cpython/Lib/dis.py

"""Disassembler of Python byte code into mnemonics."""

import sys
import string
import types

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

	With no argument, disassemble the last traceback.

	"""
	if not x:
		distb()
		return
	if type(x) is types.InstanceType:
		x = x.__class__
	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):
				print "Disassembly of %s:" % name
				try:
					dis(x1)
				except TypeError, msg:
					print "Sorry:", msg
				print
	else:
		if hasattr(x, 'im_func'):
			x = x.im_func
		if hasattr(x, 'func_code'):
			x = x.func_code
		if hasattr(x, 'co_code'):
			disassemble(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 not tb:
		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)
	n = len(code)
	i = 0
	while i < n:
		c = code[i]
		op = ord(c)
		if op == SET_LINENO and i > 0: print # Extra blank line
		if i == lasti: print '-->',
		else: print '   ',
		if i in labels: print '>>',
		else: print '  ',
		print string.rjust(`i`, 4),
		print string.ljust(opname[op], 20),
		i = i+1
		if op >= HAVE_ARGUMENT:
			oparg = ord(code[i]) + ord(code[i+1])*256
			i = i+2
			print string.rjust(`oparg`, 5),
			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] + ')',
		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

cmp_op = ('<', '<=', '==', '!=', '>', '>=', 'in', 'not in', 'is',
        'is not', 'exception match', 'BAD')

hasconst = []
hasname = []
hasjrel = []
hasjabs = []
haslocal = []
hascompare = []

opname = [''] * 256
for op in range(256): opname[op] = '<' + `op` + '>'

def def_op(name, op):
	opname[op] = name

def name_op(name, op):
	opname[op] = name
	hasname.append(op)

def jrel_op(name, op):
	opname[op] = name
	hasjrel.append(op)

def jabs_op(name, op):
	opname[op] = name
	hasjabs.append(op)

# Instruction opcodes for compiled code

def_op('STOP_CODE', 0)
def_op('POP_TOP', 1)
def_op('ROT_TWO', 2)
def_op('ROT_THREE', 3)
def_op('DUP_TOP', 4)

def_op('UNARY_POSITIVE', 10)
def_op('UNARY_NEGATIVE', 11)
def_op('UNARY_NOT', 12)
def_op('UNARY_CONVERT', 13)

def_op('UNARY_INVERT', 15)

def_op('BINARY_POWER', 19)

def_op('BINARY_MULTIPLY', 20)
def_op('BINARY_DIVIDE', 21)
def_op('BINARY_MODULO', 22)
def_op('BINARY_ADD', 23)
def_op('BINARY_SUBTRACT', 24)
def_op('BINARY_SUBSCR', 25)

def_op('SLICE+0', 30)
def_op('SLICE+1', 31)
def_op('SLICE+2', 32)
def_op('SLICE+3', 33)

def_op('STORE_SLICE+0', 40)
def_op('STORE_SLICE+1', 41)
def_op('STORE_SLICE+2', 42)
def_op('STORE_SLICE+3', 43)

def_op('DELETE_SLICE+0', 50)
def_op('DELETE_SLICE+1', 51)
def_op('DELETE_SLICE+2', 52)
def_op('DELETE_SLICE+3', 53)

def_op('STORE_SUBSCR', 60)
def_op('DELETE_SUBSCR', 61)

def_op('BINARY_LSHIFT', 62)
def_op('BINARY_RSHIFT', 63)
def_op('BINARY_AND', 64)
def_op('BINARY_XOR', 65)
def_op('BINARY_OR', 66)

def_op('PRINT_EXPR', 70)
def_op('PRINT_ITEM', 71)
def_op('PRINT_NEWLINE', 72)
def_op('PRINT_ITEM_TO', 73)
def_op('PRINT_NEWLINE_TO', 74)

def_op('BREAK_LOOP', 80)

def_op('LOAD_LOCALS', 82)
def_op('RETURN_VALUE', 83)
def_op('IMPORT_STAR', 84)
def_op('EXEC_STMT', 85)

def_op('POP_BLOCK', 87)
def_op('END_FINALLY', 88)
def_op('BUILD_CLASS', 89)

HAVE_ARGUMENT = 90		# Opcodes from here have an argument: 

name_op('STORE_NAME', 90)	# Index in name list 
name_op('DELETE_NAME', 91)	# "" 
def_op('UNPACK_SEQUENCE', 92)	# Number of tuple items 

name_op('STORE_ATTR', 95)	# Index in name list 
name_op('DELETE_ATTR', 96)	# ""
name_op('STORE_GLOBAL', 97)	# ""
name_op('DELETE_GLOBAL', 98)	# ""

def_op('LOAD_CONST', 100)	# Index in const list 
hasconst.append(100)
name_op('LOAD_NAME', 101)	# Index in name list 
def_op('BUILD_TUPLE', 102)	# Number of tuple items 
def_op('BUILD_LIST', 103)	# Number of list items 
def_op('BUILD_MAP', 104)	# Always zero for now 
name_op('LOAD_ATTR', 105)	# Index in name list 
def_op('COMPARE_OP', 106)	# Comparison operator 
hascompare.append(106)
name_op('IMPORT_NAME', 107)	# Index in name list 
name_op('IMPORT_FROM', 108)	# Index in name list 

jrel_op('JUMP_FORWARD', 110)	# Number of bytes to skip 
jrel_op('JUMP_IF_FALSE', 111)	# "" 
jrel_op('JUMP_IF_TRUE', 112)	# "" 
jabs_op('JUMP_ABSOLUTE', 113)	# Target byte offset from beginning of code 
jrel_op('FOR_LOOP', 114)	# Number of bytes to skip 

name_op('LOAD_GLOBAL', 116)	# Index in name list

jrel_op('SETUP_LOOP', 120)	# Distance to target address
jrel_op('SETUP_EXCEPT', 121)	# ""
jrel_op('SETUP_FINALLY', 122)	# ""

def_op('LOAD_FAST', 124)	# Local variable number
haslocal.append(124)
def_op('STORE_FAST', 125)	# Local variable number
haslocal.append(125)
def_op('DELETE_FAST', 126)	# Local variable number
haslocal.append(126)

def_op('SET_LINENO', 127)	# Current line number
SET_LINENO = 127

def_op('RAISE_VARARGS', 130)    # Number of raise arguments (1, 2, or 3)
def_op('CALL_FUNCTION', 131)    # #args + (#kwargs << 8)
def_op('MAKE_FUNCTION', 132)    # Number of args with default values
def_op('BUILD_SLICE', 133)      # Number of items

def_op('CALL_FUNCTION_VAR', 140)     # #args + (#kwargs << 8)
def_op('CALL_FUNCTION_KW', 141)      # #args + (#kwargs << 8)
def_op('CALL_FUNCTION_VAR_KW', 142)  # #args + (#kwargs << 8)


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 not fn:
		f = sys.stdin
	else:
		f = open(fn)
	source = f.read()
	if fn:
		f.close()
	else:
		fn = "<stdin>"
	code = compile(source, fn, "exec")
	dis(code)

if __name__ == "__main__":
	_test()