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[09/18] qapi/introspect.py: Introduce preliminary tree typing

Message ID 20210219120422.600850-10-armbru@redhat.com (mailing list archive)
State New, archived
Headers show
Series [01/18] qapi: Replace List[str] with Sequence[str] for ifcond | expand

Commit Message

Markus Armbruster Feb. 19, 2021, 12:04 p.m. UTC
From: John Snow <jsnow@redhat.com>

The types will be used in forthcoming patches to add typing. These types
describe the layout and structure of the objects passed to
_tree_to_qlit, but lack the power to describe annotations until the next

Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210216021809.134886-10-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
 scripts/qapi/introspect.py | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)
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diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 88af5383d5..c271006100 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -10,7 +10,13 @@ 
 See the COPYING file in the top-level directory.
-from typing import Optional
+from typing import (
+    Any,
+    Dict,
+    List,
+    Optional,
+    Union,
 from .common import (
@@ -26,6 +32,29 @@ 
+# This module constructs a tree data structure that is used to
+# generate the introspection information for QEMU. It is shaped
+# like a JSON value.
+# A complexity over JSON is that our values may or may not be annotated.
+# Un-annotated values may be:
+#     Scalar: str, bool, None.
+#     Non-scalar: List, Dict
+# _value = Union[str, bool, None, Dict[str, JSONValue], List[JSONValue]]
+# With optional annotations, the type of all values is:
+# JSONValue = Union[_Value, Annotated[_Value]]
+# Sadly, mypy does not support recursive types; so the _Stub alias is used to
+# mark the imprecision in the type model where we'd otherwise use JSONValue.
+_Stub = Any
+_Scalar = Union[str, bool, None]
+_NonScalar = Union[Dict[str, _Stub], List[_Stub]]
+_Value = Union[_Scalar, _NonScalar]
+# JSONValue = TODO, in a forthcoming commit.
 def _make_tree(obj, ifcond, comment=None):
     extra = {
         'if': ifcond,