#!/usr/bin/env python
# encoding: utf-8

from .renderable import Renderable

__all__ = ['Step']

class Step(Renderable):
    """
    A step is a Renderable which his only goal is to be render.
    """

    @classmethod
    def tmp_render(cls):
        """ Create a container in which the method explain return only Step object.

        >>> from .expression import Expression
        >>> exp = Expression("2*3/5")
        >>> print(exp)
        2 \\times \\frac{ 3 }{ 5 }
        >>> for i in exp.simplify().explain():
        ...     print(i)
        2 \\times \\frac{ 3 }{ 5 }
        \\frac{ 3 }{ 5 } \\times 2
        \\frac{ 3 \\times 2 }{ 5 }
        \\frac{ 6 }{ 5 }
        >>> with Step.tmp_render():
        ...     for i in exp.simplify().explain():
        ...         print(repr(i))
        < Step [2, 3, 5, /, *]>
        < Step [3, 5, /, 2, *]>
        < Step [3, 2, *, 5, /]>
        < Step [6, 5, /]>
        >>> for i in exp.simplify().explain():
        ...     print(i)
        2 \\times \\frac{ 3 }{ 5 }
        \\frac{ 3 }{ 5 } \\times 2
        \\frac{ 3 \\times 2 }{ 5 }
        \\frac{ 6 }{ 5 }

        """
        return super(Step, cls).tmp_render(Step)

    def __init__(self, exp):
        """Initiate the renderable objet

        :param pstf_tokens: the postfix list of tokens

        >>> s = Step([2, 3, '+'])
        >>> s
        < Step [2, 3, '+']>
        >>> s1 = Step([s, 5, '*'])
        >>> s1
        < Step [2, 3, '+', 5, '*']>

        """
        if isinstance(exp, Renderable):
            self.postfix_tokens = exp.postfix_tokens
        elif isinstance(exp, list):
            self.postfix_tokens = []
            for t in exp:
                try:
                    self.postfix_tokens += t.postfix_tokens
                except AttributeError:
                    self.postfix_tokens.append(t)
        else:
            raise ValueError(
                    "Can't initiate Step with {}".format(
                        exp
                        ))

    def __eq__(self, other):
        try:
            if self.postfix_tokens == other.postfix_tokens:
                return True
        except AttributeError:
            pass

        try:
            if str(self).replace(' ', '') == str(other).replace(' ',''):
                return True
        except TypeError:
            pass

        return False

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