Presently, we use a tuple to attach a dict containing annotations
(comments and compile-time conditionals) to a tree node. This is
undesirable because dicts are difficult to strongly type; promoting it
to a real class allows us to name the values and types of the
annotations we are expecting.
In terms of typing, the Annotated<T> type serves as a generic container
where the annotated node's type is preserved, allowing for greater
specificity than we'd be able to provide without a generic.
Signed-off-by: John Snow <js...@redhat.com>
---
scripts/qapi/introspect.py | 77 ++++++++++++++++++++++----------------
1 file changed, 44 insertions(+), 33 deletions(-)
diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 8e019b4a26a..b9427aba449 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -13,8 +13,12 @@
from typing import (
Any,
Dict,
+ Generic,
+ Iterable,
List,
Optional,
+ Tuple,
+ TypeVar,
Union,
)
@@ -51,15 +55,25 @@
_scalar = Union[str, bool, None]
_nonscalar = Union[Dict[str, _stub], List[_stub]]
_value = Union[_scalar, _nonscalar]
-# TreeValue = TODO, in a forthcoming commit.
+TreeValue = Union[_value, 'Annotated[_value]']
-def _make_tree(obj, ifcond, comment=None):
- extra = {
- 'if': ifcond,
- 'comment': comment
- }
- return (obj, extra)
+_NodeT = TypeVar('_NodeT', bound=_value)
+
+
+class Annotated(Generic[_NodeT]):
+ """
+ Annotated generally contains a SchemaInfo-like type (as a dict),
+ But it also used to wrap comments/ifconds around scalar leaf values,
+ for the benefit of features and enums.
+ """
+ # TODO: Remove after Python 3.7 adds @dataclass:
+ # pylint: disable=too-few-public-methods
+ def __init__(self, value: _NodeT, ifcond: Iterable[str],
+ comment: Optional[str] = None):
+ self.value = value
+ self.comment: Optional[str] = comment
+ self.ifcond: Tuple[str, ...] = tuple(ifcond)
def _tree_to_qlit(obj, level=0, dict_value=False):
@@ -67,24 +81,20 @@ def _tree_to_qlit(obj, level=0, dict_value=False):
def indent(level):
return level * 4 * ' '
- if isinstance(obj, tuple):
- ifobj, extra = obj
- ifcond = extra.get('if')
- comment = extra.get('comment')
-
+ if isinstance(obj, Annotated):
# NB: _tree_to_qlit is called recursively on the values of a key:value
# pair; those values can't be decorated with comments or conditionals.
msg = "dict values cannot have attached comments or if-conditionals."
assert not dict_value, msg
ret = ''
- if comment:
- ret += indent(level) + '/* %s */\n' % comment
- if ifcond:
- ret += gen_if(ifcond)
- ret += _tree_to_qlit(ifobj, level)
- if ifcond:
- ret += '\n' + gen_endif(ifcond)
+ if obj.comment:
+ ret += indent(level) + '/* %s */\n' % obj.comment
+ if obj.ifcond:
+ ret += gen_if(obj.ifcond)
+ ret += _tree_to_qlit(obj.value, level)
+ if obj.ifcond:
+ ret += '\n' + gen_endif(obj.ifcond)
return ret
ret = ''
@@ -201,7 +211,7 @@ def _use_type(self, typ):
@staticmethod
def _gen_features(features):
- return [_make_tree(f.name, f.ifcond) for f in features]
+ return [Annotated(f.name, f.ifcond) for f in features]
def _gen_tree(self, name, mtype, obj, ifcond, features):
comment: Optional[str] = None
@@ -215,7 +225,7 @@ def _gen_tree(self, name, mtype, obj, ifcond, features):
obj['meta-type'] = mtype
if features:
obj['features'] = self._gen_features(features)
- self._trees.append(_make_tree(obj, ifcond, comment))
+ self._trees.append(Annotated(obj, ifcond, comment))
def _gen_member(self, member):
obj = {'name': member.name, 'type': self._use_type(member.type)}
@@ -223,7 +233,7 @@ def _gen_member(self, member):
obj['default'] = None
if member.features:
obj['features'] = self._gen_features(member.features)
- return _make_tree(obj, member.ifcond)
+ return Annotated(obj, member.ifcond)
def _gen_variants(self, tag_name, variants):
return {'tag': tag_name,
@@ -231,16 +241,17 @@ def _gen_variants(self, tag_name, variants):
def _gen_variant(self, variant):
obj = {'case': variant.name, 'type': self._use_type(variant.type)}
- return _make_tree(obj, variant.ifcond)
+ return Annotated(obj, variant.ifcond)
def visit_builtin_type(self, name, info, json_type):
self._gen_tree(name, 'builtin', {'json-type': json_type}, [], None)
def visit_enum_type(self, name, info, ifcond, features, members, prefix):
- self._gen_tree(name, 'enum',
- {'values': [_make_tree(m.name, m.ifcond, None)
- for m in members]},
- ifcond, features)
+ self._gen_tree(
+ name, 'enum',
+ {'values': [Annotated(m.name, m.ifcond) for m in members]},
+ ifcond, features
+ )
def visit_array_type(self, name, info, ifcond, element_type):
element = self._use_type(element_type)
@@ -257,12 +268,12 @@ def visit_object_type_flat(self, name, info, ifcond,
features,
self._gen_tree(name, 'object', obj, ifcond, features)
def visit_alternate_type(self, name, info, ifcond, features, variants):
- self._gen_tree(name, 'alternate',
- {'members': [
- _make_tree({'type': self._use_type(m.type)},
- m.ifcond, None)
- for m in variants.variants]},
- ifcond, features)
+ self._gen_tree(
+ name, 'alternate',
+ {'members': [Annotated({'type': self._use_type(m.type)}, m.ifcond)
+ for m in variants.variants]},
+ ifcond, features
+ )
def visit_command(self, name, info, ifcond, features,
arg_type, ret_type, gen, success_response, boxed,
--
2.29.2
