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import array
import struct
import sys
from typing import Sequence, MutableSequence, Dict, Optional, Union, Generator
from clickhouse_connect.driver.exceptions import ProgrammingError, StreamClosedError, DataError
from clickhouse_connect.driver.types import Closable
# pylint: disable=invalid-name
must_swap = sys.byteorder == 'big'
int_size = array.array('i').itemsize
low_card_version = 1
array_map = {1: 'b', 2: 'h', 4: 'i', 8: 'q'}
decimal_prec = {32: 9, 64: 18, 128: 38, 256: 79}
if int_size == 2:
array_map[4] = 'l'
array_sizes = {v: k for k, v in array_map.items()}
array_sizes['f'] = 4
array_sizes['d'] = 8
np_date_types = {0: '[s]', 3: '[ms]', 6: '[us]', 9: '[ns]'}
def array_type(size: int, signed: bool):
"""
Determines the Python array.array code for the requested byte size
:param size: byte size
:param signed: whether int types should be signed or unsigned
:return: Python array.array code
"""
try:
code = array_map[size]
except KeyError:
return None
return code if signed else code.upper()
def write_array(code: str, column: Sequence, dest: MutableSequence, col_name: Optional[str]=None):
"""
Write a column of native Python data matching the array.array code
:param code: Python array.array code matching the column data type
:param column: Column of native Python values
:param dest: Destination byte buffer
:param col_name: Optional column name for error tracking
"""
try:
buff = struct.Struct(f'<{len(column)}{code}')
dest += buff.pack(*column)
except (TypeError, OverflowError, struct.error) as ex:
col_msg = ''
if col_name:
col_msg = f' for source column `{col_name}`'
raise DataError(f'Unable to create Python array{col_msg}. This is usually caused by trying to insert None ' +
'values into a ClickHouse column that is not Nullable') from ex
def write_uint64(value: int, dest: MutableSequence):
"""
Write a single UInt64 value to a binary write buffer
:param value: UInt64 value to write
:param dest: Destination byte buffer
"""
dest.extend(value.to_bytes(8, 'little'))
def write_leb128(value: int, dest: MutableSequence):
"""
Write a LEB128 encoded integer to a target binary buffer
:param value: Integer value (positive only)
:param dest: Target buffer
"""
while True:
b = value & 0x7f
value >>= 7
if value == 0:
dest.append(b)
return
dest.append(0x80 | b)
def decimal_size(prec: int):
"""
Determine the bit size of a ClickHouse or Python Decimal needed to store a value of the requested precision
:param prec: Precision of the Decimal in total number of base 10 digits
:return: Required bit size
"""
if prec < 1 or prec > 79:
raise ArithmeticError(f'Invalid precision {prec} for ClickHouse Decimal type')
if prec < 10:
return 32
if prec < 19:
return 64
if prec < 39:
return 128
return 256
def unescape_identifier(x: str) -> str:
if x.startswith('`') and x.endswith('`'):
return x[1:-1]
return x
def dict_copy(source: Dict = None, update: Optional[Dict] = None) -> Dict:
copy = source.copy() if source else {}
if update:
copy.update(update)
return copy
def dict_add(source: Dict, key: str, value: any) -> Dict:
if value is not None:
source[key] = value
return source
def empty_gen():
yield from ()
def coerce_int(val: Optional[Union[str, int]]) -> int:
if not val:
return 0
return int(val)
def coerce_bool(val: Optional[Union[str, bool]]):
if not val:
return False
return val is True or (isinstance(val, str) and val.lower() in ('true', '1', 'y', 'yes'))
def first_value(column: Sequence, nullable:bool = True):
if nullable:
return next((x for x in column if x is not None), None)
if len(column):
return column[0]
return None
class SliceView(Sequence):
"""
Provides a view into a sequence rather than copying. Borrows liberally from
https://gist.github.com/mathieucaroff/0cf094325fb5294fb54c6a577f05a2c1
Also see the discussion on SO: https://stackoverflow.com/questions/3485475/can-i-create-a-view-on-a-python-list
"""
slots = ('_source', '_range')
def __init__(self, source: Sequence, source_slice: Optional[slice] = None):
if isinstance(source, SliceView):
self._source = source._source
self._range = source._range[source_slice]
else:
self._source = source
if source_slice is None:
self._range = range(len(source))
else:
self._range = range(len(source))[source_slice]
def __len__(self):
return len(self._range)
def __getitem__(self, i):
if isinstance(i, slice):
return SliceView(self._source, i)
return self._source[self._range[i]]
def __str__(self):
r = self._range
return str(self._source[slice(r.start, r.stop, r.step)])
def __repr__(self):
r = self._range
return f'SliceView({self._source[slice(r.start, r.stop, r.step)]})'
def __eq__(self, other):
if self is other:
return True
if len(self) != len(other):
return False
for v, w in zip(self, other):
if v != w:
return False
return True
class StreamContext:
"""
Wraps a generator and its "source" in a Context. This ensures that the source will be "closed" even if the
generator is not fully consumed or there is an exception during consumption
"""
__slots__ = 'source', 'gen', '_in_context'
def __init__(self, source: Closable, gen: Generator):
self.source = source
self.gen = gen
self._in_context = False
def __iter__(self):
return self
def __next__(self):
if not self._in_context:
raise ProgrammingError('Stream should be used within a context')
return next(self.gen)
def __enter__(self):
if not self.gen:
raise StreamClosedError
self._in_context = True
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self._in_context = False
self.source.close()
self.gen = None
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