chore: import upstream snapshot with attribution

python/zvec/extension/rerank_function.py

@@ -0,0 +1,56 @@
+# Copyright 2025-present the zvec project
+#
+# 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
+#
+#     http://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 __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+
+from ..model.doc import Doc, DocList
+
+if TYPE_CHECKING:
+    from ..model.schema import FieldSchema, VectorSchema
+
+
+class RerankFunction(ABC):
+    """Abstract base class for reranker parameter containers.
+
+    Subclasses define rerank parameters and implement _to_cpp_params()
+    for conversion to C++ parameter structs (used by collection fast path).
+    Each subclass also provides a standalone rerank() implementation.
+    """
+
+    def _to_cpp_params(self):
+        """Return C++ reranker params. Override in subclasses that use C++ path."""
+        raise NotImplementedError
+
+    @abstractmethod
+    def rerank(
+        self,
+        query_results: list[list[Doc]],
+        topn: int = 10,
+        *,
+        fields: list[FieldSchema | VectorSchema] | None = None,
+    ) -> DocList:
+        """Execute rerank on sub-query results.
+
+        Args:
+            query_results: List of per-sub-query document lists.
+            topn: Maximum number of results to return.
+            fields: Per-sub-query Python FieldSchema/VectorSchema objects
+                (required for WeightedReRanker score normalization).
+
+        Returns:
+            Re-ranked document list.
+        """
+        ...