DSL for simple products and product descriptions

products_and_queries.py

class Product(object):

    def __init__(self, color, size, weight):
        self.color, self.size, self.weight = color, size, weight

class CombinableQueryMixin(object):

    def __and__(self, other):
        return CompoundQuery(self, other, anded=True)

    def __or__(self, other):
        return CompoundQuery(self, other, anded=False)

    def __invert__(self):
        self.negated = not self.negated
        return self


class BasicProductQuery(CombinableQueryMixin):

    DIMENSIONS = ['color', 'size', 'weight']

    def __init__(self, **kwargs):
        dimension, value = kwargs.items()[0]
        assert dimension in self.DIMENSIONS
        self._dimension = dimension
        self._value = value
        self.negated = False

    def __contains__(self, product):
        return (self._value == getattr(product, self._dimension)) != self.negated


class CompoundQuery(CombinableQueryMixin):

    def __init__(self, left, right, anded=True):
        self._and = anded
        self.left, self.right = left, right
        self.negated = False

    def __contains__(self, product):
        op = all if self.negated != self._and else any
        if self.negated:
            return op([not product in self.left, not product in self.right])
        else:
            return op([product in self.left, product in self.right])