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Diffstat (limited to 'lib/python2.7/test/test_strtod.py')
| -rw-r--r-- | lib/python2.7/test/test_strtod.py | 399 |
1 files changed, 0 insertions, 399 deletions
diff --git a/lib/python2.7/test/test_strtod.py b/lib/python2.7/test/test_strtod.py deleted file mode 100644 index 7bc595d..0000000 --- a/lib/python2.7/test/test_strtod.py +++ /dev/null @@ -1,399 +0,0 @@ -# Tests for the correctly-rounded string -> float conversions -# introduced in Python 2.7 and 3.1. - -import random -import struct -import unittest -import re -import sys -from test import test_support - -if getattr(sys, 'float_repr_style', '') != 'short': - raise unittest.SkipTest('correctly-rounded string->float conversions ' - 'not available on this system') - -# Correctly rounded str -> float in pure Python, for comparison. - -strtod_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).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, along with a boolean 'negative'. - m = strtod_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) - -TEST_SIZE = 10 - -class StrtodTests(unittest.TestCase): - def check_strtod(self, s): - """Compare the result of Python's builtin correctly rounded - string->float conversion (using float) to a pure Python - correctly rounded string->float implementation. Fail if the - two methods give different results.""" - - try: - fs = float(s) - except OverflowError: - got = '-inf' if s[0] == '-' else 'inf' - except MemoryError: - got = 'memory error' - else: - got = fs.hex() - expected = strtod(s) - self.assertEqual(expected, got, - "Incorrectly rounded str->float conversion for {}: " - "expected {}, got {}".format(s, expected, got)) - - def test_short_halfway_cases(self): - # exact halfway cases with a small number of significant digits - for k in 0, 5, 10, 15, 20: - # upper = smallest integer >= 2**54/5**k - upper = -(-2**54//5**k) - # lower = smallest odd number >= 2**53/5**k - lower = -(-2**53//5**k) - if lower % 2 == 0: - lower += 1 - for i in xrange(TEST_SIZE): - # Select a random odd n in [2**53/5**k, - # 2**54/5**k). Then n * 10**k gives a halfway case - # with small number of significant digits. - n, e = random.randrange(lower, upper, 2), k - - # Remove any additional powers of 5. - while n % 5 == 0: - n, e = n // 5, e + 1 - assert n % 10 in (1, 3, 7, 9) - - # Try numbers of the form n * 2**p2 * 10**e, p2 >= 0, - # until n * 2**p2 has more than 20 significant digits. - digits, exponent = n, e - while digits < 10**20: - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - # Same again, but with extra trailing zeros. - s = '{}e{}'.format(digits * 10**40, exponent - 40) - self.check_strtod(s) - digits *= 2 - - # Try numbers of the form n * 5**p2 * 10**(e - p5), p5 - # >= 0, with n * 5**p5 < 10**20. - digits, exponent = n, e - while digits < 10**20: - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - # Same again, but with extra trailing zeros. - s = '{}e{}'.format(digits * 10**40, exponent - 40) - self.check_strtod(s) - digits *= 5 - exponent -= 1 - - def test_halfway_cases(self): - # test halfway cases for the round-half-to-even rule - for i in xrange(100 * TEST_SIZE): - # bit pattern for a random finite positive (or +0.0) float - bits = random.randrange(2047*2**52) - - # convert bit pattern to a number of the form m * 2**e - e, m = divmod(bits, 2**52) - if e: - m, e = m + 2**52, e - 1 - e -= 1074 - - # add 0.5 ulps - m, e = 2*m + 1, e - 1 - - # convert to a decimal string - if e >= 0: - digits = m << e - exponent = 0 - else: - # m * 2**e = (m * 5**-e) * 10**e - digits = m * 5**-e - exponent = e - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - - def test_boundaries(self): - # boundaries expressed as triples (n, e, u), where - # n*10**e is an approximation to the boundary value and - # u*10**e is 1ulp - boundaries = [ - (10000000000000000000, -19, 1110), # a power of 2 boundary (1.0) - (17976931348623159077, 289, 1995), # overflow boundary (2.**1024) - (22250738585072013831, -327, 4941), # normal/subnormal (2.**-1022) - (0, -327, 4941), # zero - ] - for n, e, u in boundaries: - for j in xrange(1000): - digits = n + random.randrange(-3*u, 3*u) - exponent = e - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - n *= 10 - u *= 10 - e -= 1 - - def test_underflow_boundary(self): - # test values close to 2**-1075, the underflow boundary; similar - # to boundary_tests, except that the random error doesn't scale - # with n - for exponent in xrange(-400, -320): - base = 10**-exponent // 2**1075 - for j in xrange(TEST_SIZE): - digits = base + random.randrange(-1000, 1000) - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - - def test_bigcomp(self): - for ndigs in 5, 10, 14, 15, 16, 17, 18, 19, 20, 40, 41, 50: - dig10 = 10**ndigs - for i in xrange(10 * TEST_SIZE): - digits = random.randrange(dig10) - exponent = random.randrange(-400, 400) - s = '{}e{}'.format(digits, exponent) - self.check_strtod(s) - - def test_parsing(self): - # make '0' more likely to be chosen than other digits - digits = '000000123456789' - signs = ('+', '-', '') - - # put together random short valid strings - # \d*[.\d*]?e - for i in xrange(1000): - for j in xrange(TEST_SIZE): - s = random.choice(signs) - intpart_len = random.randrange(5) - s += ''.join(random.choice(digits) for _ in xrange(intpart_len)) - if random.choice([True, False]): - s += '.' - fracpart_len = random.randrange(5) - s += ''.join(random.choice(digits) - for _ in xrange(fracpart_len)) - else: - fracpart_len = 0 - if random.choice([True, False]): - s += random.choice(['e', 'E']) - s += random.choice(signs) - exponent_len = random.randrange(1, 4) - s += ''.join(random.choice(digits) - for _ in xrange(exponent_len)) - - if intpart_len + fracpart_len: - self.check_strtod(s) - else: - try: - float(s) - except ValueError: - pass - else: - assert False, "expected ValueError" - - def test_particular(self): - # inputs that produced crashes or incorrectly rounded results with - # previous versions of dtoa.c, for various reasons - test_strings = [ - # issue 7632 bug 1, originally reported failing case - '2183167012312112312312.23538020374420446192e-370', - # 5 instances of issue 7632 bug 2 - '12579816049008305546974391768996369464963024663104e-357', - '17489628565202117263145367596028389348922981857013e-357', - '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', - # two numbers demonstrating a flaw in the bigcomp 'dig == 0' - # correction block (issue 7632, bug 3) - '1.00000000000000001e44', - '1.0000000000000000100000000000000000000001e44', - # dtoa.c bug for numbers just smaller than a power of 2 (issue - # 7632, bug 4) - '99999999999999994487665465554760717039532578546e-47', - # failing case for off-by-one error introduced by METD in - # r77483 (dtoa.c cleanup), fixed in r77490 - '965437176333654931799035513671997118345570045914469' #... - '6213413350821416312194420007991306908470147322020121018368e0', - # incorrect lsb detection for round-half-to-even when - # bc->scale != 0 (issue 7632, bug 6). - '104308485241983990666713401708072175773165034278685' #... - '682646111762292409330928739751702404658197872319129' #... - '036519947435319418387839758990478549477777586673075' #... - '945844895981012024387992135617064532141489278815239' #... - '849108105951619997829153633535314849999674266169258' #... - '928940692239684771590065027025835804863585454872499' #... - '320500023126142553932654370362024104462255244034053' #... - '203998964360882487378334860197725139151265590832887' #... - '433736189468858614521708567646743455601905935595381' #... - '852723723645799866672558576993978025033590728687206' #... - '296379801363024094048327273913079612469982585674824' #... - '156000783167963081616214710691759864332339239688734' #... - '656548790656486646106983450809073750535624894296242' #... - '072010195710276073042036425579852459556183541199012' #... - '652571123898996574563824424330960027873516082763671875e-1075', - # demonstration that original fix for issue 7632 bug 1 was - # buggy; the exit condition was too strong - '247032822920623295e-341', - # demonstrate similar problem to issue 7632 bug1: crash - # with 'oversized quotient in quorem' message. - '99037485700245683102805043437346965248029601286431e-373', - '99617639833743863161109961162881027406769510558457e-373', - '98852915025769345295749278351563179840130565591462e-372', - '99059944827693569659153042769690930905148015876788e-373', - '98914979205069368270421829889078356254059760327101e-372', - # issue 7632 bug 5: the following 2 strings convert differently - '1000000000000000000000000000000000000000e-16', - '10000000000000000000000000000000000000000e-17', - # issue 7632 bug 7 - '991633793189150720000000000000000000000000000000000000000e-33', - # And another, similar, failing halfway case - '4106250198039490000000000000000000000000000000000000000e-38', - # issue 7632 bug 8: the following produced 10.0 - '10.900000000000000012345678912345678912345', - - # two humongous values from issue 7743 - '116512874940594195638617907092569881519034793229385' #... - '228569165191541890846564669771714896916084883987920' #... - '473321268100296857636200926065340769682863349205363' #... - '349247637660671783209907949273683040397979984107806' #... - '461822693332712828397617946036239581632976585100633' #... - '520260770761060725403904123144384571612073732754774' #... - '588211944406465572591022081973828448927338602556287' #... - '851831745419397433012491884869454462440536895047499' #... - '436551974649731917170099387762871020403582994193439' #... - '761933412166821484015883631622539314203799034497982' #... - '130038741741727907429575673302461380386596501187482' #... - '006257527709842179336488381672818798450229339123527' #... - '858844448336815912020452294624916993546388956561522' #... - '161875352572590420823607478788399460162228308693742' #... - '05287663441403533948204085390898399055004119873046875e-1075', - - '525440653352955266109661060358202819561258984964913' #... - '892256527849758956045218257059713765874251436193619' #... - '443248205998870001633865657517447355992225852945912' #... - '016668660000210283807209850662224417504752264995360' #... - '631512007753855801075373057632157738752800840302596' #... - '237050247910530538250008682272783660778181628040733' #... - '653121492436408812668023478001208529190359254322340' #... - '397575185248844788515410722958784640926528544043090' #... - '115352513640884988017342469275006999104519620946430' #... - '818767147966495485406577703972687838176778993472989' #... - '561959000047036638938396333146685137903018376496408' #... - '319705333868476925297317136513970189073693314710318' #... - '991252811050501448326875232850600451776091303043715' #... - '157191292827614046876950225714743118291034780466325' #... - '085141343734564915193426994587206432697337118211527' #... - '278968731294639353354774788602467795167875117481660' #... - '4738791256853675690543663283782215866825e-1180', - - # exercise exit conditions in bigcomp comparison loop - '2602129298404963083833853479113577253105939995688e2', - '260212929840496308383385347911357725310593999568896e0', - '26021292984049630838338534791135772531059399956889601e-2', - '260212929840496308383385347911357725310593999568895e0', - '260212929840496308383385347911357725310593999568897e0', - '260212929840496308383385347911357725310593999568996e0', - '260212929840496308383385347911357725310593999568866e0', - # 2**53 - '9007199254740992.00', - # 2**1024 - 2**970: exact overflow boundary. All values - # smaller than this should round to something finite; any value - # greater than or equal to this one overflows. - '179769313486231580793728971405303415079934132710037' #... - '826936173778980444968292764750946649017977587207096' #... - '330286416692887910946555547851940402630657488671505' #... - '820681908902000708383676273854845817711531764475730' #... - '270069855571366959622842914819860834936475292719074' #... - '168444365510704342711559699508093042880177904174497792', - # 2**1024 - 2**970 - tiny - '179769313486231580793728971405303415079934132710037' #... - '826936173778980444968292764750946649017977587207096' #... - '330286416692887910946555547851940402630657488671505' #... - '820681908902000708383676273854845817711531764475730' #... - '270069855571366959622842914819860834936475292719074' #... - '168444365510704342711559699508093042880177904174497791.999', - # 2**1024 - 2**970 + tiny - '179769313486231580793728971405303415079934132710037' #... - '826936173778980444968292764750946649017977587207096' #... - '330286416692887910946555547851940402630657488671505' #... - '820681908902000708383676273854845817711531764475730' #... - '270069855571366959622842914819860834936475292719074' #... - '168444365510704342711559699508093042880177904174497792.001', - # 1 - 2**-54, +-tiny - '999999999999999944488848768742172978818416595458984375e-54', - '9999999999999999444888487687421729788184165954589843749999999e-54', - '9999999999999999444888487687421729788184165954589843750000001e-54', - ] - for s in test_strings: - self.check_strtod(s) - -def test_main(): - test_support.run_unittest(StrtodTests) - -if __name__ == "__main__": - test_main() |