return spec[2:pos]
+def _signature_fromstr(cls, obj, s):
+ # Internal helper to parse content of '__text_signature__'
+ # and return a Signature based on it
+ Parameter = cls._parameter_cls
+
+ if s.endswith("/)"):
+ kind = Parameter.POSITIONAL_ONLY
+ s = s[:-2] + ')'
+ else:
+ kind = Parameter.POSITIONAL_OR_KEYWORD
+
+ first_parameter_is_self = s.startswith("($")
+ if first_parameter_is_self:
+ s = '(' + s[2:]
+
+ s = "def foo" + s + ": pass"
+
+ try:
+ module = ast.parse(s)
+ except SyntaxError:
+ module = None
+
+ if not isinstance(module, ast.Module):
+ raise ValueError("{!r} builtin has invalid signature".format(obj))
+
+ f = module.body[0]
+
+ parameters = []
+ empty = Parameter.empty
+ invalid = object()
+
+ module = None
+ module_dict = {}
+ module_name = getattr(obj, '__module__', None)
+ if module_name:
+ module = sys.modules.get(module_name, None)
+ if module:
+ module_dict = module.__dict__
+ sys_module_dict = sys.modules
+
+ def parse_name(node):
+ assert isinstance(node, ast.arg)
+ if node.annotation != None:
+ raise ValueError("Annotations are not currently supported")
+ return node.arg
+
+ def wrap_value(s):
+ try:
+ value = eval(s, module_dict)
+ except NameError:
+ try:
+ value = eval(s, sys_module_dict)
+ except NameError:
+ raise RuntimeError()
+
+ if isinstance(value, str):
+ return ast.Str(value)
+ if isinstance(value, (int, float)):
+ return ast.Num(value)
+ if isinstance(value, bytes):
+ return ast.Bytes(value)
+ if value in (True, False, None):
+ return ast.NameConstant(value)
+ raise RuntimeError()
+
+ class RewriteSymbolics(ast.NodeTransformer):
+ def visit_Attribute(self, node):
+ a = []
+ n = node
+ while isinstance(n, ast.Attribute):
+ a.append(n.attr)
+ n = n.value
+ if not isinstance(n, ast.Name):
+ raise RuntimeError()
+ a.append(n.id)
+ value = ".".join(reversed(a))
+ return wrap_value(value)
+
+ def visit_Name(self, node):
+ if not isinstance(node.ctx, ast.Load):
+ raise ValueError()
+ return wrap_value(node.id)
+
+ def p(name_node, default_node, default=empty):
+ name = parse_name(name_node)
+ if name is invalid:
+ return None
+ if default_node and default_node is not _empty:
+ try:
+ default_node = RewriteSymbolics().visit(default_node)
+ o = ast.literal_eval(default_node)
+ except ValueError:
+ o = invalid
+ if o is invalid:
+ return None
+ default = o if o is not invalid else default
+ parameters.append(Parameter(name, kind, default=default, annotation=empty))
+
+ # non-keyword-only parameters
+ args = reversed(f.args.args)
+ defaults = reversed(f.args.defaults)
+ iter = itertools.zip_longest(args, defaults, fillvalue=None)
+ for name, default in reversed(list(iter)):
+ p(name, default)
+
+ # *args
+ if f.args.vararg:
+ kind = Parameter.VAR_POSITIONAL
+ p(f.args.vararg, empty)
+
+ # keyword-only arguments
+ kind = Parameter.KEYWORD_ONLY
+ for name, default in zip(f.args.kwonlyargs, f.args.kw_defaults):
+ p(name, default)
+
+ # **kwargs
+ if f.args.kwarg:
+ kind = Parameter.VAR_KEYWORD
+ p(f.args.kwarg, empty)
+
+ if first_parameter_is_self:
+ assert parameters
+ if getattr(obj, '__self__', None):
+ # strip off self, it's already been bound
+ parameters.pop(0)
+ else:
+ # for builtins, self parameter is always positional-only!
+ p = parameters[0].replace(kind=Parameter.POSITIONAL_ONLY)
+ parameters[0] = p
+
+ return cls(parameters, return_annotation=cls.empty)
+
+
def signature(obj):
'''Get a signature object for the passed callable.'''
sig = signature(init)
if sig is None:
+ # At this point we know, that `obj` is a class, with no user-
+ # defined '__init__', '__new__', or class-level '__call__'
+
+ for base in obj.__mro__:
+ # Since '__text_signature__' is implemented as a
+ # descriptor that extracts text signature from the
+ # class docstring, if 'obj' is derived from a builtin
+ # class, its own '__text_signature__' may be 'None'.
+ # Therefore, we go through the MRO to find the first
+ # class with non-empty text signature.
+ try:
+ text_sig = base.__text_signature__
+ except AttributeError:
+ pass
+ else:
+ if text_sig:
+ # If 'obj' class has a __text_signature__ attribute:
+ # return a signature based on it
+ return _signature_fromstr(Signature, obj, text_sig)
+
+ # No '__text_signature__' was found for the 'obj' class.
+ # Last option is to check if its '__init__' is
+ # object.__init__ or type.__init__.
if type in obj.__mro__:
# 'obj' is a metaclass without user-defined __init__
- # or __new__. Return a signature of 'type' builtin.
- return signature(type)
+ # or __new__.
+ if obj.__init__ is type.__init__:
+ # Return a signature of 'type' builtin.
+ return signature(type)
else:
# We have a class (not metaclass), but no user-defined
# __init__ or __new__ for it
- return signature(object)
+ if obj.__init__ is object.__init__:
+ # Return a signature of 'object' builtin.
+ return signature(object)
elif not isinstance(obj, _NonUserDefinedCallables):
# An object with __call__
if not s:
raise ValueError("no signature found for builtin {!r}".format(func))
- Parameter = cls._parameter_cls
-
- if s.endswith("/)"):
- kind = Parameter.POSITIONAL_ONLY
- s = s[:-2] + ')'
- else:
- kind = Parameter.POSITIONAL_OR_KEYWORD
-
- first_parameter_is_self = s.startswith("($")
- if first_parameter_is_self:
- s = '(' + s[2:]
-
- s = "def foo" + s + ": pass"
-
- try:
- module = ast.parse(s)
- except SyntaxError:
- module = None
-
- if not isinstance(module, ast.Module):
- raise ValueError("{!r} builtin has invalid signature".format(func))
-
- f = module.body[0]
-
- parameters = []
- empty = Parameter.empty
- invalid = object()
-
- module = None
- module_dict = {}
- module_name = getattr(func, '__module__', None)
- if module_name:
- module = sys.modules.get(module_name, None)
- if module:
- module_dict = module.__dict__
- sys_module_dict = sys.modules
-
- def parse_name(node):
- assert isinstance(node, ast.arg)
- if node.annotation != None:
- raise ValueError("Annotations are not currently supported")
- return node.arg
-
- def wrap_value(s):
- try:
- value = eval(s, module_dict)
- except NameError:
- try:
- value = eval(s, sys_module_dict)
- except NameError:
- raise RuntimeError()
-
- if isinstance(value, str):
- return ast.Str(value)
- if isinstance(value, (int, float)):
- return ast.Num(value)
- if isinstance(value, bytes):
- return ast.Bytes(value)
- if value in (True, False, None):
- return ast.NameConstant(value)
- raise RuntimeError()
-
- class RewriteSymbolics(ast.NodeTransformer):
- def visit_Attribute(self, node):
- a = []
- n = node
- while isinstance(n, ast.Attribute):
- a.append(n.attr)
- n = n.value
- if not isinstance(n, ast.Name):
- raise RuntimeError()
- a.append(n.id)
- value = ".".join(reversed(a))
- return wrap_value(value)
-
- def visit_Name(self, node):
- if not isinstance(node.ctx, ast.Load):
- raise ValueError()
- return wrap_value(node.id)
-
- def p(name_node, default_node, default=empty):
- name = parse_name(name_node)
- if name is invalid:
- return None
- if default_node and default_node is not _empty:
- try:
- default_node = RewriteSymbolics().visit(default_node)
- o = ast.literal_eval(default_node)
- except ValueError:
- o = invalid
- if o is invalid:
- return None
- default = o if o is not invalid else default
- parameters.append(Parameter(name, kind, default=default, annotation=empty))
-
- # non-keyword-only parameters
- args = reversed(f.args.args)
- defaults = reversed(f.args.defaults)
- iter = itertools.zip_longest(args, defaults, fillvalue=None)
- for name, default in reversed(list(iter)):
- p(name, default)
-
- # *args
- if f.args.vararg:
- kind = Parameter.VAR_POSITIONAL
- p(f.args.vararg, empty)
-
- # keyword-only arguments
- kind = Parameter.KEYWORD_ONLY
- for name, default in zip(f.args.kwonlyargs, f.args.kw_defaults):
- p(name, default)
-
- # **kwargs
- if f.args.kwarg:
- kind = Parameter.VAR_KEYWORD
- p(f.args.kwarg, empty)
-
- if first_parameter_is_self:
- assert parameters
- if getattr(func, '__self__', None):
- # strip off self, it's already been bound
- parameters.pop(0)
- else:
- # for builtins, self parameter is always positional-only!
- p = parameters[0].replace(kind=Parameter.POSITIONAL_ONLY)
- parameters[0] = p
-
- return cls(parameters, return_annotation=cls.empty)
+ return _signature_fromstr(cls, func, s)
@property
def parameters(self):
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