chore: import upstream snapshot with attribution

python/mlc_llm/support/config.py

@@ -0,0 +1,111 @@
+"""
+A common base class for configuration. A configuration could be initialized from its constructor,
+a JSON string or a JSON file, and irrelevant fields during initialization are automatically moved
+to the `kwargs` field.
+
+Take model configuration as an example: it is usually a JSON file in HuggingFace that contains
+the model's hyperparameters. For instance, Vicuna-13b-v1.5-16k contains the following
+[JSON file](https://huggingface.co/lmsys/vicuna-13b-v1.5-16k/blob/main/config.json).
+The base class allows us to load the configuration from this JSON file, moving irrelevant fields
+into `kwargs`, such as `transformers_version` and `use_cache`.
+"""
+
+import dataclasses
+import json
+from pathlib import Path
+from typing import Any, Dict, Type, TypeVar  # noqa: UP035
+
+from . import logging
+from .style import bold, red
+
+logger = logging.getLogger(__name__)
+
+ConfigClass = TypeVar("ConfigClass", bound="ConfigBase")
+
+
+@dataclasses.dataclass
+class ConfigBase:
+    """Base class for configurations, providing a common interface for loading configs from a
+    JSON file or a dict. It requires the subclasses to be dataclasses, and has an `kwargs` field
+    that stores the extra fields that are not defined in the dataclass.
+    """
+
+    @classmethod
+    def from_dict(cls: Type[ConfigClass], source: Dict[str, Any]) -> ConfigClass:  # noqa: UP006
+        """Create a config object from a dictionary.
+
+        Parameters
+        ----------
+        source : Dict[str, Any]
+            Source to create config from, usually loaded from `config.json` in HuggingFace style.
+
+        Returns
+        -------
+        cfg : ConfigClass
+            An instance of the config object.
+        """
+        field_names = [field.name for field in dataclasses.fields(cls)]
+        fields = {k: v for k, v in source.items() if k in field_names}
+        kwargs = {k: v for k, v in source.items() if k not in field_names}
+        return cls(**fields, kwargs=kwargs)
+
+    @classmethod
+    def from_file(cls: Type[ConfigClass], source: Path) -> ConfigClass:  # noqa: UP006
+        """Create a config object from a file.
+
+        Parameters
+        ----------
+        cfg_cls : Type[ConfigClass]
+            The config class to create, for example, LlamaConfig.
+
+        source : pathlib.Path
+            Path to the source file, usually `config.json` in HuggingFace repo.
+
+        Returns
+        -------
+        cfg : ConfigClass
+            An instance of the config object.
+        """
+        with source.open("r", encoding="utf-8") as in_file:
+            return cls.from_dict(json.load(in_file))
+
+    def asdict(self):
+        """Convert the config object to a dictionary.
+
+        Returns
+        -------
+        Dict[str, Any]
+            A dictionary representation of the config object.
+        """
+        result = dataclasses.asdict(self)
+        result.pop("kwargs")
+        return result
+
+
+class ConfigOverrideBase:
+    """Base class for ConfigOverride, providing a common interface for overriding configs.
+    It requires the subclasses to be dataclasses.
+    """
+
+    def apply(self, config):
+        """Apply the overrides to the given config."""
+        updated = config.asdict()
+        for field in dataclasses.fields(self):
+            key = field.name
+            value = getattr(self, key)
+            if value is None:
+                continue
+            if key not in updated:
+                logger.warning(
+                    "%s: Cannot override %s, because %s does not have this field",
+                    red("Warning"),
+                    bold(key),
+                    bold(type(config).__name__),
+                )
+            else:
+                logger.info(f"Overriding {bold(key)} from {updated[key]} to {value}")
+                updated[key] = value
+        return type(config).from_dict(updated)
+
+
+__all__ = ["ConfigBase", "ConfigOverrideBase"]