Edit: /usr/lib64/python2.6/pickle.py (44811B)
"""Create portable serialized representations of Python objects.
See module cPickle for a (much) faster implementation.
See module copy_reg for a mechanism for registering custom picklers.
See module pickletools source for extensive comments.
Classes:
Pickler
Unpickler
Functions:
dump(object, file)
dumps(object) -> string
load(file) -> object
loads(string) -> object
Misc variables:
__version__
format_version
compatible_formats
"""
__version__ = "$Revision: 65524 $" # Code version
from types import *
from copy_reg import dispatch_table
from copy_reg import _extension_registry, _inverted_registry, _extension_cache
import marshal
import sys
import struct
import re
__all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
"Unpickler", "dump", "dumps", "load", "loads"]
# These are purely informational; no code uses these.
format_version = "2.0" # File format version we write
compatible_formats = ["1.0", # Original protocol 0
"1.1", # Protocol 0 with INST added
"1.2", # Original protocol 1
"1.3", # Protocol 1 with BINFLOAT added
"2.0", # Protocol 2
] # Old format versions we can read
# Keep in synch with cPickle. This is the highest protocol number we
# know how to read.
HIGHEST_PROTOCOL = 2
# Why use struct.pack() for pickling but marshal.loads() for
# unpickling? struct.pack() is 40% faster than marshal.dumps(), but
# marshal.loads() is twice as fast as struct.unpack()!
mloads = marshal.loads
class PickleError(Exception):
"""A common base class for the other pickling exceptions."""
pass
class PicklingError(PickleError):
"""This exception is raised when an unpicklable object is passed to the
dump() method.
"""
pass
class UnpicklingError(PickleError):
"""This exception is raised when there is a problem unpickling an object,
such as a security violation.
Note that other exceptions may also be raised during unpickling, including
(but not necessarily limited to) AttributeError, EOFError, ImportError,
and IndexError.
"""
pass
# An instance of _Stop is raised by Unpickler.load_stop() in response to
# the STOP opcode, passing the object that is the result of unpickling.
class _Stop(Exception):
def __init__(self, value):
self.value = value
# Jython has PyStringMap; it's a dict subclass with string keys
try:
from org.python.core import PyStringMap
except ImportError:
PyStringMap = None
# UnicodeType may or may not be exported (normally imported from types)
try:
UnicodeType
except NameError:
UnicodeType = None
# Pickle opcodes. See pickletools.py for extensive docs. The listing
# here is in kind-of alphabetical order of 1-character pickle code.
# pickletools groups them by purpose.
MARK = '(' # push special markobject on stack
STOP = '.' # every pickle ends with STOP
POP = '0' # discard topmost stack item
POP_MARK = '1' # discard stack top through topmost markobject
DUP = '2' # duplicate top stack item
FLOAT = 'F' # push float object; decimal string argument
INT = 'I' # push integer or bool; decimal string argument
BININT = 'J' # push four-byte signed int
BININT1 = 'K' # push 1-byte unsigned int
LONG = 'L' # push long; decimal string argument
BININT2 = 'M' # push 2-byte unsigned int
NONE = 'N' # push None
PERSID = 'P' # push persistent object; id is taken from string arg
BINPERSID = 'Q' # " " " ; " " " " stack
REDUCE = 'R' # apply callable to argtuple, both on stack
STRING = 'S' # push string; NL-terminated string argument
BINSTRING = 'T' # push string; counted binary string argument
SHORT_BINSTRING = 'U' # " " ; " " " " < 256 bytes
UNICODE = 'V' # push Unicode string; raw-unicode-escaped'd argument
BINUNICODE = 'X' # " " " ; counted UTF-8 string argument
APPEND = 'a' # append stack top to list below it
BUILD = 'b' # call __setstate__ or __dict__.update()
GLOBAL = 'c' # push self.find_class(modname, name); 2 string args
DICT = 'd' # build a dict from stack items
EMPTY_DICT = '}' # push empty dict
APPENDS = 'e' # extend list on stack by topmost stack slice
GET = 'g' # push item from memo on stack; index is string arg
BINGET = 'h' # " " " " " " ; " " 1-byte arg
INST = 'i' # build & push class instance
LONG_BINGET = 'j' # push item from memo on stack; index is 4-byte arg
LIST = 'l' # build list from topmost stack items
EMPTY_LIST = ']' # push empty list
OBJ = 'o' # build & push class instance
PUT = 'p' # store stack top in memo; index is string arg
BINPUT = 'q' # " " " " " ; " " 1-byte arg
LONG_BINPUT = 'r' # " " " " " ; " " 4-byte arg
SETITEM = 's' # add key+value pair to dict
TUPLE = 't' # build tuple from topmost stack items
EMPTY_TUPLE = ')' # push empty tuple
SETITEMS = 'u' # modify dict by adding topmost key+value pairs
BINFLOAT = 'G' # push float; arg is 8-byte float encoding
TRUE = 'I01\n' # not an opcode; see INT docs in pickletools.py
FALSE = 'I00\n' # not an opcode; see INT docs in pickletools.py
# Protocol 2
PROTO = '\x80' # identify pickle protocol
NEWOBJ = '\x81' # build object by applying cls.__new__ to argtuple
EXT1 = '\x82' # push object from extension registry; 1-byte index
EXT2 = '\x83' # ditto, but 2-byte index
EXT4 = '\x84' # ditto, but 4-byte index
TUPLE1 = '\x85' # build 1-tuple from stack top
TUPLE2 = '\x86' # build 2-tuple from two topmost stack items
TUPLE3 = '\x87' # build 3-tuple from three topmost stack items
NEWTRUE = '\x88' # push True
NEWFALSE = '\x89' # push False
LONG1 = '\x8a' # push long from < 256 bytes
LONG4 = '\x8b' # push really big long
_tuplesize2code = [EMPTY_TUPLE, TUPLE1, TUPLE2, TUPLE3]
__all__.extend([x for x in dir() if re.match("[A-Z][A-Z0-9_]+$",x)])
del x
# Pickling machinery
class Pickler:
def __init__(self, file, protocol=None):
"""This takes a file-like object for writing a pickle data stream.
The optional protocol argument tells the pickler to use the
given protocol; supported protocols are 0, 1, 2. The default
protocol is 0, to be backwards compatible. (Protocol 0 is the
only protocol that can be written to a file opened in text
mode and read back successfully. When using a protocol higher
than 0, make sure the file is opened in binary mode, both when
pickling and unpickling.)
Protocol 1 is more efficient than protocol 0; protocol 2 is
more efficient than protocol 1.
Specifying a negative protocol version selects the highest
protocol version supported. The higher the protocol used, the
more recent the version of Python needed to read the pickle
produced.
The file parameter must have a write() method that accepts a single
string argument. It can thus be an open file object, a StringIO
object, or any other custom object that meets this interface.
"""
if protocol is None:
protocol = 0
if protocol < 0:
protocol = HIGHEST_PROTOCOL
elif not 0 <= protocol <= HIGHEST_PROTOCOL:
raise ValueError("pickle protocol must be <= %d" % HIGHEST_PROTOCOL)
self.write = file.write
self.memo = {}
self.proto = int(protocol)
self.bin = protocol >= 1
self.fast = 0
def clear_memo(self):
"""Clears the pickler's "memo".
The memo is the data structure that remembers which objects the
pickler has already seen, so that shared or recursive objects are
pickled by reference and not by value. This method is useful when
re-using picklers.
"""
self.memo.clear()
def dump(self, obj):
"""Write a pickled representation of obj to the open file."""
if self.proto >= 2:
self.write(PROTO + chr(self.proto))
self.save(obj)
self.write(STOP)
def memoize(self, obj):
"""Store an object in the memo."""
# The Pickler memo is a dictionary mapping object ids to 2-tuples
# that contain the Unpickler memo key and the object being memoized.
# The memo key is written to the pickle and will become
# the key in the Unpickler's memo. The object is stored in the
# Pickler memo so that transient objects are kept alive during
# pickling.
# The use of the Unpickler memo length as the memo key is just a
# convention. The only requirement is that the memo values be unique.
# But there appears no advantage to any other scheme, and this
# scheme allows the Unpickler memo to be implemented as a plain (but
# growable) array, indexed by memo key.
if self.fast:
return
assert id(obj) not in self.memo
memo_len = len(self.memo)
self.write(self.put(memo_len))
self.memo[id(obj)] = memo_len, obj
# Return a PUT (BINPUT, LONG_BINPUT) opcode string, with argument i.
def put(self, i, pack=struct.pack):
if self.bin:
if i < 256:
return BINPUT + chr(i)
else:
return LONG_BINPUT + pack("
= 2 and getattr(func, "__name__", "") == "__newobj__":
# A __reduce__ implementation can direct protocol 2 to
# use the more efficient NEWOBJ opcode, while still
# allowing protocol 0 and 1 to work normally. For this to
# work, the function returned by __reduce__ should be
# called __newobj__, and its first argument should be a
# new-style class. The implementation for __newobj__
# should be as follows, although pickle has no way to
# verify this:
#
# def __newobj__(cls, *args):
# return cls.__new__(cls, *args)
#
# Protocols 0 and 1 will pickle a reference to __newobj__,
# while protocol 2 (and above) will pickle a reference to
# cls, the remaining args tuple, and the NEWOBJ code,
# which calls cls.__new__(cls, *args) at unpickling time
# (see load_newobj below). If __reduce__ returns a
# three-tuple, the state from the third tuple item will be
# pickled regardless of the protocol, calling __setstate__
# at unpickling time (see load_build below).
#
# Note that no standard __newobj__ implementation exists;
# you have to provide your own. This is to enforce
# compatibility with Python 2.2 (pickles written using
# protocol 0 or 1 in Python 2.3 should be unpicklable by
# Python 2.2).
cls = args[0]
if not hasattr(cls, "__new__"):
raise PicklingError(
"args[0] from __newobj__ args has no __new__")
if obj is not None and cls is not obj.__class__:
raise PicklingError(
"args[0] from __newobj__ args has the wrong class")
args = args[1:]
save(cls)
save(args)
write(NEWOBJ)
else:
save(func)
save(args)
write(REDUCE)
if obj is not None:
self.memoize(obj)
# More new special cases (that work with older protocols as
# well): when __reduce__ returns a tuple with 4 or 5 items,
# the 4th and 5th item should be iterators that provide list
# items and dict items (as (key, value) tuples), or None.
if listitems is not None:
self._batch_appends(listitems)
if dictitems is not None:
self._batch_setitems(dictitems)
if state is not None:
save(state)
write(BUILD)
# Methods below this point are dispatched through the dispatch table
dispatch = {}
def save_none(self, obj):
self.write(NONE)
dispatch[NoneType] = save_none
def save_bool(self, obj):
if self.proto >= 2:
self.write(obj and NEWTRUE or NEWFALSE)
else:
self.write(obj and TRUE or FALSE)
dispatch[bool] = save_bool
def save_int(self, obj, pack=struct.pack):
if self.bin:
# If the int is small enough to fit in a signed 4-byte 2's-comp
# format, we can store it more efficiently than the general
# case.
# First one- and two-byte unsigned ints:
if obj >= 0:
if obj <= 0xff:
self.write(BININT1 + chr(obj))
return
if obj <= 0xffff:
self.write("%c%c%c" % (BININT2, obj&0xff, obj>>8))
return
# Next check for 4-byte signed ints:
high_bits = obj >> 31 # note that Python shift sign-extends
if high_bits == 0 or high_bits == -1:
# All high bits are copies of bit 2**31, so the value
# fits in a 4-byte signed int.
self.write(BININT + pack("= 2:
bytes = encode_long(obj)
n = len(bytes)
if n < 256:
self.write(LONG1 + chr(n) + bytes)
else:
self.write(LONG4 + pack("d', obj))
else:
self.write(FLOAT + repr(obj) + '\n')
dispatch[FloatType] = save_float
def save_string(self, obj, pack=struct.pack):
if self.bin:
n = len(obj)
if n < 256:
self.write(SHORT_BINSTRING + chr(n) + obj)
else:
self.write(BINSTRING + pack("= 2:
for element in obj:
save(element)
# Subtle. Same as in the big comment below.
if id(obj) in memo:
get = self.get(memo[id(obj)][0])
write(POP * n + get)
else:
write(_tuplesize2code[n])
self.memoize(obj)
return
# proto 0 or proto 1 and tuple isn't empty, or proto > 1 and tuple
# has more than 3 elements.
write(MARK)
for element in obj:
save(element)
if id(obj) in memo:
# Subtle. d was not in memo when we entered save_tuple(), so
# the process of saving the tuple's elements must have saved
# the tuple itself: the tuple is recursive. The proper action
# now is to throw away everything we put on the stack, and
# simply GET the tuple (it's already constructed). This check
# could have been done in the "for element" loop instead, but
# recursive tuples are a rare thing.
get = self.get(memo[id(obj)][0])
if proto:
write(POP_MARK + get)
else: # proto 0 -- POP_MARK not available
write(POP * (n+1) + get)
return
# No recursion.
self.write(TUPLE)
self.memoize(obj)
dispatch[TupleType] = save_tuple
# save_empty_tuple() isn't used by anything in Python 2.3. However, I
# found a Pickler subclass in Zope3 that calls it, so it's not harmless
# to remove it.
def save_empty_tuple(self, obj):
self.write(EMPTY_TUPLE)
def save_list(self, obj):
write = self.write
if self.bin:
write(EMPTY_LIST)
else: # proto 0 -- can't use EMPTY_LIST
write(MARK + LIST)
self.memoize(obj)
self._batch_appends(iter(obj))
dispatch[ListType] = save_list
# Keep in synch with cPickle's BATCHSIZE. Nothing will break if it gets
# out of synch, though.
_BATCHSIZE = 1000
def _batch_appends(self, items):
# Helper to batch up APPENDS sequences
save = self.save
write = self.write
if not self.bin:
for x in items:
save(x)
write(APPEND)
return
r = xrange(self._BATCHSIZE)
while items is not None:
tmp = []
for i in r:
try:
x = items.next()
tmp.append(x)
except StopIteration:
items = None
break
n = len(tmp)
if n > 1:
write(MARK)
for x in tmp:
save(x)
write(APPENDS)
elif n:
save(tmp[0])
write(APPEND)
# else tmp is empty, and we're done
def save_dict(self, obj):
write = self.write
if self.bin:
write(EMPTY_DICT)
else: # proto 0 -- can't use EMPTY_DICT
write(MARK + DICT)
self.memoize(obj)
self._batch_setitems(obj.iteritems())
dispatch[DictionaryType] = save_dict
if not PyStringMap is None:
dispatch[PyStringMap] = save_dict
def _batch_setitems(self, items):
# Helper to batch up SETITEMS sequences; proto >= 1 only
save = self.save
write = self.write
if not self.bin:
for k, v in items:
save(k)
save(v)
write(SETITEM)
return
r = xrange(self._BATCHSIZE)
while items is not None:
tmp = []
for i in r:
try:
tmp.append(items.next())
except StopIteration:
items = None
break
n = len(tmp)
if n > 1:
write(MARK)
for k, v in tmp:
save(k)
save(v)
write(SETITEMS)
elif n:
k, v = tmp[0]
save(k)
save(v)
write(SETITEM)
# else tmp is empty, and we're done
def save_inst(self, obj):
cls = obj.__class__
memo = self.memo
write = self.write
save = self.save
if hasattr(obj, '__getinitargs__'):
args = obj.__getinitargs__()
len(args) # XXX Assert it's a sequence
_keep_alive(args, memo)
else:
args = ()
write(MARK)
if self.bin:
save(cls)
for arg in args:
save(arg)
write(OBJ)
else:
for arg in args:
save(arg)
write(INST + cls.__module__ + '\n' + cls.__name__ + '\n')
self.memoize(obj)
try:
getstate = obj.__getstate__
except AttributeError:
stuff = obj.__dict__
else:
stuff = getstate()
_keep_alive(stuff, memo)
save(stuff)
write(BUILD)
dispatch[InstanceType] = save_inst
def save_global(self, obj, name=None, pack=struct.pack):
write = self.write
memo = self.memo
if name is None:
name = obj.__name__
module = getattr(obj, "__module__", None)
if module is None:
module = whichmodule(obj, name)
try:
__import__(module)
mod = sys.modules[module]
klass = getattr(mod, name)
except (ImportError, KeyError, AttributeError):
raise PicklingError(
"Can't pickle %r: it's not found as %s.%s" %
(obj, module, name))
else:
if klass is not obj:
raise PicklingError(
"Can't pickle %r: it's not the same object as %s.%s" %
(obj, module, name))
if self.proto >= 2:
code = _extension_registry.get((module, name))
if code:
assert code > 0
if code <= 0xff:
write(EXT1 + chr(code))
elif code <= 0xffff:
write("%c%c%c" % (EXT2, code&0xff, code>>8))
else:
write(EXT4 + pack("d', self.read(8))[0])
dispatch[BINFLOAT] = load_binfloat
def load_string(self):
rep = self.readline()[:-1]
for q in "\"'": # double or single quote
if rep.startswith(q):
if not rep.endswith(q):
raise ValueError, "insecure string pickle"
rep = rep[len(q):-len(q)]
break
else:
raise ValueError, "insecure string pickle"
self.append(rep.decode("string-escape"))
dispatch[STRING] = load_string
def load_binstring(self):
len = mloads('i' + self.read(4))
self.append(self.read(len))
dispatch[BINSTRING] = load_binstring
def load_unicode(self):
self.append(unicode(self.readline()[:-1],'raw-unicode-escape'))
dispatch[UNICODE] = load_unicode
def load_binunicode(self):
len = mloads('i' + self.read(4))
self.append(unicode(self.read(len),'utf-8'))
dispatch[BINUNICODE] = load_binunicode
def load_short_binstring(self):
len = ord(self.read(1))
self.append(self.read(len))
dispatch[SHORT_BINSTRING] = load_short_binstring
def load_tuple(self):
k = self.marker()
self.stack[k:] = [tuple(self.stack[k+1:])]
dispatch[TUPLE] = load_tuple
def load_empty_tuple(self):
self.stack.append(())
dispatch[EMPTY_TUPLE] = load_empty_tuple
def load_tuple1(self):
self.stack[-1] = (self.stack[-1],)
dispatch[TUPLE1] = load_tuple1
def load_tuple2(self):
self.stack[-2:] = [(self.stack[-2], self.stack[-1])]
dispatch[TUPLE2] = load_tuple2
def load_tuple3(self):
self.stack[-3:] = [(self.stack[-3], self.stack[-2], self.stack[-1])]
dispatch[TUPLE3] = load_tuple3
def load_empty_list(self):
self.stack.append([])
dispatch[EMPTY_LIST] = load_empty_list
def load_empty_dictionary(self):
self.stack.append({})
dispatch[EMPTY_DICT] = load_empty_dictionary
def load_list(self):
k = self.marker()
self.stack[k:] = [self.stack[k+1:]]
dispatch[LIST] = load_list
def load_dict(self):
k = self.marker()
d = {}
items = self.stack[k+1:]
for i in range(0, len(items), 2):
key = items[i]
value = items[i+1]
d[key] = value
self.stack[k:] = [d]
dispatch[DICT] = load_dict
# INST and OBJ differ only in how they get a class object. It's not
# only sensible to do the rest in a common routine, the two routines
# previously diverged and grew different bugs.
# klass is the class to instantiate, and k points to the topmost mark
# object, following which are the arguments for klass.__init__.
def _instantiate(self, klass, k):
args = tuple(self.stack[k+1:])
del self.stack[k:]
instantiated = 0
if (not args and
type(klass) is ClassType and
not hasattr(klass, "__getinitargs__")):
try:
value = _EmptyClass()
value.__class__ = klass
instantiated = 1
except RuntimeError:
# In restricted execution, assignment to inst.__class__ is
# prohibited
pass
if not instantiated:
try:
value = klass(*args)
except TypeError, err:
raise TypeError, "in constructor for %s: %s" % (
klass.__name__, str(err)), sys.exc_info()[2]
self.append(value)
def load_inst(self):
module = self.readline()[:-1]
name = self.readline()[:-1]
klass = self.find_class(module, name)
self._instantiate(klass, self.marker())
dispatch[INST] = load_inst
def load_obj(self):
# Stack is ... markobject classobject arg1 arg2 ...
k = self.marker()
klass = self.stack.pop(k+1)
self._instantiate(klass, k)
dispatch[OBJ] = load_obj
def load_newobj(self):
args = self.stack.pop()
cls = self.stack[-1]
obj = cls.__new__(cls, *args)
self.stack[-1] = obj
dispatch[NEWOBJ] = load_newobj
def load_global(self):
module = self.readline()[:-1]
name = self.readline()[:-1]
klass = self.find_class(module, name)
self.append(klass)
dispatch[GLOBAL] = load_global
def load_ext1(self):
code = ord(self.read(1))
self.get_extension(code)
dispatch[EXT1] = load_ext1
def load_ext2(self):
code = mloads('i' + self.read(2) + '\000\000')
self.get_extension(code)
dispatch[EXT2] = load_ext2
def load_ext4(self):
code = mloads('i' + self.read(4))
self.get_extension(code)
dispatch[EXT4] = load_ext4
def get_extension(self, code):
nil = []
obj = _extension_cache.get(code, nil)
if obj is not nil:
self.append(obj)
return
key = _inverted_registry.get(code)
if not key:
raise ValueError("unregistered extension code %d" % code)
obj = self.find_class(*key)
_extension_cache[code] = obj
self.append(obj)
def find_class(self, module, name):
# Subclasses may override this
__import__(module)
mod = sys.modules[module]
klass = getattr(mod, name)
return klass
def load_reduce(self):
stack = self.stack
args = stack.pop()
func = stack[-1]
value = func(*args)
stack[-1] = value
dispatch[REDUCE] = load_reduce
def load_pop(self):
del self.stack[-1]
dispatch[POP] = load_pop
def load_pop_mark(self):
k = self.marker()
del self.stack[k:]
dispatch[POP_MARK] = load_pop_mark
def load_dup(self):
self.append(self.stack[-1])
dispatch[DUP] = load_dup
def load_get(self):
self.append(self.memo[self.readline()[:-1]])
dispatch[GET] = load_get
def load_binget(self):
i = ord(self.read(1))
self.append(self.memo[repr(i)])
dispatch[BINGET] = load_binget
def load_long_binget(self):
i = mloads('i' + self.read(4))
self.append(self.memo[repr(i)])
dispatch[LONG_BINGET] = load_long_binget
def load_put(self):
self.memo[self.readline()[:-1]] = self.stack[-1]
dispatch[PUT] = load_put
def load_binput(self):
i = ord(self.read(1))
self.memo[repr(i)] = self.stack[-1]
dispatch[BINPUT] = load_binput
def load_long_binput(self):
i = mloads('i' + self.read(4))
self.memo[repr(i)] = self.stack[-1]
dispatch[LONG_BINPUT] = load_long_binput
def load_append(self):
stack = self.stack
value = stack.pop()
list = stack[-1]
list.append(value)
dispatch[APPEND] = load_append
def load_appends(self):
stack = self.stack
mark = self.marker()
list = stack[mark - 1]
list.extend(stack[mark + 1:])
del stack[mark:]
dispatch[APPENDS] = load_appends
def load_setitem(self):
stack = self.stack
value = stack.pop()
key = stack.pop()
dict = stack[-1]
dict[key] = value
dispatch[SETITEM] = load_setitem
def load_setitems(self):
stack = self.stack
mark = self.marker()
dict = stack[mark - 1]
for i in range(mark + 1, len(stack), 2):
dict[stack[i]] = stack[i + 1]
del stack[mark:]
dispatch[SETITEMS] = load_setitems
def load_build(self):
stack = self.stack
state = stack.pop()
inst = stack[-1]
setstate = getattr(inst, "__setstate__", None)
if setstate:
setstate(state)
return
slotstate = None
if isinstance(state, tuple) and len(state) == 2:
state, slotstate = state
if state:
try:
inst.__dict__.update(state)
except RuntimeError:
# XXX In restricted execution, the instance's __dict__
# is not accessible. Use the old way of unpickling
# the instance variables. This is a semantic
# difference when unpickling in restricted
# vs. unrestricted modes.
# Note, however, that cPickle has never tried to do the
# .update() business, and always uses
# PyObject_SetItem(inst.__dict__, key, value) in a
# loop over state.items().
for k, v in state.items():
setattr(inst, k, v)
if slotstate:
for k, v in slotstate.items():
setattr(inst, k, v)
dispatch[BUILD] = load_build
def load_mark(self):
self.append(self.mark)
dispatch[MARK] = load_mark
def load_stop(self):
value = self.stack.pop()
raise _Stop(value)
dispatch[STOP] = load_stop
# Helper class for load_inst/load_obj
class _EmptyClass:
pass
# Encode/decode longs in linear time.
import binascii as _binascii
def encode_long(x):
r"""Encode a long to a two's complement little-endian binary string.
Note that 0L is a special case, returning an empty string, to save a
byte in the LONG1 pickling context.
>>> encode_long(0L)
''
>>> encode_long(255L)
'\xff\x00'
>>> encode_long(32767L)
'\xff\x7f'
>>> encode_long(-256L)
'\x00\xff'
>>> encode_long(-32768L)
'\x00\x80'
>>> encode_long(-128L)
'\x80'
>>> encode_long(127L)
'\x7f'
>>>
"""
if x == 0:
return ''
if x > 0:
ashex = hex(x)
assert ashex.startswith("0x")
njunkchars = 2 + ashex.endswith('L')
nibbles = len(ashex) - njunkchars
if nibbles & 1:
# need an even # of nibbles for unhexlify
ashex = "0x0" + ashex[2:]
elif int(ashex[2], 16) >= 8:
# "looks negative", so need a byte of sign bits
ashex = "0x00" + ashex[2:]
else:
# Build the 256's-complement: (1L << nbytes) + x. The trick is
# to find the number of bytes in linear time (although that should
# really be a constant-time task).
ashex = hex(-x)
assert ashex.startswith("0x")
njunkchars = 2 + ashex.endswith('L')
nibbles = len(ashex) - njunkchars
if nibbles & 1:
# Extend to a full byte.
nibbles += 1
nbits = nibbles * 4
x += 1L << nbits
assert x > 0
ashex = hex(x)
njunkchars = 2 + ashex.endswith('L')
newnibbles = len(ashex) - njunkchars
if newnibbles < nibbles:
ashex = "0x" + "0" * (nibbles - newnibbles) + ashex[2:]
if int(ashex[2], 16) < 8:
# "looks positive", so need a byte of sign bits
ashex = "0xff" + ashex[2:]
if ashex.endswith('L'):
ashex = ashex[2:-1]
else:
ashex = ashex[2:]
assert len(ashex) & 1 == 0, (x, ashex)
binary = _binascii.unhexlify(ashex)
return binary[::-1]
def decode_long(data):
r"""Decode a long from a two's complement little-endian binary string.
>>> decode_long('')
0L
>>> decode_long("\xff\x00")
255L
>>> decode_long("\xff\x7f")
32767L
>>> decode_long("\x00\xff")
-256L
>>> decode_long("\x00\x80")
-32768L
>>> decode_long("\x80")
-128L
>>> decode_long("\x7f")
127L
"""
nbytes = len(data)
if nbytes == 0:
return 0L
ashex = _binascii.hexlify(data[::-1])
n = long(ashex, 16) # quadratic time before Python 2.3; linear now
if data[-1] >= '\x80':
n -= 1L << (nbytes * 8)
return n
# Shorthands
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
def dump(obj, file, protocol=None):
Pickler(file, protocol).dump(obj)
def dumps(obj, protocol=None):
file = StringIO()
Pickler(file, protocol).dump(obj)
return file.getvalue()
def load(file):
return Unpickler(file).load()
def loads(str):
file = StringIO(str)
return Unpickler(file).load()
# Doctest
def _test():
import doctest
return doctest.testmod()
if __name__ == "__main__":
_test()