chore: import upstream snapshot with attribution

decoding/GAD/fairseq/scoring/chrf.py

@@ -0,0 +1,27 @@
+# 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.
+
+from fairseq.scoring import BaseScorer, register_scorer
+
+
+@register_scorer("chrf")
+class ChrFScorer(BaseScorer):
+    def __init__(self, args):
+        super(ChrFScorer, self).__init__(args)
+        import sacrebleu
+
+        self.sacrebleu = sacrebleu
+
+    def add_string(self, ref, pred):
+        self.ref.append(ref)
+        self.pred.append(pred)
+
+    def score(self, order=4):
+        return self.result_string(order).score
+
+    def result_string(self, order=4):
+        if order != 4:
+            raise NotImplementedError
+        return self.sacrebleu.corpus_chrf(self.pred, [self.ref]).format()