currency.py 文件源码

def to_wei(number, unit):
    """
    Takes a number of a unit and converts it to wei.
    """
    if unit.lower() not in units:
        raise ValueError(
            "Unknown unit.  Must be one of {0}".format('/'.join(units.keys()))
        )

    if is_integer(number) or is_string(number):
        d_number = decimal.Decimal(value=number)
    elif isinstance(number, float):
        d_number = decimal.Decimal(value=str(number))
    elif isinstance(number, decimal.Decimal):
        d_number = number
    else:
        raise TypeError("Unsupported type.  Must be one of integer, float, or string")

    s_number = str(number)

    if d_number == 0:
        return 0

    unit_value = units[unit.lower()]

    if d_number < 1 and '.' in s_number:
        with localcontext() as ctx:
            multiplier = len(s_number) - s_number.index('.') - 1
            ctx.prec = multiplier
            d_number = decimal.Decimal(value=number, context=ctx) * 10**multiplier
        unit_value /= 10**multiplier

    result_value = d_number * unit_value

    if result_value < MIN_WEI or result_value > MAX_WEI:
        raise ValueError("Resulting wei value must be between 1 and 2**256 - 1")

    return int(result_value)