# -*- coding: utf-8 -*-
try:
    from functools import total_ordering
except ImportError:
    """ Backport to work with Python 2.6 """
    def total_ordering(cls):
        """Class decorator that fills in missing ordering methods"""
        convert = {
            '__lt__': [
                (
                    '__gt__',
                    lambda self, other: not (self < other or self == other)
                ),
                (
                    '__le__',
                    lambda self, other: self < other or self == other
                ),
                (
                    '__ge__',
                    lambda self, other: not self < other
                )],
            '__le__': [
                (
                    '__ge__',
                    lambda self, other: not self <= other or self == other
                ),
                (
                    '__lt__',
                    lambda self, other: self <= other and not self == other
                ),
                (
                    '__gt__',
                    lambda self, other: not self <= other
                )],
            '__gt__': [
                (
                    '__lt__',
                    lambda self, other: not (self > other or self == other)
                ),
                (
                    '__ge__',
                    lambda self, other: self > other or self == other
                ),
                (
                    '__le__',
                    lambda self, other: not self > other
                )],
            '__ge__': [
                (
                    '__le__',
                    lambda self, other: (not self >= other) or self == other
                ),
                (
                    '__gt__',
                    lambda self, other: self >= other and not self == other
                ),
                (
                    '__lt__',
                    lambda self, other: not self >= other
                )]
        }
        roots = set(dir(cls)) & set(convert)
        if not roots:
            raise ValueError(
                'must define at least one ordering operation: < > <= >='
            )
        root = max(roots)       # prefer __lt__ to __le__ to __gt__ to __ge__
        for opname, opfunc in convert[root]:
            if opname not in roots:
                opfunc.__name__ = opname
                opfunc.__doc__ = getattr(int, opname).__doc__
                setattr(cls, opname, opfunc)
        return cls