Issue #17804: New function ``struct.iter_unpack`` allows for streaming struct unpacking.
diff --git a/Lib/struct.py b/Lib/struct.py
index 9bfc23f..d6bba58 100644
--- a/Lib/struct.py
+++ b/Lib/struct.py
@@ -1,6 +1,7 @@
__all__ = [
# Functions
'calcsize', 'pack', 'pack_into', 'unpack', 'unpack_from',
+ 'iter_unpack',
# Classes
'Struct',
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index eb97a2c..8ffa7e6 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -1,4 +1,6 @@
+from collections import abc
import array
+import operator
import unittest
import struct
import sys
@@ -593,8 +595,78 @@
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()