Lib/ctypes/test/test_cast.py

   1 from ctypes import *
   2 import unittest
   3 import sys
   4
   5 class Test(unittest.TestCase):
   6
   7     def test_array2pointer(self):
   8         array = (c_int * 3)(42, 17, 2)
   9
  10         # casting an array to a pointer works.
  11         ptr = cast(array, POINTER(c_int))
  12         self.assertEqual([ptr[i] for i in range(3)], [42, 17, 2])
  13
  14         if 2*sizeof(c_short) == sizeof(c_int):
  15             ptr = cast(array, POINTER(c_short))
  16             if sys.byteorder == "little":
  17                 self.assertEqual([ptr[i] for i in range(6)],
  18                                      [42, 0, 17, 0, 2, 0])
  19             else:
  20                 self.assertEqual([ptr[i] for i in range(6)],
  21                                      [0, 42, 0, 17, 0, 2])
  22
  23     def test_address2pointer(self):
  24         array = (c_int * 3)(42, 17, 2)
  25
  26         address = addressof(array)
  27         ptr = cast(c_void_p(address), POINTER(c_int))
  28         self.assertEqual([ptr[i] for i in range(3)], [42, 17, 2])
  29
  30         ptr = cast(address, POINTER(c_int))
  31         self.assertEqual([ptr[i] for i in range(3)], [42, 17, 2])
  32
  33     def test_p2a_objects(self):
  34         array = (c_char_p * 5)()
  35         self.assertEqual(array._objects, None)
  36         array[0] = "foo bar"
  37         self.assertEqual(array._objects, {'0': "foo bar"})
  38
  39         p = cast(array, POINTER(c_char_p))
  40         # array and p share a common _objects attribute
  41         self.assertTrue(p._objects is array._objects)
  42         self.assertEqual(array._objects, {'0': "foo bar", id(array): array})
  43         p[0] = "spam spam"
  44         self.assertEqual(p._objects, {'0': "spam spam", id(array): array})
  45         self.assertTrue(array._objects is p._objects)
  46         p[1] = "foo bar"
  47         self.assertEqual(p._objects, {'1': 'foo bar', '0': "spam spam", id(array): array})
  48         self.assertTrue(array._objects is p._objects)
  49
  50     def test_other(self):
  51         p = cast((c_int * 4)(1, 2, 3, 4), POINTER(c_int))
  52         self.assertEqual(p[:4], [1,2, 3, 4])
  53         self.assertEqual(p[:4:], [1, 2, 3, 4])
  54         self.assertEqual(p[3:-1:-1], [4, 3, 2, 1])
  55         self.assertEqual(p[:4:3], [1, 4])
  56         c_int()
  57         self.assertEqual(p[:4], [1, 2, 3, 4])
  58         self.assertEqual(p[:4:], [1, 2, 3, 4])
  59         self.assertEqual(p[3:-1:-1], [4, 3, 2, 1])
  60         self.assertEqual(p[:4:3], [1, 4])
  61         p[2] = 96
  62         self.assertEqual(p[:4], [1, 2, 96, 4])
  63         self.assertEqual(p[:4:], [1, 2, 96, 4])
  64         self.assertEqual(p[3:-1:-1], [4, 96, 2, 1])
  65         self.assertEqual(p[:4:3], [1, 4])
  66         c_int()
  67         self.assertEqual(p[:4], [1, 2, 96, 4])
  68         self.assertEqual(p[:4:], [1, 2, 96, 4])
  69         self.assertEqual(p[3:-1:-1], [4, 96, 2, 1])
  70         self.assertEqual(p[:4:3], [1, 4])
  71
  72     def test_char_p(self):
  73         # This didn't work: bad argument to internal function
  74         s = c_char_p("hiho")
  75         self.assertEqual(cast(cast(s, c_void_p), c_char_p).value,
  76                              "hiho")
  77
  78     try:
  79         c_wchar_p
  80     except NameError:
  81         pass
  82     else:
  83         def test_wchar_p(self):
  84             s = c_wchar_p("hiho")
  85             self.assertEqual(cast(cast(s, c_void_p), c_wchar_p).value,
  86                                  "hiho")
  87
  88 if __name__ == "__main__":
  89     unittest.main()