Mapytex/mapytex/calculus/core/compute/minus.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2017 lafrite <lafrite@Poivre>
#
# Distributed under terms of the MIT license.

"""
Minus MO: take the opposit
"""

from ..MO.mo import MO, MOnumber
from ..MO.fraction import MOFraction
from .exceptions import MinusError


def minus(left, right):
    """ Perform the minusition of left and right

    :param left: left MO
    :param right: right MO
    :returns: Tree or MO

    >>> a = MOnumber(4)
    >>> minus(None, a)
    <MOnumber - 4>
    >>> a = MOnumber(-4)
    >>> minus(None, a)
    <MOnumber 4>
    >>> b = MOnumber(0)
    >>> minus(None, b)
    <MOnumber 0>

    """
    if not left is None:
        raise MinusError(f"'-' is a 1 arity operator, left should be None (got {left})")

    return MINUSFUNCTIONS[type(right)](right)

def monumber(right):
    """ Minusing monumber

    :param right: right MOnumber
    :returns: MONumber

    >>> a = MOnumber(4)
    >>> monumber(a)
    <MOnumber - 4>

    """
    return MO.factory(- right.value)

def mofraction(right):
    """ Minusing a mofraction

    :param right: a mofraction
    :returns: Tree with the number converted into a mofraction

    >>> a = MOFraction(6, 5)
    >>> print(mofraction(a))
    -
     > None
     > /
     | > 6
     | > 5
    >>> a = MOFraction(6, 5, True)
    >>> print(mofraction(a))
    /
     > 6
     > 5
    """
    if right.negative:
        return MOFraction(right._numerator, right._denominator)

    try:
        if right._numerator < 0:
            return MOFraction(-right._numerator, right._denominator)
    except TypeError:
        pass
    try:

        if right._denominator < 0:
            return MOFraction(right._numerator, -right._denominator)
    except TypeError:
        pass

    return MOFraction(right._numerator, right._denominator, True)

# TODO: Faire un décorateur pour un enregistrement automatique |dim. mars 11 18:24:32 EAT 2018
MINUSFUNCTIONS = {
    MOnumber: monumber,
    MOFraction: mofraction,
    }

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