Source code for mlthon.basics.qty

from decimal import Decimal, Context, Inexact


class Qty(object):
    _IMPLIED_DECIMALS = 10  # Number of implied decimals
    _EXPONENT = Decimal(10) ** _IMPLIED_DECIMALS  # 10000000000
    _DECIMAL = Decimal(10) ** -_IMPLIED_DECIMALS  # 0.0000000001

    def __init__(self, raw_val: Decimal):
        self.raw_value_ = raw_val.quantize(Qty._DECIMAL, context=Context(traps=[Inexact]))

    @staticmethod
    def from_str(s: str):
        return Qty(Decimal(s))

    @staticmethod
    def from_int(i: int):
        return Qty(Decimal(i))

    @staticmethod
    def from_json(value):
        if isinstance(value, Decimal):
            return Qty(value)
        elif isinstance(value, str):
            return Qty.from_str(value)
        elif isinstance(value, int):
            return Qty.from_int(value)
        else:
            raise NotImplementedError

    @staticmethod
    def zero():
        return Qty(Decimal(0))

    @staticmethod
    def null():
        """ Note that a null Qty cannot be used to perform arithmetic comparisons with other Qty objects. """
        return Qty(Decimal('Nan'))

    def is_null(self):
        return self.raw_value_.is_nan()

    def to_float(self):
        return float(self.raw_value_)

    def to_str(self, num_decimal=_IMPLIED_DECIMALS):
        decimal = Decimal(10) ** -num_decimal
        return self.raw_value_.quantize(decimal, context=Context(traps=[Inexact])).to_eng_string()

    def __repr__(self):
        return "{Qty: " + self.raw_value_.to_eng_string() + ", implieds: " + str(Qty._IMPLIED_DECIMALS) + "}"

    def __str__(self):
        return self.raw_value_.to_eng_string()

    # Arithmetic operation
    def __add__(self, other):
        return Qty(self.raw_value_ + other.raw_value_)

    def __sub__(self, other):
        return Qty(self.raw_value_ - other.raw_value_)

    def __mul__(self, other):
        return Qty(self.raw_value_ * other.raw_value_)

    def __truediv__(self, other):
        return Qty(self.raw_value_ / other.raw_value_)

    def __neg__(self):
        return Qty(-self.raw_value_)

    # Comparison
    def __eq__(self, other):
        return self.raw_value_ == other.raw_value_

    def __lt__(self, other):
        return self.raw_value_ < other.raw_value_

    def __le__(self, other):
        return self.raw_value_ <= other.raw_value_

    def __ge__(self, other):
        return self.raw_value_ >= other.raw_value_

    def __gt__(self, other):
        return self.raw_value_ > other.raw_value_

    def __abs__(self):
        return Qty(abs(self.raw_value_))