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Copy pathstructlib.py
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108 lines (98 loc) · 2.87 KB
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##
# .python.structlib - module for extracting serialized data
##
import struct
from .functools import Composition as compose
null_sequence = b'\xff\xff\xff\xff'
# Always to and from network order.
# Create a pair, (pack, unpack) for the given `struct` format.'
def mk_pack(x):
s = struct.Struct('!' + x)
if len(x) > 1:
def pack(y, p = s.pack):
return p(*y)
return (pack, s.unpack_from)
else:
def unpack(y, p = s.unpack_from):
return p(y)[0]
return (s.pack, unpack)
byte_pack, byte_unpack = lambda x: bytes((x,)), lambda x: x[0]
double_pack, double_unpack = mk_pack("d")
float_pack, float_unpack = mk_pack("f")
dd_pack, dd_unpack = mk_pack("dd")
ddd_pack, ddd_unpack = mk_pack("ddd")
dddd_pack, dddd_unpack = mk_pack("dddd")
LH_pack, LH_unpack = mk_pack("LH")
lH_pack, lH_unpack = mk_pack("lH")
llL_pack, llL_unpack = mk_pack("llL")
qll_pack, qll_unpack = mk_pack("qll")
dll_pack, dll_unpack = mk_pack("dll")
dl_pack, dl_unpack = mk_pack("dl")
ql_pack, ql_unpack = mk_pack("ql")
hhhh_pack, hhhh_unpack = mk_pack("hhhh")
longlong_pack, longlong_unpack = mk_pack("q")
ulonglong_pack, ulonglong_unpack = mk_pack("Q")
# Optimizations for int2, int4, and int8.
try:
from ..port import optimized as opt
from sys import byteorder as bo
if bo == 'little':
short_unpack = opt.swap_int2_unpack
short_pack = opt.swap_int2_pack
ushort_unpack = opt.swap_uint2_unpack
ushort_pack = opt.swap_uint2_pack
long_unpack = opt.swap_int4_unpack
long_pack = opt.swap_int4_pack
ulong_unpack = opt.swap_uint4_unpack
ulong_pack = opt.swap_uint4_pack
if hasattr(opt, 'uint8_pack'):
longlong_unpack = opt.swap_int8_unpack
longlong_pack = opt.swap_int8_pack
ulonglong_unpack = opt.swap_uint8_unpack
ulonglong_pack = opt.swap_uint8_pack
elif bo == 'big':
short_unpack = opt.int2_unpack
short_pack = opt.int2_pack
ushort_unpack = opt.uint2_unpack
ushort_pack = opt.uint2_pack
long_unpack = opt.int4_unpack
long_pack = opt.int4_pack
ulong_unpack = opt.uint4_unpack
ulong_pack = opt.uint4_pack
if hasattr(opt, 'uint8_pack'):
longlong_unpack = opt.int8_unpack
longlong_pack = opt.int8_pack
ulonglong_unpack = opt.uint8_unpack
ulonglong_pack = opt.uint8_pack
del bo, opt
except ImportError:
short_pack, short_unpack = mk_pack("h")
ushort_pack, ushort_unpack = mk_pack("H")
long_pack, long_unpack = mk_pack("l")
ulong_pack, ulong_unpack = mk_pack("L")
def split_sized_data(
data,
ulong_unpack = ulong_unpack,
null_field = 0xFFFFFFFF,
len = len,
errmsg = "insufficient data in field {0}, required {1} bytes, {2} remaining".format
):
"""
Given serialized record data, return a tuple of tuples of type Oids and
attributes.
"""
v = memoryview(data)
f = 1
while v:
l = ulong_unpack(v)
if l == null_field:
v = v[4:]
yield None
continue
l += 4
d = v[4:l].tobytes()
if len(d) < l-4:
raise ValueError(errmsg(f, l - 4, len(d)))
v = v[l:]
f += 1
yield d