Add a new typing for memory banks.

PiperOrigin-RevId: 650013164
Change-Id: Ie896345ec66f37807aa132193cfd7197c2b911cf

concordia/typing/memory.py

@@ -0,0 +1,89 @@
+# Copyright 2023 DeepMind Technologies Limited.
+#
+# 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.
+
+"""The abstract class for a memory."""
+
+import abc
+from collections.abc import Mapping, Sequence
+from typing import Any, Protocol
+
+
+class MemoryScorer(Protocol):
+  """Typing definition for a memory scorer function."""
+
+  def __call__(self, query: str, text: str, **metadata: Any) -> float:
+    """Returns a score for a memory (text and metadata) given the query.
+
+    Args:
+      query: The query to use for retrieval.
+      text: The text of the memory.
+      **metadata: The metadata of the memory.
+    """
+
+
+class MemoryBank(metaclass=abc.ABCMeta):
+  """Base class for memory banks."""
+
+  @abc.abstractmethod
+  def add(self, text: str, metadata: Mapping[str, Any]) -> None:
+    """Adds a memory (in the form of text) to the memory bank.
+
+    The memory bank might add extra metadata to the memory.
+
+    Args:
+      text: The text to add to the memory bank.
+      metadata: The metadata associated with the memory.
+    """
+    raise NotImplementedError()
+
+  def extend(self, texts: Sequence[str], metadata: Mapping[str, Any]) -> None:
+    """Adds a sequence of memories (in the form of text) to the memory bank.
+
+    All memories will be added with the same metadata. The memory bank might add
+    extra metadata to the memories.
+
+    Args:
+      texts: The texts to add to the memory bank.
+      metadata: The metadata associated with all the memories.
+    """
+    for text in texts:
+      self.add(text, metadata)
+
+  @abc.abstractmethod
+  def retrieve(
+      self,
+      query: str,
+      scoring_fn: MemoryScorer,
+      limit: int,
+  ) -> Sequence[tuple[str, float]]:
+    """Retrieves memories from the memory bank using the given scoring function.
+
+    This function retrieves the memories from the memory bank that are most
+    relevant to the given query, according to the scoring function. The scoring
+    function is a function that takes the query, a memory (in the form of text),
+    and a dictionary of metadata and returns a score for the memory. The higher
+    the score, the more relevant the memory is to the query.
+
+    Args:
+      query: The query to use for retrieval.
+      scoring_fn: The scoring function to use.
+      limit: The maximum number of memories to retrieve. If negative, all
+        memories will be retrieved.
+
+    Returns:
+      A list of memories (in the form of text) and their scores that are most
+      relevant to the `query`. This list will be of at most `limit` elements,
+      unless `limit` is negative, in which case all memories will be returned.
+    """
+    raise NotImplementedError()