Fixes/upgrades

protocol/mizan-codegen/python/pydantic_to_rust/ir.py

@@ -0,0 +1,82 @@
+"""The typed shapes a Pydantic model lowers to before Rust is emitted.
+
+`TypeShape` is deliberately isomorphic to Mizan's KDL `TypeShape`, so the
+two can be converted without a lookup table.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Optional
+
+
+class Primitive(str, Enum):
+    INTEGER = "integer"
+    NUMBER = "number"
+    BOOLEAN = "boolean"
+    STRING = "string"
+
+
+@dataclass(frozen=True)
+class TypeShape:
+    """A recursive type shape. Exactly one variant field is set."""
+
+    primitive: Optional[Primitive] = None
+
+    int_width: Optional[int] = None
+    """8 / 16 / 32 / 64, or None when unspecified. Only read alongside
+    `primitive == INTEGER`, and only by emitters that distinguish widths."""
+
+    int_signed: Optional[bool] = None
+    """True for i8..i64, False for u8..u64, None when unspecified."""
+
+    float_width: Optional[int] = None
+    """16 / 32 / 64, or None when unspecified. Only meaningful alongside
+    `primitive == NUMBER`."""
+
+    ref: Optional[str] = None
+    list_inner: Optional["TypeShape"] = None
+    optional_inner: Optional["TypeShape"] = None
+    enum_variants: Optional[tuple[str, ...]] = None
+    union_branches: Optional[tuple["TypeShape", ...]] = None
+
+    map_value: Optional["TypeShape"] = None
+    """`dict[K, V]` value shape."""
+
+    map_key: Optional["TypeShape"] = None
+    """Set only when the key is a NewType. Wire keys are always strings;
+    this keeps the typed identity on the Rust side."""
+
+    array_element: Optional["TypeShape"] = None
+    """Fixed-length element: `tuple[T, T, T]` lowers to element T, length 3,
+    and emits `[T; 3]`."""
+
+    array_length: Optional[int] = None
+
+
+@dataclass(frozen=True)
+class DefaultValue:
+    """A field default captured during introspection. `kind` discriminates
+    how the emitter renders `literal`."""
+
+    kind: str  # integer | number | boolean | string | null | empty_seq |
+    # empty_map | tuple | enum_variant | compound_model | compound
+    literal: object
+
+
+@dataclass(frozen=True)
+class FieldDecl:
+    name: str
+    shape: TypeShape
+    required: bool
+    default: Optional[DefaultValue] = None
+
+
+@dataclass(frozen=True)
+class ModelDecl:
+    """One Pydantic class, lowered field by field."""
+
+    name: str
+    fields: tuple[FieldDecl, ...] = field(default_factory=tuple)
+    docstring: Optional[str] = None