forked from VimPlug/jedi
111 lines
3.4 KiB
Python
111 lines
3.4 KiB
Python
"""
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A static version of getattr.
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This is a backport of the Python 3 code with a little bit of additional
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information returned to enable Jedi to make decisions.
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"""
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import types
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_sentinel = object()
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def _static_getmro(klass):
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return type.__dict__['__mro__'].__get__(klass)
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def _check_instance(obj, attr):
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instance_dict = {}
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try:
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instance_dict = object.__getattribute__(obj, "__dict__")
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except AttributeError:
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pass
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return dict.get(instance_dict, attr, _sentinel)
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def _check_class(klass, attr):
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for entry in _static_getmro(klass):
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if _shadowed_dict(type(entry)) is _sentinel:
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try:
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return entry.__dict__[attr]
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except KeyError:
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pass
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return _sentinel
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def _is_type(obj):
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try:
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_static_getmro(obj)
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except TypeError:
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return False
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return True
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def _shadowed_dict(klass):
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dict_attr = type.__dict__["__dict__"]
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for entry in _static_getmro(klass):
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try:
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class_dict = dict_attr.__get__(entry)["__dict__"]
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except KeyError:
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pass
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else:
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if not (type(class_dict) is types.GetSetDescriptorType and
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class_dict.__name__ == "__dict__" and
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class_dict.__objclass__ is entry):
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return class_dict
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return _sentinel
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def _safe_hasattr(obj, name):
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return _check_class(type(obj), name) is not _sentinel
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def _safe_is_data_descriptor(obj):
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return (_safe_hasattr(obj, '__set__') or _safe_hasattr(obj, '__delete__'))
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def getattr_static(obj, attr, default=_sentinel):
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"""Retrieve attributes without triggering dynamic lookup via the
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descriptor protocol, __getattr__ or __getattribute__.
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Note: this function may not be able to retrieve all attributes
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that getattr can fetch (like dynamically created attributes)
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and may find attributes that getattr can't (like descriptors
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that raise AttributeError). It can also return descriptor objects
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instead of instance members in some cases. See the
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documentation for details.
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Returns a tuple `(attr, is_get_descriptor)`. is_get_descripter means that
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the attribute is a descriptor that has a `__get__` attribute.
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"""
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instance_result = _sentinel
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if not _is_type(obj):
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klass = type(obj)
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dict_attr = _shadowed_dict(klass)
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if (dict_attr is _sentinel or
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type(dict_attr) is types.MemberDescriptorType):
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instance_result = _check_instance(obj, attr)
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else:
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klass = obj
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klass_result = _check_class(klass, attr)
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if instance_result is not _sentinel and klass_result is not _sentinel:
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if _safe_hasattr(klass_result, '__get__') \
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and _safe_is_data_descriptor(klass_result):
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# A get/set descriptor has priority over everything.
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return klass_result, True
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if instance_result is not _sentinel:
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return instance_result, False
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if klass_result is not _sentinel:
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return klass_result, _safe_hasattr(klass_result, '__get__')
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if obj is klass:
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# for types we check the metaclass too
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for entry in _static_getmro(type(klass)):
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if _shadowed_dict(type(entry)) is _sentinel:
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try:
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return entry.__dict__[attr], False
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except KeyError:
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pass
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if default is not _sentinel:
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return default, False
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raise AttributeError(attr)
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