Issue #14288: Serialization support for builtin iterators.

Include/iterobject.h

@@ -18,6 +18,8 @@ PyAPI_FUNC(PyObject *) PySeqIter_New(PyObject *);
 
 PyAPI_FUNC(PyObject *) PyCallIter_New(PyObject *, PyObject *);
 
+PyAPI_FUNC(PyObject *) _PyIter_GetBuiltin(const char *iter);
+
 #ifdef __cplusplus
 }
 #endif

Lib/test/seq_tests.py

@@ -4,6 +4,7 @@ Tests common to tuple, list and UserList.UserList
 
 import unittest
 import sys
+import pickle
 
 # Various iterables
 # This is used for checking the constructor (here and in test_deque.py)
@@ -388,3 +389,9 @@ class CommonTest(unittest.TestCase):
         self.assertEqual(a.index(0, -4*sys.maxsize, 4*sys.maxsize), 2)
         self.assertRaises(ValueError, a.index, 0, 4*sys.maxsize,-4*sys.maxsize)
         self.assertRaises(ValueError, a.index, 2, 0, -10)
+
+    def test_pickle(self):
+        lst = self.type2test([4, 5, 6, 7])
+        lst2 = pickle.loads(pickle.dumps(lst))
+        self.assertEqual(lst2, lst)
+        self.assertNotEqual(id(lst2), id(lst))

Lib/test/test_array.py

@@ -285,6 +285,20 @@ class BaseTest(unittest.TestCase):
             self.assertEqual(a.x, b.x)
             self.assertEqual(type(a), type(b))
 
+    def test_iterator_pickle(self):
+        data = array.array(self.typecode, self.example)
+        orgit = iter(data)
+        d = pickle.dumps(orgit)
+        it = pickle.loads(d)
+        self.assertEqual(type(orgit), type(it))
+        self.assertEqual(list(it), list(data))
+
+        if len(data):
+            it = pickle.loads(d)
+            next(it)
+            d = pickle.dumps(it)
+            self.assertEqual(list(it), list(data)[1:])
+
     def test_insert(self):
         a = array.array(self.typecode, self.example)
         a.insert(0, self.example[0])

Lib/test/test_builtin.py

@@ -14,6 +14,7 @@ import random
 import traceback
 from test.support import TESTFN, unlink,  run_unittest, check_warnings
 from operator import neg
+import pickle
 try:
     import pty, signal
 except ImportError:
@@ -110,7 +111,30 @@ class TestFailingIter:
     def __iter__(self):
         raise RuntimeError
 
+def filter_char(arg):
+    return ord(arg) > ord("d")
+
+def map_char(arg):
+    return chr(ord(arg)+1)
+
 class BuiltinTest(unittest.TestCase):
+    # Helper to check picklability
+    def check_iter_pickle(self, it, seq):
+        itorg = it
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(list(it), seq)
+
+        #test the iterator after dropping one from it
+        it = pickle.loads(d)
+        try:
+            next(it)
+        except StopIteration:
+            return
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(list(it), seq[1:])
 
     def test_import(self):
         __import__('sys')
@@ -566,6 +590,11 @@ class BuiltinTest(unittest.TestCase):
         self.assertEqual(list(filter(lambda x: x>=3, (1, 2, 3, 4))), [3, 4])
         self.assertRaises(TypeError, list, filter(42, (1, 2)))
 
+    def test_filter_pickle(self):
+        f1 = filter(filter_char, "abcdeabcde")
+        f2 = filter(filter_char, "abcdeabcde")
+        self.check_iter_pickle(f1, list(f2))
+
     def test_getattr(self):
         self.assertTrue(getattr(sys, 'stdout') is sys.stdout)
         self.assertRaises(TypeError, getattr, sys, 1)
@@ -759,6 +788,11 @@ class BuiltinTest(unittest.TestCase):
             raise RuntimeError
         self.assertRaises(RuntimeError, list, map(badfunc, range(5)))
 
+    def test_map_pickle(self):
+        m1 = map(map_char, "Is this the real life?")
+        m2 = map(map_char, "Is this the real life?")
+        self.check_iter_pickle(m1, list(m2))
+
     def test_max(self):
         self.assertEqual(max('123123'), '3')
         self.assertEqual(max(1, 2, 3), 3)
@@ -1300,6 +1334,13 @@ class BuiltinTest(unittest.TestCase):
                     return i
         self.assertRaises(ValueError, list, zip(BadSeq(), BadSeq()))
 
+    def test_zip_pickle(self):
+        a = (1, 2, 3)
+        b = (4, 5, 6)
+        t = [(1, 4), (2, 5), (3, 6)]
+        z1 = zip(a, b)
+        self.check_iter_pickle(z1, t)
+
     def test_format(self):
         # Test the basic machinery of the format() builtin.  Don't test
         #  the specifics of the various formatters

Lib/test/test_bytes.py

@@ -518,6 +518,24 @@ class BaseBytesTest(unittest.TestCase):
                 q = pickle.loads(ps)
                 self.assertEqual(b, q)
 
+    def test_iterator_pickling(self):
+        for b in b"", b"a", b"abc", b"\xffab\x80", b"\0\0\377\0\0":
+            it = itorg = iter(self.type2test(b))
+            data = list(self.type2test(b))
+            d = pickle.dumps(it)
+            it = pickle.loads(d)
+            self.assertEqual(type(itorg), type(it))
+            self.assertEqual(list(it), data)
+
+            it = pickle.loads(d)
+            try:
+                next(it)
+            except StopIteration:
+                continue
+            d = pickle.dumps(it)
+            it = pickle.loads(d)
+            self.assertEqual(list(it), data[1:])
+
     def test_strip(self):
         b = self.type2test(b'mississippi')
         self.assertEqual(b.strip(b'i'), b'mississipp')

Lib/test/test_deque.py

@@ -471,6 +471,19 @@ class TestBasic(unittest.TestCase):
 ##            self.assertNotEqual(id(d), id(e))
 ##            self.assertEqual(id(e), id(e[-1]))
 
+    def test_iterator_pickle(self):
+        data = deque(range(200))
+        it = itorg = iter(data)
+        d = pickle.dumps(it)
+        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)
+        self.assertEqual(list(it), list(data)[1:])
+
     def test_deepcopy(self):
         mut = [10]
         d = deque([mut])

Lib/test/test_dict.py

@@ -2,7 +2,9 @@ import unittest
 from test import support
 
 import collections, random, string
+import collections.abc
 import gc, weakref
+import pickle
 
 
 class DictTest(unittest.TestCase):
@@ -803,6 +805,58 @@ class DictTest(unittest.TestCase):
             pass
         self._tracked(MyDict())
 
+    def test_iterator_pickling(self):
+        data = {1:"a", 2:"b", 3:"c"}
+        it = iter(data)
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(sorted(it), sorted(data))
+
+        it = pickle.loads(d)
+        try:
+            drop = next(it)
+        except StopIteration:
+            return
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        del data[drop]
+        self.assertEqual(sorted(it), sorted(data))
+
+    def test_itemiterator_pickling(self):
+        data = {1:"a", 2:"b", 3:"c"}
+        # dictviews aren't picklable, only their iterators
+        itorg = iter(data.items())
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        # note that the type of type of the unpickled iterator
+        # is not necessarily the same as the original.  It is
+        # merely an object supporting the iterator protocol, yielding
+        # the same objects as the original one.
+        # self.assertEqual(type(itorg), type(it))
+        self.assertTrue(isinstance(it, collections.abc.Iterator))
+        self.assertEqual(dict(it), data)
+
+        it = pickle.loads(d)
+        drop = next(it)
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        del data[drop[0]]
+        self.assertEqual(dict(it), data)
+
+    def test_valuesiterator_pickling(self):
+        data = {1:"a", 2:"b", 3:"c"}
+        # data.values() isn't picklable, only its iterator
+        it = iter(data.values())
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(sorted(list(it)), sorted(list(data.values())))
+
+        it = pickle.loads(d)
+        drop = next(it)
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        values = list(it) + [drop]
+        self.assertEqual(sorted(values), sorted(list(data.values())))
 
 from test import mapping_tests
 

Lib/test/test_enumerate.py

@@ -1,5 +1,6 @@
 import unittest
 import sys
+import pickle
 
 from test import support
 
@@ -61,7 +62,25 @@ class N:
     def __iter__(self):
         return self
 
-class EnumerateTestCase(unittest.TestCase):
+class PickleTest:
+    # Helper to check picklability
+    def check_pickle(self, itorg, seq):
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(list(it), seq)
+
+        it = pickle.loads(d)
+        try:
+            next(it)
+        except StopIteration:
+            self.assertFalse(seq[1:])
+            return
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(list(it), seq[1:])
+
+class EnumerateTestCase(unittest.TestCase, PickleTest):
 
     enum = enumerate
     seq, res = 'abc', [(0,'a'), (1,'b'), (2,'c')]
@@ -73,6 +92,9 @@ class EnumerateTestCase(unittest.TestCase):
         self.assertEqual(list(self.enum(self.seq)), self.res)
         self.enum.__doc__
 
+    def test_pickle(self):
+        self.check_pickle(self.enum(self.seq), self.res)
+
     def test_getitemseqn(self):
         self.assertEqual(list(self.enum(G(self.seq))), self.res)
         e = self.enum(G(''))
@@ -126,7 +148,7 @@ class TestBig(EnumerateTestCase):
     seq = range(10,20000,2)
     res = list(zip(range(20000), seq))
 
-class TestReversed(unittest.TestCase):
+class TestReversed(unittest.TestCase, PickleTest):
 
     def test_simple(self):
         class A:
@@ -212,6 +234,10 @@ class TestReversed(unittest.TestCase):
         ngi = NoGetItem()
         self.assertRaises(TypeError, reversed, ngi)
 
+    def test_pickle(self):
+        for data in 'abc', range(5), tuple(enumerate('abc')), range(1,17,5):
+            self.check_pickle(reversed(data), list(data)[::-1])
+
 
 class EnumerateStartTestCase(EnumerateTestCase):
 

Lib/test/test_iter.py

@@ -2,6 +2,8 @@
 
 import unittest
 from test.support import run_unittest, TESTFN, unlink, cpython_only
+import pickle
+import collections.abc
 
 # Test result of triple loop (too big to inline)
 TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
@@ -28,6 +30,8 @@ class BasicIterClass:
             raise StopIteration
         self.i = res + 1
         return res
+    def __iter__(self):
+        return self
 
 class IteratingSequenceClass:
     def __init__(self, n):
@@ -49,7 +53,9 @@ class SequenceClass:
 class TestCase(unittest.TestCase):
 
     # Helper to check that an iterator returns a given sequence
-    def check_iterator(self, it, seq):
+    def check_iterator(self, it, seq, pickle=True):
+        if pickle:
+            self.check_pickle(it, seq)
         res = []
         while 1:
             try:
@@ -60,12 +66,33 @@ class TestCase(unittest.TestCase):
         self.assertEqual(res, seq)
 
     # Helper to check that a for loop generates a given sequence
-    def check_for_loop(self, expr, seq):
+    def check_for_loop(self, expr, seq, pickle=True):
+        if pickle:
+            self.check_pickle(iter(expr), seq)
         res = []
         for val in expr:
             res.append(val)
         self.assertEqual(res, seq)
 
+    # Helper to check picklability
+    def check_pickle(self, itorg, seq):
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        # Cannot assert type equality because dict iterators unpickle as list
+        # iterators.
+        # self.assertEqual(type(itorg), type(it))
+        self.assertTrue(isinstance(it, collections.abc.Iterator))
+        self.assertEqual(list(it), seq)
+
+        it = pickle.loads(d)
+        try:
+            next(it)
+        except StopIteration:
+            return
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(list(it), seq[1:])
+
     # Test basic use of iter() function
     def test_iter_basic(self):
         self.check_iterator(iter(range(10)), list(range(10)))
@@ -138,7 +165,7 @@ class TestCase(unittest.TestCase):
                 if i > 100:
                     raise IndexError # Emergency stop
                 return i
-        self.check_iterator(iter(C(), 10), list(range(10)))
+        self.check_iterator(iter(C(), 10), list(range(10)), pickle=False)
 
     # Test two-argument iter() with function
     def test_iter_function(self):
@@ -146,7 +173,7 @@ class TestCase(unittest.TestCase):
             i = state[0]
             state[0] = i+1
             return i
-        self.check_iterator(iter(spam, 10), list(range(10)))
+        self.check_iterator(iter(spam, 10), list(range(10)), pickle=False)
 
     # Test two-argument iter() with function that raises StopIteration
     def test_iter_function_stop(self):
@@ -156,7 +183,7 @@ class TestCase(unittest.TestCase):
                 raise StopIteration
             state[0] = i+1
             return i
-        self.check_iterator(iter(spam, 20), list(range(10)))
+        self.check_iterator(iter(spam, 20), list(range(10)), pickle=False)
 
     # Test exception propagation through function iterator
     def test_exception_function(self):
@@ -198,7 +225,7 @@ class TestCase(unittest.TestCase):
                 if i == 10:
                     raise StopIteration
                 return SequenceClass.__getitem__(self, i)
-        self.check_for_loop(MySequenceClass(20), list(range(10)))
+        self.check_for_loop(MySequenceClass(20), list(range(10)), pickle=False)
 
     # Test a big range
     def test_iter_big_range(self):
@@ -237,8 +264,8 @@ class TestCase(unittest.TestCase):
             f.close()
         f = open(TESTFN, "r")
         try:
-            self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
+            self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"], pickle=False)
-            self.check_for_loop(f, [])
+            self.check_for_loop(f, [], pickle=False)
         finally:
             f.close()
             try:

Lib/test/test_itertools.py

@@ -37,6 +37,13 @@ def isOdd(x):
     'Test predicate'
     return x%2==1
 
+def tupleize(*args):
+    return args
+
+def irange(n):
+    for i in range(n):
+        yield i
+
 class StopNow:
     'Class emulating an empty iterable.'
     def __iter__(self):
@@ -55,8 +62,59 @@ def fact(n):
     'Factorial'
     return prod(range(1, n+1))
 
+# root level methods for pickling ability
+def testR(r):
+    return r[0]
+
+def testR2(r):
+    return r[2]
+
+def underten(x):
+    return x<10
+
 class TestBasicOps(unittest.TestCase):
 
+    def pickletest(self, it, stop=4, take=1, compare=None):
+        """Test that an iterator is the same after pickling, also when part-consumed"""
+        def expand(it, i=0):
+            # Recursively expand iterables, within sensible bounds
+            if i > 10:
+                raise RuntimeError("infinite recursion encountered")
+            if isinstance(it, str):
+                return it
+            try:
+                l = list(islice(it, stop))
+            except TypeError:
+                return it # can't expand it
+            return [expand(e, i+1) for e in l]
+
+        # Test the initial copy against the original
+        dump = pickle.dumps(it)
+        i2 = pickle.loads(dump)
+        self.assertEqual(type(it), type(i2))
+        a, b = expand(it), expand(i2)
+        self.assertEqual(a, b)
+        if compare:
+            c = expand(compare)
+            self.assertEqual(a, c)
+
+        # Take from the copy, and create another copy and compare them.
+        i3 = pickle.loads(dump)
+        took = 0
+        try:
+            for i in range(take):
+                next(i3)
+                took += 1
+        except StopIteration:
+            pass #in case there is less data than 'take'
+        dump = pickle.dumps(i3)
+        i4 = pickle.loads(dump)
+        a, b = expand(i3), expand(i4)
+        self.assertEqual(a, b)
+        if compare:
+            c = expand(compare[took:])
+            self.assertEqual(a, c);
+
     def test_accumulate(self):
         self.assertEqual(list(accumulate(range(10))),               # one positional arg
                           [0, 1, 3, 6, 10, 15, 21, 28, 36, 45])
@@ -83,6 +141,7 @@ class TestBasicOps(unittest.TestCase):
                          [2, 16, 144, 720, 5040, 0, 0, 0, 0, 0])
         with self.assertRaises(TypeError):
             list(accumulate(s, chr))                                # unary-operation
+        self.pickletest(accumulate(range(10)))                      # test pickling
 
     def test_chain(self):
 
@@ -106,14 +165,43 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(take(4, chain.from_iterable(['abc', 'def'])), list('abcd'))
         self.assertRaises(TypeError, list, chain.from_iterable([2, 3]))
 
+    def test_chain_reducible(self):
+        operators = [copy.deepcopy,
+                     lambda s: pickle.loads(pickle.dumps(s))]
+        for oper in operators:
+            it = chain('abc', 'def')
+            self.assertEqual(list(oper(it)), list('abcdef'))
+            self.assertEqual(next(it), 'a')
+            self.assertEqual(list(oper(it)), list('bcdef'))
+
+            self.assertEqual(list(oper(chain(''))), [])
+            self.assertEqual(take(4, oper(chain('abc', 'def'))), list('abcd'))
+            self.assertRaises(TypeError, list, oper(chain(2, 3)))
+        self.pickletest(chain('abc', 'def'), compare=list('abcdef'))
+
     def test_combinations(self):
         self.assertRaises(TypeError, combinations, 'abc')       # missing r argument
         self.assertRaises(TypeError, combinations, 'abc', 2, 1) # too many arguments
         self.assertRaises(TypeError, combinations, None)        # pool is not iterable
         self.assertRaises(ValueError, combinations, 'abc', -2)  # r is negative
-        self.assertEqual(list(combinations('abc', 32)), [])     # r > n
+
-        self.assertEqual(list(combinations(range(4), 3)),
+        for op in (lambda a:a, lambda a:pickle.loads(pickle.dumps(a))):
-                                           [(0,1,2), (0,1,3), (0,2,3), (1,2,3)])
+            self.assertEqual(list(op(combinations('abc', 32))), [])     # r > n
+
+            self.assertEqual(list(op(combinations('ABCD', 2))),
+                             [('A','B'), ('A','C'), ('A','D'), ('B','C'), ('B','D'), ('C','D')])
+            testIntermediate = combinations('ABCD', 2)
+            next(testIntermediate)
+            self.assertEqual(list(op(testIntermediate)),
+                             [('A','C'), ('A','D'), ('B','C'), ('B','D'), ('C','D')])
+
+            self.assertEqual(list(op(combinations(range(4), 3))),
+                             [(0,1,2), (0,1,3), (0,2,3), (1,2,3)])
+            testIntermediate = combinations(range(4), 3)
+            next(testIntermediate)
+            self.assertEqual(list(op(testIntermediate)),
+                             [(0,1,3), (0,2,3), (1,2,3)])
+
 
         def combinations1(iterable, r):
             'Pure python version shown in the docs'
@@ -168,6 +256,9 @@ class TestBasicOps(unittest.TestCase):
                 self.assertEqual(result, list(combinations2(values, r))) # matches second pure python version
                 self.assertEqual(result, list(combinations3(values, r))) # matches second pure python version
 
+                self.pickletest(combinations(values, r))                 # test pickling
+
+        # Test implementation detail:  tuple re-use
     @support.impl_detail("tuple reuse is specific to CPython")
     def test_combinations_tuple_reuse(self):
         self.assertEqual(len(set(map(id, combinations('abcde', 3)))), 1)
@@ -179,8 +270,15 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, cwr, 'abc', 2, 1) # too many arguments
         self.assertRaises(TypeError, cwr, None)        # pool is not iterable
         self.assertRaises(ValueError, cwr, 'abc', -2)  # r is negative
-        self.assertEqual(list(cwr('ABC', 2)),
+
-                         [('A','A'), ('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
+        for op in (lambda a:a, lambda a:pickle.loads(pickle.dumps(a))):
+            self.assertEqual(list(op(cwr('ABC', 2))),
+                             [('A','A'), ('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
+            testIntermediate = cwr('ABC', 2)
+            next(testIntermediate)
+            self.assertEqual(list(op(testIntermediate)),
+                             [('A','B'), ('A','C'), ('B','B'), ('B','C'), ('C','C')])
+
 
         def cwr1(iterable, r):
             'Pure python version shown in the docs'
@@ -239,6 +337,10 @@ class TestBasicOps(unittest.TestCase):
                 self.assertEqual(result, list(cwr1(values, r)))         # matches first pure python version
                 self.assertEqual(result, list(cwr2(values, r)))         # matches second pure python version
 
+                self.pickletest(cwr(values,r))                          # test pickling
+
+        # Test implementation detail:  tuple re-use
+
     @support.impl_detail("tuple reuse is specific to CPython")
     def test_combinations_with_replacement_tuple_reuse(self):
         cwr = combinations_with_replacement
@@ -305,6 +407,8 @@ class TestBasicOps(unittest.TestCase):
                     self.assertEqual(result, list(permutations(values, None))) # test r as None
                     self.assertEqual(result, list(permutations(values)))       # test default r
 
+                self.pickletest(permutations(values, r))                # test pickling
+
     @support.impl_detail("tuple resuse is CPython specific")
     def test_permutations_tuple_reuse(self):
         self.assertEqual(len(set(map(id, permutations('abcde', 3)))), 1)
@@ -359,6 +463,24 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, compress, range(6))            # too few args
         self.assertRaises(TypeError, compress, range(6), None)      # too many args
 
+        # check copy, deepcopy, pickle
+        for op in (lambda a:copy.copy(a), lambda a:copy.deepcopy(a), lambda a:pickle.loads(pickle.dumps(a))):
+            for data, selectors, result1, result2 in [
+                ('ABCDEF', [1,0,1,0,1,1], 'ACEF', 'CEF'),
+                ('ABCDEF', [0,0,0,0,0,0], '', ''),
+                ('ABCDEF', [1,1,1,1,1,1], 'ABCDEF', 'BCDEF'),
+                ('ABCDEF', [1,0,1], 'AC', 'C'),
+                ('ABC', [0,1,1,1,1,1], 'BC', 'C'),
+                ]:
+
+                self.assertEqual(list(op(compress(data=data, selectors=selectors))), list(result1))
+                self.assertEqual(list(op(compress(data, selectors))), list(result1))
+                testIntermediate = compress(data, selectors)
+                if result1:
+                    next(testIntermediate)
+                    self.assertEqual(list(op(testIntermediate)), list(result2))
+
+
     def test_count(self):
         self.assertEqual(lzip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
         self.assertEqual(lzip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
@@ -393,7 +515,7 @@ class TestBasicOps(unittest.TestCase):
             c = count(value)
             self.assertEqual(next(copy.copy(c)), value)
             self.assertEqual(next(copy.deepcopy(c)), value)
-            self.assertEqual(next(pickle.loads(pickle.dumps(c))), value)
+            self.pickletest(count(value))
 
         #check proper internal error handling for large "step' sizes
         count(1, maxsize+5); sys.exc_info()
@@ -440,6 +562,7 @@ class TestBasicOps(unittest.TestCase):
                 else:
                     r2 = ('count(%r, %r)' % (i, j)).replace('L', '')
                 self.assertEqual(r1, r2)
+                self.pickletest(count(i, j))
 
     def test_cycle(self):
         self.assertEqual(take(10, cycle('abc')), list('abcabcabca'))
@@ -448,6 +571,18 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, cycle, 5)
         self.assertEqual(list(islice(cycle(gen3()),10)), [0,1,2,0,1,2,0,1,2,0])
 
+        # check copy, deepcopy, pickle
+        c = cycle('abc')
+        self.assertEqual(next(c), 'a')
+        #simple copy currently not supported, because __reduce__ returns
+        #an internal iterator
+        #self.assertEqual(take(10, copy.copy(c)), list('bcabcabcab'))
+        self.assertEqual(take(10, copy.deepcopy(c)), list('bcabcabcab'))
+        self.assertEqual(take(10, pickle.loads(pickle.dumps(c))), list('bcabcabcab'))
+        next(c)
+        self.assertEqual(take(10, pickle.loads(pickle.dumps(c))), list('cabcabcabc'))
+        self.pickletest(cycle('abc'))
+
     def test_groupby(self):
         # Check whether it accepts arguments correctly
         self.assertEqual([], list(groupby([])))
@@ -466,18 +601,37 @@ class TestBasicOps(unittest.TestCase):
                 dup.append(elem)
         self.assertEqual(s, dup)
 
+        # Check normal pickled
+        dup = []
+        for k, g in pickle.loads(pickle.dumps(groupby(s, testR))):
+            for elem in g:
+                self.assertEqual(k, elem[0])
+                dup.append(elem)
+        self.assertEqual(s, dup)
+
         # Check nested case
         dup = []
-        for k, g in groupby(s, lambda r:r[0]):
+        for k, g in groupby(s, testR):
-            for ik, ig in groupby(g, lambda r:r[2]):
+            for ik, ig in groupby(g, testR2):
                 for elem in ig:
                     self.assertEqual(k, elem[0])
                     self.assertEqual(ik, elem[2])
                     dup.append(elem)
         self.assertEqual(s, dup)
 
+        # Check nested and pickled
+        dup = []
+        for k, g in pickle.loads(pickle.dumps(groupby(s, testR))):
+            for ik, ig in pickle.loads(pickle.dumps(groupby(g, testR2))):
+                for elem in ig:
+                    self.assertEqual(k, elem[0])
+                    self.assertEqual(ik, elem[2])
+                    dup.append(elem)
+        self.assertEqual(s, dup)
+
+
         # Check case where inner iterator is not used
-        keys = [k for k, g in groupby(s, lambda r:r[0])]
+        keys = [k for k, g in groupby(s, testR)]
         expectedkeys = set([r[0] for r in s])
         self.assertEqual(set(keys), expectedkeys)
         self.assertEqual(len(keys), len(expectedkeys))
@@ -548,6 +702,20 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, filter, isEven, 3)
         self.assertRaises(TypeError, next, filter(range(6), range(6)))
 
+        # check copy, deepcopy, pickle
+        ans = [0,2,4]
+
+        c = filter(isEven, range(6))
+        self.assertEqual(list(copy.copy(c)), ans)
+        c = filter(isEven, range(6))
+        self.assertEqual(list(copy.deepcopy(c)), ans)
+        c = filter(isEven, range(6))
+        self.assertEqual(list(pickle.loads(pickle.dumps(c))), ans)
+        next(c)
+        self.assertEqual(list(pickle.loads(pickle.dumps(c))), ans[1:])
+        c = filter(isEven, range(6))
+        self.pickletest(c)
+
     def test_filterfalse(self):
         self.assertEqual(list(filterfalse(isEven, range(6))), [1,3,5])
         self.assertEqual(list(filterfalse(None, [0,1,0,2,0])), [0,0,0])
@@ -558,6 +726,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, filterfalse, lambda x:x, range(6), 7)
         self.assertRaises(TypeError, filterfalse, isEven, 3)
         self.assertRaises(TypeError, next, filterfalse(range(6), range(6)))
+        self.pickletest(filterfalse(isEven, range(6)))
 
     def test_zip(self):
         # XXX This is rather silly now that builtin zip() calls zip()...
@@ -582,6 +751,23 @@ class TestBasicOps(unittest.TestCase):
         ids = list(map(id, list(zip('abc', 'def'))))
         self.assertEqual(len(dict.fromkeys(ids)), len(ids))
 
+        # check copy, deepcopy, pickle
+        ans = [(x,y) for x, y in copy.copy(zip('abc',count()))]
+        self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
+
+        ans = [(x,y) for x, y in copy.deepcopy(zip('abc',count()))]
+        self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
+
+        ans = [(x,y) for x, y in pickle.loads(pickle.dumps(zip('abc',count())))]
+        self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
+
+        testIntermediate = zip('abc',count())
+        next(testIntermediate)
+        ans = [(x,y) for x, y in pickle.loads(pickle.dumps(testIntermediate))]
+        self.assertEqual(ans, [('b', 1), ('c', 2)])
+
+        self.pickletest(zip('abc', count()))
+
     def test_ziplongest(self):
         for args in [
                 ['abc', range(6)],
@@ -631,6 +817,12 @@ class TestBasicOps(unittest.TestCase):
         ids = list(map(id, list(zip_longest('abc', 'def'))))
         self.assertEqual(len(dict.fromkeys(ids)), len(ids))
 
+    def test_zip_longest_pickling(self):
+        self.pickletest(zip_longest("abc", "def"))
+        self.pickletest(zip_longest("abc", "defgh"))
+        self.pickletest(zip_longest("abc", "defgh", fillvalue=1))
+        self.pickletest(zip_longest("", "defgh"))
+
     def test_bug_7244(self):
 
         class Repeater:
@@ -734,6 +926,20 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(len(set(map(id, product('abc', 'def')))), 1)
         self.assertNotEqual(len(set(map(id, list(product('abc', 'def'))))), 1)
 
+    def test_product_pickling(self):
+        # check copy, deepcopy, pickle
+        for args, result in [
+            ([], [()]),                     # zero iterables
+            (['ab'], [('a',), ('b',)]),     # one iterable
+            ([range(2), range(3)], [(0,0), (0,1), (0,2), (1,0), (1,1), (1,2)]),     # two iterables
+            ([range(0), range(2), range(3)], []),           # first iterable with zero length
+            ([range(2), range(0), range(3)], []),           # middle iterable with zero length
+            ([range(2), range(3), range(0)], []),           # last iterable with zero length
+            ]:
+            self.assertEqual(list(copy.copy(product(*args))), result)
+            self.assertEqual(list(copy.deepcopy(product(*args))), result)
+            self.pickletest(product(*args))
+
     def test_repeat(self):
         self.assertEqual(list(repeat(object='a', times=3)), ['a', 'a', 'a'])
         self.assertEqual(lzip(range(3),repeat('a')),
@@ -752,11 +958,16 @@ class TestBasicOps(unittest.TestCase):
         list(r)
         self.assertEqual(repr(r), 'repeat((1+0j), 0)')
 
+        # check copy, deepcopy, pickle
+        c = repeat(object='a', times=10)
+        self.assertEqual(next(c), 'a')
+        self.assertEqual(take(2, copy.copy(c)), list('a' * 2))
+        self.assertEqual(take(2, copy.deepcopy(c)), list('a' * 2))
+        self.pickletest(repeat(object='a', times=10))
+
     def test_map(self):
         self.assertEqual(list(map(operator.pow, range(3), range(1,7))),
                          [0**1, 1**2, 2**3])
-        def tupleize(*args):
-            return args
         self.assertEqual(list(map(tupleize, 'abc', range(5))),
                          [('a',0),('b',1),('c',2)])
         self.assertEqual(list(map(tupleize, 'abc', count())),
@@ -771,6 +982,18 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(ValueError, next, map(errfunc, [4], [5]))
         self.assertRaises(TypeError, next, map(onearg, [4], [5]))
 
+        # check copy, deepcopy, pickle
+        ans = [('a',0),('b',1),('c',2)]
+
+        c = map(tupleize, 'abc', count())
+        self.assertEqual(list(copy.copy(c)), ans)
+
+        c = map(tupleize, 'abc', count())
+        self.assertEqual(list(copy.deepcopy(c)), ans)
+
+        c = map(tupleize, 'abc', count())
+        self.pickletest(c)
+
     def test_starmap(self):
         self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
                          [0**1, 1**2, 2**3])
@@ -785,6 +1008,18 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(ValueError, next, starmap(errfunc, [(4,5)]))
         self.assertRaises(TypeError, next, starmap(onearg, [(4,5)]))
 
+        # check copy, deepcopy, pickle
+        ans = [0**1, 1**2, 2**3]
+
+        c = starmap(operator.pow, zip(range(3), range(1,7)))
+        self.assertEqual(list(copy.copy(c)), ans)
+
+        c = starmap(operator.pow, zip(range(3), range(1,7)))
+        self.assertEqual(list(copy.deepcopy(c)), ans)
+
+        c = starmap(operator.pow, zip(range(3), range(1,7)))
+        self.pickletest(c)
+
     def test_islice(self):
         for args in [          # islice(args) should agree with range(args)
                 (10, 20, 3),
@@ -817,17 +1052,18 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(list(it), list(range(3, 10)))
 
         # Test invalid arguments
-        self.assertRaises(TypeError, islice, range(10))
+        ra = range(10)
-        self.assertRaises(TypeError, islice, range(10), 1, 2, 3, 4)
+        self.assertRaises(TypeError, islice, ra)
-        self.assertRaises(ValueError, islice, range(10), -5, 10, 1)
+        self.assertRaises(TypeError, islice, ra, 1, 2, 3, 4)
-        self.assertRaises(ValueError, islice, range(10), 1, -5, -1)
+        self.assertRaises(ValueError, islice, ra, -5, 10, 1)
-        self.assertRaises(ValueError, islice, range(10), 1, 10, -1)
+        self.assertRaises(ValueError, islice, ra, 1, -5, -1)
-        self.assertRaises(ValueError, islice, range(10), 1, 10, 0)
+        self.assertRaises(ValueError, islice, ra, 1, 10, -1)
-        self.assertRaises(ValueError, islice, range(10), 'a')
+        self.assertRaises(ValueError, islice, ra, 1, 10, 0)
-        self.assertRaises(ValueError, islice, range(10), 'a', 1)
+        self.assertRaises(ValueError, islice, ra, 'a')
-        self.assertRaises(ValueError, islice, range(10), 1, 'a')
+        self.assertRaises(ValueError, islice, ra, 'a', 1)
-        self.assertRaises(ValueError, islice, range(10), 'a', 1, 1)
+        self.assertRaises(ValueError, islice, ra, 1, 'a')
-        self.assertRaises(ValueError, islice, range(10), 1, 'a', 1)
+        self.assertRaises(ValueError, islice, ra, 'a', 1, 1)
+        self.assertRaises(ValueError, islice, ra, 1, 'a', 1)
         self.assertEqual(len(list(islice(count(), 1, 10, maxsize))), 1)
 
         # Issue #10323:  Less islice in a predictable state
@@ -835,9 +1071,22 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(list(islice(c, 1, 3, 50)), [1])
         self.assertEqual(next(c), 3)
 
+        # check copy, deepcopy, pickle
+        for args in [          # islice(args) should agree with range(args)
+                (10, 20, 3),
+                (10, 3, 20),
+                (10, 20),
+                (10, 3),
+                (20,)
+                ]:
+            self.assertEqual(list(copy.copy(islice(range(100), *args))),
+                             list(range(*args)))
+            self.assertEqual(list(copy.deepcopy(islice(range(100), *args))),
+                             list(range(*args)))
+            self.pickletest(islice(range(100), *args))
+
     def test_takewhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
-        underten = lambda x: x<10
         self.assertEqual(list(takewhile(underten, data)), [1, 3, 5])
         self.assertEqual(list(takewhile(underten, [])), [])
         self.assertRaises(TypeError, takewhile)
@@ -849,9 +1098,14 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(list(t), [1, 1, 1])
         self.assertRaises(StopIteration, next, t)
 
+        # check copy, deepcopy, pickle
+        self.assertEqual(list(copy.copy(takewhile(underten, data))), [1, 3, 5])
+        self.assertEqual(list(copy.deepcopy(takewhile(underten, data))),
+                        [1, 3, 5])
+        self.pickletest(takewhile(underten, data))
+
     def test_dropwhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
-        underten = lambda x: x<10
         self.assertEqual(list(dropwhile(underten, data)), [20, 2, 4, 6, 8])
         self.assertEqual(list(dropwhile(underten, [])), [])
         self.assertRaises(TypeError, dropwhile)
@@ -860,11 +1114,14 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, next, dropwhile(10, [(4,5)]))
         self.assertRaises(ValueError, next, dropwhile(errfunc, [(4,5)]))
 
+        # check copy, deepcopy, pickle
+        self.assertEqual(list(copy.copy(dropwhile(underten, data))), [20, 2, 4, 6, 8])
+        self.assertEqual(list(copy.deepcopy(dropwhile(underten, data))),
+                        [20, 2, 4, 6, 8])
+        self.pickletest(dropwhile(underten, data))
+
     def test_tee(self):
         n = 200
-        def irange(n):
-            for i in range(n):
-                yield i
 
         a, b = tee([])        # test empty iterator
         self.assertEqual(list(a), [])
@@ -949,6 +1206,67 @@ class TestBasicOps(unittest.TestCase):
         del a
         self.assertRaises(ReferenceError, getattr, p, '__class__')
 
+        ans = list('abc')
+        long_ans = list(range(10000))
+
+        # check copy
+        a, b = tee('abc')
+        self.assertEqual(list(copy.copy(a)), ans)
+        self.assertEqual(list(copy.copy(b)), ans)
+        a, b = tee(list(range(10000)))
+        self.assertEqual(list(copy.copy(a)), long_ans)
+        self.assertEqual(list(copy.copy(b)), long_ans)
+
+        # check partially consumed copy
+        a, b = tee('abc')
+        take(2, a)
+        take(1, b)
+        self.assertEqual(list(copy.copy(a)), ans[2:])
+        self.assertEqual(list(copy.copy(b)), ans[1:])
+        self.assertEqual(list(a), ans[2:])
+        self.assertEqual(list(b), ans[1:])
+        a, b = tee(range(10000))
+        take(100, a)
+        take(60, b)
+        self.assertEqual(list(copy.copy(a)), long_ans[100:])
+        self.assertEqual(list(copy.copy(b)), long_ans[60:])
+        self.assertEqual(list(a), long_ans[100:])
+        self.assertEqual(list(b), long_ans[60:])
+
+        # check deepcopy
+        a, b = tee('abc')
+        self.assertEqual(list(copy.deepcopy(a)), ans)
+        self.assertEqual(list(copy.deepcopy(b)), ans)
+        self.assertEqual(list(a), ans)
+        self.assertEqual(list(b), ans)
+        a, b = tee(range(10000))
+        self.assertEqual(list(copy.deepcopy(a)), long_ans)
+        self.assertEqual(list(copy.deepcopy(b)), long_ans)
+        self.assertEqual(list(a), long_ans)
+        self.assertEqual(list(b), long_ans)
+
+        # check partially consumed deepcopy
+        a, b = tee('abc')
+        take(2, a)
+        take(1, b)
+        self.assertEqual(list(copy.deepcopy(a)), ans[2:])
+        self.assertEqual(list(copy.deepcopy(b)), ans[1:])
+        self.assertEqual(list(a), ans[2:])
+        self.assertEqual(list(b), ans[1:])
+        a, b = tee(range(10000))
+        take(100, a)
+        take(60, b)
+        self.assertEqual(list(copy.deepcopy(a)), long_ans[100:])
+        self.assertEqual(list(copy.deepcopy(b)), long_ans[60:])
+        self.assertEqual(list(a), long_ans[100:])
+        self.assertEqual(list(b), long_ans[60:])
+
+        # check pickle
+        self.pickletest(iter(tee('abc')))
+        a, b = tee('abc')
+        self.pickletest(a, compare=ans)
+        self.pickletest(b, compare=ans)
+
     def test_StopIteration(self):
         self.assertRaises(StopIteration, next, zip())
 
@@ -974,9 +1292,21 @@ class TestBasicOps(unittest.TestCase):
 
 class TestExamples(unittest.TestCase):
 
-    def test_accumlate(self):
+    def test_accumulate(self):
         self.assertEqual(list(accumulate([1,2,3,4,5])), [1, 3, 6, 10, 15])
 
+    def test_accumulate_reducible(self):
+        # check copy, deepcopy, pickle
+        data = [1, 2, 3, 4, 5]
+        accumulated = [1, 3, 6, 10, 15]
+        it = accumulate(data)
+
+        self.assertEqual(list(pickle.loads(pickle.dumps(it))), accumulated[:])
+        self.assertEqual(next(it), 1)
+        self.assertEqual(list(pickle.loads(pickle.dumps(it))), accumulated[1:])
+        self.assertEqual(list(copy.deepcopy(it)), accumulated[1:])
+        self.assertEqual(list(copy.copy(it)), accumulated[1:])
+
     def test_chain(self):
         self.assertEqual(''.join(chain('ABC', 'DEF')), 'ABCDEF')
 

Lib/test/test_list.py

@@ -1,5 +1,6 @@
 import sys
 from test import support, list_tests
+import pickle
 
 class ListTest(list_tests.CommonTest):
     type2test = list
@@ -69,6 +70,33 @@ class ListTest(list_tests.CommonTest):
         check(10)       # check our checking code
         check(1000000)
 
+    def test_iterator_pickle(self):
+        # Userlist iterators don't support pickling yet since
+        # they are based on generators.
+        data = self.type2test([4, 5, 6, 7])
+        it = itorg = iter(data)
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(self.type2test(it), self.type2test(data))
+
+        it = pickle.loads(d)
+        next(it)
+        d = pickle.dumps(it)
+        self.assertEqual(self.type2test(it), self.type2test(data)[1:])
+
+    def test_reversed_pickle(self):
+        data = self.type2test([4, 5, 6, 7])
+        it = itorg = reversed(data)
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(self.type2test(it), self.type2test(reversed(data)))
+
+        it = pickle.loads(d)
+        next(it)
+        d = pickle.dumps(it)
+        self.assertEqual(self.type2test(it), self.type2test(reversed(data))[1:])
 
 def test_main(verbose=None):
     support.run_unittest(ListTest)

Lib/test/test_range.py

@@ -341,13 +341,35 @@ class RangeTest(unittest.TestCase):
 
     def test_pickling(self):
         testcases = [(13,), (0, 11), (-22, 10), (20, 3, -1),
-                     (13, 21, 3), (-2, 2, 2)]
+                     (13, 21, 3), (-2, 2, 2), (2**65, 2**65+2)]
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             for t in testcases:
                 r = range(*t)
                 self.assertEqual(list(pickle.loads(pickle.dumps(r, proto))),
                                  list(r))
 
+    def test_iterator_pickling(self):
+        testcases = [(13,), (0, 11), (-22, 10), (20, 3, -1),
+                     (13, 21, 3), (-2, 2, 2), (2**65, 2**65+2)]
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            for t in testcases:
+                it = itorg = iter(range(*t))
+                data = list(range(*t))
+
+                d = pickle.dumps(it)
+                it = pickle.loads(d)
+                self.assertEqual(type(itorg), type(it))
+                self.assertEqual(list(it), data)
+
+                it = pickle.loads(d)
+                try:
+                    next(it)
+                except StopIteration:
+                    continue
+                d = pickle.dumps(it)
+                it = pickle.loads(d)
+                self.assertEqual(list(it), data[1:])
+
     def test_odd_bug(self):
         # This used to raise a "SystemError: NULL result without error"
         # because the range validation step was eating the exception

Lib/test/test_set.py

@@ -9,6 +9,7 @@ from random import randrange, shuffle
 import sys
 import warnings
 import collections
+import collections.abc
 
 class PassThru(Exception):
     pass
@@ -234,6 +235,26 @@ class TestJointOps(unittest.TestCase):
                 dup = pickle.loads(p)
                 self.assertEqual(self.s.x, dup.x)
 
+    def test_iterator_pickling(self):
+        itorg = iter(self.s)
+        data = self.thetype(self.s)
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        # Set iterators unpickle as list iterators due to the
+        # undefined order of set items.
+        # self.assertEqual(type(itorg), type(it))
+        self.assertTrue(isinstance(it, collections.abc.Iterator))
+        self.assertEqual(self.thetype(it), data)
+
+        it = pickle.loads(d)
+        try:
+            drop = next(it)
+        except StopIteration:
+            return
+        d = pickle.dumps(it)
+        it = pickle.loads(d)
+        self.assertEqual(self.thetype(it), data - self.thetype((drop,)))
+
     def test_deepcopy(self):
         class Tracer:
             def __init__(self, value):

Lib/test/test_tuple.py

@@ -1,6 +1,7 @@
 from test import support, seq_tests
 
 import gc
+import pickle
 
 class TupleTest(seq_tests.CommonTest):
     type2test = tuple
@@ -164,6 +165,34 @@ class TupleTest(seq_tests.CommonTest):
         check(10)       # check our checking code
         check(1000000)
 
+    def test_iterator_pickle(self):
+        # Userlist iterators don't support pickling yet since
+        # they are based on generators.
+        data = self.type2test([4, 5, 6, 7])
+        itorg = iter(data)
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(self.type2test(it), self.type2test(data))
+
+        it = pickle.loads(d)
+        next(it)
+        d = pickle.dumps(it)
+        self.assertEqual(self.type2test(it), self.type2test(data)[1:])
+
+    def test_reversed_pickle(self):
+        data = self.type2test([4, 5, 6, 7])
+        itorg = reversed(data)
+        d = pickle.dumps(itorg)
+        it = pickle.loads(d)
+        self.assertEqual(type(itorg), type(it))
+        self.assertEqual(self.type2test(it), self.type2test(reversed(data)))
+
+        it = pickle.loads(d)
+        next(it)
+        d = pickle.dumps(it)
+        self.assertEqual(self.type2test(it), self.type2test(reversed(data))[1:])
+
 def test_main():
     support.run_unittest(TupleTest)
 

Modules/_collectionsmodule.c

@@ -1121,6 +1121,35 @@ dequeiter_next(dequeiterobject *it)
     return item;
 }
 
+static PyObject *
+dequeiter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    Py_ssize_t i, index=0;
+    PyObject *deque;
+    dequeiterobject *it;
+    if (!PyArg_ParseTuple(args, "O!|n", &deque_type, &deque, &index))
+        return NULL;
+    assert(type == &dequeiter_type);
+
+    it = (dequeiterobject*)deque_iter((dequeobject *)deque);
+    if (!it)
+        return NULL;
+    /* consume items from the queue */
+    for(i=0; i<index; i++) {
+        PyObject *item = dequeiter_next(it);
+        if (item) {
+            Py_DECREF(item);
+        } else {
+            if (it->counter) {
+                Py_DECREF(it);
+                return NULL;
+            } else
+                break;
+        }
+    }
+    return (PyObject*)it;
+}
+
 static PyObject *
 dequeiter_len(dequeiterobject *it)
 {
@@ -1129,14 +1158,21 @@ dequeiter_len(dequeiterobject *it)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+dequeiter_reduce(dequeiterobject *it)
+{
+    return Py_BuildValue("O(On)", Py_TYPE(it), it->deque, it->deque->len - it->counter);
+}
+
 static PyMethodDef dequeiter_methods[] = {
     {"__length_hint__", (PyCFunction)dequeiter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)dequeiter_reduce, METH_NOARGS, reduce_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
 static PyTypeObject dequeiter_type = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    "deque_iterator",                           /* tp_name */
+    "_collections._deque_iterator",              /* tp_name */
     sizeof(dequeiterobject),                    /* tp_basicsize */
     0,                                          /* tp_itemsize */
     /* methods */
@@ -1164,6 +1200,16 @@ static PyTypeObject dequeiter_type = {
     PyObject_SelfIter,                          /* tp_iter */
     (iternextfunc)dequeiter_next,               /* tp_iternext */
     dequeiter_methods,                          /* tp_methods */
+    0,                                          /* tp_members */
+    0,                                          /* tp_getset */
+    0,                                          /* tp_base */
+    0,                                          /* tp_dict */
+    0,                                          /* tp_descr_get */
+    0,                                          /* tp_descr_set */
+    0,                                          /* tp_dictoffset */
+    0,                                          /* tp_init */
+    0,                                          /* tp_alloc */
+    dequeiter_new,                              /* tp_new */
     0,
 };
 
@@ -1217,9 +1263,38 @@ dequereviter_next(dequeiterobject *it)
     return item;
 }
 
+static PyObject *
+dequereviter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    Py_ssize_t i, index=0;
+    PyObject *deque;
+    dequeiterobject *it;
+    if (!PyArg_ParseTuple(args, "O!|n", &deque_type, &deque, &index))
+        return NULL;
+    assert(type == &dequereviter_type);
+
+    it = (dequeiterobject*)deque_reviter((dequeobject *)deque);
+    if (!it)
+        return NULL;
+    /* consume items from the queue */
+    for(i=0; i<index; i++) {
+        PyObject *item = dequereviter_next(it);
+        if (item) {
+            Py_DECREF(item);
+        } else {
+            if (it->counter) {
+                Py_DECREF(it);
+                return NULL;
+            } else
+                break;
+        }
+    }
+    return (PyObject*)it;
+}
+
 static PyTypeObject dequereviter_type = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    "deque_reverse_iterator",                   /* tp_name */
+    "_collections._deque_reverse_iterator",      /* tp_name */
     sizeof(dequeiterobject),                    /* tp_basicsize */
     0,                                          /* tp_itemsize */
     /* methods */
@@ -1247,6 +1322,16 @@ static PyTypeObject dequereviter_type = {
     PyObject_SelfIter,                          /* tp_iter */
     (iternextfunc)dequereviter_next,            /* tp_iternext */
     dequeiter_methods,                          /* tp_methods */
+    0,                                          /* tp_members */
+    0,                                          /* tp_getset */
+    0,                                          /* tp_base */
+    0,                                          /* tp_dict */
+    0,                                          /* tp_descr_get */
+    0,                                          /* tp_descr_set */
+    0,                                          /* tp_dictoffset */
+    0,                                          /* tp_init */
+    0,                                          /* tp_alloc */
+    dequereviter_new,                           /* tp_new */
     0,
 };
 
@@ -1653,9 +1738,13 @@ PyInit__collections(void)
 
     if (PyType_Ready(&dequeiter_type) < 0)
         return NULL;
+    Py_INCREF(&dequeiter_type);
+    PyModule_AddObject(m, "_deque_iterator", (PyObject *)&dequeiter_type);
 
     if (PyType_Ready(&dequereviter_type) < 0)
         return NULL;
+    Py_INCREF(&dequereviter_type);
+    PyModule_AddObject(m, "_deque_reverse_iterator", (PyObject *)&dequereviter_type);
 
     return m;
 }

Modules/arraymodule.c

@@ -2753,6 +2753,34 @@ arrayiter_traverse(arrayiterobject *it, visitproc visit, void *arg)
     return 0;
 }
 
+static PyObject *
+arrayiter_reduce(arrayiterobject *it)
+{
+    return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("iter"),
+                         it->ao, it->index);
+}
+
+static PyObject *
+arrayiter_setstate(arrayiterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (index < 0)
+        index = 0;
+    it->index = index;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+static PyMethodDef arrayiter_methods[] = {
+    {"__reduce__",      (PyCFunction)arrayiter_reduce, METH_NOARGS,
+     reduce_doc},
+    {"__setstate__",    (PyCFunction)arrayiter_setstate, METH_O,
+     setstate_doc},
+    {NULL, NULL} /* sentinel */
+};
+
 static PyTypeObject PyArrayIter_Type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "arrayiterator",                        /* tp_name */
@@ -2782,7 +2810,7 @@ static PyTypeObject PyArrayIter_Type = {
     0,                                      /* tp_weaklistoffset */
     PyObject_SelfIter,                          /* tp_iter */
     (iternextfunc)arrayiter_next,               /* tp_iternext */
-    0,                                          /* tp_methods */
+    arrayiter_methods,                      /* tp_methods */
 };
 
 

Objects/bytearrayobject.c

@@ -3003,7 +3003,7 @@ bytearrayiter_next(bytesiterobject *it)
 }
 
 static PyObject *
-bytesarrayiter_length_hint(bytesiterobject *it)
+bytearrayiter_length_hint(bytesiterobject *it)
 {
     Py_ssize_t len = 0;
     if (it->it_seq)
@@ -3014,9 +3014,41 @@ bytesarrayiter_length_hint(bytesiterobject *it)
 PyDoc_STRVAR(length_hint_doc,
     "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+bytearrayiter_reduce(bytesiterobject *it)
+{
+    if (it->it_seq != NULL) {
+        return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("iter"),
+                             it->it_seq, it->it_index);
+    } else {
+        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
+        if (u == NULL)
+            return NULL;
+        return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), u);
+    }
+}
+
+static PyObject *
+bytearrayiter_setstate(bytesiterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (index < 0)
+        index = 0;
+    it->it_index = index;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef bytearrayiter_methods[] = {
-    {"__length_hint__", (PyCFunction)bytesarrayiter_length_hint, METH_NOARGS,
+    {"__length_hint__", (PyCFunction)bytearrayiter_length_hint, METH_NOARGS,
      length_hint_doc},
+     {"__reduce__",      (PyCFunction)bytearrayiter_reduce, METH_NOARGS,
+     reduce_doc},
+    {"__setstate__",    (PyCFunction)bytearrayiter_setstate, METH_O,
+     setstate_doc},
     {NULL, NULL} /* sentinel */
 };
 

Objects/bytesobject.c

@@ -3074,9 +3074,43 @@ striter_len(striterobject *it)
 PyDoc_STRVAR(length_hint_doc,
              "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+striter_reduce(striterobject *it)
+{
+    if (it->it_seq != NULL) {
+        return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("iter"),
+                             it->it_seq, it->it_index);
+    } else {
+        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
+        if (u == NULL)
+            return NULL;
+        return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), u);
+    }
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
+static PyObject *
+striter_setstate(striterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (index < 0)
+        index = 0;
+    it->it_index = index;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef striter_methods[] = {
     {"__length_hint__", (PyCFunction)striter_len, METH_NOARGS,
      length_hint_doc},
+    {"__reduce__",      (PyCFunction)striter_reduce, METH_NOARGS,
+     reduce_doc},
+    {"__setstate__",    (PyCFunction)striter_setstate, METH_O,
+     setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 

Objects/dictobject.c

@@ -2323,9 +2323,16 @@ dictiter_len(dictiterobject *di)
 PyDoc_STRVAR(length_hint_doc,
              "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+dictiter_reduce(dictiterobject *di);
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
 static PyMethodDef dictiter_methods[] = {
     {"__length_hint__", (PyCFunction)dictiter_len, METH_NOARGS,
      length_hint_doc},
+     {"__reduce__", (PyCFunction)dictiter_reduce, METH_NOARGS,
+     reduce_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -2560,6 +2567,52 @@ PyTypeObject PyDictIterItem_Type = {
 };
 
 
+static PyObject *
+dictiter_reduce(dictiterobject *di)
+{
+    PyObject *list;
+    dictiterobject tmp;
+
+    list = PyList_New(0);
+    if (!list)
+        return NULL;
+
+    /* copy the itertor state */
+    tmp = *di;
+    Py_XINCREF(tmp.di_dict);
+    
+    /* iterate the temporary into a list */
+    for(;;) {
+        PyObject *element = 0;
+        if (Py_TYPE(di) == &PyDictIterItem_Type)
+            element = dictiter_iternextitem(&tmp);
+        else if (Py_TYPE(di) == &PyDictIterKey_Type)
+            element = dictiter_iternextkey(&tmp);
+        else if (Py_TYPE(di) == &PyDictIterValue_Type)
+            element = dictiter_iternextvalue(&tmp);
+        else
+            assert(0);
+        if (element) {
+            if (PyList_Append(list, element)) {
+                Py_DECREF(element);
+                Py_DECREF(list);
+                Py_XDECREF(tmp.di_dict);
+                return NULL;
+            }
+            Py_DECREF(element);
+        } else
+            break;
+    }
+    Py_XDECREF(tmp.di_dict);
+    /* check for error */
+    if (tmp.di_dict != NULL) {
+        /* we have an error */
+        Py_DECREF(list);
+        return NULL;
+    }
+    return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), list);
+}
+
 /***********************************************/
 /* View objects for keys(), items(), values(). */
 /***********************************************/

Objects/enumobject.c

@@ -158,6 +158,22 @@ enum_next(enumobject *en)
     return result;
 }
 
+static PyObject *
+enum_reduce(enumobject *en)
+{
+    if (en->en_longindex != NULL)
+        return Py_BuildValue("O(OO)", Py_TYPE(en), en->en_sit, en->en_longindex);
+    else
+        return Py_BuildValue("O(On)", Py_TYPE(en), en->en_sit, en->en_index);
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
+static PyMethodDef enum_methods[] = {
+    {"__reduce__", (PyCFunction)enum_reduce, METH_NOARGS, reduce_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
 PyDoc_STRVAR(enum_doc,
 "enumerate(iterable[, start]) -> iterator for index, value of iterable\n"
 "\n"
@@ -197,7 +213,7 @@ PyTypeObject PyEnum_Type = {
     0,                              /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
     (iternextfunc)enum_next,        /* tp_iternext */
-    0,                              /* tp_methods */
+    enum_methods,                   /* tp_methods */
     0,                              /* tp_members */
     0,                              /* tp_getset */
     0,                              /* tp_base */
@@ -319,8 +335,40 @@ reversed_len(reversedobject *ro)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+reversed_reduce(reversedobject *ro)
+{
+    if (ro->seq)
+        return Py_BuildValue("O(O)n", Py_TYPE(ro), ro->seq, ro->index);
+    else
+        return Py_BuildValue("O(())", Py_TYPE(ro));
+}
+
+static PyObject *
+reversed_setstate(reversedobject *ro, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (ro->seq != 0) {
+        Py_ssize_t n = PySequence_Size(ro->seq);
+        if (n < 0)
+            return NULL;
+        if (index < -1)
+            index = -1;
+        else if (index > n-1)
+            index = n-1;
+        ro->index = index;
+    }
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef reversediter_methods[] = {
     {"__length_hint__", (PyCFunction)reversed_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)reversed_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", (PyCFunction)reversed_setstate, METH_O, setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 

Objects/iterobject.c

@@ -2,6 +2,19 @@
 
 #include "Python.h"
 
+/* Convenience function to get builtins.iter or builtins.reversed */
+PyObject *
+_PyIter_GetBuiltin(const char *iter)
+{
+    PyObject *mod, *attr;
+    mod = PyImport_ImportModule("builtins");
+    if (mod ==  NULL)
+        return NULL;
+    attr = PyObject_GetAttrString(mod, iter);
+    Py_DECREF(mod);
+    return attr;
+}
+
 typedef struct {
     PyObject_HEAD
     long      it_index;
@@ -88,8 +101,38 @@ iter_len(seqiterobject *it)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+iter_reduce(seqiterobject *it)
+{
+    if (it->it_seq != NULL)
+        return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("iter"),
+                             it->it_seq, it->it_index);
+    else
+        return Py_BuildValue("N(())", _PyIter_GetBuiltin("iter"));
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
+static PyObject *
+iter_setstate(seqiterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (it->it_seq != NULL) {
+        if (index < 0)
+            index = 0;
+        it->it_index = index;
+    }
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef seqiter_methods[] = {
     {"__length_hint__", (PyCFunction)iter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)iter_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", (PyCFunction)iter_setstate, METH_O, setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -195,6 +238,21 @@ calliter_iternext(calliterobject *it)
     return NULL;
 }
 
+static PyObject *
+calliter_reduce(calliterobject *it)
+{
+    if (it->it_callable != NULL && it->it_sentinel != NULL)
+        return Py_BuildValue("N(OO)", _PyIter_GetBuiltin("iter"),
+                             it->it_callable, it->it_sentinel);
+    else
+        return Py_BuildValue("N(())", _PyIter_GetBuiltin("iter"));
+}
+
+static PyMethodDef calliter_methods[] = {
+    {"__reduce__", (PyCFunction)calliter_reduce, METH_NOARGS, reduce_doc},
+    {NULL,              NULL}           /* sentinel */
+};
+
 PyTypeObject PyCallIter_Type = {
     PyVarObject_HEAD_INIT(&PyType_Type, 0)
     "callable_iterator",                        /* tp_name */
@@ -224,7 +282,7 @@ PyTypeObject PyCallIter_Type = {
     0,                                          /* tp_weaklistoffset */
     PyObject_SelfIter,                          /* tp_iter */
     (iternextfunc)calliter_iternext,            /* tp_iternext */
-    0,                                          /* tp_methods */
+    calliter_methods,                           /* tp_methods */
 };
 
 

Objects/listobject.c

@@ -2660,11 +2660,18 @@ static void listiter_dealloc(listiterobject *);
 static int listiter_traverse(listiterobject *, visitproc, void *);
 static PyObject *listiter_next(listiterobject *);
 static PyObject *listiter_len(listiterobject *);
+static PyObject *listiter_reduce_general(void *_it, int forward);
+static PyObject *listiter_reduce(listiterobject *);
+static PyObject *listiter_setstate(listiterobject *, PyObject *state);
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
 
 static PyMethodDef listiter_methods[] = {
     {"__length_hint__", (PyCFunction)listiter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)listiter_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", (PyCFunction)listiter_setstate, METH_O, setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -2771,6 +2778,27 @@ listiter_len(listiterobject *it)
     }
     return PyLong_FromLong(0);
 }
+
+static PyObject *
+listiter_reduce(listiterobject *it)
+{
+    return listiter_reduce_general(it, 1);
+}
+
+static PyObject *
+listiter_setstate(listiterobject *it, PyObject *state)
+{
+    long index = PyLong_AsLong(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (it->it_seq != NULL) {
+        if (index < 0)
+            index = 0;
+        it->it_index = index;
+    }
+    Py_RETURN_NONE;
+}
+
 /*********************** List Reverse Iterator **************************/
 
 typedef struct {
@@ -2784,9 +2812,13 @@ static void listreviter_dealloc(listreviterobject *);
 static int listreviter_traverse(listreviterobject *, visitproc, void *);
 static PyObject *listreviter_next(listreviterobject *);
 static PyObject *listreviter_len(listreviterobject *);
+static PyObject *listreviter_reduce(listreviterobject *);
+static PyObject *listreviter_setstate(listreviterobject *, PyObject *);
 
 static PyMethodDef listreviter_methods[] = {
     {"__length_hint__", (PyCFunction)listreviter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)listreviter_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", (PyCFunction)listreviter_setstate, METH_O, setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -2883,3 +2915,51 @@ listreviter_len(listreviterobject *it)
         len = 0;
     return PyLong_FromSsize_t(len);
 }
+
+static PyObject *
+listreviter_reduce(listreviterobject *it)
+{
+    return listiter_reduce_general(it, 0);
+}
+
+static PyObject *
+listreviter_setstate(listreviterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (it->it_seq != NULL) {
+        if (index < -1)
+            index = -1;
+        else if (index > PyList_GET_SIZE(it->it_seq) - 1)
+            index = PyList_GET_SIZE(it->it_seq) - 1;
+        it->it_index = index;
+    }
+    Py_RETURN_NONE;
+}
+
+/* common pickling support */
+
+static PyObject *
+listiter_reduce_general(void *_it, int forward)
+{
+    PyObject *list;
+
+    /* the objects are not the same, index is of different types! */
+    if (forward) {
+        listiterobject *it = (listiterobject *)_it;
+        if (it->it_seq)
+            return Py_BuildValue("N(O)l", _PyIter_GetBuiltin("iter"),
+                                 it->it_seq, it->it_index);
+    } else {
+        listreviterobject *it = (listreviterobject *)_it;
+        if (it->it_seq)
+            return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("reversed"),
+                                 it->it_seq, it->it_index);
+    }
+    /* empty iterator, create an empty list */
+    list = PyList_New(0);
+    if (list == NULL)
+        return NULL;
+    return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), list);
+}

Objects/rangeobject.c

@@ -964,9 +964,59 @@ rangeiter_len(rangeiterobject *r)
 PyDoc_STRVAR(length_hint_doc,
              "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+rangeiter_reduce(rangeiterobject *r)
+{
+    PyObject *start=NULL, *stop=NULL, *step=NULL;
+    PyObject *range;
+    
+    /* create a range object for pickling */
+    start = PyLong_FromLong(r->start);
+    if (start == NULL)
+        goto err;
+    stop = PyLong_FromLong(r->start + r->len * r->step);
+    if (stop == NULL)
+        goto err;
+    step = PyLong_FromLong(r->step);
+    if (step == NULL)
+        goto err;
+    range = (PyObject*)make_range_object(&PyRange_Type,
+                               start, stop, step);
+    if (range == NULL)
+        goto err;
+    /* return the result */
+    return Py_BuildValue("N(N)i", _PyIter_GetBuiltin("iter"), range, r->index);
+err:
+    Py_XDECREF(start);
+    Py_XDECREF(stop);
+    Py_XDECREF(step);
+    return NULL;
+}
+
+static PyObject *
+rangeiter_setstate(rangeiterobject *r, PyObject *state)
+{
+    long index = PyLong_AsLong(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (index < 0 || index >= r->len) {
+        PyErr_SetString(PyExc_ValueError, "index out of range");
+        return NULL;
+    }
+    r->index = index;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef rangeiter_methods[] = {
     {"__length_hint__", (PyCFunction)rangeiter_len, METH_NOARGS,
         length_hint_doc},
+    {"__reduce__", (PyCFunction)rangeiter_reduce, METH_NOARGS,
+        reduce_doc},
+    {"__setstate__", (PyCFunction)rangeiter_setstate, METH_O,
+        setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -1095,9 +1145,51 @@ longrangeiter_len(longrangeiterobject *r, PyObject *no_args)
     return PyNumber_Subtract(r->len, r->index);
 }
 
+static PyObject *
+longrangeiter_reduce(longrangeiterobject *r)
+{
+    PyObject *product, *stop=NULL;
+    PyObject *range;
+
+    /* create a range object for pickling.  Must calculate the "stop" value */
+    product = PyNumber_Multiply(r->len, r->step);
+    if (product == NULL)
+        return NULL;
+    stop = PyNumber_Add(r->start, product);
+    Py_DECREF(product);
+    if (stop ==  NULL)
+        return NULL;
+    Py_INCREF(r->start);
+    Py_INCREF(r->step);
+    range =  (PyObject*)make_range_object(&PyRange_Type,
+                               r->start, stop, r->step);
+    if (range == NULL) {
+        Py_DECREF(r->start);
+        Py_DECREF(stop);
+        Py_DECREF(r->step);
+        return NULL;
+    }
+
+    /* return the result */
+    return Py_BuildValue("N(N)O", _PyIter_GetBuiltin("iter"), range, r->index);
+}
+
+static PyObject *
+longrangeiter_setstate(longrangeiterobject *r, PyObject *state)
+{
+    Py_CLEAR(r->index);
+    r->index = state;
+    Py_INCREF(r->index);
+    Py_RETURN_NONE;
+}
+
 static PyMethodDef longrangeiter_methods[] = {
     {"__length_hint__", (PyCFunction)longrangeiter_len, METH_NOARGS,
         length_hint_doc},
+    {"__reduce__", (PyCFunction)longrangeiter_reduce, METH_NOARGS,
+        reduce_doc},
+    {"__setstate__", (PyCFunction)longrangeiter_setstate, METH_O,
+        setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 

Objects/setobject.c

@@ -819,8 +819,51 @@ setiter_len(setiterobject *si)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *setiter_iternext(setiterobject *si);
+
+static PyObject *
+setiter_reduce(setiterobject *si)
+{
+    PyObject *list;
+    setiterobject tmp;
+
+    list = PyList_New(0);
+    if (!list)
+        return NULL;
+
+    /* copy the itertor state */
+    tmp = *si;
+    Py_XINCREF(tmp.si_set);
+    
+    /* iterate the temporary into a list */
+    for(;;) {
+        PyObject *element = setiter_iternext(&tmp);
+        if (element) {
+            if (PyList_Append(list, element)) {
+                Py_DECREF(element);
+                Py_DECREF(list);
+                Py_XDECREF(tmp.si_set);
+                return NULL;
+            }
+            Py_DECREF(element);
+        } else
+            break;
+    }
+    Py_XDECREF(tmp.si_set);
+    /* check for error */
+    if (tmp.si_set != NULL) {
+        /* we have an error */
+        Py_DECREF(list);
+        return NULL;
+    }
+    return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), list);
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
 static PyMethodDef setiter_methods[] = {
     {"__length_hint__", (PyCFunction)setiter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)setiter_reduce, METH_NOARGS, reduce_doc},
     {NULL,              NULL}           /* sentinel */
 };
 
@@ -1964,8 +2007,6 @@ done:
     return result;
 }
 
-PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
-
 static PyObject *
 set_sizeof(PySetObject *so)
 {

Objects/tupleobject.c

@@ -967,8 +967,39 @@ tupleiter_len(tupleiterobject *it)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+tupleiter_reduce(tupleiterobject *it)
+{
+    if (it->it_seq)
+        return Py_BuildValue("N(O)l", _PyIter_GetBuiltin("iter"),
+                             it->it_seq, it->it_index);
+    else
+        return Py_BuildValue("N(())", _PyIter_GetBuiltin("iter"));
+}
+
+static PyObject *
+tupleiter_setstate(tupleiterobject *it, PyObject *state)
+{
+    long index = PyLong_AsLong(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (it->it_seq != NULL) {
+        if (index < 0)
+            index = 0;
+        else if (it->it_seq != NULL && index > PyTuple_GET_SIZE(it->it_seq))
+            index = PyTuple_GET_SIZE(it->it_seq);
+        it->it_index = index;
+    }
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef tupleiter_methods[] = {
     {"__length_hint__", (PyCFunction)tupleiter_len, METH_NOARGS, length_hint_doc},
+    {"__reduce__", (PyCFunction)tupleiter_reduce, METH_NOARGS, reduce_doc},
+    {"__setstate__", (PyCFunction)tupleiter_setstate, METH_O, setstate_doc},
     {NULL,              NULL}           /* sentinel */
 };
 

Objects/unicodeobject.c

@@ -14382,9 +14382,43 @@ unicodeiter_len(unicodeiterobject *it)
 
 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
 
+static PyObject *
+unicodeiter_reduce(unicodeiterobject *it)
+{
+    if (it->it_seq != NULL) {
+        return Py_BuildValue("N(O)n", _PyIter_GetBuiltin("iter"),
+                             it->it_seq, it->it_index);
+    } else {
+        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
+        if (u == NULL)
+            return NULL;
+        return Py_BuildValue("N(N)", _PyIter_GetBuiltin("iter"), u);
+    }
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
+static PyObject *
+unicodeiter_setstate(unicodeiterobject *it, PyObject *state)
+{
+    Py_ssize_t index = PyLong_AsSsize_t(state);
+    if (index == -1 && PyErr_Occurred())
+        return NULL;
+    if (index < 0)
+        index = 0;
+    it->it_index = index;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(setstate_doc, "Set state information for unpickling.");
+
 static PyMethodDef unicodeiter_methods[] = {
     {"__length_hint__", (PyCFunction)unicodeiter_len, METH_NOARGS,
      length_hint_doc},
+    {"__reduce__",      (PyCFunction)unicodeiter_reduce, METH_NOARGS,
+     reduce_doc},
+    {"__setstate__",    (PyCFunction)unicodeiter_setstate, METH_O,
+     setstate_doc},
     {NULL,      NULL}       /* sentinel */
 };
 

Python/bltinmodule.c

@@ -438,6 +438,19 @@ filter_next(filterobject *lz)
     }
 }
 
+static PyObject *
+filter_reduce(filterobject *lz)
+{
+    return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
+}
+
+PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
+
+static PyMethodDef filter_methods[] = {
+    {"__reduce__",   (PyCFunction)filter_reduce,   METH_NOARGS, reduce_doc},
+    {NULL,           NULL}           /* sentinel */
+};
+
 PyDoc_STRVAR(filter_doc,
 "filter(function or None, iterable) --> filter object\n\
 \n\
@@ -474,7 +487,7 @@ PyTypeObject PyFilter_Type = {
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
     (iternextfunc)filter_next,          /* tp_iternext */
-    0,                                  /* tp_methods */
+    filter_methods,                     /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */
     0,                                  /* tp_base */
@@ -1054,6 +1067,31 @@ map_next(mapobject *lz)
     return result;
 }
 
+static PyObject *
+map_reduce(mapobject *lz)
+{
+    Py_ssize_t numargs = PyTuple_GET_SIZE(lz->iters);
+    PyObject *args = PyTuple_New(numargs+1);
+    Py_ssize_t i;
+    if (args == NULL)
+        return NULL;
+    Py_INCREF(lz->func);
+    PyTuple_SET_ITEM(args, 0, lz->func);
+    for (i = 0; i<numargs; i++){
+        PyObject *it = PyTuple_GET_ITEM(lz->iters, i);
+        Py_INCREF(it);
+        PyTuple_SET_ITEM(args, i+1, it);
+    }
+
+    return Py_BuildValue("ON", Py_TYPE(lz), args);
+}
+
+static PyMethodDef map_methods[] = {
+    {"__reduce__",   (PyCFunction)map_reduce,   METH_NOARGS, reduce_doc},
+    {NULL,           NULL}           /* sentinel */
+};
+
+
 PyDoc_STRVAR(map_doc,
 "map(func, *iterables) --> map object\n\
 \n\
@@ -1090,7 +1128,7 @@ PyTypeObject PyMap_Type = {
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
     (iternextfunc)map_next,     /* tp_iternext */
-    0,                                  /* tp_methods */
+    map_methods,                        /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */
     0,                                  /* tp_base */
@@ -2238,6 +2276,18 @@ zip_next(zipobject *lz)
     return result;
 }
 
+static PyObject *
+zip_reduce(zipobject *lz)
+{
+    /* Just recreate the zip with the internal iterator tuple */
+    return Py_BuildValue("OO", Py_TYPE(lz), lz->ittuple);
+}
+
+static PyMethodDef zip_methods[] = {
+    {"__reduce__",   (PyCFunction)zip_reduce,   METH_NOARGS, reduce_doc},
+    {NULL,           NULL}           /* sentinel */
+};
+
 PyDoc_STRVAR(zip_doc,
 "zip(iter1 [,iter2 [...]]) --> zip object\n\
 \n\
@@ -2276,7 +2326,7 @@ PyTypeObject PyZip_Type = {
     0,                                  /* tp_weaklistoffset */
     PyObject_SelfIter,                  /* tp_iter */
     (iternextfunc)zip_next,     /* tp_iternext */
-    0,                                  /* tp_methods */
+    zip_methods,                        /* tp_methods */
     0,                                  /* tp_members */
     0,                                  /* tp_getset */
     0,                                  /* tp_base */