dis.py

Go to the documentation of this file.

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

import sys
import types

__all__ = ["dis","disassemble","distb","disco","opname","cmp_op",
           "hasconst","hasname","hasjrel","hasjabs","haslocal",
           "hascompare", "hasfree"]

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, '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 type(x1) in (types.MethodType,
                            types.FunctionType,
                            types.CodeType):
                print "Disassembly of %s:" % name
                try:
                    dis(x1)
                except TypeError, msg:
                    print "Sorry:", msg
                print
    elif 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
    extended_arg = 0
    free = None
    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 `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 `oparg`.rjust(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] + ')',
            elif op in hasfree:
                if free is None:
                    free = co.co_cellvars + co.co_freevars
                print '(' + free[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 = []
hasfree = []

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('ROT_FOUR', 5)

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('BINARY_FLOOR_DIVIDE', 26)
def_op('BINARY_TRUE_DIVIDE', 27)
def_op('INPLACE_FLOOR_DIVIDE', 28)
def_op('INPLACE_TRUE_DIVIDE', 29)

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('INPLACE_ADD', 55)
def_op('INPLACE_SUBTRACT', 56)
def_op('INPLACE_MULTIPLY', 57)
def_op('INPLACE_DIVIDE', 58)
def_op('INPLACE_MODULO', 59)
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('INPLACE_POWER', 67)
def_op('GET_ITER', 68)

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('INPLACE_LSHIFT', 75)
def_op('INPLACE_RSHIFT', 76)
def_op('INPLACE_AND', 77)
def_op('INPLACE_XOR', 78)
def_op('INPLACE_OR', 79)
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('YIELD_STMT', 86)

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
jrel_op('FOR_ITER', 93)

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('DUP_TOPX', 99)          # number of items to duplicate
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

jabs_op('CONTINUE_LOOP', 119)   # Target address
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('MAKE_CLOSURE', 134)
def_op('LOAD_CLOSURE', 135)
hasfree.append(135)
def_op('LOAD_DEREF', 136)
hasfree.append(136)
def_op('STORE_DEREF', 137)
hasfree.append(137)

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_op('EXTENDED_ARG', 143)
EXTENDED_ARG = 143

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()