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

"""
Tokens: practical envelop of math object

"""
from ..renders import renders

class Token(object):

    """ Token: practical envelop of an math object """

    RENDER = 'txt'

    def __init__(self, mo, name="", ancestor = None):
        self._mo = mo
        self.name = name
        self._mathtype = None
        self._ancestor = ancestor

    @classmethod
    def random(cls):
        raise NotImplemented

    def explain(self):
        """ Yield every calculus step which have lead to self
        
        :example:
        >>> from mapytex.calculus.API import Expression
        >>> e = Expression.from_str("2+3*4")
        >>> f = e.simplify()
        >>> f
        <Integer 14>
        >>> for s in f.explain():
        ...     print(s)
        2 + 3 * 4
        2 + 12
        14
        """
        try:
            yield from self._ancestor.explain()
            yield self
        except AttributeError:
            yield self

    def __repr__(self):
        return f"<{self.__class__.__name__} {self.__txt__}>"

    def __str__(self):
        return renders[self.RENDER](self._mo)

    @property
    def __txt__(self):
        return self._mo.__txt__

    @property
    def __tex__(self):
        return self._mo.__tex__





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