x

libs/core/langchain_core/globals.py

@@ -1,7 +1,9 @@
 # flake8: noqa
 """Global values and configuration that apply to all of LangChain."""
+import abc
+import contextlib
 import warnings
-from typing import TYPE_CHECKING, Optional
+from typing import TYPE_CHECKING, Optional, Any, Generator
 
 if TYPE_CHECKING:
     from langchain_core.caches import BaseCache
@@ -15,6 +17,22 @@ _verbose: bool = False
 _debug: bool = False
 _llm_cache: Optional["BaseCache"] = None
 
+class BaseRenderer(abc.ABC):
+    def render_html(self, obj: Any) -> str:
+        """Render an object as HTML."""
+        raise NotImplementedError
+
+
+class DefaultRenderer(BaseRenderer):
+    def render_html(self, obj: Any) -> str:
+        """Render an object as HTML."""
+        if hasattr(obj, "_repr_html_"):
+            return obj._repr_html_()
+        return str(obj)
+
+
+_renderer: Optional[BaseRenderer] = None
+
 
 def set_verbose(value: bool) -> None:
     """Set a new value for the `verbose` global setting."""
@@ -195,3 +213,30 @@ def get_llm_cache() -> "BaseCache":
 
     global _llm_cache
     return _llm_cache or old_llm_cache
+
+
+def set_renderer(renderer: BaseRenderer) -> None:
+    """Set a new renderer."""
+    global _renderer
+    _renderer = renderer
+
+
+def get_renderer() -> BaseRenderer:
+    """Get the current renderer."""
+    global _renderer
+    return _renderer or DefaultRenderer()
+
+
+@contextlib.contextmanager
+def with_renderer(renderer: BaseRenderer) -> Generator[None, None, None]:
+    """Context manager for temporarily setting a new renderer."""
+    global _renderer
+    # Save the current value
+    original_value = _renderer
+    try:
+        # Update the global value
+        _renderer = renderer
+        yield
+    finally:
+        # Restore the original value
+        _renderer = original_value

libs/core/langchain_core/messages/base.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Sequence, Union, cast
 
+from langchain_core.globals import get_renderer
 from langchain_core.load.serializable import Serializable
 from langchain_core.pydantic_v1 import Extra, Field
 from langchain_core.utils import get_bolded_text
@@ -87,6 +88,10 @@ class BaseMessage(Serializable):
     def pretty_print(self) -> None:
         print(self.pretty_repr(html=is_interactive_env()))  # noqa: T201
 
+    def _repr_html_(self) -> str:
+        """Print HTML representation of the message."""
+        return get_renderer().render_html(self)
+
 
 def merge_content(
     first_content: Union[str, List[Union[str, Dict]]],

libs/core/langchain_core/prompts/base.py

@@ -279,6 +279,12 @@ class BasePromptTemplate(
         else:
             raise ValueError(f"{save_path} must be json or yaml")
 
+    def _repr_html_(self) -> str:
+        """Print HTML representation of the message."""
+        from langchain_core.globals import get_renderer
+
+        return get_renderer().render_html(self)
+
 
 def _get_document_info(doc: Document, prompt: BasePromptTemplate[str]) -> Dict:
     base_info = {"page_content": doc.page_content, **doc.metadata}

libs/core/langchain_core/prompts/chat.py

@@ -106,6 +106,12 @@ class BaseMessagePromptTemplate(Serializable, ABC):
         prompt = ChatPromptTemplate(messages=[self])  # type: ignore[call-arg]
         return prompt + other
 
+    def _repr_html_(self) -> str:
+        """Print HTML representation of the message."""
+        from langchain_core.globals import get_renderer
+
+        return get_renderer().render_html(self)
+
 
 class MessagesPlaceholder(BaseMessagePromptTemplate):
     """Prompt template that assumes variable is already list of messages.

libs/core/langchain_core/runnables/graph.py

@@ -464,3 +464,8 @@ class Graph:
             background_color=background_color,
             padding=padding,
         )
+
+    def _repr_html_(self) -> str:
+        from langchain_core.globals import get_renderer
+
+        return get_renderer().render_html(self)