Move ModelConfig from config/__init__.py to config/model.py (#25252)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/config/utils.py

@@ -1,8 +1,13 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
+import ast
+import inspect
+import textwrap
 from dataclasses import MISSING, Field, field, fields, is_dataclass
-from typing import TYPE_CHECKING, TypeVar
+from typing import TYPE_CHECKING, Any, TypeVar
+
+import regex as re
 
 if TYPE_CHECKING:
     from _typeshed import DataclassInstance
@@ -45,3 +50,96 @@ def get_field(cls: ConfigType, name: str) -> Field:
         return field(default=default)
     raise ValueError(
         f"{cls.__name__}.{name} must have a default value or default factory.")
+
+
+def contains_object_print(text: str) -> bool:
+    """
+    Check if the text looks like a printed Python object, e.g.
+    contains any substring matching the pattern: "at 0xFFFFFFF>"
+    We match against 0x followed by 2-16 hex chars (there's
+    a max of 16 on a 64-bit system).
+
+    Args:
+        text (str): The text to check
+
+    Returns:
+        result (bool): `True` if a match is found, `False` otherwise.
+    """
+    pattern = r'at 0x[a-fA-F0-9]{2,16}>'
+    match = re.search(pattern, text)
+    return match is not None
+
+
+def assert_hashable(text: str) -> bool:
+    if not contains_object_print(text):
+        return True
+    raise AssertionError(
+        f"vLLM tried to hash some configs that may have Python objects ids "
+        f"in them. This is a bug, please file an issue. "
+        f"Text being hashed: {text}")
+
+
+def get_attr_docs(cls: type[Any]) -> dict[str, str]:
+    """
+    Get any docstrings placed after attribute assignments in a class body.
+
+    https://davidism.com/mit-license/
+    """
+
+    def pairwise(iterable):
+        """
+        Manually implement https://docs.python.org/3/library/itertools.html#itertools.pairwise
+
+        Can be removed when Python 3.9 support is dropped.
+        """
+        iterator = iter(iterable)
+        a = next(iterator, None)
+
+        for b in iterator:
+            yield a, b
+            a = b
+
+    try:
+        cls_node = ast.parse(textwrap.dedent(inspect.getsource(cls))).body[0]
+    except (OSError, KeyError, TypeError):
+        # HACK: Python 3.13+ workaround - set missing __firstlineno__
+        # Workaround can be removed after we upgrade to pydantic==2.12.0
+        with open(inspect.getfile(cls)) as f:
+            for i, line in enumerate(f):
+                if f"class {cls.__name__}" in line and ":" in line:
+                    cls.__firstlineno__ = i + 1
+                    break
+        cls_node = ast.parse(textwrap.dedent(inspect.getsource(cls))).body[0]
+
+    if not isinstance(cls_node, ast.ClassDef):
+        raise TypeError("Given object was not a class.")
+
+    out = {}
+
+    # Consider each pair of nodes.
+    for a, b in pairwise(cls_node.body):
+        # Must be an assignment then a constant string.
+        if (not isinstance(a, (ast.Assign, ast.AnnAssign))
+                or not isinstance(b, ast.Expr)
+                or not isinstance(b.value, ast.Constant)
+                or not isinstance(b.value.value, str)):
+            continue
+
+        doc = inspect.cleandoc(b.value.value)
+
+        # An assignment can have multiple targets (a = b = v), but an
+        # annotated assignment only has one target.
+        targets = a.targets if isinstance(a, ast.Assign) else [a.target]
+
+        for target in targets:
+            # Must be assigning to a plain name.
+            if not isinstance(target, ast.Name):
+                continue
+
+            out[target.id] = doc
+
+    return out
+
+
+def is_init_field(cls: ConfigType, name: str) -> bool:
+    return next(f for f in fields(cls) if f.name == name).init