From 136ffaa9bdc35edadc9000b81fd438c15d749324 Mon Sep 17 00:00:00 2001
From: Kurt Shuster <kshuster@fb.com>
Date: Mon, 13 Sep 2021 13:34:01 -0400
Subject: [PATCH] add msc mutator (#3966)

---
 parlai/tasks/msc/agents.py   |  1 +
 parlai/tasks/msc/mutators.py | 30 ++++++++++++++++++++++++++++++
 tests/test_mutators.py       | 13 +++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 parlai/tasks/msc/mutators.py

diff --git a/parlai/tasks/msc/agents.py b/parlai/tasks/msc/agents.py
index 60ca0b77b56..a0978d9f488 100644
--- a/parlai/tasks/msc/agents.py
+++ b/parlai/tasks/msc/agents.py
@@ -31,6 +31,7 @@
     UI_OPT,
     COMMON_CONFIG,
 )
+import parlai.tasks.msc.mutators  # type: ignore
 
 
 NOPERSONA = '__NO__PERSONA__BEAM__MIN__LEN__20__'
diff --git a/parlai/tasks/msc/mutators.py b/parlai/tasks/msc/mutators.py
new file mode 100644
index 00000000000..158cf018476
--- /dev/null
+++ b/parlai/tasks/msc/mutators.py
@@ -0,0 +1,30 @@
+#!/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.
+import random
+from typing import List
+from parlai.core.message import Message
+from parlai.core.mutators import register_mutator, ManyEpisodeMutator
+
+
+@register_mutator("ltm_mutator")
+class LongTermMemoryMutator(ManyEpisodeMutator):
+    """
+    Replaces the episode labels in messages with "personal_knwowledge".
+
+    Episodes are flattened to ensure dialogue history is maintained appropriately.
+    """
+
+    def many_episode_mutation(self, episode: List[Message]) -> List[List[Message]]:
+        history = []
+        for message in episode:
+            if message['text'] == '__SILENCE__':
+                continue
+            history.append(message.pop('text'))
+            message['text'] = '\n'.join(history)
+            labels = message.pop('labels')
+            message['labels'] = ["personal_knowledge"]
+            yield [message]
+            history.append(random.choice(labels))
diff --git a/tests/test_mutators.py b/tests/test_mutators.py
index c26a2712987..1e2a49e3a5e 100644
--- a/tests/test_mutators.py
+++ b/tests/test_mutators.py
@@ -227,6 +227,19 @@ def test_word_shuffle(self):
         assert set(ex3['text'].split()) == set(EXAMPLE3['text'].split())
         assert set(ex4['text'].split()) == set(EXAMPLE4['text'].split())
 
+    def test_msc_ltm_mutator(self):
+        from parlai.tasks.msc.mutators import LongTermMemoryMutator
+
+        ex1, ex2, ex3, ex4 = self._apply_mutator(LongTermMemoryMutator)
+
+        assert (
+            ex1['labels']
+            == ex2['labels']
+            == ex3['labels']
+            == ex4['labels']
+            == ['personal_knowledge']
+        )
+
 
 class TestMutatorStickiness(unittest.TestCase):
     """