1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
import re
from ..utils import str_coercible
path_matcher = re.compile(r'^[A-Za-z0-9_]+(\.[A-Za-z0-9_]+)*$')
@str_coercible
class Ltree:
"""
Ltree class wraps a valid string label path. It provides various
convenience properties and methods.
::
from sqlalchemy_utils import Ltree
Ltree('1.2.3').path # '1.2.3'
Ltree always validates the given path.
::
Ltree(None) # raises TypeError
Ltree('..') # raises ValueError
Validator is also available as class method.
::
Ltree.validate('1.2.3')
Ltree.validate(None) # raises TypeError
Ltree supports equality operators.
::
Ltree('Countries.Finland') == Ltree('Countries.Finland')
Ltree('Countries.Germany') != Ltree('Countries.Finland')
Ltree objects are hashable.
::
assert hash(Ltree('Finland')) == hash('Finland')
Ltree objects have length.
::
assert len(Ltree('1.2')) == 2
assert len(Ltree('some.one.some.where')) # 4
You can easily find subpath indexes.
::
assert Ltree('1.2.3').index('2.3') == 1
assert Ltree('1.2.3.4.5').index('3.4') == 2
Ltree objects can be sliced.
::
assert Ltree('1.2.3')[0:2] == Ltree('1.2')
assert Ltree('1.2.3')[1:] == Ltree('2.3')
Finding longest common ancestor.
::
assert Ltree('1.2.3.4.5').lca('1.2.3', '1.2.3.4', '1.2.3') == '1.2'
assert Ltree('1.2.3.4.5').lca('1.2', '1.2.3') == '1'
Ltree objects can be concatenated.
::
assert Ltree('1.2') + Ltree('1.2') == Ltree('1.2.1.2')
"""
def __init__(self, path_or_ltree):
if isinstance(path_or_ltree, Ltree):
self.path = path_or_ltree.path
elif isinstance(path_or_ltree, str):
self.validate(path_or_ltree)
self.path = path_or_ltree
else:
raise TypeError(
"Ltree() argument must be a string or an Ltree, not '{}'"
.format(
type(path_or_ltree).__name__
)
)
@classmethod
def validate(cls, path):
if path_matcher.match(path) is None:
raise ValueError(
f"'{path}' is not a valid ltree path."
)
def __len__(self):
return len(self.path.split('.'))
def index(self, other):
subpath = Ltree(other).path.split('.')
parts = self.path.split('.')
for index, _ in enumerate(parts):
if parts[index:len(subpath) + index] == subpath:
return index
raise ValueError('subpath not found')
def descendant_of(self, other):
"""
is left argument a descendant of right (or equal)?
::
assert Ltree('1.2.3.4.5').descendant_of('1.2.3')
"""
subpath = self[:len(Ltree(other))]
return subpath == other
def ancestor_of(self, other):
"""
is left argument an ancestor of right (or equal)?
::
assert Ltree('1.2.3').ancestor_of('1.2.3.4.5')
"""
subpath = Ltree(other)[:len(self)]
return subpath == self
def __getitem__(self, key):
if isinstance(key, int):
return Ltree(self.path.split('.')[key])
elif isinstance(key, slice):
return Ltree('.'.join(self.path.split('.')[key]))
raise TypeError(
'Ltree indices must be integers, not {}'.format(
key.__class__.__name__
)
)
def lca(self, *others):
"""
Lowest common ancestor, i.e., longest common prefix of paths
::
assert Ltree('1.2.3.4.5').lca('1.2.3', '1.2.3.4', '1.2.3') == '1.2'
"""
other_parts = [Ltree(other).path.split('.') for other in others]
parts = self.path.split('.')
for index, element in enumerate(parts):
if any(
other[index] != element or
len(other) <= index + 1 or
len(parts) == index + 1
for other in other_parts
):
if index == 0:
return None
return Ltree('.'.join(parts[0:index]))
def __add__(self, other):
return Ltree(self.path + '.' + Ltree(other).path)
def __radd__(self, other):
return Ltree(other) + self
def __eq__(self, other):
if isinstance(other, Ltree):
return self.path == other.path
elif isinstance(other, str):
return self.path == other
else:
return NotImplemented
def __hash__(self):
return hash(self.path)
def __ne__(self, other):
return not (self == other)
def __repr__(self):
return f'{self.__class__.__name__}({self.path!r})'
def __unicode__(self):
return self.path
def __contains__(self, label):
return label in self.path.split('.')
def __gt__(self, other):
return self.path > other.path
def __lt__(self, other):
return self.path < other.path
def __ge__(self, other):
return self.path >= other.path
def __le__(self, other):
return self.path <= other.path
|
