Lib/bdb.py

   1 # Debugger basics
   2
   3 import sys
   4 import types
   5
   6 BdbQuit = 'bdb.BdbQuit' # Exception to give up completely
   7
   8
   9 class Bdb:
  10
  11         """Generic Python debugger base class.
  12
  13         This class takes care of details of the trace facility;
  14         a derived class should implement user interaction.
  15         The standard debugger class (pdb.Pdb) is an example.
  16         """
  17
  18         def __init__(self):
  19                 self.breaks = {}
  20                 # We want to have a method self.canonic() which
  21                 # canonicalizes filenames before comparing them
  22                 # but we want the default to be a very fast no-op.
  23                 # Solution: the built-in str function.
  24                 if not hasattr(self, "canonic"):
  25                         self.canonic = str
  26
  27         def reset(self):
  28                 import linecache
  29                 linecache.checkcache()
  30                 self.botframe = None
  31                 self.stopframe = None
  32                 self.returnframe = None
  33                 self.quitting = 0
  34
  35         def trace_dispatch(self, frame, event, arg):
  36                 if self.quitting:
  37                         return # None
  38                 if event == 'line':
  39                         return self.dispatch_line(frame)
  40                 if event == 'call':
  41                         return self.dispatch_call(frame, arg)
  42                 if event == 'return':
  43                         return self.dispatch_return(frame, arg)
  44                 if event == 'exception':
  45                         return self.dispatch_exception(frame, arg)
  46                 print 'bdb.Bdb.dispatch: unknown debugging event:', `event`
  47                 return self.trace_dispatch
  48
  49         def dispatch_line(self, frame):
  50                 if self.stop_here(frame) or self.break_here(frame):
  51                         self.user_line(frame)
  52                         if self.quitting: raise BdbQuit
  53                 return self.trace_dispatch
  54
  55         def dispatch_call(self, frame, arg):
  56                 # XXX 'arg' is no longer used
  57                 if self.botframe is None:
  58                         # First call of dispatch since reset()
  59                         self.botframe = frame
  60                         return self.trace_dispatch
  61                 if not (self.stop_here(frame) or self.break_anywhere(frame)):
  62                         # No need to trace this function
  63                         return # None
  64                 self.user_call(frame, arg)
  65                 if self.quitting: raise BdbQuit
  66                 return self.trace_dispatch
  67
  68         def dispatch_return(self, frame, arg):
  69                 if self.stop_here(frame) or frame == self.returnframe:
  70                         self.user_return(frame, arg)
  71                         if self.quitting: raise BdbQuit
  72
  73         def dispatch_exception(self, frame, arg):
  74                 if self.stop_here(frame):
  75                         self.user_exception(frame, arg)
  76                         if self.quitting: raise BdbQuit
  77                 return self.trace_dispatch
  78
  79         # Normally derived classes don't override the following
  80         # methods, but they may if they want to redefine the
  81         # definition of stopping and breakpoints.
  82
  83         def stop_here(self, frame):
  84                 if self.stopframe is None:
  85                         return 1
  86                 if frame is self.stopframe:
  87                         return 1
  88                 while frame is not None and frame is not self.stopframe:
  89                         if frame is self.botframe:
  90                                 return 1
  91                         frame = frame.f_back
  92                 return 0
  93
  94         def break_here(self, frame):
  95                 filename = self.canonic(frame.f_code.co_filename)
  96                 if not self.breaks.has_key(filename):
  97                         return 0
  98                 lineno = frame.f_lineno
  99                 if not lineno in self.breaks[filename]:
 100                         return 0
 101                 # flag says ok to delete temp. bp
 102                 (bp, flag) = effective(filename, lineno, frame)
 103                 if bp:
 104                         self.currentbp = bp.number
 105                         if (flag and bp.temporary):
 106                                 self.do_clear(str(bp.number))
 107                         return 1
 108                 else:
 109                         return 0
 110
 111         def break_anywhere(self, frame):
 112                 return self.breaks.has_key(
 113                     self.canonic(frame.f_code.co_filename))
 114
 115         # Derived classes should override the user_* methods
 116         # to gain control.
 117
 118         def user_call(self, frame, argument_list):
 119                 # This method is called when there is the remote possibility
 120                 # that we ever need to stop in this function
 121                 pass
 122
 123         def user_line(self, frame):
 124                 # This method is called when we stop or break at this line
 125                 pass
 126
 127         def user_return(self, frame, return_value):
 128                 # This method is called when a return trap is set here
 129                 pass
 130
 131         def user_exception(self, frame, (exc_type, exc_value, exc_traceback)):
 132                 # This method is called if an exception occurs,
 133                 # but only if we are to stop at or just below this level
 134                 pass
 135
 136         # Derived classes and clients can call the following methods
 137         # to affect the stepping state.
 138
 139         def set_step(self):
 140                 # Stop after one line of code
 141                 self.stopframe = None
 142                 self.returnframe = None
 143                 self.quitting = 0
 144
 145         def set_next(self, frame):
 146                 # Stop on the next line in or below the given frame
 147                 self.stopframe = frame
 148                 self.returnframe = None
 149                 self.quitting = 0
 150
 151         def set_return(self, frame):
 152                 # Stop when returning from the given frame
 153                 self.stopframe = frame.f_back
 154                 self.returnframe = frame
 155                 self.quitting = 0
 156
 157         def set_trace(self):
 158                 # Start debugging from here
 159                 try:
 160                         1 + ''
 161                 except:
 162                         frame = sys.exc_info()[2].tb_frame.f_back
 163                 self.reset()
 164                 while frame:
 165                         frame.f_trace = self.trace_dispatch
 166                         self.botframe = frame
 167                         frame = frame.f_back
 168                 self.set_step()
 169                 sys.settrace(self.trace_dispatch)
 170
 171         def set_continue(self):
 172                 # Don't stop except at breakpoints or when finished
 173                 self.stopframe = self.botframe
 174                 self.returnframe = None
 175                 self.quitting = 0
 176                 if not self.breaks:
 177                         # no breakpoints; run without debugger overhead
 178                         sys.settrace(None)
 179                         try:
 180                                 1 + ''  # raise an exception
 181                         except:
 182                                 frame = sys.exc_info()[2].tb_frame.f_back
 183                         while frame and frame is not self.botframe:
 184                                 del frame.f_trace
 185                                 frame = frame.f_back
 186
 187         def set_quit(self):
 188                 self.stopframe = self.botframe
 189                 self.returnframe = None
 190                 self.quitting = 1
 191                 sys.settrace(None)
 192
 193         # Derived classes and clients can call the following methods
 194         # to manipulate breakpoints.  These methods return an
 195         # error message is something went wrong, None if all is well.
 196         # Set_break prints out the breakpoint line and file:lineno.
 197         # Call self.get_*break*() to see the breakpoints or better
 198         # for bp in Breakpoint.bpbynumber: if bp: bp.bpprint().
 199
 200         def set_break(self, filename, lineno, temporary=0, cond = None):
 201                 filename = self.canonic(filename)
 202                 import linecache # Import as late as possible
 203                 line = linecache.getline(filename, lineno)
 204                 if not line:
 205                         return 'Line %s:%d does not exist' % (filename,
 206                                                                lineno)
 207                 if not self.breaks.has_key(filename):
 208                         self.breaks[filename] = []
 209                 list = self.breaks[filename]
 210                 if not lineno in list:
 211                         list.append(lineno)
 212                 bp = Breakpoint(filename, lineno, temporary, cond)
 213
 214         def clear_break(self, filename, lineno):
 215                 filename = self.canonic(filename)
 216                 if not self.breaks.has_key(filename):
 217                         return 'There are no breakpoints in %s' % filename
 218                 if lineno not in self.breaks[filename]:
 219                         return 'There is no breakpoint at %s:%d' % (filename,
 220                                                                     lineno)
 221                 # If there's only one bp in the list for that file,line
 222                 # pair, then remove the breaks entry
 223                 for bp in Breakpoint.bplist[filename, lineno][:]:
 224                         bp.deleteMe()
 225                 if not Breakpoint.bplist.has_key((filename, lineno)):
 226                         self.breaks[filename].remove(lineno)
 227                 if not self.breaks[filename]:
 228                         del self.breaks[filename]
 229
 230         def clear_bpbynumber(self, arg):
 231                 try:
 232                         number = int(arg)
 233                 except:
 234                         return 'Non-numeric breakpoint number (%s)' % arg
 235                 try:
 236                         bp = Breakpoint.bpbynumber[number]
 237                 except IndexError:
 238                         return 'Breakpoint number (%d) out of range' % number
 239                 if not bp:
 240                         return 'Breakpoint (%d) already deleted' % number
 241                 self.clear_break(bp.file, bp.line)
 242
 243         def clear_all_file_breaks(self, filename):
 244                 filename = self.canonic(filename)
 245                 if not self.breaks.has_key(filename):
 246                         return 'There are no breakpoints in %s' % filename
 247                 for line in self.breaks[filename]:
 248                         blist = Breakpoint.bplist[filename, line]
 249                         for bp in blist:
 250                                 bp.deleteMe()
 251                 del self.breaks[filename]
 252
 253         def clear_all_breaks(self):
 254                 if not self.breaks:
 255                         return 'There are no breakpoints'
 256                 for bp in Breakpoint.bpbynumber:
 257                         if bp:
 258                                 bp.deleteMe()
 259                 self.breaks = {}
 260
 261         def get_break(self, filename, lineno):
 262                 filename = self.canonic(filename)
 263                 return self.breaks.has_key(filename) and \
 264                         lineno in self.breaks[filename]
 265
 266         def get_breaks(self, filename, lineno):
 267                 filename = self.canonic(filename)
 268                 return self.breaks.has_key(filename) and \
 269                         lineno in self.breaks[filename] and \
 270                         Breakpoint.bplist[filename, lineno] or []
 271
 272         def get_file_breaks(self, filename):
 273                 filename = self.canonic(filename)
 274                 if self.breaks.has_key(filename):
 275                         return self.breaks[filename]
 276                 else:
 277                         return []
 278
 279         def get_all_breaks(self):
 280                 return self.breaks
 281
 282         # Derived classes and clients can call the following method
 283         # to get a data structure representing a stack trace.
 284
 285         def get_stack(self, f, t):
 286                 stack = []
 287                 if t and t.tb_frame is f:
 288                         t = t.tb_next
 289                 while f is not None:
 290                         stack.append((f, f.f_lineno))
 291                         if f is self.botframe:
 292                                 break
 293                         f = f.f_back
 294                 stack.reverse()
 295                 i = max(0, len(stack) - 1)
 296                 while t is not None:
 297                         stack.append((t.tb_frame, t.tb_lineno))
 298                         t = t.tb_next
 299                 return stack, i
 300
 301         #
 302
 303         def format_stack_entry(self, frame_lineno, lprefix=': '):
 304                 import linecache, repr, string
 305                 frame, lineno = frame_lineno
 306                 filename = self.canonic(frame.f_code.co_filename)
 307                 s = filename + '(' + `lineno` + ')'
 308                 if frame.f_code.co_name:
 309                         s = s + frame.f_code.co_name
 310                 else:
 311                         s = s + "<lambda>"
 312                 if frame.f_locals.has_key('__args__'):
 313                         args = frame.f_locals['__args__']
 314                 else:
 315                         args = None
 316                 if args:
 317                         s = s + repr.repr(args)
 318                 else:
 319                         s = s + '()'
 320                 if frame.f_locals.has_key('__return__'):
 321                         rv = frame.f_locals['__return__']
 322                         s = s + '->'
 323                         s = s + repr.repr(rv)
 324                 line = linecache.getline(filename, lineno)
 325                 if line: s = s + lprefix + string.strip(line)
 326                 return s
 327
 328         # The following two methods can be called by clients to use
 329         # a debugger to debug a statement, given as a string.
 330
 331         def run(self, cmd, globals=None, locals=None):
 332                 if globals is None:
 333                         import __main__
 334                         globals = __main__.__dict__
 335                 if locals is None:
 336                         locals = globals
 337                 self.reset()
 338                 sys.settrace(self.trace_dispatch)
 339                 if type(cmd) <> types.CodeType:
 340                         cmd = cmd+'\n'
 341                 try:
 342                         try:
 343                                 exec cmd in globals, locals
 344                         except BdbQuit:
 345                                 pass
 346                 finally:
 347                         self.quitting = 1
 348                         sys.settrace(None)
 349
 350         def runeval(self, expr, globals=None, locals=None):
 351                 if globals is None:
 352                         import __main__
 353                         globals = __main__.__dict__
 354                 if locals is None:
 355                         locals = globals
 356                 self.reset()
 357                 sys.settrace(self.trace_dispatch)
 358                 if type(expr) <> types.CodeType:
 359                         expr = expr+'\n'
 360                 try:
 361                         try:
 362                                 return eval(expr, globals, locals)
 363                         except BdbQuit:
 364                                 pass
 365                 finally:
 366                         self.quitting = 1
 367                         sys.settrace(None)
 368
 369         def runctx(self, cmd, globals, locals):
 370                 # B/W compatibility
 371                 self.run(cmd, globals, locals)
 372
 373         # This method is more useful to debug a single function call.
 374
 375         def runcall(self, func, *args):
 376                 self.reset()
 377                 sys.settrace(self.trace_dispatch)
 378                 res = None
 379                 try:
 380                         try:
 381                                 res = apply(func, args)
 382                         except BdbQuit:
 383                                 pass
 384                 finally:
 385                         self.quitting = 1
 386                         sys.settrace(None)
 387                 return res
 388
 389
 390 def set_trace():
 391         Bdb().set_trace()
 392
 393
 394 class Breakpoint:
 395
 396         """Breakpoint class
 397
 398         Implements temporary breakpoints, ignore counts, disabling and
 399         (re)-enabling, and conditionals.
 400
 401         Breakpoints are indexed by number through bpbynumber and by
 402         the file,line tuple using bplist.  The former points to a
 403         single instance of class Breakpoint.  The latter points to a
 404         list of such instances since there may be more than one
 405         breakpoint per line.
 406
 407         """
 408
 409         # XXX Keeping state in the class is a mistake -- this means
 410         # you cannot have more than one active Bdb instance.
 411
 412         next = 1                # Next bp to be assigned
 413         bplist = {}             # indexed by (file, lineno) tuple
 414         bpbynumber = [None]     # Each entry is None or an instance of Bpt
 415                                 # index 0 is unused, except for marking an
 416                                 # effective break .... see effective()
 417
 418         def __init__(self, file, line, temporary=0, cond = None):
 419                 self.file = file        # This better be in canonical form!
 420                 self.line = line
 421                 self.temporary = temporary
 422                 self.cond = cond
 423                 self.enabled = 1
 424                 self.ignore = 0
 425                 self.hits = 0
 426                 self.number = Breakpoint.next
 427                 Breakpoint.next = Breakpoint.next + 1
 428                 # Build the two lists
 429                 self.bpbynumber.append(self)
 430                 if self.bplist.has_key((file, line)):
 431                         self.bplist[file, line].append(self)
 432                 else:
 433                         self.bplist[file, line] = [self]
 434
 435
 436         def deleteMe(self):
 437                 index = (self.file, self.line)
 438                 self.bpbynumber[self.number] = None   # No longer in list
 439                 self.bplist[index].remove(self)
 440                 if not self.bplist[index]:
 441                         # No more bp for this f:l combo
 442                         del self.bplist[index]
 443
 444         def enable(self):
 445                 self.enabled = 1
 446
 447         def disable(self):
 448                 self.enabled = 0
 449
 450         def bpprint(self):
 451                 if self.temporary:
 452                    disp = 'del  '
 453                 else:
 454                    disp = 'keep '
 455                 if self.enabled:
 456                    disp = disp + 'yes'
 457                 else:
 458                    disp = disp + 'no '
 459                 print '%-4dbreakpoint    %s at %s:%d' % (self.number, disp,
 460                                                          self.file, self.line)
 461                 if self.cond:
 462                         print '\tstop only if %s' % (self.cond,)
 463                 if self.ignore:
 464                         print '\tignore next %d hits' % (self.ignore)
 465                 if (self.hits):
 466                         if (self.hits > 1): ss = 's'
 467                         else: ss = ''
 468                         print ('\tbreakpoint already hit %d time%s' %
 469                                (self.hits, ss))
 470
 471 # -----------end of Breakpoint class----------
 472
 473 # Determines if there is an effective (active) breakpoint at this
 474 # line of code.  Returns breakpoint number or 0 if none
 475 def effective(file, line, frame):
 476         """Determine which breakpoint for this file:line is to be acted upon.
 477
 478         Called only if we know there is a bpt at this
 479         location.  Returns breakpoint that was triggered and a flag
 480         that indicates if it is ok to delete a temporary bp.
 481
 482         """
 483         possibles = Breakpoint.bplist[file,line]
 484         for i in range(0, len(possibles)):
 485                 b = possibles[i]
 486                 if b.enabled == 0:
 487                         continue
 488                 # Count every hit when bp is enabled
 489                 b.hits = b.hits + 1
 490                 if not b.cond:
 491                         # If unconditional, and ignoring,
 492                         # go on to next, else break
 493                         if b.ignore > 0:
 494                                 b.ignore = b.ignore -1
 495                                 continue
 496                         else:
 497                                 # breakpoint and marker that's ok
 498                                 # to delete if temporary
 499                                 return (b,1)
 500                 else:
 501                         # Conditional bp.
 502                         # Ignore count applies only to those bpt hits where the
 503                         # condition evaluates to true.
 504                         try:
 505                                 val = eval(b.cond, frame.f_globals,
 506                                            frame.f_locals)
 507                                 if val:
 508                                         if b.ignore > 0:
 509                                                 b.ignore = b.ignore -1
 510                                                 # continue
 511                                         else:
 512                                                 return (b,1)
 513                                 # else:
 514                                 #       continue
 515                         except:
 516                                 # if eval fails, most conservative
 517                                 # thing is to stop on breakpoint
 518                                 # regardless of ignore count.
 519                                 # Don't delete temporary,
 520                                 # as another hint to user.
 521                                 return (b,0)
 522         return (None, None)
 523
 524 # -------------------- testing --------------------
 525
 526 class Tdb(Bdb):
 527         def user_call(self, frame, args):
 528                 name = frame.f_code.co_name
 529                 if not name: name = '???'
 530                 print '+++ call', name, args
 531         def user_line(self, frame):
 532                 import linecache, string
 533                 name = frame.f_code.co_name
 534                 if not name: name = '???'
 535                 fn = self.canonic(frame.f_code.co_filename)
 536                 line = linecache.getline(fn, frame.f_lineno)
 537                 print '+++', fn, frame.f_lineno, name, ':', string.strip(line)
 538         def user_return(self, frame, retval):
 539                 print '+++ return', retval
 540         def user_exception(self, frame, exc_stuff):
 541                 print '+++ exception', exc_stuff
 542                 self.set_continue()
 543
 544 def foo(n):
 545         print 'foo(', n, ')'
 546         x = bar(n*10)
 547         print 'bar returned', x
 548
 549 def bar(a):
 550         print 'bar(', a, ')'
 551         return a/2
 552
 553 def test():
 554         t = Tdb()
 555         t.run('import bdb; bdb.foo(10)')