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Issue #17804: New function `struct.iter_unpack` allows for streaming struct unpacking.

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This commit is contained in:
Antoine Pitrou 2013-04-27 00:20:04 +02:00
parent 3da670749a
commit 9f14681959
5 changed files with 262 additions and 1 deletions
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74
Lib/test/test_struct.py
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@ -1,4 +1,6 @@
from collections import abc
import array
import operator
import unittest
import struct
import sys
@ -593,8 +595,78 @@ class StructTest(unittest.TestCase):
self.check_sizeof('0s', 1)
self.check_sizeof('0c', 0)
class UnpackIteratorTest(unittest.TestCase):
"""
Tests for iterative unpacking (struct.Struct.iter_unpack).
"""
def test_construct(self):
def _check_iterator(it):
self.assertIsInstance(it, abc.Iterator)
self.assertIsInstance(it, abc.Iterable)
s = struct.Struct('>ibcp')
it = s.iter_unpack(b"")
_check_iterator(it)
it = s.iter_unpack(b"1234567")
_check_iterator(it)
# Wrong bytes length
with self.assertRaises(struct.error):
s.iter_unpack(b"123456")
with self.assertRaises(struct.error):
s.iter_unpack(b"12345678")
# Zero-length struct
s = struct.Struct('>')
with self.assertRaises(struct.error):
s.iter_unpack(b"")
with self.assertRaises(struct.error):
s.iter_unpack(b"12")
def test_iterate(self):
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertEqual(next(it), (0x0b0c0d0e, 15))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_arbitrary_buffer(self):
s = struct.Struct('>IB')
b = bytes(range(1, 11))
it = s.iter_unpack(memoryview(b))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_length_hint(self):
lh = operator.length_hint
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(lh(it), 3)
next(it)
self.assertEqual(lh(it), 2)
next(it)
self.assertEqual(lh(it), 1)
next(it)
self.assertEqual(lh(it), 0)
self.assertRaises(StopIteration, next, it)
self.assertEqual(lh(it), 0)
def test_module_func(self):
# Sanity check for the global struct.iter_unpack()
it = struct.iter_unpack('>IB', bytes(range(1, 11)))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_main():
support.run_unittest(StructTest)
support.run_unittest(__name__)
if __name__ == '__main__':
test_main()