2018-10-31 16:08:29 +00:00
|
|
|
from __future__ import absolute_import, division, unicode_literals
|
|
|
|
|
|
2021-12-01 20:47:00 +00:00
|
|
|
try:
|
|
|
|
|
from collections.abc import Mapping
|
|
|
|
|
except ImportError: # Python 2.7
|
|
|
|
|
from collections import Mapping
|
2018-10-31 16:08:29 +00:00
|
|
|
|
|
|
|
|
|
|
|
|
|
class Trie(Mapping):
|
|
|
|
|
"""Abstract base class for tries"""
|
|
|
|
|
|
|
|
|
|
def keys(self, prefix=None):
|
|
|
|
|
# pylint:disable=arguments-differ
|
|
|
|
|
keys = super(Trie, self).keys()
|
|
|
|
|
|
|
|
|
|
if prefix is None:
|
|
|
|
|
return set(keys)
|
|
|
|
|
|
|
|
|
|
return {x for x in keys if x.startswith(prefix)}
|
|
|
|
|
|
|
|
|
|
def has_keys_with_prefix(self, prefix):
|
|
|
|
|
for key in self.keys():
|
|
|
|
|
if key.startswith(prefix):
|
|
|
|
|
return True
|
|
|
|
|
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
def longest_prefix(self, prefix):
|
|
|
|
|
if prefix in self:
|
|
|
|
|
return prefix
|
|
|
|
|
|
|
|
|
|
for i in range(1, len(prefix) + 1):
|
|
|
|
|
if prefix[:-i] in self:
|
|
|
|
|
return prefix[:-i]
|
|
|
|
|
|
|
|
|
|
raise KeyError(prefix)
|
|
|
|
|
|
|
|
|
|
def longest_prefix_item(self, prefix):
|
|
|
|
|
lprefix = self.longest_prefix(prefix)
|
|
|
|
|
return (lprefix, self[lprefix])
|
