cpython/Lib/dis.py

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"""Disassembler of Python byte code into mnemonics."""
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import sys
import types
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from opcode import *
from opcode import __all__ as _opcodes_all
__all__ = ["dis","disassemble","distb","disco"] + _opcodes_all
del _opcodes_all
def dis(x=None):
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"""Disassemble classes, methods, functions, or code.
With no argument, disassemble the last traceback.
"""
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if x is None:
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distb()
return
if type(x) is types.InstanceType:
x = x.__class__
if hasattr(x, 'im_func'):
x = x.im_func
if hasattr(x, 'func_code'):
x = x.func_code
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if hasattr(x, '__dict__'):
items = x.__dict__.items()
items.sort()
for name, x1 in items:
if type(x1) in (types.MethodType,
types.FunctionType,
types.CodeType,
types.ClassType):
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print "Disassembly of %s:" % name
try:
dis(x1)
except TypeError, msg:
print "Sorry:", msg
print
elif hasattr(x, 'co_code'):
disassemble(x)
elif isinstance(x, str):
disassemble_string(x)
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else:
raise TypeError, \
"don't know how to disassemble %s objects" % \
type(x).__name__
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def distb(tb=None):
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"""Disassemble a traceback (default: last traceback)."""
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if tb is None:
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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)
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def disassemble(co, lasti=-1):
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"""Disassemble a code object."""
code = co.co_code
byte_increments = [ord(c) for c in co.co_lnotab[0::2]]
line_increments = [ord(c) for c in co.co_lnotab[1::2]]
table_length = len(byte_increments) # == len(line_increments)
lineno = co.co_firstlineno
table_index = 0
while (table_index < table_length
and byte_increments[table_index] == 0):
lineno += line_increments[table_index]
table_index += 1
addr = 0
line_incr = 0
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labels = findlabels(code)
n = len(code)
i = 0
extended_arg = 0
free = None
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while i < n:
c = code[i]
op = ord(c)
if i >= addr:
lineno += line_incr
while table_index < table_length:
addr += byte_increments[table_index]
line_incr = line_increments[table_index]
table_index += 1
if line_incr:
break
else:
addr = sys.maxint
if i > 0:
print
print "%3d"%lineno,
else:
print ' ',
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if i == lasti: print '-->',
else: print ' ',
if i in labels: print '>>',
else: print ' ',
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print `i`.rjust(4),
print opname[op].ljust(20),
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i = i+1
if op >= HAVE_ARGUMENT:
oparg = ord(code[i]) + ord(code[i+1])*256 + extended_arg
extended_arg = 0
i = i+2
if op == EXTENDED_ARG:
extended_arg = oparg*65536L
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print `oparg`.rjust(5),
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if op in hasconst:
print '(' + `co.co_consts[oparg]` + ')',
elif op in hasname:
print '(' + co.co_names[oparg] + ')',
elif op in hasjrel:
print '(to ' + `i + oparg` + ')',
elif op in haslocal:
print '(' + co.co_varnames[oparg] + ')',
elif op in hascompare:
print '(' + cmp_op[oparg] + ')',
elif op in hasfree:
if free is None:
free = co.co_cellvars + co.co_freevars
print '(' + free[oparg] + ')',
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print
def disassemble_string(code, lasti=-1, varnames=None, names=None,
constants=None):
labels = findlabels(code)
n = len(code)
i = 0
while i < n:
c = code[i]
op = ord(c)
if op == opmap['SET_LINENO'] and i > 0:
print # Extra blank line
if i == lasti: print '-->',
else: print ' ',
if i in labels: print '>>',
else: print ' ',
print `i`.rjust(4),
print opname[op].ljust(15),
i = i+1
if op >= HAVE_ARGUMENT:
oparg = ord(code[i]) + ord(code[i+1])*256
i = i+2
print `oparg`.rjust(5),
if op in hasconst:
if constants:
print '(' + `constants[oparg]` + ')',
else:
print '(%d)'%oparg,
elif op in hasname:
if names is not None:
print '(' + names[oparg] + ')',
else:
print '(%d)'%oparg,
elif op in hasjrel:
print '(to ' + `i + oparg` + ')',
elif op in haslocal:
if varnames:
print '(' + varnames[oparg] + ')',
else:
print '(%d)' % oparg,
elif op in hascompare:
print '(' + cmp_op[oparg] + ')',
print
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disco = disassemble # XXX For backwards compatibility
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def findlabels(code):
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"""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:
c = code[i]
op = ord(c)
i = i+1
if op >= HAVE_ARGUMENT:
oparg = ord(code[i]) + ord(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
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def _test():
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"""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
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if fn is None:
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f = sys.stdin
else:
f = open(fn)
source = f.read()
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if fn is not None:
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f.close()
else:
fn = "<stdin>"
code = compile(source, fn, "exec")
dis(code)
if __name__ == "__main__":
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_test()