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820 lines
29 KiB
Python
820 lines
29 KiB
Python
"""Function signature objects for callables
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Back port of Python 3.3's function signature tools from the inspect module,
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modified to be compatible with Python 2.6, 2.7 and 3.2+.
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"""
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#-----------------------------------------------------------------------------
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# Python 3.3 stdlib inspect.py is public domain
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#
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# Backports Copyright (C) 2013 Aaron Iles
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# Used under Apache License Version 2.0
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#
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# Further Changes are Copyright (C) 2013 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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from __future__ import absolute_import, division, print_function
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import itertools
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import functools
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import re
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import types
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# patch for single-file
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# we don't support 2.6, so we can just import OrderedDict
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from collections import OrderedDict
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__version__ = '0.3'
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# end patch
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__all__ = ['BoundArguments', 'Parameter', 'Signature', 'signature']
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_WrapperDescriptor = type(type.__call__)
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_MethodWrapper = type(all.__call__)
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_NonUserDefinedCallables = (_WrapperDescriptor,
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_MethodWrapper,
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types.BuiltinFunctionType)
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def formatannotation(annotation, base_module=None):
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if isinstance(annotation, type):
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if annotation.__module__ in ('builtins', '__builtin__', base_module):
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return annotation.__name__
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return annotation.__module__+'.'+annotation.__name__
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return repr(annotation)
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def _get_user_defined_method(cls, method_name, *nested):
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try:
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if cls is type:
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return
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meth = getattr(cls, method_name)
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for name in nested:
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meth = getattr(meth, name, meth)
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except AttributeError:
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return
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else:
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if not isinstance(meth, _NonUserDefinedCallables):
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# Once '__signature__' will be added to 'C'-level
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# callables, this check won't be necessary
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return meth
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def signature(obj):
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'''Get a signature object for the passed callable.'''
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if not callable(obj):
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raise TypeError('{0!r} is not a callable object'.format(obj))
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if isinstance(obj, types.MethodType):
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# In this case we skip the first parameter of the underlying
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# function (usually `self` or `cls`).
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sig = signature(obj.__func__)
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return sig.replace(parameters=tuple(sig.parameters.values())[1:])
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try:
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sig = obj.__signature__
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except AttributeError:
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pass
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else:
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if sig is not None:
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return sig
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try:
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# Was this function wrapped by a decorator?
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wrapped = obj.__wrapped__
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except AttributeError:
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pass
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else:
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return signature(wrapped)
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if isinstance(obj, types.FunctionType):
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return Signature.from_function(obj)
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if isinstance(obj, functools.partial):
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sig = signature(obj.func)
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new_params = OrderedDict(sig.parameters.items())
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partial_args = obj.args or ()
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partial_keywords = obj.keywords or {}
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try:
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ba = sig.bind_partial(*partial_args, **partial_keywords)
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except TypeError as ex:
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msg = 'partial object {0!r} has incorrect arguments'.format(obj)
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raise ValueError(msg)
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for arg_name, arg_value in ba.arguments.items():
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param = new_params[arg_name]
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if arg_name in partial_keywords:
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# We set a new default value, because the following code
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# is correct:
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#
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# >>> def foo(a): print(a)
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# >>> print(partial(partial(foo, a=10), a=20)())
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# 20
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# >>> print(partial(partial(foo, a=10), a=20)(a=30))
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# 30
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#
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# So, with 'partial' objects, passing a keyword argument is
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# like setting a new default value for the corresponding
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# parameter
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#
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# We also mark this parameter with '_partial_kwarg'
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# flag. Later, in '_bind', the 'default' value of this
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# parameter will be added to 'kwargs', to simulate
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# the 'functools.partial' real call.
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new_params[arg_name] = param.replace(default=arg_value,
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_partial_kwarg=True)
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elif (param.kind not in (_VAR_KEYWORD, _VAR_POSITIONAL) and
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not param._partial_kwarg):
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new_params.pop(arg_name)
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return sig.replace(parameters=new_params.values())
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sig = None
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if isinstance(obj, type):
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# obj is a class or a metaclass
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# First, let's see if it has an overloaded __call__ defined
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# in its metaclass
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call = _get_user_defined_method(type(obj), '__call__')
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if call is not None:
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sig = signature(call)
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else:
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# Now we check if the 'obj' class has a '__new__' method
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new = _get_user_defined_method(obj, '__new__')
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if new is not None:
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sig = signature(new)
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else:
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# Finally, we should have at least __init__ implemented
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init = _get_user_defined_method(obj, '__init__')
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if init is not None:
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sig = signature(init)
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elif not isinstance(obj, _NonUserDefinedCallables):
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# An object with __call__
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# We also check that the 'obj' is not an instance of
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# _WrapperDescriptor or _MethodWrapper to avoid
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# infinite recursion (and even potential segfault)
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call = _get_user_defined_method(type(obj), '__call__', 'im_func')
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if call is not None:
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sig = signature(call)
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if sig is not None:
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return sig
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if isinstance(obj, types.BuiltinFunctionType):
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# Raise a nicer error message for builtins
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msg = 'no signature found for builtin function {0!r}'.format(obj)
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raise ValueError(msg)
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raise ValueError('callable {0!r} is not supported by signature'.format(obj))
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class _void(object):
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'''A private marker - used in Parameter & Signature'''
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class _empty(object):
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pass
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class _ParameterKind(int):
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def __new__(self, *args, **kwargs):
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obj = int.__new__(self, *args)
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obj._name = kwargs['name']
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return obj
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def __str__(self):
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return self._name
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def __repr__(self):
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return '<_ParameterKind: {0!r}>'.format(self._name)
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_POSITIONAL_ONLY = _ParameterKind(0, name='POSITIONAL_ONLY')
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_POSITIONAL_OR_KEYWORD = _ParameterKind(1, name='POSITIONAL_OR_KEYWORD')
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_VAR_POSITIONAL = _ParameterKind(2, name='VAR_POSITIONAL')
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_KEYWORD_ONLY = _ParameterKind(3, name='KEYWORD_ONLY')
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_VAR_KEYWORD = _ParameterKind(4, name='VAR_KEYWORD')
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class Parameter(object):
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'''Represents a parameter in a function signature.
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Has the following public attributes:
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* name : str
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The name of the parameter as a string.
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* default : object
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The default value for the parameter if specified. If the
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parameter has no default value, this attribute is not set.
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* annotation
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The annotation for the parameter if specified. If the
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parameter has no annotation, this attribute is not set.
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* kind : str
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Describes how argument values are bound to the parameter.
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Possible values: `Parameter.POSITIONAL_ONLY`,
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`Parameter.POSITIONAL_OR_KEYWORD`, `Parameter.VAR_POSITIONAL`,
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`Parameter.KEYWORD_ONLY`, `Parameter.VAR_KEYWORD`.
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'''
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__slots__ = ('_name', '_kind', '_default', '_annotation', '_partial_kwarg')
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POSITIONAL_ONLY = _POSITIONAL_ONLY
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POSITIONAL_OR_KEYWORD = _POSITIONAL_OR_KEYWORD
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VAR_POSITIONAL = _VAR_POSITIONAL
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KEYWORD_ONLY = _KEYWORD_ONLY
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VAR_KEYWORD = _VAR_KEYWORD
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empty = _empty
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def __init__(self, name, kind, default=_empty, annotation=_empty,
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_partial_kwarg=False):
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if kind not in (_POSITIONAL_ONLY, _POSITIONAL_OR_KEYWORD,
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_VAR_POSITIONAL, _KEYWORD_ONLY, _VAR_KEYWORD):
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raise ValueError("invalid value for 'Parameter.kind' attribute")
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self._kind = kind
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if default is not _empty:
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if kind in (_VAR_POSITIONAL, _VAR_KEYWORD):
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msg = '{0} parameters cannot have default values'.format(kind)
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raise ValueError(msg)
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self._default = default
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self._annotation = annotation
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if name is None:
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if kind != _POSITIONAL_ONLY:
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raise ValueError("None is not a valid name for a "
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"non-positional-only parameter")
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self._name = name
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else:
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name = str(name)
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if kind != _POSITIONAL_ONLY and not re.match(r'[a-z_]\w*$', name, re.I):
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msg = '{0!r} is not a valid parameter name'.format(name)
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raise ValueError(msg)
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self._name = name
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self._partial_kwarg = _partial_kwarg
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@property
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def name(self):
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return self._name
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@property
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def default(self):
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return self._default
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@property
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def annotation(self):
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return self._annotation
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@property
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def kind(self):
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return self._kind
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def replace(self, name=_void, kind=_void, annotation=_void,
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default=_void, _partial_kwarg=_void):
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'''Creates a customized copy of the Parameter.'''
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if name is _void:
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name = self._name
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if kind is _void:
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kind = self._kind
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if annotation is _void:
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annotation = self._annotation
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if default is _void:
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default = self._default
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if _partial_kwarg is _void:
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_partial_kwarg = self._partial_kwarg
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return type(self)(name, kind, default=default, annotation=annotation,
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_partial_kwarg=_partial_kwarg)
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def __str__(self):
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kind = self.kind
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formatted = self._name
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if kind == _POSITIONAL_ONLY:
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if formatted is None:
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formatted = ''
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formatted = '<{0}>'.format(formatted)
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# Add annotation and default value
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if self._annotation is not _empty:
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formatted = '{0}:{1}'.format(formatted,
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formatannotation(self._annotation))
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if self._default is not _empty:
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formatted = '{0}={1}'.format(formatted, repr(self._default))
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if kind == _VAR_POSITIONAL:
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formatted = '*' + formatted
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elif kind == _VAR_KEYWORD:
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formatted = '**' + formatted
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return formatted
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def __repr__(self):
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return '<{0} at {1:#x} {2!r}>'.format(self.__class__.__name__,
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id(self), self.name)
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def __hash__(self):
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msg = "unhashable type: '{0}'".format(self.__class__.__name__)
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raise TypeError(msg)
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def __eq__(self, other):
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return (issubclass(other.__class__, Parameter) and
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self._name == other._name and
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self._kind == other._kind and
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self._default == other._default and
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self._annotation == other._annotation)
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def __ne__(self, other):
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return not self.__eq__(other)
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class BoundArguments(object):
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'''Result of `Signature.bind` call. Holds the mapping of arguments
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to the function's parameters.
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Has the following public attributes:
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* arguments : OrderedDict
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An ordered mutable mapping of parameters' names to arguments' values.
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Does not contain arguments' default values.
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* signature : Signature
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The Signature object that created this instance.
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* args : tuple
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Tuple of positional arguments values.
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* kwargs : dict
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Dict of keyword arguments values.
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'''
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def __init__(self, signature, arguments):
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self.arguments = arguments
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self._signature = signature
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@property
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def signature(self):
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return self._signature
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@property
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def args(self):
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args = []
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for param_name, param in self._signature.parameters.items():
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if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
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param._partial_kwarg):
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# Keyword arguments mapped by 'functools.partial'
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# (Parameter._partial_kwarg is True) are mapped
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# in 'BoundArguments.kwargs', along with VAR_KEYWORD &
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# KEYWORD_ONLY
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break
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try:
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arg = self.arguments[param_name]
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except KeyError:
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# We're done here. Other arguments
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# will be mapped in 'BoundArguments.kwargs'
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break
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else:
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if param.kind == _VAR_POSITIONAL:
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# *args
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args.extend(arg)
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else:
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# plain argument
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args.append(arg)
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return tuple(args)
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@property
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def kwargs(self):
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kwargs = {}
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kwargs_started = False
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for param_name, param in self._signature.parameters.items():
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if not kwargs_started:
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if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
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param._partial_kwarg):
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kwargs_started = True
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else:
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if param_name not in self.arguments:
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kwargs_started = True
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continue
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if not kwargs_started:
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continue
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try:
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arg = self.arguments[param_name]
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except KeyError:
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pass
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else:
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if param.kind == _VAR_KEYWORD:
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# **kwargs
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kwargs.update(arg)
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else:
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# plain keyword argument
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kwargs[param_name] = arg
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return kwargs
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def __hash__(self):
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msg = "unhashable type: '{0}'".format(self.__class__.__name__)
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raise TypeError(msg)
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def __eq__(self, other):
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return (issubclass(other.__class__, BoundArguments) and
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self.signature == other.signature and
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self.arguments == other.arguments)
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def __ne__(self, other):
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return not self.__eq__(other)
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class Signature(object):
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'''A Signature object represents the overall signature of a function.
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It stores a Parameter object for each parameter accepted by the
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function, as well as information specific to the function itself.
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A Signature object has the following public attributes and methods:
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* parameters : OrderedDict
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An ordered mapping of parameters' names to the corresponding
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Parameter objects (keyword-only arguments are in the same order
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as listed in `code.co_varnames`).
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* return_annotation : object
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The annotation for the return type of the function if specified.
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If the function has no annotation for its return type, this
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attribute is not set.
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* bind(*args, **kwargs) -> BoundArguments
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Creates a mapping from positional and keyword arguments to
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parameters.
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* bind_partial(*args, **kwargs) -> BoundArguments
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Creates a partial mapping from positional and keyword arguments
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to parameters (simulating 'functools.partial' behavior.)
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'''
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__slots__ = ('_return_annotation', '_parameters')
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_parameter_cls = Parameter
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_bound_arguments_cls = BoundArguments
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empty = _empty
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def __init__(self, parameters=None, return_annotation=_empty,
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__validate_parameters__=True):
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'''Constructs Signature from the given list of Parameter
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objects and 'return_annotation'. All arguments are optional.
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'''
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if parameters is None:
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params = OrderedDict()
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else:
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if __validate_parameters__:
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params = OrderedDict()
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top_kind = _POSITIONAL_ONLY
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for idx, param in enumerate(parameters):
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kind = param.kind
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if kind < top_kind:
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msg = 'wrong parameter order: {0} before {1}'
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msg = msg.format(top_kind, param.kind)
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raise ValueError(msg)
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else:
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top_kind = kind
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name = param.name
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if name is None:
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name = str(idx)
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param = param.replace(name=name)
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if name in params:
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msg = 'duplicate parameter name: {0!r}'.format(name)
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raise ValueError(msg)
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params[name] = param
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else:
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params = OrderedDict(((param.name, param)
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for param in parameters))
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self._parameters = params
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self._return_annotation = return_annotation
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@classmethod
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def from_function(cls, func):
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'''Constructs Signature for the given python function'''
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if not isinstance(func, types.FunctionType):
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raise TypeError('{0!r} is not a Python function'.format(func))
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Parameter = cls._parameter_cls
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# Parameter information.
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func_code = func.__code__
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pos_count = func_code.co_argcount
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arg_names = func_code.co_varnames
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positional = tuple(arg_names[:pos_count])
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keyword_only_count = getattr(func_code, 'co_kwonlyargcount', 0)
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keyword_only = arg_names[pos_count:(pos_count + keyword_only_count)]
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annotations = getattr(func, '__annotations__', {})
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defaults = func.__defaults__
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kwdefaults = getattr(func, '__kwdefaults__', None)
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if defaults:
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pos_default_count = len(defaults)
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else:
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pos_default_count = 0
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parameters = []
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# Non-keyword-only parameters w/o defaults.
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non_default_count = pos_count - pos_default_count
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for name in positional[:non_default_count]:
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annotation = annotations.get(name, _empty)
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parameters.append(Parameter(name, annotation=annotation,
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kind=_POSITIONAL_OR_KEYWORD))
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# ... w/ defaults.
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for offset, name in enumerate(positional[non_default_count:]):
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annotation = annotations.get(name, _empty)
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parameters.append(Parameter(name, annotation=annotation,
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kind=_POSITIONAL_OR_KEYWORD,
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default=defaults[offset]))
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# *args
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if func_code.co_flags & 0x04:
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name = arg_names[pos_count + keyword_only_count]
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annotation = annotations.get(name, _empty)
|
|
parameters.append(Parameter(name, annotation=annotation,
|
|
kind=_VAR_POSITIONAL))
|
|
|
|
# Keyword-only parameters.
|
|
for name in keyword_only:
|
|
default = _empty
|
|
if kwdefaults is not None:
|
|
default = kwdefaults.get(name, _empty)
|
|
|
|
annotation = annotations.get(name, _empty)
|
|
parameters.append(Parameter(name, annotation=annotation,
|
|
kind=_KEYWORD_ONLY,
|
|
default=default))
|
|
# **kwargs
|
|
if func_code.co_flags & 0x08:
|
|
index = pos_count + keyword_only_count
|
|
if func_code.co_flags & 0x04:
|
|
index += 1
|
|
|
|
name = arg_names[index]
|
|
annotation = annotations.get(name, _empty)
|
|
parameters.append(Parameter(name, annotation=annotation,
|
|
kind=_VAR_KEYWORD))
|
|
|
|
return cls(parameters,
|
|
return_annotation=annotations.get('return', _empty),
|
|
__validate_parameters__=False)
|
|
|
|
@property
|
|
def parameters(self):
|
|
try:
|
|
return types.MappingProxyType(self._parameters)
|
|
except AttributeError:
|
|
return OrderedDict(self._parameters.items())
|
|
|
|
@property
|
|
def return_annotation(self):
|
|
return self._return_annotation
|
|
|
|
def replace(self, parameters=_void, return_annotation=_void):
|
|
'''Creates a customized copy of the Signature.
|
|
Pass 'parameters' and/or 'return_annotation' arguments
|
|
to override them in the new copy.
|
|
'''
|
|
|
|
if parameters is _void:
|
|
parameters = self.parameters.values()
|
|
|
|
if return_annotation is _void:
|
|
return_annotation = self._return_annotation
|
|
|
|
return type(self)(parameters,
|
|
return_annotation=return_annotation)
|
|
|
|
def __hash__(self):
|
|
msg = "unhashable type: '{0}'".format(self.__class__.__name__)
|
|
raise TypeError(msg)
|
|
|
|
def __eq__(self, other):
|
|
if (not issubclass(type(other), Signature) or
|
|
self.return_annotation != other.return_annotation or
|
|
len(self.parameters) != len(other.parameters)):
|
|
return False
|
|
|
|
other_positions = dict((param, idx)
|
|
for idx, param in enumerate(other.parameters.keys()))
|
|
|
|
for idx, (param_name, param) in enumerate(self.parameters.items()):
|
|
if param.kind == _KEYWORD_ONLY:
|
|
try:
|
|
other_param = other.parameters[param_name]
|
|
except KeyError:
|
|
return False
|
|
else:
|
|
if param != other_param:
|
|
return False
|
|
else:
|
|
try:
|
|
other_idx = other_positions[param_name]
|
|
except KeyError:
|
|
return False
|
|
else:
|
|
if (idx != other_idx or
|
|
param != other.parameters[param_name]):
|
|
return False
|
|
|
|
return True
|
|
|
|
def __ne__(self, other):
|
|
return not self.__eq__(other)
|
|
|
|
def _bind(self, args, kwargs, partial=False):
|
|
'''Private method. Don't use directly.'''
|
|
|
|
arguments = OrderedDict()
|
|
|
|
parameters = iter(self.parameters.values())
|
|
parameters_ex = ()
|
|
arg_vals = iter(args)
|
|
|
|
if partial:
|
|
# Support for binding arguments to 'functools.partial' objects.
|
|
# See 'functools.partial' case in 'signature()' implementation
|
|
# for details.
|
|
for param_name, param in self.parameters.items():
|
|
if (param._partial_kwarg and param_name not in kwargs):
|
|
# Simulating 'functools.partial' behavior
|
|
kwargs[param_name] = param.default
|
|
|
|
while True:
|
|
# Let's iterate through the positional arguments and corresponding
|
|
# parameters
|
|
try:
|
|
arg_val = next(arg_vals)
|
|
except StopIteration:
|
|
# No more positional arguments
|
|
try:
|
|
param = next(parameters)
|
|
except StopIteration:
|
|
# No more parameters. That's it. Just need to check that
|
|
# we have no `kwargs` after this while loop
|
|
break
|
|
else:
|
|
if param.kind == _VAR_POSITIONAL:
|
|
# That's OK, just empty *args. Let's start parsing
|
|
# kwargs
|
|
break
|
|
elif param.name in kwargs:
|
|
if param.kind == _POSITIONAL_ONLY:
|
|
msg = '{arg!r} parameter is positional only, ' \
|
|
'but was passed as a keyword'
|
|
msg = msg.format(arg=param.name)
|
|
raise TypeError(msg)
|
|
parameters_ex = (param,)
|
|
break
|
|
elif (param.kind == _VAR_KEYWORD or
|
|
param.default is not _empty):
|
|
# That's fine too - we have a default value for this
|
|
# parameter. So, lets start parsing `kwargs`, starting
|
|
# with the current parameter
|
|
parameters_ex = (param,)
|
|
break
|
|
else:
|
|
if partial:
|
|
parameters_ex = (param,)
|
|
break
|
|
else:
|
|
msg = '{arg!r} parameter lacking default value'
|
|
msg = msg.format(arg=param.name)
|
|
raise TypeError(msg)
|
|
else:
|
|
# We have a positional argument to process
|
|
try:
|
|
param = next(parameters)
|
|
except StopIteration:
|
|
raise TypeError('too many positional arguments')
|
|
else:
|
|
if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
|
|
# Looks like we have no parameter for this positional
|
|
# argument
|
|
raise TypeError('too many positional arguments')
|
|
|
|
if param.kind == _VAR_POSITIONAL:
|
|
# We have an '*args'-like argument, let's fill it with
|
|
# all positional arguments we have left and move on to
|
|
# the next phase
|
|
values = [arg_val]
|
|
values.extend(arg_vals)
|
|
arguments[param.name] = tuple(values)
|
|
break
|
|
|
|
if param.name in kwargs:
|
|
raise TypeError('multiple values for argument '
|
|
'{arg!r}'.format(arg=param.name))
|
|
|
|
arguments[param.name] = arg_val
|
|
|
|
# Now, we iterate through the remaining parameters to process
|
|
# keyword arguments
|
|
kwargs_param = None
|
|
for param in itertools.chain(parameters_ex, parameters):
|
|
if param.kind == _POSITIONAL_ONLY:
|
|
# This should never happen in case of a properly built
|
|
# Signature object (but let's have this check here
|
|
# to ensure correct behaviour just in case)
|
|
raise TypeError('{arg!r} parameter is positional only, '
|
|
'but was passed as a keyword'. \
|
|
format(arg=param.name))
|
|
|
|
if param.kind == _VAR_KEYWORD:
|
|
# Memorize that we have a '**kwargs'-like parameter
|
|
kwargs_param = param
|
|
continue
|
|
|
|
param_name = param.name
|
|
try:
|
|
arg_val = kwargs.pop(param_name)
|
|
except KeyError:
|
|
# We have no value for this parameter. It's fine though,
|
|
# if it has a default value, or it is an '*args'-like
|
|
# parameter, left alone by the processing of positional
|
|
# arguments.
|
|
if (not partial and param.kind != _VAR_POSITIONAL and
|
|
param.default is _empty):
|
|
raise TypeError('{arg!r} parameter lacking default value'. \
|
|
format(arg=param_name))
|
|
|
|
else:
|
|
arguments[param_name] = arg_val
|
|
|
|
if kwargs:
|
|
if kwargs_param is not None:
|
|
# Process our '**kwargs'-like parameter
|
|
arguments[kwargs_param.name] = kwargs
|
|
else:
|
|
raise TypeError('too many keyword arguments')
|
|
|
|
return self._bound_arguments_cls(self, arguments)
|
|
|
|
def bind(self, *args, **kwargs):
|
|
'''Get a BoundArguments object, that maps the passed `args`
|
|
and `kwargs` to the function's signature. Raises `TypeError`
|
|
if the passed arguments can not be bound.
|
|
'''
|
|
return self._bind(args, kwargs)
|
|
|
|
def bind_partial(self, *args, **kwargs):
|
|
'''Get a BoundArguments object, that partially maps the
|
|
passed `args` and `kwargs` to the function's signature.
|
|
Raises `TypeError` if the passed arguments can not be bound.
|
|
'''
|
|
return self._bind(args, kwargs, partial=True)
|
|
|
|
def __str__(self):
|
|
result = []
|
|
render_kw_only_separator = True
|
|
for idx, param in enumerate(self.parameters.values()):
|
|
formatted = str(param)
|
|
|
|
kind = param.kind
|
|
if kind == _VAR_POSITIONAL:
|
|
# OK, we have an '*args'-like parameter, so we won't need
|
|
# a '*' to separate keyword-only arguments
|
|
render_kw_only_separator = False
|
|
elif kind == _KEYWORD_ONLY and render_kw_only_separator:
|
|
# We have a keyword-only parameter to render and we haven't
|
|
# rendered an '*args'-like parameter before, so add a '*'
|
|
# separator to the parameters list ("foo(arg1, *, arg2)" case)
|
|
result.append('*')
|
|
# This condition should be only triggered once, so
|
|
# reset the flag
|
|
render_kw_only_separator = False
|
|
|
|
result.append(formatted)
|
|
|
|
rendered = '({0})'.format(', '.join(result))
|
|
|
|
if self.return_annotation is not _empty:
|
|
anno = formatannotation(self.return_annotation)
|
|
rendered += ' -> {0}'.format(anno)
|
|
|
|
return rendered
|