98 lines
1.8 KiB
Python
98 lines
1.8 KiB
Python
#! /usr/bin/env python
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# -*- coding: utf-8 -*-
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# vim:fenc=utf-8
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#
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# Copyright © 2017 lafrite <lafrite@Poivre>
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#
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# Distributed under terms of the MIT license.
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"""
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Minus MO: take the opposit
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"""
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from multipledispatch import Dispatcher
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from ..MO.mo import MO, MOnumber
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from ..MO.fraction import MOFraction
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from .exceptions import MinusError
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minus_doc = """ Opposite of a MO
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:param left: None
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:param right: right MO
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:returns: Tree or MO
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"""
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minus = Dispatcher("minus", doc=minus_doc)
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@minus.register(type(None), MOnumber)
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def monumber(left, right):
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"""
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>>> a = MOnumber(4)
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>>> minus(None, a)
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<MOnumber - 4>
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"""
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return MO.factory(- right.value)
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@minus.register(type(None), MOFraction)
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def mofraction(left, right):
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""" 4 differents cases
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Either fraction , numerator or denominator is negative
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>>> a = MOFraction(6, 5)
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>>> print(minus(None, a))
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-
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> None
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> /
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| > 6
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| > 5
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The fraction is negative
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>>> a = MOFraction(6, 5, True)
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>>> print(minus(None, a))
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/
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> 6
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> 5
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Numerator is negative
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>>> a = MOFraction(-6, 5)
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>>> print(minus(None, a))
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/
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> 6
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> 5
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Denominators is negative
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>>> a = MOFraction(6, -5)
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>>> print(minus(None, a))
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/
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> 6
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> 5
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"""
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if right.negative:
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return MOFraction(right._numerator, right._denominator)
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try:
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if right._numerator < 0:
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return MOFraction(-right._numerator, right._denominator)
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except TypeError:
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pass
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try:
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if right._denominator < 0:
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return MOFraction(right._numerator, -right._denominator)
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except TypeError:
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pass
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return MOFraction(right._numerator, right._denominator, True)
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# -----------------------------
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# Reglages pour 'vim'
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# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
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# cursor: 16 del
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