Refine MLX ReAct tool-call parsing

Author: diego-coder

libs/community/langchain_community/chat_models/mlx.py

@@ -2,6 +2,9 @@
 
 import json
 import logging
+import re
+import uuid
+
 from typing import (
     Any,
     Callable,
@@ -11,6 +14,7 @@
     Literal,
     Optional,
     Sequence,
+    Tuple,
     Type,
     Union,
 )
@@ -26,7 +30,13 @@
     AIMessageChunk,
     BaseMessage,
     HumanMessage,
+    InvalidToolCall,
     SystemMessage,
+    ToolCall,
+)
+from langchain_core.output_parsers.openai_tools import (
+    make_invalid_tool_call,
+    parse_tool_call,
 )
 from langchain_core.outputs import (
     ChatGeneration,
@@ -45,6 +55,52 @@
 DEFAULT_SYSTEM_PROMPT = """You are a helpful, respectful, and honest assistant."""
 
 
+def _parse_react_tool_calls(
+    text: str,
+) -> Tuple[list[ToolCall] | None, list[InvalidToolCall]]:
+    """Extract ReAct-style tool calls from plain text output.
+
+    Args:
+        text: Raw model generation text.
+
+    Returns:
+        A tuple containing a list of parsed ``ToolCall`` objects if any were
+        detected, otherwise ``None``, and a list of ``InvalidToolCall`` objects
+        for unparseable patterns.
+    """
+
+    tool_calls: list[ToolCall] = []
+    invalid_tool_calls: list[InvalidToolCall] = []
+
+    bracket_pattern = r"Action:\s*(?P<name>[\w.-]+)\[(?P<input>[^\]]+)\]"
+    separate_pattern = (
+        r"Action:\s*(?P<name>[^\n]+)\nAction Input:\s*(?P<input>[^\n]+)"
+    )
+
+    matches = list(re.finditer(bracket_pattern, text))
+    if not matches:
+        matches = list(re.finditer(separate_pattern, text))
+
+    for match in matches:
+        name = match.group("name").strip()
+        arg_text = match.group("input").strip()
+        try:
+            args = json.loads(arg_text)
+            if not isinstance(args, dict):
+                args = {"input": args}
+        except Exception:
+            args = {"input": arg_text}
+        tool_calls.append(ToolCall(id=str(uuid.uuid4()), name=name, args=args))
+
+    if not tool_calls and "Action:" in text:
+        invalid_tool_calls.append(
+            make_invalid_tool_call(text, "Could not parse ReAct tool call")
+        )
+        return None, invalid_tool_calls
+
+    return tool_calls or None, invalid_tool_calls
+
+
 class ChatMLX(BaseChatModel):
     """MLX chat models.
 
@@ -170,8 +226,41 @@ def _to_chat_result(llm_result: LLMResult) -> ChatResult:
         chat_generations = []
 
         for g in llm_result.generations[0]:
+            tool_calls: list[ToolCall] = []
+            invalid_tool_calls: list[InvalidToolCall] = []
+            additional_kwargs: Dict[str, Any] = {}
+
+            if isinstance(g.generation_info, dict):
+                raw_tool_calls = g.generation_info.get("tool_calls")
+            else:
+                raw_tool_calls = None
+
+            if raw_tool_calls:
+                additional_kwargs["tool_calls"] = raw_tool_calls
+                for raw_tool_call in raw_tool_calls:
+                    try:
+                        tc = parse_tool_call(raw_tool_call, return_id=True)
+                    except Exception as e:
+                        invalid_tool_calls.append(
+                            make_invalid_tool_call(raw_tool_call, str(e))
+                        )
+                    else:
+                        if tc:
+                            tool_calls.append(tc)
+            else:
+                react_tool_calls, invalid_reacts = _parse_react_tool_calls(g.text)
+                if react_tool_calls is not None:
+                    tool_calls.extend(react_tool_calls)
+                invalid_tool_calls.extend(invalid_reacts)
+
             chat_generation = ChatGeneration(
-                message=AIMessage(content=g.text), generation_info=g.generation_info
+                message=AIMessage(
+                    content=g.text,
+                    additional_kwargs=additional_kwargs,
+                    tool_calls=tool_calls,
+                    invalid_tool_calls=invalid_tool_calls,
+                ),
+                generation_info=g.generation_info,
             )
             chat_generations.append(chat_generation)