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from decimal import Decimal, localcontext
from .base import FormatColumn
from .exceptions import ColumnTypeMismatchException
from .intcolumn import Int128Column, Int256Column
class DecimalColumn(FormatColumn):
py_types = (Decimal, float, int)
max_precision = None
def __init__(self, precision, scale, types_check=False, **kwargs):
self.precision = precision
self.scale = scale
super(DecimalColumn, self).__init__(**kwargs)
if types_check:
def check_item(value):
parts = str(value).split('.')
int_part = parts[0]
if len(int_part) > precision:
raise ColumnTypeMismatchException(value)
self.check_item = check_item
def after_read_items(self, items, nulls_map=None):
if self.scale >= 1:
scale = 10 ** self.scale
if nulls_map is None:
return tuple(Decimal(item) / scale for item in items)
else:
return tuple(
(None if is_null else Decimal(items[i]) / scale)
for i, is_null in enumerate(nulls_map)
)
else:
if nulls_map is None:
return tuple(Decimal(item) for item in items)
else:
return tuple(
(None if is_null else Decimal(items[i]))
for i, is_null in enumerate(nulls_map)
)
def before_write_items(self, items, nulls_map=None):
null_value = self.null_value
if self.scale >= 1:
scale = 10 ** self.scale
for i, item in enumerate(items):
if nulls_map and nulls_map[i]:
items[i] = null_value
else:
items[i] = int(Decimal(str(item)) * scale)
else:
for i, item in enumerate(items):
if nulls_map and nulls_map[i]:
items[i] = null_value
else:
items[i] = int(Decimal(str(item)))
# Override default precision to the maximum supported by underlying type.
def _write_data(self, items, buf):
with localcontext() as ctx:
ctx.prec = self.max_precision
super(DecimalColumn, self)._write_data(items, buf)
def _read_data(self, n_items, buf, nulls_map=None):
with localcontext() as ctx:
ctx.prec = self.max_precision
return super(DecimalColumn, self)._read_data(
n_items, buf, nulls_map=nulls_map
)
class Decimal32Column(DecimalColumn):
format = 'i'
max_precision = 9
class Decimal64Column(DecimalColumn):
format = 'q'
max_precision = 18
class Decimal128Column(DecimalColumn, Int128Column):
max_precision = 38
class Decimal256Column(DecimalColumn, Int256Column):
max_precision = 76
def create_decimal_column(spec, column_options):
precision, scale = spec[8:-1].split(',')
precision, scale = int(precision), int(scale)
# Maximum precisions for underlying types are:
# Int32 10**9
# Int64 10**18
# Int128 10**38
# Int256 10**76
if precision <= 9:
cls = Decimal32Column
elif precision <= 18:
cls = Decimal64Column
elif precision <= 38:
cls = Decimal128Column
else:
cls = Decimal256Column
return cls(precision, scale, **column_options)
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