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cpython/Lib/test/test_deque.py

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from collections import deque
import unittest
from test import support, seq_tests
import gc
import weakref
import copy
import pickle
from io import StringIO
import random
import struct
BIG = 100000
def fail():
raise SyntaxError
yield 1
class BadCmp:
def __eq__(self, other):
raise RuntimeError
class MutateCmp:
def __init__(self, deque, result):
self.deque = deque
self.result = result
def __eq__(self, other):
self.deque.clear()
return self.result
class TestBasic(unittest.TestCase):
def test_basics(self):
d = deque(range(-5125, -5000))
d.__init__(range(200))
for i in range(200, 400):
d.append(i)
for i in reversed(range(-200, 0)):
d.appendleft(i)
self.assertEqual(list(d), list(range(-200, 400)))
self.assertEqual(len(d), 600)
left = [d.popleft() for i in range(250)]
self.assertEqual(left, list(range(-200, 50)))
self.assertEqual(list(d), list(range(50, 400)))
right = [d.pop() for i in range(250)]
right.reverse()
self.assertEqual(right, list(range(150, 400)))
self.assertEqual(list(d), list(range(50, 150)))
def test_maxlen(self):
self.assertRaises(ValueError, deque, 'abc', -1)
self.assertRaises(ValueError, deque, 'abc', -2)
it = iter(range(10))
d = deque(it, maxlen=3)
self.assertEqual(list(it), [])
self.assertEqual(repr(d), 'deque([7, 8, 9], maxlen=3)')
self.assertEqual(list(d), [7, 8, 9])
self.assertEqual(d, deque(range(10), 3))
d.append(10)
self.assertEqual(list(d), [8, 9, 10])
d.appendleft(7)
self.assertEqual(list(d), [7, 8, 9])
d.extend([10, 11])
self.assertEqual(list(d), [9, 10, 11])
d.extendleft([8, 7])
self.assertEqual(list(d), [7, 8, 9])
d = deque(range(200), maxlen=10)
d.append(d)
support.unlink(support.TESTFN)
fo = open(support.TESTFN, "w")
try:
fo.write(str(d))
fo.close()
fo = open(support.TESTFN, "r")
self.assertEqual(fo.read(), repr(d))
finally:
fo.close()
support.unlink(support.TESTFN)
d = deque(range(10), maxlen=None)
self.assertEqual(repr(d), 'deque([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])')
fo = open(support.TESTFN, "w")
try:
fo.write(str(d))
fo.close()
fo = open(support.TESTFN, "r")
self.assertEqual(fo.read(), repr(d))
finally:
fo.close()
support.unlink(support.TESTFN)
def test_maxlen_zero(self):
it = iter(range(100))
deque(it, maxlen=0)
self.assertEqual(list(it), [])
it = iter(range(100))
d = deque(maxlen=0)
d.extend(it)
self.assertEqual(list(it), [])
it = iter(range(100))
d = deque(maxlen=0)
d.extendleft(it)
self.assertEqual(list(it), [])
def test_maxlen_attribute(self):
self.assertEqual(deque().maxlen, None)
self.assertEqual(deque('abc').maxlen, None)
self.assertEqual(deque('abc', maxlen=4).maxlen, 4)
self.assertEqual(deque('abc', maxlen=2).maxlen, 2)
self.assertEqual(deque('abc', maxlen=0).maxlen, 0)
with self.assertRaises(AttributeError):
d = deque('abc')
d.maxlen = 10
def test_count(self):
for s in ('', 'abracadabra', 'simsalabim'*500+'abc'):
s = list(s)
d = deque(s)
for letter in 'abcdefghijklmnopqrstuvwxyz':
self.assertEqual(s.count(letter), d.count(letter), (s, d, letter))
self.assertRaises(TypeError, d.count) # too few args
self.assertRaises(TypeError, d.count, 1, 2) # too many args
class BadCompare:
def __eq__(self, other):
raise ArithmeticError
d = deque([1, 2, BadCompare(), 3])
self.assertRaises(ArithmeticError, d.count, 2)
d = deque([1, 2, 3])
self.assertRaises(ArithmeticError, d.count, BadCompare())
class MutatingCompare:
def __eq__(self, other):
self.d.pop()
return True
m = MutatingCompare()
d = deque([1, 2, 3, m, 4, 5])
m.d = d
self.assertRaises(RuntimeError, d.count, 3)
# test issue11004
# block advance failed after rotation aligned elements on right side of block
d = deque([None]*16)
for i in range(len(d)):
d.rotate(-1)
d.rotate(1)
self.assertEqual(d.count(1), 0)
self.assertEqual(d.count(None), 16)
def test_comparisons(self):
d = deque('xabc'); d.popleft()
for e in [d, deque('abc'), deque('ab'), deque(), list(d)]:
self.assertEqual(d==e, type(d)==type(e) and list(d)==list(e))
self.assertEqual(d!=e, not(type(d)==type(e) and list(d)==list(e)))
args = map(deque, ('', 'a', 'b', 'ab', 'ba', 'abc', 'xba', 'xabc', 'cba'))
for x in args:
for y in args:
self.assertEqual(x == y, list(x) == list(y), (x,y))
self.assertEqual(x != y, list(x) != list(y), (x,y))
self.assertEqual(x < y, list(x) < list(y), (x,y))
self.assertEqual(x <= y, list(x) <= list(y), (x,y))
self.assertEqual(x > y, list(x) > list(y), (x,y))
self.assertEqual(x >= y, list(x) >= list(y), (x,y))
def test_contains(self):
n = 200
d = deque(range(n))
for i in range(n):
self.assertTrue(i in d)
self.assertTrue((n+1) not in d)
# Test detection of mutation during iteration
d = deque(range(n))
d[n//2] = MutateCmp(d, False)
with self.assertRaises(RuntimeError):
n in d
# Test detection of comparison exceptions
d = deque(range(n))
d[n//2] = BadCmp()
with self.assertRaises(RuntimeError):
n in d
def test_extend(self):
d = deque('a')
self.assertRaises(TypeError, d.extend, 1)
d.extend('bcd')
self.assertEqual(list(d), list('abcd'))
d.extend(d)
self.assertEqual(list(d), list('abcdabcd'))
def test_iadd(self):
d = deque('a')
d += 'bcd'
self.assertEqual(list(d), list('abcd'))
d += d
self.assertEqual(list(d), list('abcdabcd'))
def test_extendleft(self):
d = deque('a')
self.assertRaises(TypeError, d.extendleft, 1)
d.extendleft('bcd')
self.assertEqual(list(d), list(reversed('abcd')))
d.extendleft(d)
self.assertEqual(list(d), list('abcddcba'))
d = deque()
d.extendleft(range(1000))
self.assertEqual(list(d), list(reversed(range(1000))))
self.assertRaises(SyntaxError, d.extendleft, fail())
def test_getitem(self):
n = 200
d = deque(range(n))
l = list(range(n))
for i in range(n):
d.popleft()
l.pop(0)
if random.random() < 0.5:
d.append(i)
l.append(i)
for j in range(1-len(l), len(l)):
assert d[j] == l[j]
d = deque('superman')
self.assertEqual(d[0], 's')
self.assertEqual(d[-1], 'n')
d = deque()
self.assertRaises(IndexError, d.__getitem__, 0)
self.assertRaises(IndexError, d.__getitem__, -1)
def test_index(self):
for n in 1, 2, 30, 40, 200:
d = deque(range(n))
for i in range(n):
self.assertEqual(d.index(i), i)
with self.assertRaises(ValueError):
d.index(n+1)
# Test detection of mutation during iteration
d = deque(range(n))
d[n//2] = MutateCmp(d, False)
with self.assertRaises(RuntimeError):
d.index(n)
# Test detection of comparison exceptions
d = deque(range(n))
d[n//2] = BadCmp()
with self.assertRaises(RuntimeError):
d.index(n)
# Test start and stop arguments behavior matches list.index()
elements = 'ABCDEFGHI'
nonelement = 'Z'
d = deque(elements * 2)
s = list(elements * 2)
for start in range(-5 - len(s)*2, 5 + len(s) * 2):
for stop in range(-5 - len(s)*2, 5 + len(s) * 2):
for element in elements + 'Z':
try:
target = s.index(element, start, stop)
except ValueError:
with self.assertRaises(ValueError):
d.index(element, start, stop)
else:
self.assertEqual(d.index(element, start, stop), target)
def test_insert(self):
# Test to make sure insert behaves like lists
elements = 'ABCDEFGHI'
for i in range(-5 - len(elements)*2, 5 + len(elements) * 2):
d = deque('ABCDEFGHI')
s = list('ABCDEFGHI')
d.insert(i, 'Z')
s.insert(i, 'Z')
self.assertEqual(list(d), s)
def test_setitem(self):
n = 200
d = deque(range(n))
for i in range(n):
d[i] = 10 * i
self.assertEqual(list(d), [10*i for i in range(n)])
l = list(d)
for i in range(1-n, 0, -1):
d[i] = 7*i
l[i] = 7*i
self.assertEqual(list(d), l)
def test_delitem(self):
n = 500 # O(n**2) test, don't make this too big
d = deque(range(n))
self.assertRaises(IndexError, d.__delitem__, -n-1)
self.assertRaises(IndexError, d.__delitem__, n)
for i in range(n):
self.assertEqual(len(d), n-i)
j = random.randrange(-len(d), len(d))
val = d[j]
self.assertIn(val, d)
del d[j]
self.assertNotIn(val, d)
self.assertEqual(len(d), 0)
def test_reverse(self):
n = 500 # O(n**2) test, don't make this too big
data = [random.random() for i in range(n)]
for i in range(n):
d = deque(data[:i])
r = d.reverse()
self.assertEqual(list(d), list(reversed(data[:i])))
self.assertIs(r, None)
d.reverse()
self.assertEqual(list(d), data[:i])
self.assertRaises(TypeError, d.reverse, 1) # Arity is zero
def test_rotate(self):
s = tuple('abcde')
n = len(s)
d = deque(s)
d.rotate(1) # verify rot(1)
self.assertEqual(''.join(d), 'eabcd')
d = deque(s)
d.rotate(-1) # verify rot(-1)
self.assertEqual(''.join(d), 'bcdea')
d.rotate() # check default to 1
self.assertEqual(tuple(d), s)
for i in range(n*3):
d = deque(s)
e = deque(d)
d.rotate(i) # check vs. rot(1) n times
for j in range(i):
e.rotate(1)
self.assertEqual(tuple(d), tuple(e))
d.rotate(-i) # check that it works in reverse
self.assertEqual(tuple(d), s)
e.rotate(n-i) # check that it wraps forward
self.assertEqual(tuple(e), s)
for i in range(n*3):
d = deque(s)
e = deque(d)
d.rotate(-i)
for j in range(i):
e.rotate(-1) # check vs. rot(-1) n times
self.assertEqual(tuple(d), tuple(e))
d.rotate(i) # check that it works in reverse
self.assertEqual(tuple(d), s)
e.rotate(i-n) # check that it wraps backaround
self.assertEqual(tuple(e), s)
d = deque(s)
e = deque(s)
e.rotate(BIG+17) # verify on long series of rotates
dr = d.rotate
for i in range(BIG+17):
dr()
self.assertEqual(tuple(d), tuple(e))
self.assertRaises(TypeError, d.rotate, 'x') # Wrong arg type
self.assertRaises(TypeError, d.rotate, 1, 10) # Too many args
d = deque()
d.rotate() # rotate an empty deque
self.assertEqual(d, deque())
def test_len(self):
d = deque('ab')
self.assertEqual(len(d), 2)
d.popleft()
self.assertEqual(len(d), 1)
d.pop()
self.assertEqual(len(d), 0)
self.assertRaises(IndexError, d.pop)
self.assertEqual(len(d), 0)
d.append('c')
self.assertEqual(len(d), 1)
d.appendleft('d')
self.assertEqual(len(d), 2)
d.clear()
self.assertEqual(len(d), 0)
def test_underflow(self):
d = deque()
self.assertRaises(IndexError, d.pop)
self.assertRaises(IndexError, d.popleft)
def test_clear(self):
d = deque(range(100))
self.assertEqual(len(d), 100)
d.clear()
self.assertEqual(len(d), 0)
self.assertEqual(list(d), [])
d.clear() # clear an emtpy deque
self.assertEqual(list(d), [])
def test_remove(self):
d = deque('abcdefghcij')
d.remove('c')
self.assertEqual(d, deque('abdefghcij'))
d.remove('c')
self.assertEqual(d, deque('abdefghij'))
self.assertRaises(ValueError, d.remove, 'c')
self.assertEqual(d, deque('abdefghij'))
# Handle comparison errors
d = deque(['a', 'b', BadCmp(), 'c'])
e = deque(d)
self.assertRaises(RuntimeError, d.remove, 'c')
for x, y in zip(d, e):
# verify that original order and values are retained.
self.assertTrue(x is y)
# Handle evil mutator
for match in (True, False):
d = deque(['ab'])
d.extend([MutateCmp(d, match), 'c'])
self.assertRaises(IndexError, d.remove, 'c')
self.assertEqual(d, deque())
def test_repr(self):
d = deque(range(200))
e = eval(repr(d))
self.assertEqual(list(d), list(e))
d.append(d)
self.assertIn('...', repr(d))
def test_print(self):
d = deque(range(200))
d.append(d)
try:
support.unlink(support.TESTFN)
fo = open(support.TESTFN, "w")
print(d, file=fo, end='')
fo.close()
fo = open(support.TESTFN, "r")
self.assertEqual(fo.read(), repr(d))
finally:
fo.close()
support.unlink(support.TESTFN)
def test_init(self):
self.assertRaises(TypeError, deque, 'abc', 2, 3);
self.assertRaises(TypeError, deque, 1);
def test_hash(self):
self.assertRaises(TypeError, hash, deque('abc'))
def test_long_steadystate_queue_popleft(self):
for size in (0, 1, 2, 100, 1000):
d = deque(range(size))
append, pop = d.append, d.popleft
for i in range(size, BIG):
append(i)
x = pop()
if x != i - size:
self.assertEqual(x, i-size)
self.assertEqual(list(d), list(range(BIG-size, BIG)))
def test_long_steadystate_queue_popright(self):
for size in (0, 1, 2, 100, 1000):
d = deque(reversed(range(size)))
append, pop = d.appendleft, d.pop
for i in range(size, BIG):
append(i)
x = pop()
if x != i - size:
self.assertEqual(x, i-size)
self.assertEqual(list(reversed(list(d))),
list(range(BIG-size, BIG)))
def test_big_queue_popleft(self):
pass
d = deque()
append, pop = d.append, d.popleft
for i in range(BIG):
append(i)
for i in range(BIG):
x = pop()
if x != i:
self.assertEqual(x, i)
def test_big_queue_popright(self):
d = deque()
append, pop = d.appendleft, d.pop
for i in range(BIG):
append(i)
for i in range(BIG):
x = pop()
if x != i:
self.assertEqual(x, i)
def test_big_stack_right(self):
d = deque()
append, pop = d.append, d.pop
for i in range(BIG):
append(i)
for i in reversed(range(BIG)):
x = pop()
if x != i:
self.assertEqual(x, i)
self.assertEqual(len(d), 0)
def test_big_stack_left(self):
d = deque()
append, pop = d.appendleft, d.popleft
for i in range(BIG):
append(i)
for i in reversed(range(BIG)):
x = pop()
if x != i:
self.assertEqual(x, i)
self.assertEqual(len(d), 0)
def test_roundtrip_iter_init(self):
d = deque(range(200))
e = deque(d)
self.assertNotEqual(id(d), id(e))
self.assertEqual(list(d), list(e))
def test_pickle(self):
d = deque(range(200))
for i in range(pickle.HIGHEST_PROTOCOL + 1):
s = pickle.dumps(d, i)
e = pickle.loads(s)
self.assertNotEqual(id(d), id(e))
self.assertEqual(list(d), list(e))
## def test_pickle_recursive(self):
## d = deque('abc')
## d.append(d)
## for i in range(pickle.HIGHEST_PROTOCOL + 1):
## e = pickle.loads(pickle.dumps(d, i))
## self.assertNotEqual(id(d), id(e))
## self.assertEqual(id(e), id(e[-1]))
def test_iterator_pickle(self):
data = deque(range(200))
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
it = itorg = iter(data)
d = pickle.dumps(it, proto)
it = pickle.loads(d)
self.assertEqual(type(itorg), type(it))
self.assertEqual(list(it), list(data))
it = pickle.loads(d)
next(it)
d = pickle.dumps(it, proto)
self.assertEqual(list(it), list(data)[1:])
def test_deepcopy(self):
mut = [10]
d = deque([mut])
e = copy.deepcopy(d)
self.assertEqual(list(d), list(e))
mut[0] = 11
self.assertNotEqual(id(d), id(e))
self.assertNotEqual(list(d), list(e))
def test_copy(self):
mut = [10]
d = deque([mut])
e = copy.copy(d)
self.assertEqual(list(d), list(e))
mut[0] = 11
self.assertNotEqual(id(d), id(e))
self.assertEqual(list(d), list(e))
def test_copy_method(self):
mut = [10]
d = deque([mut])
e = d.copy()
self.assertEqual(list(d), list(e))
mut[0] = 11
self.assertNotEqual(id(d), id(e))
self.assertEqual(list(d), list(e))
def test_reversed(self):
for s in ('abcd', range(2000)):
self.assertEqual(list(reversed(deque(s))), list(reversed(s)))
def test_reversed_new(self):
klass = type(reversed(deque()))
for s in ('abcd', range(2000)):
self.assertEqual(list(klass(deque(s))), list(reversed(s)))
def test_gc_doesnt_blowup(self):
import gc
# This used to assert-fail in deque_traverse() under a debug
# build, or run wild with a NULL pointer in a release build.
d = deque()
for i in range(100):
d.append(1)
gc.collect()
def test_container_iterator(self):
# Bug #3680: tp_traverse was not implemented for deque iterator objects
class C(object):
pass
for i in range(2):
obj = C()
ref = weakref.ref(obj)
if i == 0:
container = deque([obj, 1])
else:
container = reversed(deque([obj, 1]))
obj.x = iter(container)
del obj, container
gc.collect()
self.assertTrue(ref() is None, "Cycle was not collected")
check_sizeof = support.check_sizeof
@support.cpython_only
def test_sizeof(self):
BLOCKLEN = 64
basesize = support.calcobjsize('2P4nlP')
blocksize = struct.calcsize('2P%dP' % BLOCKLEN)
self.assertEqual(object.__sizeof__(deque()), basesize)
check = self.check_sizeof
check(deque(), basesize + blocksize)
check(deque('a'), basesize + blocksize)
check(deque('a' * (BLOCKLEN - 1)), basesize + blocksize)
check(deque('a' * BLOCKLEN), basesize + 2 * blocksize)
check(deque('a' * (42 * BLOCKLEN)), basesize + 43 * blocksize)
class TestVariousIteratorArgs(unittest.TestCase):
def test_constructor(self):
for s in ("123", "", range(1000), ('do', 1.2), range(2000,2200,5)):
for g in (seq_tests.Sequence, seq_tests.IterFunc,
seq_tests.IterGen, seq_tests.IterFuncStop,
seq_tests.itermulti, seq_tests.iterfunc):
self.assertEqual(list(deque(g(s))), list(g(s)))
self.assertRaises(TypeError, deque, seq_tests.IterNextOnly(s))
self.assertRaises(TypeError, deque, seq_tests.IterNoNext(s))
self.assertRaises(ZeroDivisionError, deque, seq_tests.IterGenExc(s))
def test_iter_with_altered_data(self):
d = deque('abcdefg')
it = iter(d)
d.pop()
self.assertRaises(RuntimeError, next, it)
def test_runtime_error_on_empty_deque(self):
d = deque()
it = iter(d)
d.append(10)
self.assertRaises(RuntimeError, next, it)
class Deque(deque):
pass
class DequeWithBadIter(deque):
def __iter__(self):
raise TypeError
class TestSubclass(unittest.TestCase):
def test_basics(self):
d = Deque(range(25))
d.__init__(range(200))
for i in range(200, 400):
d.append(i)
for i in reversed(range(-200, 0)):
d.appendleft(i)
self.assertEqual(list(d), list(range(-200, 400)))
self.assertEqual(len(d), 600)
left = [d.popleft() for i in range(250)]
self.assertEqual(left, list(range(-200, 50)))
self.assertEqual(list(d), list(range(50, 400)))
right = [d.pop() for i in range(250)]
right.reverse()
self.assertEqual(right, list(range(150, 400)))
self.assertEqual(list(d), list(range(50, 150)))
d.clear()
self.assertEqual(len(d), 0)
def test_copy_pickle(self):
d = Deque('abc')
e = d.__copy__()
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
e = Deque(d)
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
s = pickle.dumps(d, proto)
e = pickle.loads(s)
self.assertNotEqual(id(d), id(e))
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
d = Deque('abcde', maxlen=4)
e = d.__copy__()
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
e = Deque(d)
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
s = pickle.dumps(d, proto)
e = pickle.loads(s)
self.assertNotEqual(id(d), id(e))
self.assertEqual(type(d), type(e))
self.assertEqual(list(d), list(e))
## def test_pickle(self):
## d = Deque('abc')
## d.append(d)
##
## e = pickle.loads(pickle.dumps(d))
## self.assertNotEqual(id(d), id(e))
## self.assertEqual(type(d), type(e))
## dd = d.pop()
## ee = e.pop()
## self.assertEqual(id(e), id(ee))
## self.assertEqual(d, e)
##
## d.x = d
## e = pickle.loads(pickle.dumps(d))
## self.assertEqual(id(e), id(e.x))
##
## d = DequeWithBadIter('abc')
## self.assertRaises(TypeError, pickle.dumps, d)
def test_weakref(self):
d = deque('gallahad')
p = weakref.proxy(d)
self.assertEqual(str(p), str(d))
d = None
self.assertRaises(ReferenceError, str, p)
def test_strange_subclass(self):
class X(deque):
def __iter__(self):
return iter([])
d1 = X([1,2,3])
d2 = X([4,5,6])
d1 == d2 # not clear if this is supposed to be True or False,
# but it used to give a SystemError
class SubclassWithKwargs(deque):
def __init__(self, newarg=1):
deque.__init__(self)
class TestSubclassWithKwargs(unittest.TestCase):
def test_subclass_with_kwargs(self):
# SF bug #1486663 -- this used to erroneously raise a TypeError
SubclassWithKwargs(newarg=1)
#==============================================================================
libreftest = """
Example from the Library Reference: Doc/lib/libcollections.tex
>>> from collections import deque
>>> d = deque('ghi') # make a new deque with three items
>>> for elem in d: # iterate over the deque's elements
... print(elem.upper())
G
H
I
>>> d.append('j') # add a new entry to the right side
>>> d.appendleft('f') # add a new entry to the left side
>>> d # show the representation of the deque
deque(['f', 'g', 'h', 'i', 'j'])
>>> d.pop() # return and remove the rightmost item
'j'
>>> d.popleft() # return and remove the leftmost item
'f'
>>> list(d) # list the contents of the deque
['g', 'h', 'i']
>>> d[0] # peek at leftmost item
'g'
>>> d[-1] # peek at rightmost item
'i'
>>> list(reversed(d)) # list the contents of a deque in reverse
['i', 'h', 'g']
>>> 'h' in d # search the deque
True
>>> d.extend('jkl') # add multiple elements at once
>>> d
deque(['g', 'h', 'i', 'j', 'k', 'l'])
>>> d.rotate(1) # right rotation
>>> d
deque(['l', 'g', 'h', 'i', 'j', 'k'])
>>> d.rotate(-1) # left rotation
>>> d
deque(['g', 'h', 'i', 'j', 'k', 'l'])
>>> deque(reversed(d)) # make a new deque in reverse order
deque(['l', 'k', 'j', 'i', 'h', 'g'])
>>> d.clear() # empty the deque
>>> d.pop() # cannot pop from an empty deque
Traceback (most recent call last):
File "<pyshell#6>", line 1, in -toplevel-
d.pop()
IndexError: pop from an empty deque
>>> d.extendleft('abc') # extendleft() reverses the input order
>>> d
deque(['c', 'b', 'a'])
>>> def delete_nth(d, n):
... d.rotate(-n)
... d.popleft()
... d.rotate(n)
...
>>> d = deque('abcdef')
>>> delete_nth(d, 2) # remove the entry at d[2]
>>> d
deque(['a', 'b', 'd', 'e', 'f'])
>>> def roundrobin(*iterables):
... pending = deque(iter(i) for i in iterables)
... while pending:
... task = pending.popleft()
... try:
... yield next(task)
... except StopIteration:
... continue
... pending.append(task)
...
>>> for value in roundrobin('abc', 'd', 'efgh'):
... print(value)
...
a
d
e
b
f
c
g
h
>>> def maketree(iterable):
... d = deque(iterable)
... while len(d) > 1:
... pair = [d.popleft(), d.popleft()]
... d.append(pair)
... return list(d)
...
>>> print(maketree('abcdefgh'))
[[[['a', 'b'], ['c', 'd']], [['e', 'f'], ['g', 'h']]]]
"""
#==============================================================================
__test__ = {'libreftest' : libreftest}
def test_main(verbose=None):
import sys
test_classes = (
TestBasic,
TestVariousIteratorArgs,
TestSubclass,
TestSubclassWithKwargs,
)
support.run_unittest(*test_classes)
# verify reference counting
if verbose and hasattr(sys, "gettotalrefcount"):
import gc
counts = [None] * 5
for i in range(len(counts)):
support.run_unittest(*test_classes)
gc.collect()
counts[i] = sys.gettotalrefcount()
print(counts)
# doctests
from test import test_deque
support.run_doctest(test_deque, verbose)
if __name__ == "__main__":
test_main(verbose=True)
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