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Contents
# Copyright 2012 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Iterator wrapper that allows you to check whether the wrapped iterator
is empty and whether it has more than 1 element.
"""
class PluralityCheckableIterator(object):
def __init__(self, it):
self.it = it.__iter__()
self.head = []
# Populate first 2 elems into head so we can check whether iterator has
# more than 1 item.
for i in range(0, 2):
self.__populate_head__()
def __populate_head__(self):
try:
e = self.it.next()
self.underlying_iter_empty = False
self.head.append(e)
except StopIteration:
# Indicates we can no longer call next() on underlying iterator, but
# there could still be elements left to iterate in head.
self.underlying_iter_empty = True
def __iter__(self):
while len(self.head) > 0:
yield self.next()
else:
raise StopIteration()
def next(self):
# Backfill into head each time we pop an element so we can always check
# for emptiness and for has_plurality().
self.__populate_head__()
return self.head.pop(0)
def is_empty(self):
return len(self.head) == 0
def has_plurality(self):
return len(self.head) > 1
Version data entries
25 entries across 25 versions & 3 rubygems