Harrison/official pre release (#8106)

libs/experimental/langchain_experimental/llms/jsonformer_decoder.py

@@ -0,0 +1,60 @@
+"""Experimental implementation of jsonformer wrapped LLM."""
+from __future__ import annotations
+
+import json
+from typing import TYPE_CHECKING, Any, List, Optional, cast
+
+from langchain.callbacks.manager import CallbackManagerForLLMRun
+from langchain.llms.huggingface_pipeline import HuggingFacePipeline
+from pydantic import Field, root_validator
+
+if TYPE_CHECKING:
+    import jsonformer
+
+
+def import_jsonformer() -> jsonformer:
+    """Lazily import jsonformer."""
+    try:
+        import jsonformer
+    except ImportError:
+        raise ValueError(
+            "Could not import jsonformer python package. "
+            "Please install it with `pip install jsonformer`."
+        )
+    return jsonformer
+
+
+class JsonFormer(HuggingFacePipeline):
+    json_schema: dict = Field(..., description="The JSON Schema to complete.")
+    max_new_tokens: int = Field(
+        default=200, description="Maximum number of new tokens to generate."
+    )
+    debug: bool = Field(default=False, description="Debug mode.")
+
+    @root_validator
+    def check_jsonformer_installation(cls, values: dict) -> dict:
+        import_jsonformer()
+        return values
+
+    def _call(
+        self,
+        prompt: str,
+        stop: Optional[List[str]] = None,
+        run_manager: Optional[CallbackManagerForLLMRun] = None,
+        **kwargs: Any,
+    ) -> str:
+        jsonformer = import_jsonformer()
+        from transformers import Text2TextGenerationPipeline
+
+        pipeline = cast(Text2TextGenerationPipeline, self.pipeline)
+
+        model = jsonformer.Jsonformer(
+            model=pipeline.model,
+            tokenizer=pipeline.tokenizer,
+            json_schema=self.json_schema,
+            prompt=prompt,
+            max_number_tokens=self.max_new_tokens,
+            debug=self.debug,
+        )
+        text = model()
+        return json.dumps(text)