from __future__ import absolute_import, division, unicode_literals
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try:
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from collections.abc import Mapping
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except ImportError: # Python 2.7
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from collections import Mapping
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class Trie(Mapping):
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"""Abstract base class for tries"""
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def keys(self, prefix=None):
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# pylint:disable=arguments-differ
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keys = super(Trie, self).keys()
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if prefix is None:
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return set(keys)
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return {x for x in keys if x.startswith(prefix)}
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def has_keys_with_prefix(self, prefix):
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for key in self.keys():
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if key.startswith(prefix):
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return True
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return False
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def longest_prefix(self, prefix):
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if prefix in self:
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return prefix
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for i in range(1, len(prefix) + 1):
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if prefix[:-i] in self:
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return prefix[:-i]
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raise KeyError(prefix)
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def longest_prefix_item(self, prefix):
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lprefix = self.longest_prefix(prefix)
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return (lprefix, self[lprefix])
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