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v0.8.1
v0.8.1
https://github.com/python/cpython
Tip revision: 1da43e5e916949c8e849e656d9d05fa4b9d6836c authored by Benjamin Peterson on 26 June 2009, 13:21:52 UTC
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
Tip revision: 1da43e5
dis.py
"""Disassembler of Python byte code into mnemonics."""
import sys
import types
from opcode import *
from opcode import __all__ as _opcodes_all
__all__ = ["dis", "disassemble", "distb", "disco",
"findlinestarts", "findlabels"] + _opcodes_all
del _opcodes_all
def dis(x=None):
"""Disassemble classes, methods, functions, or code.
With no argument, disassemble the last traceback.
"""
if x is None:
distb()
return
if hasattr(x, '__func__'):
x = x.__func__
if hasattr(x, '__code__'):
x = x.__code__
if hasattr(x, '__dict__'):
items = sorted(x.__dict__.items())
for name, x1 in items:
if isinstance(x1, (types.MethodType, types.FunctionType,
types.CodeType, type)):
print("Disassembly of %s:" % name)
try:
dis(x1)
except TypeError as msg:
print("Sorry:", msg)
print()
elif hasattr(x, 'co_code'):
disassemble(x)
elif isinstance(x, (bytes, bytearray)):
disassemble_string(x)
else:
raise TypeError("don't know how to disassemble %s objects" %
type(x).__name__)
def distb(tb=None):
"""Disassemble a traceback (default: last traceback)."""
if tb is None:
try:
tb = sys.last_traceback
except AttributeError:
raise RuntimeError("no last traceback to disassemble")
while tb.tb_next: tb = tb.tb_next
disassemble(tb.tb_frame.f_code, tb.tb_lasti)
# XXX This duplicates information from code.h, also duplicated in inspect.py.
# XXX Maybe this ought to be put in a central location, like opcode.py?
flag2name = {
1: "OPTIMIZED",
2: "NEWLOCALS",
4: "VARARGS",
8: "VARKEYWORDS",
16: "NESTED",
32: "GENERATOR",
64: "NOFREE",
}
def pretty_flags(flags):
"""Return pretty representation of code flags."""
names = []
for i in range(32):
flag = 1<<i
if flags & flag:
names.append(flag2name.get(flag, hex(flag)))
flags ^= flag
if not flags:
break
else:
names.append(hex(flags))
return ", ".join(names)
def show_code(co):
"""Show details about a code object."""
print("Name: ", co.co_name)
print("Filename: ", co.co_filename)
print("Argument count: ", co.co_argcount)
print("Kw-only arguments:", co.co_kwonlyargcount)
print("Number of locals: ", co.co_nlocals)
print("Stack size: ", co.co_stacksize)
print("Flags: ", pretty_flags(co.co_flags))
if co.co_consts:
print("Constants:")
for i_c in enumerate(co.co_consts):
print("%4d: %r" % i_c)
if co.co_names:
print("Names:")
for i_n in enumerate(co.co_names):
print("%4d: %s" % i_n)
if co.co_varnames:
print("Variable names:")
for i_n in enumerate(co.co_varnames):
print("%4d: %s" % i_n)
if co.co_freevars:
print("Free variables:")
for i_n in enumerate(co.co_freevars):
print("%4d: %s" % i_n)
if co.co_cellvars:
print("Cell variables:")
for i_n in enumerate(co.co_cellvars):
print("%4d: %s" % i_n)
def disassemble(co, lasti=-1):
"""Disassemble a code object."""
code = co.co_code
labels = findlabels(code)
linestarts = dict(findlinestarts(co))
n = len(code)
i = 0
extended_arg = 0
free = None
while i < n:
op = code[i]
if i in linestarts:
if i > 0:
print()
print("%3d" % linestarts[i], end=' ')
else:
print(' ', end=' ')
if i == lasti: print('-->', end=' ')
else: print(' ', end=' ')
if i in labels: print('>>', end=' ')
else: print(' ', end=' ')
print(repr(i).rjust(4), end=' ')
print(opname[op].ljust(20), end=' ')
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256 + extended_arg
extended_arg = 0
i = i+2
if op == EXTENDED_ARG:
extended_arg = oparg*65536
print(repr(oparg).rjust(5), end=' ')
if op in hasconst:
print('(' + repr(co.co_consts[oparg]) + ')', end=' ')
elif op in hasname:
print('(' + co.co_names[oparg] + ')', end=' ')
elif op in hasjrel:
print('(to ' + repr(i + oparg) + ')', end=' ')
elif op in haslocal:
print('(' + co.co_varnames[oparg] + ')', end=' ')
elif op in hascompare:
print('(' + cmp_op[oparg] + ')', end=' ')
elif op in hasfree:
if free is None:
free = co.co_cellvars + co.co_freevars
print('(' + free[oparg] + ')', end=' ')
print()
def disassemble_string(code, lasti=-1, varnames=None, names=None,
constants=None):
labels = findlabels(code)
n = len(code)
i = 0
while i < n:
op = code[i]
if i == lasti: print('-->', end=' ')
else: print(' ', end=' ')
if i in labels: print('>>', end=' ')
else: print(' ', end=' ')
print(repr(i).rjust(4), end=' ')
print(opname[op].ljust(15), end=' ')
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256
i = i+2
print(repr(oparg).rjust(5), end=' ')
if op in hasconst:
if constants:
print('(' + repr(constants[oparg]) + ')', end=' ')
else:
print('(%d)'%oparg, end=' ')
elif op in hasname:
if names is not None:
print('(' + names[oparg] + ')', end=' ')
else:
print('(%d)'%oparg, end=' ')
elif op in hasjrel:
print('(to ' + repr(i + oparg) + ')', end=' ')
elif op in haslocal:
if varnames:
print('(' + varnames[oparg] + ')', end=' ')
else:
print('(%d)' % oparg, end=' ')
elif op in hascompare:
print('(' + cmp_op[oparg] + ')', end=' ')
print()
disco = disassemble # XXX For backwards compatibility
def findlabels(code):
"""Detect all offsets in a byte code which are jump targets.
Return the list of offsets.
"""
labels = []
n = len(code)
i = 0
while i < n:
op = code[i]
i = i+1
if op >= HAVE_ARGUMENT:
oparg = code[i] + code[i+1]*256
i = i+2
label = -1
if op in hasjrel:
label = i+oparg
elif op in hasjabs:
label = oparg
if label >= 0:
if label not in labels:
labels.append(label)
return labels
def findlinestarts(code):
"""Find the offsets in a byte code which are start of lines in the source.
Generate pairs (offset, lineno) as described in Python/compile.c.
"""
byte_increments = list(code.co_lnotab[0::2])
line_increments = list(code.co_lnotab[1::2])
lastlineno = None
lineno = code.co_firstlineno
addr = 0
for byte_incr, line_incr in zip(byte_increments, line_increments):
if byte_incr:
if lineno != lastlineno:
yield (addr, lineno)
lastlineno = lineno
addr += byte_incr
lineno += line_incr
if lineno != lastlineno:
yield (addr, lineno)
def _test():
"""Simple test program to disassemble a file."""
if sys.argv[1:]:
if sys.argv[2:]:
sys.stderr.write("usage: python dis.py [-|file]\n")
sys.exit(2)
fn = sys.argv[1]
if not fn or fn == "-":
fn = None
else:
fn = None
if fn is None:
f = sys.stdin
else:
f = open(fn)
source = f.read()
if fn is not None:
f.close()
else:
fn = "<stdin>"
code = compile(source, fn, "exec")
dis(code)
if __name__ == "__main__":
_test()