tax.py 文件源码

def _reverse_unit_compute(cls, price_unit, taxes, date):
        rate, amount = 0, 0
        update_unit_price = False
        unit_price_variation_amount = 0
        unit_price_variation_rate = 0
        for _, group_taxes in groupby(taxes, key=cls._group_taxes):
            group_taxes = list(group_taxes)
            g_rate, g_amount = cls._reverse_rate_amount(group_taxes, date)
            if update_unit_price:
                g_amount += unit_price_variation_amount * g_rate
                g_rate += unit_price_variation_rate * g_rate

            g_update_unit_price = any(t.update_unit_price for t in group_taxes)
            update_unit_price |= g_update_unit_price
            if g_update_unit_price:
                unit_price_variation_amount += g_amount
                unit_price_variation_rate += g_rate

            rate += g_rate
            amount += g_amount

        return (price_unit - amount) / (1 + rate)