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# Copyright (C) 2009, 2010 Canonical Ltd
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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 2 of the License, or
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# (at your option) any later version.
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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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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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"""The pure-python implementation of the StaticTuple type.
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Note that it is generally just implemented as using tuples of tuples of
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class StaticTuple(tuple):
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"""A static type, similar to a tuple of strings."""
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def __new__(cls, *args):
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# Make the empty StaticTuple a singleton
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if not args and _empty_tuple is not None:
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return tuple.__new__(cls, args)
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def __init__(self, *args):
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"""Create a new 'StaticTuple'"""
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if num_keys < 0 or num_keys > 255:
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raise TypeError('StaticTuple(...) takes from 0 to 255 items')
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if type(bit) not in _valid_types:
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raise TypeError('StaticTuple can only point to'
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' StaticTuple, str, unicode, int, float, bool, or'
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' None not %s' % (type(bit),))
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# We don't need to pass args to tuple.__init__, because that was
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# already handled in __new__.
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return '%s%s' % (self.__class__.__name__, tuple.__repr__(self))
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return (StaticTuple, tuple(self))
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def __add__(self, other):
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"""Concatenate self with other"""
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return StaticTuple.from_sequence(tuple.__add__(self, other))
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return _interned_tuples.setdefault(self, self)
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def from_sequence(seq):
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"""Convert a sequence object into a StaticTuple instance."""
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if isinstance(seq, StaticTuple):
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return StaticTuple(*seq)
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_valid_types = (bytes, str, StaticTuple, int, float, None.__class__, bool)
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# Have to set it to None first, so that __new__ can determine whether
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# the _empty_tuple singleton has been created yet or not.
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_empty_tuple = StaticTuple()