text: #!/usr/bin/env python3
  # Copyright (c) Facebook, Inc. and its affiliates.
  #
  # This source code is licensed under the MIT license found in the
  # LICENSE file in the root directory of this source tree.
  """
  BLEU scoring of generated translations against reference translations.
  """
  
  import argparse
  import os
  import sys
  
  from fairseq import bleu
  from fairseq.data import dictionary
  
  
  def get_parser():
      parser = argparse.ArgumentParser(description='Command-line script for BLEU scoring.')
      # fmt: off
      parser.add_argument('-s', '--sys', default='-', help='system output')
      parser.add_argument('-r', '--ref', required=True, help='references')
      parser.add_argument('-o', '--order', default=4, metavar='N',
                          type=int, help='consider ngrams up to this order')
      parser.add_argument('--ignore-case', action='store_true',
                          help='case-insensitive scoring')
      parser.add_argument('--sacrebleu', action='store_true',
                          help='score with sacrebleu')
      parser.add_argument('--sentence-bleu', action='store_true',
                          help='report sentence-level BLEUs (i.e., with +1 smoothing)')
      # fmt: on
      return parser
  
  
  def cli_main():
      parser = get_parser()
      args = parser.parse_args()
      print(args)
  
      assert args.sys == '-' or os.path.exists(args.sys), \
          "System output file {} does not exist".format(args.sys)
      assert os.path.exists(args.ref), \
          "Reference file {} does not exist".format(args.ref)
  
      dict = dictionary.Dictionary()
  
      def readlines(fd):
          for line in fd.readlines():
              if args.ignore_case:
                  yield line.lower()
              else:
                  yield line
  
      if args.sacrebleu:
          import sacrebleu
  
          def score(fdsys):
              with open(args.ref) as fdref:
                  bleu_score = sacrebleu.corpus_bleu(fdsys, [fdref])
                  print(sacrebleu.corpus_bleu(fdsys, [fdref]))
      elif args.sentence_bleu:
          def score(fdsys):
              with open(args.ref) as fdref:
                  scorer = bleu.Scorer(dict.pad(), dict.eos(), dict.unk())
                  for i, (sys_tok, ref_tok) in enumerate(zip(readlines(fdsys), readlines(fdref))):
                      scorer.reset(one_init=True)
                      sys_tok = dict.encode_line(sys_tok)
                      ref_tok = dict.encode_line(ref_tok)
                      scorer.add(ref_tok, sys_tok)
                      print(i, scorer.result_string(args.order))
      else:
          def score(fdsys):
              with open(args.ref) as fdref:
                  
                  scorer = bleu.Scorer(dict.pad(), dict.eos(), dict.unk())
                  for sys_tok, ref_tok in zip(readlines(fdsys), readlines(fdref)):
                      sys_tok = dict.encode_line(sys_tok)
                      ref_tok = dict.encode_line(ref_tok)
                      scorer.add(ref_tok, sys_tok)
                  print(scorer.result_string(args.order))
  
      if args.sys == '-':
          score(sys.stdin)
      else:
          with open(args.sys, 'r') as f:
              score(f)
  
  
  if __name__ == '__main__':
      cli_main()
  