"""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

_have_code = (types.MethodType, types.FunctionType, types.CodeType,
types.ClassType, type)

def dis(x=None):
"""Disassemble classes, methods, functions, or code.

With no argument, disassemble the last traceback.

"""
if x is None:
distb()
return
if isinstance(x, types.InstanceType):
x = x.__class__
if hasattr(x, 'im_func'):
x = x.im_func
if hasattr(x, 'func_code'):
x = x.func_code
if hasattr(x, '__dict__'):
items = x.__dict__.items()
items.sort()
for name, x1 in items:
if isinstance(x1, _have_code):
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)
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)

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:
c = code[i]
op = ord(c)
if i in linestarts:
if i > 0:
print
print "%3d" % linestarts[i],
else:
print ' ',

if i == lasti: print '-->',
else: print ' ',
if i in labels: print '>>',
else: print ' ',
print repr(i).rjust(4),
print opname[op].ljust(20),
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
print repr(oparg).rjust(5),
if op in hasconst:
print '(' + repr(co.co_consts[oparg]) + ')',
elif op in hasname:
print '(' + co.co_names[oparg] + ')',
elif op in hasjrel:
print '(to ' + repr(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] + ')',
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 i == lasti: print '-->',
else: print ' ',
if i in labels: print '>>',
else: print ' ',
print repr(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 repr(oparg).rjust(5),
if op in hasconst:
if constants:
print '(' + repr(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 ' + repr(i + oparg) + ')',
elif op in haslocal:
if varnames:
print '(' + varnames[oparg] + ')',
else:
print '(%d)' % oparg,
elif op in hascompare:
print '(' + cmp_op[oparg] + ')',
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:
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

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 = [ord(c) for c in code.co_lnotab[0::2]]
line_increments = [ord(c) for c in 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()