84 lines
3.3 KiB
Python
84 lines
3.3 KiB
Python
"""
|
|
Functionality copied from the toolz package to avoid having
|
|
to add toolz as a dependency.
|
|
|
|
See https://github.com/pytoolz/toolz/.
|
|
|
|
toolz is relased under BSD licence. Below is the licence text
|
|
from toolz as it appeared when copying the code.
|
|
|
|
--------------------------------------------------------------
|
|
|
|
Copyright (c) 2013 Matthew Rocklin
|
|
|
|
All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions are met:
|
|
|
|
a. Redistributions of source code must retain the above copyright notice,
|
|
this list of conditions and the following disclaimer.
|
|
b. Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in the
|
|
documentation and/or other materials provided with the distribution.
|
|
c. Neither the name of toolz nor the names of its contributors
|
|
may be used to endorse or promote products derived from this software
|
|
without specific prior written permission.
|
|
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
|
|
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
|
|
DAMAGE.
|
|
"""
|
|
import operator
|
|
from functools import reduce
|
|
|
|
|
|
def get_in(keys, coll, default=None, no_default=False):
|
|
"""
|
|
NB: This is a straight copy of the get_in implementation found in
|
|
the toolz library (https://github.com/pytoolz/toolz/). It works
|
|
with persistent data structures as well as the corresponding
|
|
datastructures from the stdlib.
|
|
|
|
Returns coll[i0][i1]...[iX] where [i0, i1, ..., iX]==keys.
|
|
|
|
If coll[i0][i1]...[iX] cannot be found, returns ``default``, unless
|
|
``no_default`` is specified, then it raises KeyError or IndexError.
|
|
|
|
``get_in`` is a generalization of ``operator.getitem`` for nested data
|
|
structures such as dictionaries and lists.
|
|
>>> from pyrsistent import freeze
|
|
>>> transaction = freeze({'name': 'Alice',
|
|
... 'purchase': {'items': ['Apple', 'Orange'],
|
|
... 'costs': [0.50, 1.25]},
|
|
... 'credit card': '5555-1234-1234-1234'})
|
|
>>> get_in(['purchase', 'items', 0], transaction)
|
|
'Apple'
|
|
>>> get_in(['name'], transaction)
|
|
'Alice'
|
|
>>> get_in(['purchase', 'total'], transaction)
|
|
>>> get_in(['purchase', 'items', 'apple'], transaction)
|
|
>>> get_in(['purchase', 'items', 10], transaction)
|
|
>>> get_in(['purchase', 'total'], transaction, 0)
|
|
0
|
|
>>> get_in(['y'], {}, no_default=True)
|
|
Traceback (most recent call last):
|
|
...
|
|
KeyError: 'y'
|
|
"""
|
|
try:
|
|
return reduce(operator.getitem, keys, coll)
|
|
except (KeyError, IndexError, TypeError):
|
|
if no_default:
|
|
raise
|
|
return default
|