multiple: langchain 0.2 in master (#21191)

0.2rc 

migrations

- [x] Move memory
- [x] Move remaining retrievers
- [x] graph_qa chains
- [x] some dependency from evaluation code potentially on math utils
- [x] Move openapi chain from `langchain.chains.api.openapi` to
`langchain_community.chains.openapi`
- [x] Migrate `langchain.chains.ernie_functions` to
`langchain_community.chains.ernie_functions`
- [x] migrate `langchain/chains/llm_requests.py` to
`langchain_community.chains.llm_requests`
- [x] Moving `langchain_community.cross_enoders.base:BaseCrossEncoder`
->
`langchain_community.retrievers.document_compressors.cross_encoder:BaseCrossEncoder`
(namespace not ideal, but it needs to be moved to `langchain` to avoid
circular deps)
- [x] unit tests langchain -- add pytest.mark.community to some unit
tests that will stay in langchain
- [x] unit tests community -- move unit tests that depend on community
to community
- [x] mv integration tests that depend on community to community
- [x] mypy checks

Other todo

- [x] Make deprecation warnings not noisy (need to use warn deprecated
and check that things are implemented properly)
- [x] Update deprecation messages with timeline for code removal (likely
we actually won't be removing things until 0.4 release) -- will give
people more time to transition their code.
- [ ] Add information to deprecation warning to show users how to
migrate their code base using langchain-cli
- [ ] Remove any unnecessary requirements in langchain (e.g., is
SQLALchemy required?)

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/langchain_community/chains/openapi/response_chain.py

@@ -0,0 +1,57 @@
+"""Response parser."""
+
+import json
+import re
+from typing import Any
+
+from langchain.chains.api.openapi.prompts import RESPONSE_TEMPLATE
+from langchain.chains.llm import LLMChain
+from langchain_core.language_models import BaseLanguageModel
+from langchain_core.output_parsers import BaseOutputParser
+from langchain_core.prompts.prompt import PromptTemplate
+
+
+class APIResponderOutputParser(BaseOutputParser):
+    """Parse the response and error tags."""
+
+    def _load_json_block(self, serialized_block: str) -> str:
+        try:
+            response_content = json.loads(serialized_block, strict=False)
+            return response_content.get("response", "ERROR parsing response.")
+        except json.JSONDecodeError:
+            return "ERROR parsing response."
+        except:
+            raise
+
+    def parse(self, llm_output: str) -> str:
+        """Parse the response and error tags."""
+        json_match = re.search(r"```json(.*?)```", llm_output, re.DOTALL)
+        if json_match:
+            return self._load_json_block(json_match.group(1).strip())
+        else:
+            raise ValueError(f"No response found in output: {llm_output}.")
+
+    @property
+    def _type(self) -> str:
+        return "api_responder"
+
+
+class APIResponderChain(LLMChain):
+    """Get the response parser."""
+
+    @classmethod
+    def is_lc_serializable(cls) -> bool:
+        return False
+
+    @classmethod
+    def from_llm(
+        cls, llm: BaseLanguageModel, verbose: bool = True, **kwargs: Any
+    ) -> LLMChain:
+        """Get the response parser."""
+        output_parser = APIResponderOutputParser()
+        prompt = PromptTemplate(
+            template=RESPONSE_TEMPLATE,
+            output_parser=output_parser,
+            input_variables=["response", "instructions"],
+        )
+        return cls(prompt=prompt, llm=llm, verbose=verbose, **kwargs)