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

"""
Computing with MO
"""

from .exceptions import ComputeError
from .add import add
from .minus import minus
from .multiply import multiply
from .divide import divide

OPERATIONS = {
        "+": add, 
        "-": minus, 
        "*": multiply,
        "/": divide,
        }

def compute(node, left_v, right_v):
    """ 
    Computing a node 

    :example:

    >>> from ..MO.mo import MOnumber
    >>> compute("+", MOnumber(1), MOnumber(2))
    <MOnumber 3>
    >>> compute("-", None, MOnumber(2))
    <MOnumber - 2>
    >>> compute("*", MOnumber(1), MOnumber(2))
    <MOnumber 2>
    >>> compute("~", MOnumber(1), MOnumber(2))
    Traceback (most recent call last):
        ...
    mapytex.calculus.core.compute.exceptions.ComputeError: Unknown operation (~)
    """
    try:
        operation = OPERATIONS[node]
    except KeyError:
        raise ComputeError(f"Unknown operation ({node})")

    return operation(left_v, right_v)


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