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author | shadchin <shadchin@yandex-team.com> | 2024-02-12 07:53:52 +0300 |
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committer | Daniil Cherednik <dcherednik@ydb.tech> | 2024-02-14 14:26:16 +0000 |
commit | 31f2a419764a8ba77c2a970cfc80056c6cd06756 (patch) | |
tree | c1995d239eba8571cefc640f6648e1d5dd4ce9e2 /contrib/tools/python3/src/Lib/fractions.py | |
parent | fe2ef02b38d9c85d80060963b265a1df9f38c3bb (diff) | |
download | ydb-31f2a419764a8ba77c2a970cfc80056c6cd06756.tar.gz |
Update Python from 3.11.8 to 3.12.2
Diffstat (limited to 'contrib/tools/python3/src/Lib/fractions.py')
-rw-r--r-- | contrib/tools/python3/src/Lib/fractions.py | 402 |
1 files changed, 317 insertions, 85 deletions
diff --git a/contrib/tools/python3/src/Lib/fractions.py b/contrib/tools/python3/src/Lib/fractions.py index a7a7fea5ca..88b418fe38 100644 --- a/contrib/tools/python3/src/Lib/fractions.py +++ b/contrib/tools/python3/src/Lib/fractions.py @@ -4,6 +4,7 @@ """Fraction, infinite-precision, rational numbers.""" from decimal import Decimal +import functools import math import numbers import operator @@ -20,13 +21,46 @@ _PyHASH_MODULUS = sys.hash_info.modulus # _PyHASH_MODULUS. _PyHASH_INF = sys.hash_info.inf +@functools.lru_cache(maxsize = 1 << 14) +def _hash_algorithm(numerator, denominator): + + # To make sure that the hash of a Fraction agrees with the hash + # of a numerically equal integer, float or Decimal instance, we + # follow the rules for numeric hashes outlined in the + # documentation. (See library docs, 'Built-in Types'). + + try: + dinv = pow(denominator, -1, _PyHASH_MODULUS) + except ValueError: + # ValueError means there is no modular inverse. + hash_ = _PyHASH_INF + else: + # The general algorithm now specifies that the absolute value of + # the hash is + # (|N| * dinv) % P + # where N is self._numerator and P is _PyHASH_MODULUS. That's + # optimized here in two ways: first, for a non-negative int i, + # hash(i) == i % P, but the int hash implementation doesn't need + # to divide, and is faster than doing % P explicitly. So we do + # hash(|N| * dinv) + # instead. Second, N is unbounded, so its product with dinv may + # be arbitrarily expensive to compute. The final answer is the + # same if we use the bounded |N| % P instead, which can again + # be done with an int hash() call. If 0 <= i < P, hash(i) == i, + # so this nested hash() call wastes a bit of time making a + # redundant copy when |N| < P, but can save an arbitrarily large + # amount of computation for large |N|. + hash_ = hash(hash(abs(numerator)) * dinv) + result = hash_ if numerator >= 0 else -hash_ + return -2 if result == -1 else result + _RATIONAL_FORMAT = re.compile(r""" \A\s* # optional whitespace at the start, (?P<sign>[-+]?) # an optional sign, then (?=\d|\.\d) # lookahead for digit or .digit (?P<num>\d*|\d+(_\d+)*) # numerator (possibly empty) (?: # followed by - (?:/(?P<denom>\d+(_\d+)*))? # an optional denominator + (?:\s*/\s*(?P<denom>\d+(_\d+)*))? # an optional denominator | # or (?:\.(?P<decimal>\d*|\d+(_\d+)*))? # an optional fractional part (?:E(?P<exp>[-+]?\d+(_\d+)*))? # and optional exponent @@ -35,6 +69,96 @@ _RATIONAL_FORMAT = re.compile(r""" """, re.VERBOSE | re.IGNORECASE) +# Helpers for formatting + +def _round_to_exponent(n, d, exponent, no_neg_zero=False): + """Round a rational number to the nearest multiple of a given power of 10. + + Rounds the rational number n/d to the nearest integer multiple of + 10**exponent, rounding to the nearest even integer multiple in the case of + a tie. Returns a pair (sign: bool, significand: int) representing the + rounded value (-1)**sign * significand * 10**exponent. + + If no_neg_zero is true, then the returned sign will always be False when + the significand is zero. Otherwise, the sign reflects the sign of the + input. + + d must be positive, but n and d need not be relatively prime. + """ + if exponent >= 0: + d *= 10**exponent + else: + n *= 10**-exponent + + # The divmod quotient is correct for round-ties-towards-positive-infinity; + # In the case of a tie, we zero out the least significant bit of q. + q, r = divmod(n + (d >> 1), d) + if r == 0 and d & 1 == 0: + q &= -2 + + sign = q < 0 if no_neg_zero else n < 0 + return sign, abs(q) + + +def _round_to_figures(n, d, figures): + """Round a rational number to a given number of significant figures. + + Rounds the rational number n/d to the given number of significant figures + using the round-ties-to-even rule, and returns a triple + (sign: bool, significand: int, exponent: int) representing the rounded + value (-1)**sign * significand * 10**exponent. + + In the special case where n = 0, returns a significand of zero and + an exponent of 1 - figures, for compatibility with formatting. + Otherwise, the returned significand satisfies + 10**(figures - 1) <= significand < 10**figures. + + d must be positive, but n and d need not be relatively prime. + figures must be positive. + """ + # Special case for n == 0. + if n == 0: + return False, 0, 1 - figures + + # Find integer m satisfying 10**(m - 1) <= abs(n)/d <= 10**m. (If abs(n)/d + # is a power of 10, either of the two possible values for m is fine.) + str_n, str_d = str(abs(n)), str(d) + m = len(str_n) - len(str_d) + (str_d <= str_n) + + # Round to a multiple of 10**(m - figures). The significand we get + # satisfies 10**(figures - 1) <= significand <= 10**figures. + exponent = m - figures + sign, significand = _round_to_exponent(n, d, exponent) + + # Adjust in the case where significand == 10**figures, to ensure that + # 10**(figures - 1) <= significand < 10**figures. + if len(str(significand)) == figures + 1: + significand //= 10 + exponent += 1 + + return sign, significand, exponent + + +# Pattern for matching float-style format specifications; +# supports 'e', 'E', 'f', 'F', 'g', 'G' and '%' presentation types. +_FLOAT_FORMAT_SPECIFICATION_MATCHER = re.compile(r""" + (?: + (?P<fill>.)? + (?P<align>[<>=^]) + )? + (?P<sign>[-+ ]?) + (?P<no_neg_zero>z)? + (?P<alt>\#)? + # A '0' that's *not* followed by another digit is parsed as a minimum width + # rather than a zeropad flag. + (?P<zeropad>0(?=[0-9]))? + (?P<minimumwidth>0|[1-9][0-9]*)? + (?P<thousands_sep>[,_])? + (?:\.(?P<precision>0|[1-9][0-9]*))? + (?P<presentation_type>[eEfFgG%]) +""", re.DOTALL | re.VERBOSE).fullmatch + + class Fraction(numbers.Rational): """This class implements rational numbers. @@ -59,7 +183,7 @@ class Fraction(numbers.Rational): __slots__ = ('_numerator', '_denominator') # We're immutable, so use __new__ not __init__ - def __new__(cls, numerator=0, denominator=None, *, _normalize=True): + def __new__(cls, numerator=0, denominator=None): """Constructs a Rational. Takes a string like '3/2' or '1.5', another Rational instance, a @@ -155,12 +279,11 @@ class Fraction(numbers.Rational): if denominator == 0: raise ZeroDivisionError('Fraction(%s, 0)' % numerator) - if _normalize: - g = math.gcd(numerator, denominator) - if denominator < 0: - g = -g - numerator //= g - denominator //= g + g = math.gcd(numerator, denominator) + if denominator < 0: + g = -g + numerator //= g + denominator //= g self._numerator = numerator self._denominator = denominator return self @@ -177,7 +300,7 @@ class Fraction(numbers.Rational): elif not isinstance(f, float): raise TypeError("%s.from_float() only takes floats, not %r (%s)" % (cls.__name__, f, type(f).__name__)) - return cls(*f.as_integer_ratio()) + return cls._from_coprime_ints(*f.as_integer_ratio()) @classmethod def from_decimal(cls, dec): @@ -189,13 +312,28 @@ class Fraction(numbers.Rational): raise TypeError( "%s.from_decimal() only takes Decimals, not %r (%s)" % (cls.__name__, dec, type(dec).__name__)) - return cls(*dec.as_integer_ratio()) + return cls._from_coprime_ints(*dec.as_integer_ratio()) + + @classmethod + def _from_coprime_ints(cls, numerator, denominator, /): + """Convert a pair of ints to a rational number, for internal use. + + The ratio of integers should be in lowest terms and the denominator + should be positive. + """ + obj = super(Fraction, cls).__new__(cls) + obj._numerator = numerator + obj._denominator = denominator + return obj + + def is_integer(self): + """Return True if the Fraction is an integer.""" + return self._denominator == 1 def as_integer_ratio(self): - """Return the integer ratio as a tuple. + """Return a pair of integers, whose ratio is equal to the original Fraction. - Return a tuple of two integers, whose ratio is equal to the - Fraction and with a positive denominator. + The ratio is in lowest terms and has a positive denominator. """ return (self._numerator, self._denominator) @@ -245,14 +383,16 @@ class Fraction(numbers.Rational): break p0, q0, p1, q1 = p1, q1, p0+a*p1, q2 n, d = d, n-a*d - k = (max_denominator-q0)//q1 - bound1 = Fraction(p0+k*p1, q0+k*q1) - bound2 = Fraction(p1, q1) - if abs(bound2 - self) <= abs(bound1-self): - return bound2 + + # Determine which of the candidates (p0+k*p1)/(q0+k*q1) and p1/q1 is + # closer to self. The distance between them is 1/(q1*(q0+k*q1)), while + # the distance from p1/q1 to self is d/(q1*self._denominator). So we + # need to compare 2*(q0+k*q1) with self._denominator/d. + if 2*d*(q0+k*q1) <= self._denominator: + return Fraction._from_coprime_ints(p1, q1) else: - return bound1 + return Fraction._from_coprime_ints(p0+k*p1, q0+k*q1) @property def numerator(a): @@ -274,6 +414,122 @@ class Fraction(numbers.Rational): else: return '%s/%s' % (self._numerator, self._denominator) + def __format__(self, format_spec, /): + """Format this fraction according to the given format specification.""" + + # Backwards compatiblility with existing formatting. + if not format_spec: + return str(self) + + # Validate and parse the format specifier. + match = _FLOAT_FORMAT_SPECIFICATION_MATCHER(format_spec) + if match is None: + raise ValueError( + f"Invalid format specifier {format_spec!r} " + f"for object of type {type(self).__name__!r}" + ) + elif match["align"] is not None and match["zeropad"] is not None: + # Avoid the temptation to guess. + raise ValueError( + f"Invalid format specifier {format_spec!r} " + f"for object of type {type(self).__name__!r}; " + "can't use explicit alignment when zero-padding" + ) + fill = match["fill"] or " " + align = match["align"] or ">" + pos_sign = "" if match["sign"] == "-" else match["sign"] + no_neg_zero = bool(match["no_neg_zero"]) + alternate_form = bool(match["alt"]) + zeropad = bool(match["zeropad"]) + minimumwidth = int(match["minimumwidth"] or "0") + thousands_sep = match["thousands_sep"] + precision = int(match["precision"] or "6") + presentation_type = match["presentation_type"] + trim_zeros = presentation_type in "gG" and not alternate_form + trim_point = not alternate_form + exponent_indicator = "E" if presentation_type in "EFG" else "e" + + # Round to get the digits we need, figure out where to place the point, + # and decide whether to use scientific notation. 'point_pos' is the + # relative to the _end_ of the digit string: that is, it's the number + # of digits that should follow the point. + if presentation_type in "fF%": + exponent = -precision + if presentation_type == "%": + exponent -= 2 + negative, significand = _round_to_exponent( + self._numerator, self._denominator, exponent, no_neg_zero) + scientific = False + point_pos = precision + else: # presentation_type in "eEgG" + figures = ( + max(precision, 1) + if presentation_type in "gG" + else precision + 1 + ) + negative, significand, exponent = _round_to_figures( + self._numerator, self._denominator, figures) + scientific = ( + presentation_type in "eE" + or exponent > 0 + or exponent + figures <= -4 + ) + point_pos = figures - 1 if scientific else -exponent + + # Get the suffix - the part following the digits, if any. + if presentation_type == "%": + suffix = "%" + elif scientific: + suffix = f"{exponent_indicator}{exponent + point_pos:+03d}" + else: + suffix = "" + + # String of output digits, padded sufficiently with zeros on the left + # so that we'll have at least one digit before the decimal point. + digits = f"{significand:0{point_pos + 1}d}" + + # Before padding, the output has the form f"{sign}{leading}{trailing}", + # where `leading` includes thousands separators if necessary and + # `trailing` includes the decimal separator where appropriate. + sign = "-" if negative else pos_sign + leading = digits[: len(digits) - point_pos] + frac_part = digits[len(digits) - point_pos :] + if trim_zeros: + frac_part = frac_part.rstrip("0") + separator = "" if trim_point and not frac_part else "." + trailing = separator + frac_part + suffix + + # Do zero padding if required. + if zeropad: + min_leading = minimumwidth - len(sign) - len(trailing) + # When adding thousands separators, they'll be added to the + # zero-padded portion too, so we need to compensate. + leading = leading.zfill( + 3 * min_leading // 4 + 1 if thousands_sep else min_leading + ) + + # Insert thousands separators if required. + if thousands_sep: + first_pos = 1 + (len(leading) - 1) % 3 + leading = leading[:first_pos] + "".join( + thousands_sep + leading[pos : pos + 3] + for pos in range(first_pos, len(leading), 3) + ) + + # We now have a sign and a body. Pad with fill character if necessary + # and return. + body = leading + trailing + padding = fill * (minimumwidth - len(sign) - len(body)) + if align == ">": + return padding + sign + body + elif align == "<": + return sign + body + padding + elif align == "^": + half = len(padding) // 2 + return padding[:half] + sign + body + padding[half:] + else: # align == "=" + return sign + padding + body + def _operator_fallbacks(monomorphic_operator, fallback_operator): """Generates forward and reverse operators given a purely-rational operator and a function from the operator module. @@ -355,8 +611,10 @@ class Fraction(numbers.Rational): """ def forward(a, b): - if isinstance(b, (int, Fraction)): + if isinstance(b, Fraction): return monomorphic_operator(a, b) + elif isinstance(b, int): + return monomorphic_operator(a, Fraction(b)) elif isinstance(b, float): return fallback_operator(float(a), b) elif isinstance(b, complex): @@ -369,7 +627,7 @@ class Fraction(numbers.Rational): def reverse(b, a): if isinstance(a, numbers.Rational): # Includes ints. - return monomorphic_operator(a, b) + return monomorphic_operator(Fraction(a), b) elif isinstance(a, numbers.Real): return fallback_operator(float(a), float(b)) elif isinstance(a, numbers.Complex): @@ -451,40 +709,40 @@ class Fraction(numbers.Rational): def _add(a, b): """a + b""" - na, da = a.numerator, a.denominator - nb, db = b.numerator, b.denominator + na, da = a._numerator, a._denominator + nb, db = b._numerator, b._denominator g = math.gcd(da, db) if g == 1: - return Fraction(na * db + da * nb, da * db, _normalize=False) + return Fraction._from_coprime_ints(na * db + da * nb, da * db) s = da // g t = na * (db // g) + nb * s g2 = math.gcd(t, g) if g2 == 1: - return Fraction(t, s * db, _normalize=False) - return Fraction(t // g2, s * (db // g2), _normalize=False) + return Fraction._from_coprime_ints(t, s * db) + return Fraction._from_coprime_ints(t // g2, s * (db // g2)) __add__, __radd__ = _operator_fallbacks(_add, operator.add) def _sub(a, b): """a - b""" - na, da = a.numerator, a.denominator - nb, db = b.numerator, b.denominator + na, da = a._numerator, a._denominator + nb, db = b._numerator, b._denominator g = math.gcd(da, db) if g == 1: - return Fraction(na * db - da * nb, da * db, _normalize=False) + return Fraction._from_coprime_ints(na * db - da * nb, da * db) s = da // g t = na * (db // g) - nb * s g2 = math.gcd(t, g) if g2 == 1: - return Fraction(t, s * db, _normalize=False) - return Fraction(t // g2, s * (db // g2), _normalize=False) + return Fraction._from_coprime_ints(t, s * db) + return Fraction._from_coprime_ints(t // g2, s * (db // g2)) __sub__, __rsub__ = _operator_fallbacks(_sub, operator.sub) def _mul(a, b): """a * b""" - na, da = a.numerator, a.denominator - nb, db = b.numerator, b.denominator + na, da = a._numerator, a._denominator + nb, db = b._numerator, b._denominator g1 = math.gcd(na, db) if g1 > 1: na //= g1 @@ -493,15 +751,17 @@ class Fraction(numbers.Rational): if g2 > 1: nb //= g2 da //= g2 - return Fraction(na * nb, db * da, _normalize=False) + return Fraction._from_coprime_ints(na * nb, db * da) __mul__, __rmul__ = _operator_fallbacks(_mul, operator.mul) def _div(a, b): """a / b""" # Same as _mul(), with inversed b. - na, da = a.numerator, a.denominator - nb, db = b.numerator, b.denominator + nb, db = b._numerator, b._denominator + if nb == 0: + raise ZeroDivisionError('Fraction(%s, 0)' % db) + na, da = a._numerator, a._denominator g1 = math.gcd(na, nb) if g1 > 1: na //= g1 @@ -513,7 +773,7 @@ class Fraction(numbers.Rational): n, d = na * db, nb * da if d < 0: n, d = -n, -d - return Fraction(n, d, _normalize=False) + return Fraction._from_coprime_ints(n, d) __truediv__, __rtruediv__ = _operator_fallbacks(_div, operator.truediv) @@ -550,17 +810,17 @@ class Fraction(numbers.Rational): if b.denominator == 1: power = b.numerator if power >= 0: - return Fraction(a._numerator ** power, - a._denominator ** power, - _normalize=False) - elif a._numerator >= 0: - return Fraction(a._denominator ** -power, - a._numerator ** -power, - _normalize=False) + return Fraction._from_coprime_ints(a._numerator ** power, + a._denominator ** power) + elif a._numerator > 0: + return Fraction._from_coprime_ints(a._denominator ** -power, + a._numerator ** -power) + elif a._numerator == 0: + raise ZeroDivisionError('Fraction(%s, 0)' % + a._denominator ** -power) else: - return Fraction((-a._denominator) ** -power, - (-a._numerator) ** -power, - _normalize=False) + return Fraction._from_coprime_ints((-a._denominator) ** -power, + (-a._numerator) ** -power) else: # A fractional power will generally produce an # irrational number. @@ -584,15 +844,15 @@ class Fraction(numbers.Rational): def __pos__(a): """+a: Coerces a subclass instance to Fraction""" - return Fraction(a._numerator, a._denominator, _normalize=False) + return Fraction._from_coprime_ints(a._numerator, a._denominator) def __neg__(a): """-a""" - return Fraction(-a._numerator, a._denominator, _normalize=False) + return Fraction._from_coprime_ints(-a._numerator, a._denominator) def __abs__(a): """abs(a)""" - return Fraction(abs(a._numerator), a._denominator, _normalize=False) + return Fraction._from_coprime_ints(abs(a._numerator), a._denominator) def __int__(a, _index=operator.index): """int(a)""" @@ -610,12 +870,12 @@ class Fraction(numbers.Rational): def __floor__(a): """math.floor(a)""" - return a.numerator // a.denominator + return a._numerator // a._denominator def __ceil__(a): """math.ceil(a)""" # The negations cleverly convince floordiv to return the ceiling. - return -(-a.numerator // a.denominator) + return -(-a._numerator // a._denominator) def __round__(self, ndigits=None): """round(self, ndigits) @@ -623,10 +883,11 @@ class Fraction(numbers.Rational): Rounds half toward even. """ if ndigits is None: - floor, remainder = divmod(self.numerator, self.denominator) - if remainder * 2 < self.denominator: + d = self._denominator + floor, remainder = divmod(self._numerator, d) + if remainder * 2 < d: return floor - elif remainder * 2 > self.denominator: + elif remainder * 2 > d: return floor + 1 # Deal with the half case: elif floor % 2 == 0: @@ -644,36 +905,7 @@ class Fraction(numbers.Rational): def __hash__(self): """hash(self)""" - - # To make sure that the hash of a Fraction agrees with the hash - # of a numerically equal integer, float or Decimal instance, we - # follow the rules for numeric hashes outlined in the - # documentation. (See library docs, 'Built-in Types'). - - try: - dinv = pow(self._denominator, -1, _PyHASH_MODULUS) - except ValueError: - # ValueError means there is no modular inverse. - hash_ = _PyHASH_INF - else: - # The general algorithm now specifies that the absolute value of - # the hash is - # (|N| * dinv) % P - # where N is self._numerator and P is _PyHASH_MODULUS. That's - # optimized here in two ways: first, for a non-negative int i, - # hash(i) == i % P, but the int hash implementation doesn't need - # to divide, and is faster than doing % P explicitly. So we do - # hash(|N| * dinv) - # instead. Second, N is unbounded, so its product with dinv may - # be arbitrarily expensive to compute. The final answer is the - # same if we use the bounded |N| % P instead, which can again - # be done with an int hash() call. If 0 <= i < P, hash(i) == i, - # so this nested hash() call wastes a bit of time making a - # redundant copy when |N| < P, but can save an arbitrarily large - # amount of computation for large |N|. - hash_ = hash(hash(abs(self._numerator)) * dinv) - result = hash_ if self._numerator >= 0 else -hash_ - return -2 if result == -1 else result + return _hash_algorithm(self._numerator, self._denominator) def __eq__(a, b): """a == b""" |