text: # Copyright 2018 The Cirq Developers
  #
  # 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
  #
  #     https://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 typing import List, Optional
  
  from cirq.google import XmonQubit
  
  
  class LineSequence:
  
      def __init__(self, line: List[XmonQubit]) -> None:
          self.line = line
  
      def __eq__(self, other):
          if not isinstance(other, type(self)):
              return NotImplemented
          return self.line == other.line
  
      def __ne__(self, other):
          return not self == other
  
      def __hash__(self):
          return hash(tuple(self.line))
  
      # TODO: def as_list() -> List[LineQubit]?
  
  
  
  class LinePlacement:
  
      def __init__(self, lines: List[LineSequence]) -> None:
          self.lines = lines
  
      def __eq__(self, other):
          if not isinstance(other, type(self)):
              return NotImplemented
          return self.lines == other.lines
  
      def __ne__(self, other):
          return not self == other
  
      def __hash__(self):
          return hash(tuple(self.lines))
  
  
  def longest_sequence_index(sequences: List[List[XmonQubit]]) -> Optional[int]:
      """Gives the position of a longest sequence.
  
      Args:
          sequences: List of node sequences.
  
      Returns:
          Index of the longest sequence from the sequences list. If more than one
          longest sequence exist, the first one is returned. None is returned for
          empty list.
      """
      if sequences:
          return max(range(len(sequences)), key=lambda i: len(sequences[i]))
      return None
  