cpython/Lib/numbers.py

394 lines
10 KiB
Python

# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Abstract Base Classes (ABCs) for numbers, according to PEP 3141.
TODO: Fill out more detailed documentation on the operators."""
from __future__ import division
from abc import ABCMeta, abstractmethod, abstractproperty
__all__ = ["Number", "Exact", "Inexact",
"Complex", "Real", "Rational", "Integral",
]
class Number(object):
"""All numbers inherit from this class.
If you just want to check if an argument x is a number, without
caring what kind, use isinstance(x, Number).
"""
__metaclass__ = ABCMeta
class Exact(Number):
"""Operations on instances of this type are exact.
As long as the result of a homogenous operation is of the same
type, you can assume that it was computed exactly, and there are
no round-off errors. Laws like commutativity and associativity
hold.
"""
Exact.register(int)
Exact.register(long)
class Inexact(Number):
"""Operations on instances of this type are inexact.
Given X, an instance of Inexact, it is possible that (X + -X) + 3
== 3, but X + (-X + 3) == 0. The exact form this error takes will
vary by type, but it's generally unsafe to compare this type for
equality.
"""
Inexact.register(complex)
Inexact.register(float)
# Inexact.register(decimal.Decimal)
class Complex(Number):
"""Complex defines the operations that work on the builtin complex type.
In short, those are: a conversion to complex, .real, .imag, +, -,
*, /, abs(), .conjugate, ==, and !=.
If it is given heterogenous arguments, and doesn't have special
knowledge about them, it should fall back to the builtin complex
type as described below.
"""
@abstractmethod
def __complex__(self):
"""Return a builtin complex instance. Called for complex(self)."""
# Will be __bool__ in 3.0.
def __nonzero__(self):
"""True if self != 0. Called for bool(self)."""
return self != 0
@abstractproperty
def real(self):
"""Retrieve the real component of this number.
This should subclass Real.
"""
raise NotImplementedError
@abstractproperty
def imag(self):
"""Retrieve the real component of this number.
This should subclass Real.
"""
raise NotImplementedError
@abstractmethod
def __add__(self, other):
"""self + other"""
raise NotImplementedError
@abstractmethod
def __radd__(self, other):
"""other + self"""
raise NotImplementedError
@abstractmethod
def __neg__(self):
"""-self"""
raise NotImplementedError
@abstractmethod
def __pos__(self):
"""+self"""
raise NotImplementedError
def __sub__(self, other):
"""self - other"""
return self + -other
def __rsub__(self, other):
"""other - self"""
return -self + other
@abstractmethod
def __mul__(self, other):
"""self * other"""
raise NotImplementedError
@abstractmethod
def __rmul__(self, other):
"""other * self"""
raise NotImplementedError
@abstractmethod
def __div__(self, other):
"""self / other without __future__ division
May promote to float.
"""
raise NotImplementedError
@abstractmethod
def __rdiv__(self, other):
"""other / self without __future__ division"""
raise NotImplementedError
@abstractmethod
def __truediv__(self, other):
"""self / other with __future__ division.
Should promote to float when necessary.
"""
raise NotImplementedError
@abstractmethod
def __rtruediv__(self, other):
"""other / self with __future__ division"""
raise NotImplementedError
@abstractmethod
def __pow__(self, exponent):
"""self**exponent; should promote to float or complex when necessary."""
raise NotImplementedError
@abstractmethod
def __rpow__(self, base):
"""base ** self"""
raise NotImplementedError
@abstractmethod
def __abs__(self):
"""Returns the Real distance from 0. Called for abs(self)."""
raise NotImplementedError
@abstractmethod
def conjugate(self):
"""(x+y*i).conjugate() returns (x-y*i)."""
raise NotImplementedError
@abstractmethod
def __eq__(self, other):
"""self == other"""
raise NotImplementedError
# __ne__ is inherited from object and negates whatever __eq__ does.
Complex.register(complex)
class Real(Complex):
"""To Complex, Real adds the operations that work on real numbers.
In short, those are: a conversion to float, trunc(), divmod,
%, <, <=, >, and >=.
Real also provides defaults for the derived operations.
"""
@abstractmethod
def __float__(self):
"""Any Real can be converted to a native float object.
Called for float(self)."""
raise NotImplementedError
@abstractmethod
def __trunc__(self):
"""trunc(self): Truncates self to an Integral.
Returns an Integral i such that:
* i>0 iff self>0;
* abs(i) <= abs(self);
* for any Integral j satisfying the first two conditions,
abs(i) >= abs(j) [i.e. i has "maximal" abs among those].
i.e. "truncate towards 0".
"""
raise NotImplementedError
def __divmod__(self, other):
"""divmod(self, other): The pair (self // other, self % other).
Sometimes this can be computed faster than the pair of
operations.
"""
return (self // other, self % other)
def __rdivmod__(self, other):
"""divmod(other, self): The pair (self // other, self % other).
Sometimes this can be computed faster than the pair of
operations.
"""
return (other // self, other % self)
@abstractmethod
def __floordiv__(self, other):
"""self // other: The floor() of self/other."""
raise NotImplementedError
@abstractmethod
def __rfloordiv__(self, other):
"""other // self: The floor() of other/self."""
raise NotImplementedError
@abstractmethod
def __mod__(self, other):
"""self % other"""
raise NotImplementedError
@abstractmethod
def __rmod__(self, other):
"""other % self"""
raise NotImplementedError
@abstractmethod
def __lt__(self, other):
"""self < other
< on Reals defines a total ordering, except perhaps for NaN."""
raise NotImplementedError
@abstractmethod
def __le__(self, other):
"""self <= other"""
raise NotImplementedError
# Concrete implementations of Complex abstract methods.
def __complex__(self):
"""complex(self) == complex(float(self), 0)"""
return complex(float(self))
@property
def real(self):
"""Real numbers are their real component."""
return +self
@property
def imag(self):
"""Real numbers have no imaginary component."""
return 0
def conjugate(self):
"""Conjugate is a no-op for Reals."""
return +self
Real.register(float)
# Real.register(decimal.Decimal)
class Rational(Real, Exact):
""".numerator and .denominator should be in lowest terms."""
@abstractproperty
def numerator(self):
raise NotImplementedError
@abstractproperty
def denominator(self):
raise NotImplementedError
# Concrete implementation of Real's conversion to float.
def __float__(self):
"""float(self) = self.numerator / self.denominator"""
return self.numerator / self.denominator
class Integral(Rational):
"""Integral adds a conversion to long and the bit-string operations."""
@abstractmethod
def __long__(self):
"""long(self)"""
raise NotImplementedError
def __index__(self):
"""index(self)"""
return long(self)
@abstractmethod
def __pow__(self, exponent, modulus=None):
"""self ** exponent % modulus, but maybe faster.
Accept the modulus argument if you want to support the
3-argument version of pow(). Raise a TypeError if exponent < 0
or any argument isn't Integral. Otherwise, just implement the
2-argument version described in Complex.
"""
raise NotImplementedError
@abstractmethod
def __lshift__(self, other):
"""self << other"""
raise NotImplementedError
@abstractmethod
def __rlshift__(self, other):
"""other << self"""
raise NotImplementedError
@abstractmethod
def __rshift__(self, other):
"""self >> other"""
raise NotImplementedError
@abstractmethod
def __rrshift__(self, other):
"""other >> self"""
raise NotImplementedError
@abstractmethod
def __and__(self, other):
"""self & other"""
raise NotImplementedError
@abstractmethod
def __rand__(self, other):
"""other & self"""
raise NotImplementedError
@abstractmethod
def __xor__(self, other):
"""self ^ other"""
raise NotImplementedError
@abstractmethod
def __rxor__(self, other):
"""other ^ self"""
raise NotImplementedError
@abstractmethod
def __or__(self, other):
"""self | other"""
raise NotImplementedError
@abstractmethod
def __ror__(self, other):
"""other | self"""
raise NotImplementedError
@abstractmethod
def __invert__(self):
"""~self"""
raise NotImplementedError
# Concrete implementations of Rational and Real abstract methods.
def __float__(self):
"""float(self) == float(long(self))"""
return float(long(self))
@property
def numerator(self):
"""Integers are their own numerators."""
return +self
@property
def denominator(self):
"""Integers have a denominator of 1."""
return 1
Integral.register(int)
Integral.register(long)