chore: add a utility to generate a schema file

docs/source/config_file.rst

@@ -802,11 +802,11 @@ section of the command line docs.
 
 .. confval:: extra_checks
 
-   :type: boolean
-   :default: False
+    :type: boolean
+    :default: False
 
-   This flag enables additional checks that are technically correct but may be impractical.
-   See :option:`mypy --extra-checks` for more info.
+    This flag enables additional checks that are technically correct but may be impractical.
+    See :option:`mypy --extra-checks` for more info.
 
 .. confval:: implicit_reexport
 
@@ -830,39 +830,39 @@ section of the command line docs.
 
 .. confval:: strict_equality
 
-   :type: boolean
-   :default: False
+    :type: boolean
+    :default: False
 
-   Prohibit equality checks, identity checks, and container checks between
-   non-overlapping types (except ``None``).
+    Prohibit equality checks, identity checks, and container checks between
+    non-overlapping types (except ``None``).
 
 .. confval:: strict_equality_for_none
 
-   :type: boolean
-   :default: False
+    :type: boolean
+    :default: False
 
-   Include ``None`` in strict equality checks (requires :confval:`strict_equality`
-   to be activated).
+    Include ``None`` in strict equality checks (requires :confval:`strict_equality`
+    to be activated).
 
 .. confval:: strict_bytes
 
-   :type: boolean
-   :default: False
+    :type: boolean
+    :default: False
 
-   Disable treating ``bytearray`` and ``memoryview`` as subtypes of ``bytes``.
-   This will be enabled by default in *mypy 2.0*.
+    Disable treating ``bytearray`` and ``memoryview`` as subtypes of ``bytes``.
+    This will be enabled by default in *mypy 2.0*.
 
 .. confval:: strict
 
-   :type: boolean
-   :default: False
+    :type: boolean
+    :default: False
 
-   Enable all optional error checking flags.  You can see the list of
-   flags enabled by strict mode in the full :option:`mypy --help`
-   output.
+    Enable all optional error checking flags.  You can see the list of
+    flags enabled by strict mode in the full :option:`mypy --help`
+    output.
 
-   Note: the exact list of flags enabled by :confval:`strict` may
-   change over time.
+    Note: the exact list of flags enabled by :confval:`strict` may
+    change over time.
 
 
 Configuring error messages

misc/make_schema.py

@@ -0,0 +1,119 @@
+from __future__ import annotations
+
+import dataclasses
+import json
+import re
+import sys
+import textwrap
+from collections.abc import Generator, Sequence
+from pathlib import Path
+from typing import Any
+
+DIR = Path(__file__).parent.resolve()
+
+assert sys.version_info > (3, 9)
+
+
+@dataclasses.dataclass(frozen=True)
+class ConfigOpt:
+    name: str
+    type_str: str
+    is_global: bool
+    description: str
+    default: str | None
+
+    def define(self) -> dict[str, str]:
+        retval: dict[str, Any] = {"description": self.description}
+        if self.default is not None:
+            match self.type_str:
+                case "boolean":
+                    retval["default"] = {"true": True, "false": False}[self.default.lower()]
+                case "integer":
+                    retval["default"] = int(self.default)
+                case "string":
+                    retval["default"] = self.default.strip("`")
+                case _:
+                    msg = f"Default not supported for {self.type_str}"
+                    raise RuntimeError(msg)
+        match self.type_str:
+            case "boolean" | "integer" | "string":
+                retval["type"] = self.type_str
+            case "comma-separated list of strings" | "regular expression":
+                retval["oneOf"] = [
+                    {"type": "string"},
+                    {"type": "array", "items": {"type": "string"}},
+                ]
+            case _:
+                msg = f"{self.type_str} not supported for type"
+                raise RuntimeError(msg)
+
+        return retval
+
+
+def parse_rst_docs(txt: str) -> Generator[ConfigOpt, None, None]:
+    for match in re.finditer(r".. confval:: ([^\s]*)\n\n((?:    .*\n|\n)*)", txt):
+        name, body = match.groups()
+        body = textwrap.dedent(body)
+        body_match = re.match(r":type: (.*?)\n(?::default: (.*?)\n)?(.*)$", body, re.DOTALL)
+        assert body_match is not None, f"{name} missing type and default!\n{body!r}"
+        type_str, default, inner = body_match.groups()
+        is_global = "only be set in the global section" in body
+        description = inner.strip().split("\n\n")[0].replace("\n", " ")
+        # Patches
+        if name == "mypy_path":
+            type_str = "comma-separated list of strings"
+        yield ConfigOpt(
+            name=name,
+            type_str=type_str,
+            is_global=is_global,
+            description=description,
+            default=default,
+        )
+
+
+def make_schema(opts: Sequence[ConfigOpt]) -> dict[str, Any]:
+    definitions = {s.name: s.define() for s in opts}
+    overrides = {s.name: {"$ref": f"#/properties/{s.name}"} for s in opts if not s.is_global}
+    module = {
+        "oneOf": [
+            {"type": "string"},
+            {"type": "array", "items": {"type": "string"}, "minItems": 1},
+        ]
+    }
+
+    # Improve some fields
+    definitions["follow_imports"]["enum"] = ["normal", "silent", "skip", "error"]
+
+    # Undocumented fields
+    definitions["show_error_codes"] = {
+        "type": "boolean",
+        "default": True,
+        "description": "DEPRECATED and UNDOCUMENTED: Now defaults to true, use `hide_error_codes` if you need to disable error codes instead.",
+        "deprecated": True,
+    }
+
+    return {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "$id": "https://json.schemastore.org/partial-mypy.json",
+        "additionalProperties": False,
+        "type": "object",
+        "properties": {
+            **definitions,
+            "overrides": {
+                "type": "array",
+                "items": {
+                    "type": "object",
+                    "additionalProperties": False,
+                    "required": ["module"],
+                    "minProperties": 2,
+                    "properties": {"module": module, **overrides},
+                },
+            },
+        },
+    }
+
+
+if __name__ == "__main__":
+    filepath = DIR.parent / "docs/source/config_file.rst"
+    opts = parse_rst_docs(filepath.read_text())
+    print(json.dumps(make_schema(list(opts)), indent=2))