mirror of
https://github.com/python/cpython.git
synced 2025-10-30 21:21:22 +00:00
284d927625
Issue #1580: New free format floating point representation based on "Floating-Point Printer Sample Code", by Robert G. Burger. For example repr(11./5) now returns '2.2' instead of '2.2000000000000002'. Thanks to noam for the patch! I had to modify doubledigits.c slightly to support X64 and IA64 machines on Windows. I also added the new file to the three project files.
140 lines
5.4 KiB
Python
140 lines
5.4 KiB
Python
|
|
import unittest, struct
|
|
import os
|
|
from test import test_support
|
|
|
|
class FormatFunctionsTestCase(unittest.TestCase):
|
|
|
|
def setUp(self):
|
|
self.save_formats = {'double':float.__getformat__('double'),
|
|
'float':float.__getformat__('float')}
|
|
|
|
def tearDown(self):
|
|
float.__setformat__('double', self.save_formats['double'])
|
|
float.__setformat__('float', self.save_formats['float'])
|
|
|
|
def test_getformat(self):
|
|
self.assert_(float.__getformat__('double') in
|
|
['unknown', 'IEEE, big-endian', 'IEEE, little-endian'])
|
|
self.assert_(float.__getformat__('float') in
|
|
['unknown', 'IEEE, big-endian', 'IEEE, little-endian'])
|
|
self.assertRaises(ValueError, float.__getformat__, 'chicken')
|
|
self.assertRaises(TypeError, float.__getformat__, 1)
|
|
|
|
def test_setformat(self):
|
|
for t in 'double', 'float':
|
|
float.__setformat__(t, 'unknown')
|
|
if self.save_formats[t] == 'IEEE, big-endian':
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
t, 'IEEE, little-endian')
|
|
elif self.save_formats[t] == 'IEEE, little-endian':
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
t, 'IEEE, big-endian')
|
|
else:
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
t, 'IEEE, big-endian')
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
t, 'IEEE, little-endian')
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
t, 'chicken')
|
|
self.assertRaises(ValueError, float.__setformat__,
|
|
'chicken', 'unknown')
|
|
|
|
BE_DOUBLE_INF = '\x7f\xf0\x00\x00\x00\x00\x00\x00'
|
|
LE_DOUBLE_INF = ''.join(reversed(BE_DOUBLE_INF))
|
|
BE_DOUBLE_NAN = '\x7f\xf8\x00\x00\x00\x00\x00\x00'
|
|
LE_DOUBLE_NAN = ''.join(reversed(BE_DOUBLE_NAN))
|
|
|
|
BE_FLOAT_INF = '\x7f\x80\x00\x00'
|
|
LE_FLOAT_INF = ''.join(reversed(BE_FLOAT_INF))
|
|
BE_FLOAT_NAN = '\x7f\xc0\x00\x00'
|
|
LE_FLOAT_NAN = ''.join(reversed(BE_FLOAT_NAN))
|
|
|
|
# on non-IEEE platforms, attempting to unpack a bit pattern
|
|
# representing an infinity or a NaN should raise an exception.
|
|
|
|
class UnknownFormatTestCase(unittest.TestCase):
|
|
def setUp(self):
|
|
self.save_formats = {'double':float.__getformat__('double'),
|
|
'float':float.__getformat__('float')}
|
|
float.__setformat__('double', 'unknown')
|
|
float.__setformat__('float', 'unknown')
|
|
|
|
def tearDown(self):
|
|
float.__setformat__('double', self.save_formats['double'])
|
|
float.__setformat__('float', self.save_formats['float'])
|
|
|
|
def test_double_specials_dont_unpack(self):
|
|
for fmt, data in [('>d', BE_DOUBLE_INF),
|
|
('>d', BE_DOUBLE_NAN),
|
|
('<d', LE_DOUBLE_INF),
|
|
('<d', LE_DOUBLE_NAN)]:
|
|
self.assertRaises(ValueError, struct.unpack, fmt, data)
|
|
|
|
def test_float_specials_dont_unpack(self):
|
|
for fmt, data in [('>f', BE_FLOAT_INF),
|
|
('>f', BE_FLOAT_NAN),
|
|
('<f', LE_FLOAT_INF),
|
|
('<f', LE_FLOAT_NAN)]:
|
|
self.assertRaises(ValueError, struct.unpack, fmt, data)
|
|
|
|
|
|
# on an IEEE platform, all we guarantee is that bit patterns
|
|
# representing infinities or NaNs do not raise an exception; all else
|
|
# is accident (today).
|
|
# let's also try to guarantee that -0.0 and 0.0 don't get confused.
|
|
|
|
class IEEEFormatTestCase(unittest.TestCase):
|
|
if float.__getformat__("double").startswith("IEEE"):
|
|
def test_double_specials_do_unpack(self):
|
|
for fmt, data in [('>d', BE_DOUBLE_INF),
|
|
('>d', BE_DOUBLE_NAN),
|
|
('<d', LE_DOUBLE_INF),
|
|
('<d', LE_DOUBLE_NAN)]:
|
|
struct.unpack(fmt, data)
|
|
|
|
if float.__getformat__("float").startswith("IEEE"):
|
|
def test_float_specials_do_unpack(self):
|
|
for fmt, data in [('>f', BE_FLOAT_INF),
|
|
('>f', BE_FLOAT_NAN),
|
|
('<f', LE_FLOAT_INF),
|
|
('<f', LE_FLOAT_NAN)]:
|
|
struct.unpack(fmt, data)
|
|
|
|
if float.__getformat__("double").startswith("IEEE"):
|
|
def test_negative_zero(self):
|
|
import math
|
|
def pos_pos():
|
|
return 0.0, math.atan2(0.0, -1)
|
|
def pos_neg():
|
|
return 0.0, math.atan2(-0.0, -1)
|
|
def neg_pos():
|
|
return -0.0, math.atan2(0.0, -1)
|
|
def neg_neg():
|
|
return -0.0, math.atan2(-0.0, -1)
|
|
self.assertEquals(pos_pos(), neg_pos())
|
|
self.assertEquals(pos_neg(), neg_neg())
|
|
|
|
|
|
class ReprTestCase(unittest.TestCase):
|
|
def test_repr(self):
|
|
floats_file = open(os.path.join(os.path.split(__file__)[0],
|
|
'floating_points.txt'))
|
|
for line in floats_file:
|
|
line = line.strip()
|
|
if not line or line.startswith('#'):
|
|
continue
|
|
v = eval(line)
|
|
self.assertEqual(v, eval(repr(v)))
|
|
floats_file.close()
|
|
|
|
|
|
def test_main():
|
|
test_support.run_unittest(
|
|
FormatFunctionsTestCase,
|
|
UnknownFormatTestCase,
|
|
IEEEFormatTestCase,
|
|
ReprTestCase)
|
|
|
|
if __name__ == '__main__':
|
|
test_main()
|