# Source code for review.base

```
#
# base.py
#
# Copyright (c) 2016-2017 Junpei Kawamoto
#
# This file is part of rgmining-review.
#
# rgmining-review is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# rgmining-review is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Foobar. If not, see <http://www.gnu.org/licenses/>.
#
"""Defines abstract Review and Summary classes.
"""
import math
import numbers
class _ImmutableAdditiveGroup(object):
"""Immutable additive group.
Subclass must implement __add__, __neg__, and __eq__, then this class
complements __sub__ and __ne__.
"""
__slots__ = ()
def __add__(self, _):
raise NotImplementedError("Subclasses must implement __add__.")
def __sub__(self, other):
return self + (-other)
def __neg__(self):
raise NotImplementedError("Subclasses must implement __neg__.")
def __eq__(self, _):
raise NotImplementedError("Subclasses must implement __eq__.")
def __ne__(self, other):
return not self == other
class _MultipliableImmutableAdditiveGroup(_ImmutableAdditiveGroup):
"""Multipliable immutable additive group.
This is a subclass of _ImmutableAdditiveGroup.
Subclass must implement __add__, __rmul__, and __eq__, then this class
complements __div__ and __neg__.
"""
__slots__ = ()
def __rmul__(self, _):
# value must be a number.
raise NotImplementedError("Subclasses must implement __rmul__")
def __div__(self, value):
return self.__truediv__(value)
def __truediv__(self, value):
if not isinstance(value, numbers.Number):
raise TypeError("value must be an instance of numbers.Number")
return (1. / value) * self
def __floordiv__(self, value):
if not isinstance(value, numbers.Number):
raise TypeError("value must be an instance of numbers.Number")
return math.floor((1. / value) * self)
def __neg__(self):
return -1 * self
[docs]class Review(_MultipliableImmutableAdditiveGroup):
"""Abstruct class of Review.
Review is defined on a multipliable immutable additive group.
Subclass must implement the following methods;
- _eq_:
- _add_:
- _rmul_:
Review also needs to implement a property `score` to return the review
score itselt. The returned score must be a float number.
Attribute:
date: the date when this review was posted.
"""
__slots__ = ("date")
def __init__(self, date=None):
self.date = date
def __mul__(self, other):
return self.__rmul__(other)
@property
def score(self):
"""A float value representing score of this review. """
raise NotImplementedError
[docs]class Summary(object):
""" Abstract class of summary of reviews.
Summary only needs to define `differenct` and `norm` methods.
`difference` computes difference between a summary and a review.
`norm` maps a summary to a float value.
Each summary type might be related to a review type.
Summary must implements a class method `review_class` to return the
associated review class.
"""
__slots__ = ()
[docs] def difference(self, r):
"""Compute a difference between this summary and a given review score.
Args:
An instance of Review.
Returns:
The difference between of the summary and the given review.
"""
raise NotImplementedError
@property
def score(self):
"""Return a float value representing this summary.
"""
raise NotImplementedError
[docs] @classmethod
def review_class(cls):
"""A review class associated with this summary. """
raise NotImplementedError
```