diff options
| -rw-r--r-- | Lib/test/test_float.py | 102 | ||||
| -rw-r--r-- | Lib/test/test_strtod.py | 6 |
2 files changed, 6 insertions, 102 deletions
diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py index cabeb16..5932b96 100644 --- a/Lib/test/test_float.py +++ b/Lib/test/test_float.py @@ -7,7 +7,6 @@ import math from math import isinf, isnan, copysign, ldexp import operator import random, fractions -import re INF = float("inf") NAN = float("nan") @@ -21,74 +20,6 @@ requires_IEEE_754 = unittest.skipUnless( test_dir = os.path.dirname(__file__) or os.curdir format_testfile = os.path.join(test_dir, 'formatfloat_testcases.txt') -finite_decimal_parser = re.compile(r""" # A numeric string consists of: - (?P<sign>[-+])? # an optional sign, followed by - (?=\d|\.\d) # a number with at least one digit - (?P<int>\d*) # having a (possibly empty) integer part - (?:\.(?P<frac>\d*))? # followed by an optional fractional part - (?:E(?P<exp>[-+]?\d+))? # and an optional exponent - \Z -""", re.VERBOSE | re.IGNORECASE | re.UNICODE).match - -# Pure Python version of correctly rounded string->float conversion. -# Avoids any use of floating-point by returning the result as a hex string. -def strtod(s, mant_dig=53, min_exp = -1021, max_exp = 1024): - """Convert a finite decimal string to a hex string representing an - IEEE 754 binary64 float. Return 'inf' or '-inf' on overflow. - This function makes no use of floating-point arithmetic at any - stage.""" - - # parse string into a pair of integers 'a' and 'b' such that - # abs(decimal value) = a/b, and a boolean 'negative'. - m = finite_decimal_parser(s) - if m is None: - raise ValueError('invalid numeric string') - fraction = m.group('frac') or '' - intpart = int(m.group('int') + fraction) - exp = int(m.group('exp') or '0') - len(fraction) - negative = m.group('sign') == '-' - a, b = intpart*10**max(exp, 0), 10**max(0, -exp) - - # quick return for zeros - if not a: - return '-0x0.0p+0' if negative else '0x0.0p+0' - - # compute exponent e for result; may be one too small in the case - # that the rounded value of a/b lies in a different binade from a/b - d = a.bit_length() - b.bit_length() - d += (a >> d if d >= 0 else a << -d) >= b - e = max(d, min_exp) - mant_dig - - # approximate a/b by number of the form q * 2**e; adjust e if necessary - a, b = a << max(-e, 0), b << max(e, 0) - q, r = divmod(a, b) - if 2*r > b or 2*r == b and q & 1: - q += 1 - if q.bit_length() == mant_dig+1: - q //= 2 - e += 1 - - # double check that (q, e) has the right form - assert q.bit_length() <= mant_dig and e >= min_exp - mant_dig - assert q.bit_length() == mant_dig or e == min_exp - mant_dig - - # check for overflow and underflow - if e + q.bit_length() > max_exp: - return '-inf' if negative else 'inf' - if not q: - return '-0x0.0p+0' if negative else '0x0.0p+0' - - # for hex representation, shift so # bits after point is a multiple of 4 - hexdigs = 1 + (mant_dig-2)//4 - shift = 3 - (mant_dig-2)%4 - q, e = q << shift, e - shift - return '{}0x{:x}.{:0{}x}p{:+d}'.format( - '-' if negative else '', - q // 16**hexdigs, - q % 16**hexdigs, - hexdigs, - e + 4*hexdigs) - class GeneralFloatCases(unittest.TestCase): def test_float(self): @@ -1334,38 +1265,6 @@ class HexFloatTestCase(unittest.TestCase): else: self.identical(x, fromHex(toHex(x))) -class StrtodTestCase(unittest.TestCase): - def check_string(self, s): - expected = strtod(s) - try: - fs = float(s) - except OverflowError: - got = '-inf' if s[0] == '-' else 'inf' - else: - got = fs.hex() - self.assertEqual(expected, got, - "Incorrectly rounded str->float conversion for " - "{}: expected {}, got {}".format(s, expected, got)) - - @unittest.skipUnless(getattr(sys, 'float_repr_style', '') == 'short', - "applies only when using short float repr style") - def test_bug7632(self): - # check a few particular values that gave incorrectly rounded - # results with previous versions of dtoa.c - test_strings = [ - '94393431193180696942841837085033647913224148539854e-358', - '12579816049008305546974391768996369464963024663104e-357', - '17489628565202117263145367596028389348922981857013e-357', - '18487398785991994634182916638542680759613590482273e-357', - '32002864200581033134358724675198044527469366773928e-358', - '73608278998966969345824653500136787876436005957953e-358', - '64774478836417299491718435234611299336288082136054e-358', - '13704940134126574534878641876947980878824688451169e-357', - '46697445774047060960624497964425416610480524760471e-358', - ] - for s in test_strings: - self.check_string(s) - def test_main(): support.run_unittest( @@ -1378,7 +1277,6 @@ def test_main(): RoundTestCase, InfNanTest, HexFloatTestCase, - StrtodTestCase, ) if __name__ == '__main__': diff --git a/Lib/test/test_strtod.py b/Lib/test/test_strtod.py index e99693c..127e868 100644 --- a/Lib/test/test_strtod.py +++ b/Lib/test/test_strtod.py @@ -23,6 +23,8 @@ strtod_parser = re.compile(r""" # A numeric string consists of: \Z """, re.VERBOSE | re.IGNORECASE).match +# Pure Python version of correctly rounded string->float conversion. +# Avoids any use of floating-point by returning the result as a hex string. def strtod(s, mant_dig=53, min_exp = -1021, max_exp = 1024): """Convert a finite decimal string to a hex string representing an IEEE 754 binary64 float. Return 'inf' or '-inf' on overflow. @@ -259,6 +261,10 @@ class StrtodTests(unittest.TestCase): '18487398785991994634182916638542680759613590482273e-357', '32002864200581033134358724675198044527469366773928e-358', '94393431193180696942841837085033647913224148539854e-358', + '73608278998966969345824653500136787876436005957953e-358', + '64774478836417299491718435234611299336288082136054e-358', + '13704940134126574534878641876947980878824688451169e-357', + '46697445774047060960624497964425416610480524760471e-358', # failing case for bug introduced by METD in r77451 (attempted # fix for issue 7632, bug 2), and fixed in r77482. '28639097178261763178489759107321392745108491825303e-311', |