Removed the new LONG2 opcode: it's extravagant. If LONG1 isn't enough,
then the embedded argument consumes at least 256 bytes. The difference
between a 3-byte prefix (LONG2 + 2 bytes) and a 5-byte prefix (LONG4 +
4 bytes) is at worst less than 1%. Note that binary strings and binary
Unicode strings also have only "size is 1 byte, or size is 4 bytes?"
flavors, and I expect for the same reason. The only place a 2-byte
thingie was used was in BININT2, where the 2 bytes make up the *entire*
embedded argument (and now EXT2 also does this); that's a large savings
over 4 bytes, because the total opcode+argument size is so small in
the BININT2/EXT2 case.
Removed the TAKEN_FROM_ARGUMENT "number of bytes" code, and bifurcated it
into TAKEN_FROM_ARGUMENT1 and TAKEN_FROM_ARGUMENT4. Now there's enough
info in ArgumentDescriptor objects to deduce the # of bytes consumed by
each opcode.
Rearranged the order in which proto2 opcodes are listed in pickle.py.
diff --git a/Lib/pickletools.py b/Lib/pickletools.py
index 90df209..2f52f3b 100644
--- a/Lib/pickletools.py
+++ b/Lib/pickletools.py
@@ -125,7 +125,8 @@
# Represents the number of bytes consumed by a two-argument opcode where
# the first argument gives the number of bytes in the second argument.
-TAKEN_FROM_ARGUMENT = -2
+TAKEN_FROM_ARGUMENT1 = -2 # num bytes is 1-byte unsigned int
+TAKEN_FROM_ARGUMENT4 = -3 # num bytes is 4-byte signed little-endian int
class ArgumentDescriptor(object):
__slots__ = (
@@ -133,7 +134,8 @@
'name',
# length of argument, in bytes; an int; UP_TO_NEWLINE and
- # TAKEN_FROM_ARGUMENT are negative values for variable-length cases
+ # TAKEN_FROM_ARGUMENT{1,4} are negative values for variable-length
+ # cases
'n',
# a function taking a file-like object, reading this kind of argument
@@ -150,8 +152,9 @@
self.name = name
assert isinstance(n, int) and (n >= 0 or
- n is UP_TO_NEWLINE or
- n is TAKEN_FROM_ARGUMENT)
+ n in (UP_TO_NEWLINE,
+ TAKEN_FROM_ARGUMENT1,
+ TAKEN_FROM_ARGUMENT4))
self.n = n
self.reader = reader
@@ -341,7 +344,7 @@
string4 = ArgumentDescriptor(
name="string4",
- n=TAKEN_FROM_ARGUMENT,
+ n=TAKEN_FROM_ARGUMENT4,
reader=read_string4,
doc="""A counted string.
@@ -370,7 +373,7 @@
string1 = ArgumentDescriptor(
name="string1",
- n=TAKEN_FROM_ARGUMENT,
+ n=TAKEN_FROM_ARGUMENT1,
reader=read_string1,
doc="""A counted string.
@@ -434,7 +437,7 @@
unicodestring4 = ArgumentDescriptor(
name="unicodestring4",
- n=TAKEN_FROM_ARGUMENT,
+ n=TAKEN_FROM_ARGUMENT4,
reader=read_unicodestring4,
doc="""A counted Unicode string.
@@ -626,7 +629,7 @@
long1 = ArgumentDescriptor(
name="long1",
- n=TAKEN_FROM_ARGUMENT,
+ n=TAKEN_FROM_ARGUMENT1,
reader=read_long1,
doc="""A binary long, little-endian, using 1-byte size.
@@ -634,36 +637,6 @@
many bytes and interprets them as a little-endian 2's-complement long.
""")
-def read_long2(f):
- r"""
- >>> import StringIO
- >>> read_long2(StringIO.StringIO("\x02\x00\xff\x00"))
- 255L
- >>> read_long2(StringIO.StringIO("\x02\x00\xff\x7f"))
- 32767L
- >>> read_long2(StringIO.StringIO("\x02\x00\x00\xff"))
- -256L
- >>> read_long2(StringIO.StringIO("\x02\x00\x00\x80"))
- -32768L
- >>>
- """
-
- n = read_uint2(f)
- data = f.read(n)
- if len(data) != n:
- raise ValueError("not enough data in stream to read long2")
- return decode_long(data)
-
-long2 = ArgumentDescriptor(
- name="long2",
- n=TAKEN_FROM_ARGUMENT,
- reader=read_long2,
- doc="""A binary long, little-endian, using 2-byte size.
-
- This first reads two byte as an unsigned size, then reads that
- many bytes and interprets them as a little-endian 2's-complement long.
- """)
-
def read_long4(f):
r"""
>>> import StringIO
@@ -688,7 +661,7 @@
long4 = ArgumentDescriptor(
name="long4",
- n=TAKEN_FROM_ARGUMENT,
+ n=TAKEN_FROM_ARGUMENT4,
reader=read_long4,
doc="""A binary representation of a long, little-endian.
@@ -1705,19 +1678,8 @@
A more efficient encoding of a Python long; the long1 encoding
says it all."""),
- I(name="LONG2",
- code='\x8b',
- arg=long2,
- stack_before=[],
- stack_after=[pylong],
- proto=2,
- doc="""Long integer using two-byte length.
-
- A more efficient encoding of a Python long; the long2 encoding
- says it all."""),
-
I(name="LONG4",
- code='\x8c',
+ code='\x8b',
arg=long4,
stack_before=[],
stack_after=[pylong],