129 lines
4.4 KiB
Python
Executable file
129 lines
4.4 KiB
Python
Executable file
#!/usr/bin/env python3
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#
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# MMGen Wallet, a terminal-based cryptocurrency wallet
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# Copyright (C)2013-2025 The MMGen Project <mmgen@tuta.io>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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base_obj: base objects with no internal imports for the MMGen suite
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"""
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class AsyncInit(type):
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async def __call__(cls, *args, **kwargs):
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instance = cls.__new__(cls, *args, **kwargs)
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await type(instance).__init__(instance, *args, **kwargs)
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return instance
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class AttrCtrlMeta(type):
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def __call__(cls, *args, **kwargs):
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instance = super().__call__(*args, **kwargs)
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if instance._autolock:
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instance._lock()
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return instance
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class AttrCtrl(metaclass=AttrCtrlMeta):
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"""
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After instance is locked, forbid setting any attribute if the attribute is not present
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in either the class or instance dict.
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Ensure that attribute's type matches that of the instance attribute, or the class
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attribute, if _use_class_attr is True. If the instance or class attribute is set
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to None, no type checking is performed.
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If _default_to_none is True, return None when accessing non-existent attributes
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instead of raising AttributeError.
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"""
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_autolock = True
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_locked = False
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_use_class_attr = False
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_default_to_none = False
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_skip_type_check = ()
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_delete_ok = ()
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def _lock(self):
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self._locked = True
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def __getattr__(self, name):
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if self._locked and self._default_to_none:
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return None
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else:
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raise AttributeError(f'{self} has no attribute {name!r}')
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def __setattr__(self, name, value):
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if self._locked:
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assert name != '_locked', 'lock can be set only once'
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def do_error(name, value, ref_val):
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raise AttributeError(
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f'{value!r}: invalid value for attribute {name!r}'
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+ ' of {} object (must be of type {}, not {})'.format(
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type(self).__name__,
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type(ref_val).__name__,
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type(value).__name__))
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if not (name in self.__dict__ or hasattr(type(self), name)):
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raise AttributeError(f'{type(self).__name__} object has no attribute {name!r}')
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ref_val = getattr(type(self), name) if self._use_class_attr else getattr(self, name)
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if (
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(name not in self._skip_type_check)
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and (ref_val is not None)
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and not isinstance(value, type(ref_val))
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):
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do_error(name, value, ref_val)
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return object.__setattr__(self, name, value)
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def __delattr__(self, name):
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if self._locked and not name in self._delete_ok:
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raise AttributeError('attribute cannot be deleted')
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return object.__delattr__(self, name)
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class Lockable(AttrCtrl):
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"""
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After instance is locked, its attributes become read-only, with the following exceptions:
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- if an attribute's name is in _set_ok, it can be set once after locking, if unset
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- if an attribute's name is in _reset_ok, read-only restrictions are bypassed and only
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AttrCtrl checking is performed
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An attribute is considered unset if its value is None, or if it evaluates to False but is
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not zero; or if it is not present in the instance __dict__ when _use_class_attr is True.
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"""
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_set_ok = ()
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_reset_ok = ()
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def _lock(self):
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for name in ('_set_ok', '_reset_ok'):
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for attr in getattr(self, name):
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assert hasattr(self, attr), (
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f'attribute {attr!r} in {name!r} not found in {type(self).__name__} object {id(self)}')
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super()._lock()
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def __setattr__(self, name, value):
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if self._locked and (name in self.__dict__ or hasattr(type(self), name)):
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val = getattr(self, name)
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if name not in (self._set_ok + self._reset_ok):
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raise AttributeError(f'attribute {name!r} of {type(self).__name__} object is read-only')
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elif name not in self._reset_ok:
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if not (
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(val != 0 and not val) or
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(self._use_class_attr and name not in self.__dict__)):
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raise AttributeError(
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f'attribute {name!r} of {type(self).__name__} object is already set,'
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+ ' and resetting is forbidden')
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return AttrCtrl.__setattr__(self, name, value)
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