def emit_union(m: Module, item: Item, *, resolver: Resolver) -> Definition:
typename = goname(item.type_.__name__)
kind_typename = typename + "Kind"
# type <typename> {
# Kind string `json:"$kind"`
# ...
# }
m.stmt(f"type {typename} struct {{")
with m.scope():
m.stmt(f'Kind {kind_typename} `json:"$kind"` // discriminator')
for subtype in item.args:
gotype: str = resolver.resolve_gotype(subtype)
m.append(f"{gotype} *{gotype}")
m.stmt(
f' `json:"{untitleize(str(gotype)).rstrip("_")},omitempty"`')
m.stmt("}")
m.sep()
# UnmarshalJSON
discriminator_field = ("$kind", typeinfo.typeinfo(str), metadata())
discriminator_field[-1]["_override_type"] = kind_typename
pseudo_fields = [(sub_type.__name__, typeinfo.typeinfo(sub_type),
metadata(required=False)) for sub_type in item.args]
pseudo_item = Item(
type_=item.type_,
fields=[discriminator_field] + pseudo_fields,
args=[],
)
unmarshalJSON_definition = emit_unmarshalJSON(m,
pseudo_item,
resolver=resolver)
m.sep()
# one-of validation
assert unmarshalJSON_definition.code_module is not None
this = m.symbol(f"{item.type_.__name__[0].lower()}")
maperr_pkg = m.import_("github.com/podhmo/maperr")
sm = unmarshalJSON_definition.code_module
sm.stmt("// one-of?")
sm.stmt("{")
with sm.scope():
for go_name, info, _ in pseudo_item.fields[1:]:
with sm.if_(
f'{this}.Kind == "{go_name}" && {this}.{go_name} == nil'):
sm.stmt(
f'err = err.Add("{go_name}", {maperr_pkg}.Message{{Text: "treated as {go_name}, but no data"}})'
)
sm.stmt("}")
# enums
emit_enums(m, item.type_, resolver=resolver, name=kind_typename)
definition = Definition(name=typename, code_module=None)
return definition
**metadata: t.Optional[t.Any],
) -> None:
pass
m = Module()
m.toplevel = m.submodule(import_unique=True)
m.sep()
spec = fnspec(f)
with m.class_("F"):
for name, typ, kind in spec.parameters:
if typ.__module__ != "builtins":
m.toplevel.import_(typ.__module__)
info = typeinfo(typ)
rhs = spec.type_str_of(info.normalized)
if info.is_optional:
rhs = LazyFormat("typing.Optional[{}]", rhs)
if kind == "var_kw":
rhs = LazyFormat("typing.Dict[str, {}]", rhs)
elif kind == "var_args":
rhs = LazyFormat("typing.List[{}]", rhs)
elif kind == "kw_defaults" or kind == "args_defaults":
rhs = LazyFormat("{} = {}", rhs, spec.default_of(name))
m.stmt("{}: {}", name, rhs)
print(m)