core: Add ruff rules PLR (#30696)

Add ruff rules [PLR](https://docs.astral.sh/ruff/rules/#refactor-plr)
Except PLR09xxx and PLR2004.

Co-authored-by: Eugene Yurtsev <[email protected]>

Author: cbornet

libs/core/langchain_core/callbacks/file.py

@@ -53,11 +53,10 @@ def on_chain_start(
         """
         if "name" in kwargs:
             name = kwargs["name"]
+        elif serialized:
+            name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
         else:
-            if serialized:
-                name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
-            else:
-                name = "<unknown>"
+            name = "<unknown>"
         print_text(
             f"\n\n\033[1m> Entering new {name} chain...\033[0m",
             end="\n",

libs/core/langchain_core/callbacks/manager.py

@@ -364,19 +364,16 @@ async def _ahandle_event_for_handler(
             event = getattr(handler, event_name)
             if asyncio.iscoroutinefunction(event):
                 await event(*args, **kwargs)
+            elif handler.run_inline:
+                event(*args, **kwargs)
             else:
-                if handler.run_inline:
-                    event(*args, **kwargs)
-                else:
-                    await asyncio.get_event_loop().run_in_executor(
-                        None,
-                        cast(
-                            "Callable",
-                            functools.partial(
-                                copy_context().run, event, *args, **kwargs
-                            ),
-                        ),
-                    )
+                await asyncio.get_event_loop().run_in_executor(
+                    None,
+                    cast(
+                        "Callable",
+                        functools.partial(copy_context().run, event, *args, **kwargs),
+                    ),
+                )
     except NotImplementedError as e:
         if event_name == "on_chat_model_start":
             message_strings = [get_buffer_string(m) for m in args[1]]
@@ -2426,12 +2423,11 @@ def _configure(
                     for handler in callback_manager.handlers
                 ):
                     callback_manager.add_handler(var_handler, inheritable)
-            else:
-                if not any(
-                    isinstance(handler, handler_class)
-                    for handler in callback_manager.handlers
-                ):
-                    callback_manager.add_handler(var_handler, inheritable)
+            elif not any(
+                isinstance(handler, handler_class)
+                for handler in callback_manager.handlers
+            ):
+                callback_manager.add_handler(var_handler, inheritable)
     return callback_manager
 
 

libs/core/langchain_core/callbacks/stdout.py

@@ -37,11 +37,10 @@ def on_chain_start(
         """
         if "name" in kwargs:
             name = kwargs["name"]
+        elif serialized:
+            name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
         else:
-            if serialized:
-                name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
-            else:
-                name = "<unknown>"
+            name = "<unknown>"
         print(f"\n\n\033[1m> Entering new {name} chain...\033[0m")  # noqa: T201
 
     @override

libs/core/langchain_core/indexing/api.py

@@ -316,7 +316,7 @@ def index(
         )
         raise ValueError(msg)
 
-    if (cleanup == "incremental" or cleanup == "scoped_full") and source_id_key is None:
+    if (cleanup in {"incremental", "scoped_full"}) and source_id_key is None:
         msg = (
             "Source id key is required when cleanup mode is incremental or scoped_full."
         )
@@ -379,7 +379,7 @@ def index(
             source_id_assigner(doc) for doc in hashed_docs
         ]
 
-        if cleanup == "incremental" or cleanup == "scoped_full":
+        if cleanup in {"incremental", "scoped_full"}:
             # source ids are required.
             for source_id, hashed_doc in zip(source_ids, hashed_docs):
                 if source_id is None:
@@ -622,7 +622,7 @@ async def aindex(
         )
         raise ValueError(msg)
 
-    if (cleanup == "incremental" or cleanup == "scoped_full") and source_id_key is None:
+    if (cleanup in {"incremental", "scoped_full"}) and source_id_key is None:
         msg = (
             "Source id key is required when cleanup mode is incremental or scoped_full."
         )
@@ -667,11 +667,10 @@ async def aindex(
             # In such a case, we use the load method and convert it to an async
             # iterator.
             async_doc_iterator = _to_async_iterator(docs_source.load())
+    elif hasattr(docs_source, "__aiter__"):
+        async_doc_iterator = docs_source  # type: ignore[assignment]
     else:
-        if hasattr(docs_source, "__aiter__"):
-            async_doc_iterator = docs_source  # type: ignore[assignment]
-        else:
-            async_doc_iterator = _to_async_iterator(docs_source)
+        async_doc_iterator = _to_async_iterator(docs_source)
 
     source_id_assigner = _get_source_id_assigner(source_id_key)
 
@@ -694,7 +693,7 @@ async def aindex(
             source_id_assigner(doc) for doc in hashed_docs
         ]
 
-        if cleanup == "incremental" or cleanup == "scoped_full":
+        if cleanup in {"incremental", "scoped_full"}:
             # If the cleanup mode is incremental, source ids are required.
             for source_id, hashed_doc in zip(source_ids, hashed_docs):
                 if source_id is None:

libs/core/langchain_core/language_models/chat_models.py

@@ -955,13 +955,12 @@ def _generate_with_cache(
                     )
                 chunks.append(chunk)
             result = generate_from_stream(iter(chunks))
+        elif inspect.signature(self._generate).parameters.get("run_manager"):
+            result = self._generate(
+                messages, stop=stop, run_manager=run_manager, **kwargs
+            )
         else:
-            if inspect.signature(self._generate).parameters.get("run_manager"):
-                result = self._generate(
-                    messages, stop=stop, run_manager=run_manager, **kwargs
-                )
-            else:
-                result = self._generate(messages, stop=stop, **kwargs)
+            result = self._generate(messages, stop=stop, **kwargs)
 
         # Add response metadata to each generation
         for idx, generation in enumerate(result.generations):
@@ -1028,13 +1027,12 @@ async def _agenerate_with_cache(
                     )
                 chunks.append(chunk)
             result = generate_from_stream(iter(chunks))
+        elif inspect.signature(self._agenerate).parameters.get("run_manager"):
+            result = await self._agenerate(
+                messages, stop=stop, run_manager=run_manager, **kwargs
+            )
         else:
-            if inspect.signature(self._agenerate).parameters.get("run_manager"):
-                result = await self._agenerate(
-                    messages, stop=stop, run_manager=run_manager, **kwargs
-                )
-            else:
-                result = await self._agenerate(messages, stop=stop, **kwargs)
+            result = await self._agenerate(messages, stop=stop, **kwargs)
 
         # Add response metadata to each generation
         for idx, generation in enumerate(result.generations):

libs/core/langchain_core/messages/base.py

@@ -170,17 +170,16 @@ def merge_content(
             # If both are lists
             merged = merge_lists(cast("list", merged), content)  # type: ignore
         # If the first content is a list, and the second content is a string
+        # If the last element of the first content is a string
+        # Add the second content to the last element
+        elif merged and isinstance(merged[-1], str):
+            merged[-1] += content
+        # If second content is an empty string, treat as a no-op
+        elif content == "":
+            pass
         else:
-            # If the last element of the first content is a string
-            # Add the second content to the last element
-            if merged and isinstance(merged[-1], str):
-                merged[-1] += content
-            # If second content is an empty string, treat as a no-op
-            elif content == "":
-                pass
-            else:
-                # Otherwise, add the second content as a new element of the list
-                merged.append(content)
+            # Otherwise, add the second content as a new element of the list
+            merged.append(content)
     return merged