abc.edu
      """
  
      def __init__(self):
          super().__init__(name="electronic", kind="verbalize")
          user_name = (
              pynutil.delete("username:")
              + delete_space
              + pynutil.delete("\"")
              + pynini.closure(NEMO_NOT_QUOTE, 1)
              + pynutil.delete("\"")
          )
          domain = (
              pynutil.delete("domain:")
              + delete_space
              + pynutil.delete("\"")
              + pynini.closure(NEMO_NOT_QUOTE, 1)
              + pynutil.delete("\"")
          )
  
          protocol = (
              pynutil.delete("protocol:")
              + delete_space
              + pynutil.delete("\"")
              + pynini.closure(NEMO_NOT_QUOTE, 1)
              + pynutil.delete("\"")
          )
  
          graph = user_name + delete_space + pynutil.insert("@") + domain
          graph |= protocol
  
          delete_tokens = self.delete_tokens(graph)
          self.fst = delete_tokens.optimize()
  