summaryrefslogtreecommitdiff
path: root/Lib/dis.py
blob: f878d11ab911f1bdcf5883c523fcc3d1df3ee0ff (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
"""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"] + _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 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,
                            types.ClassType):
                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

    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

    labels = findlabels(code)
    n = len(code)
    i = 0
    extended_arg = 0
    free = None
    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 '   ',

        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

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

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 _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()