# -*- coding: utf-8 -*-
"""Common collection classes."""
from __future__ import print_function, division, absolute_import
from functools import reduce
from .compat import text_type
# http://stackoverflow.com/a/14620633/2127762
[docs]class AttrDict(dict):
"""Sub-classes dict, and further allows attribute-like access to dictionary items.
Examples:
>>> d = AttrDict({'a': 1})
>>> d.a, d['a'], d.get('a')
(1, 1, 1)
>>> d.b = 2
>>> d.b, d['b']
(2, 2)
"""
def __init__(self, *args, **kwargs):
super(AttrDict, self).__init__(*args, **kwargs)
self.__dict__ = self
[docs]class frozendict(dict):
def __key(self):
return tuple((k, self[k]) for k in sorted(self))
def __hash__(self):
return hash(self.__key())
def __eq__(self, other):
return self.__key() == other.__key()
[docs]def first(seq, key=lambda x: bool(x), default=None, apply=lambda x: x):
"""Give the first value that satisfies the key test.
Args:
seq (iterable):
key (callable): test for each element of iterable
default: returned when all elements fail test
apply (callable): applied to element before return
Returns: first element in seq that passes key, mutated with optional apply
Examples:
>>> first([0, False, None, [], (), 42])
42
>>> first([0, False, None, [], ()]) is None
True
>>> first([0, False, None, [], ()], default='ohai')
'ohai'
>>> import re
>>> m = first(re.match(regex, 'abc') for regex in ['b.*', 'a(.*)'])
>>> m.group(1)
'bc'
The optional `key` argument specifies a one-argument predicate function
like that used for `filter()`. The `key` argument, if supplied, must be
in keyword form. For example:
>>> first([1, 1, 3, 4, 5], key=lambda x: x % 2 == 0)
4
"""
return next((apply(x) for x in seq if key(x)), default)
[docs]def firstitem(map, key=lambda k, v: bool(k), default=None, apply=lambda k, v: (k, v)):
return next((apply(k, v) for k, v in map if key(k, v)), default)
[docs]def last(seq, key=lambda x: bool(x), default=None, apply=lambda x: x):
return next((apply(x) for x in reversed(seq) if key(x)), default)
[docs]def call_each(seq):
"""Calls each element of sequence to invoke the side effect.
Args:
seq:
Returns: None
"""
try:
reduce(lambda _, y: y(), seq)
except TypeError as e:
if text_type(e) != "reduce() of empty sequence with no initial value":
raise