"""Debugger basics""" import sys import os import types __all__ = ["BdbQuit","Bdb","Breakpoint"] class BdbQuit(Exception): """Exception to give up completely""" class Bdb: """Generic Python debugger base class. This class takes care of details of the trace facility; a derived class should implement user interaction. The standard debugger class (pdb.Pdb) is an example. """ def __init__(self): self.breaks = {} self.fncache = {} def canonic(self, filename): if filename == "<" + filename[1:-1] + ">": return filename canonic = self.fncache.get(filename) if not canonic: canonic = os.path.abspath(filename) canonic = os.path.normcase(canonic) self.fncache[filename] = canonic return canonic def reset(self): import linecache linecache.checkcache() self.botframe = None self._set_stopinfo(None, None) def trace_dispatch(self, frame, event, arg): if self.quitting: return # None if event == 'line': return self.dispatch_line(frame) if event == 'call': return self.dispatch_call(frame, arg) if event == 'return': return self.dispatch_return(frame, arg) if event == 'exception': return self.dispatch_exception(frame, arg) if event == 'c_call': return self.trace_dispatch if event == 'c_exception': return self.trace_dispatch if event == 'c_return': return self.trace_dispatch print 'bdb.Bdb.dispatch: unknown debugging event:', repr(event) return self.trace_dispatch def dispatch_line(self, frame): if self.stop_here(frame) or self.break_here(frame): self.user_line(frame) if self.quitting: raise BdbQuit return self.trace_dispatch def dispatch_call(self, frame, arg): # XXX 'arg' is no longer used if self.botframe is None: # First call of dispatch since reset() self.botframe = frame.f_back # (CT) Note that this may also be None! return self.trace_dispatch if not (self.stop_here(frame) or self.break_anywhere(frame)): # No need to trace this function return # None self.user_call(frame, arg) if self.quitting: raise BdbQuit return self.trace_dispatch def dispatch_return(self, frame, arg): if self.stop_here(frame) or frame == self.returnframe: self.user_return(frame, arg) if self.quitting: raise BdbQuit return self.trace_dispatch def dispatch_exception(self, frame, arg): if self.stop_here(frame): self.user_exception(frame, arg) if self.quitting: raise BdbQuit return self.trace_dispatch # Normally derived classes don't override the following # methods, but they may if they want to redefine the # definition of stopping and breakpoints. def stop_here(self, frame): # (CT) stopframe may now also be None, see dispatch_call. # (CT) the former test for None is therefore removed from here. if frame is self.stopframe: if self.stoplineno == -1: return False return frame.f_lineno >= self.stoplineno while frame is not None and frame is not self.stopframe: if frame is self.botframe: return True frame = frame.f_back return False def break_here(self, frame): filename = self.canonic(frame.f_code.co_filename) if not filename in self.breaks: return False lineno = frame.f_lineno if not lineno in self.breaks[filename]: # The line itself has no breakpoint, but maybe the line is the # first line of a function with breakpoint set by function name. lineno = frame.f_code.co_firstlineno if not lineno in self.breaks[filename]: return False # flag says ok to delete temp. bp (bp, flag) = effective(filename, lineno, frame) if bp: self.currentbp = bp.number if (flag and bp.temporary): self.do_clear(str(bp.number)) return True else: return False def do_clear(self, arg): raise NotImplementedError, "subclass of bdb must implement do_clear()" def break_anywhere(self, frame): return self.canonic(frame.f_code.co_filename) in self.breaks # Derived classes should override the user_* methods # to gain control. def user_call(self, frame, argument_list): """This method is called when there is the remote possibility that we ever need to stop in this function.""" pass def user_line(self, frame): """This method is called when we stop or break at this line.""" pass def user_return(self, frame, return_value): """This method is called when a return trap is set here.""" pass def user_exception(self, frame, exc_info): exc_type, exc_value, exc_traceback = exc_info """This method is called if an exception occurs, but only if we are to stop at or just below this level.""" pass def _set_stopinfo(self, stopframe, returnframe, stoplineno=0): self.stopframe = stopframe self.returnframe = returnframe self.quitting = 0 # stoplineno >= 0 means: stop at line >= the stoplineno # stoplineno -1 means: don't stop at all self.stoplineno = stoplineno # Derived classes and clients can call the following methods # to affect the stepping state. def set_until(self, frame): #the name "until" is borrowed from gdb """Stop when the line with the line no greater than the current one is reached or when returning from current frame""" self._set_stopinfo(frame, frame, frame.f_lineno+1) def set_step(self): """Stop after one line of code.""" self._set_stopinfo(None, None) def set_next(self, frame): """Stop on the next line in or below the given frame.""" self._set_stopinfo(frame, None) def set_return(self, frame): """Stop when returning from the given frame.""" self._set_stopinfo(frame.f_back, frame) def set_trace(self, frame=None): """Start debugging from `frame`. If frame is not specified, debugging starts from caller's frame. """ if frame is None: frame = sys._getframe().f_back self.reset() while frame: frame.f_trace = self.trace_dispatch self.botframe = frame frame = frame.f_back self.set_step() sys.settrace(self.trace_dispatch) def set_continue(self): # Don't stop except at breakpoints or when finished self._set_stopinfo(self.botframe, None, -1) if not self.breaks: # no breakpoints; run without debugger overhead sys.settrace(None) frame = sys._getframe().f_back while frame and frame is not self.botframe: del frame.f_trace frame = frame.f_back def set_quit(self): self.stopframe = self.botframe self.returnframe = None self.quitting = 1 sys.settrace(None) # Derived classes and clients can call the following methods # to manipulate breakpoints. These methods return an # error message is something went wrong, None if all is well. # Set_break prints out the breakpoint line and file:lineno. # Call self.get_*break*() to see the breakpoints or better # for bp in Breakpoint.bpbynumber: if bp: bp.bpprint(). def set_break(self, filename, lineno, temporary=0, cond = None, funcname=None): filename = self.canonic(filename) import linecache # Import as late as possible line = linecache.getline(filename, lineno) if not line: return 'Line %s:%d does not exist' % (filename, lineno) if not filename in self.breaks: self.breaks[filename] = [] list = self.breaks[filename] if not lineno in list: list.append(lineno) bp = Breakpoint(filename, lineno, temporary, cond, funcname) def clear_break(self, filename, lineno): filename = self.canonic(filename) if not filename in self.breaks: return 'There are no breakpoints in %s' % filename if lineno not in self.breaks[filename]: return 'There is no breakpoint at %s:%d' % (filename, lineno) # If there's only one bp in the list for that file,line # pair, then remove the breaks entry for bp in Breakpoint.bplist[filename, lineno][:]: bp.deleteMe() if not Breakpoint.bplist.has_key((filename, lineno)): self.breaks[filename].remove(lineno) if not self.breaks[filename]: del self.breaks[filename] def clear_bpbynumber(self, arg): try: number = int(arg) except: return 'Non-numeric breakpoint number (%s)' % arg try: bp = Breakpoint.bpbynumber[number] except IndexError: return 'Breakpoint number (%d) out of range' % number if not bp: return 'Breakpoint (%d) already deleted' % number self.clear_break(bp.file, bp.line) def clear_all_file_breaks(self, filename): filename = self.canonic(filename) if not filename in self.breaks: return 'There are no breakpoints in %s' % filename for line in self.breaks[filename]: blist = Breakpoint.bplist[filename, line] for bp in blist: bp.deleteMe() del self.breaks[filename] def clear_all_breaks(self): if not self.breaks: return 'There are no breakpoints' for bp in Breakpoint.bpbynumber: if bp: bp.deleteMe() self.breaks = {} def get_break(self, filename, lineno): filename = self.canonic(filename) return filename in self.breaks and \ lineno in self.breaks[filename] def get_breaks(self, filename, lineno): filename = self.canonic(filename) return filename in self.breaks and \ lineno in self.breaks[filename] and \ Breakpoint.bplist[filename, lineno] or [] def get_file_breaks(self, filename): filename = self.canonic(filename) if filename in self.breaks: return self.breaks[filename] else: return [] def get_all_breaks(self): return self.breaks # Derived classes and clients can call the following method # to get a data structure representing a stack trace. def get_stack(self, f, t): stack = [] if t and t.tb_frame is f: t = t.tb_next while f is not None: stack.append((f, f.f_lineno)) if f is self.botframe: break f = f.f_back stack.reverse() i = max(0, len(stack) - 1) while t is not None: stack.append((t.tb_frame, t.tb_lineno)) t = t.tb_next if f is None: i = max(0, len(stack) - 1) return stack, i # def format_stack_entry(self, frame_lineno, lprefix=': '): import linecache, repr frame, lineno = frame_lineno filename = self.canonic(frame.f_code.co_filename) s = '%s(%r)' % (filename, lineno) if frame.f_code.co_name: s = s + frame.f_code.co_name else: s = s + "" if '__args__' in frame.f_locals: args = frame.f_locals['__args__'] else: args = None if args: s = s + repr.repr(args) else: s = s + '()' if '__return__' in frame.f_locals: rv = frame.f_locals['__return__'] s = s + '->' s = s + repr.repr(rv) line = linecache.getline(filename, lineno, frame.f_globals) if line: s = s + lprefix + line.strip() return s # The following two methods can be called by clients to use # a debugger to debug a statement, given as a string. def run(self, cmd, globals=None, locals=None): if globals is None: import __main__ globals = __main__.__dict__ if locals is None: locals = globals self.reset() sys.settrace(self.trace_dispatch) if not isinstance(cmd, types.CodeType): cmd = cmd+'\n' try: exec cmd in globals, locals except BdbQuit: pass finally: self.quitting = 1 sys.settrace(None) def runeval(self, expr, globals=None, locals=None): if globals is None: import __main__ globals = __main__.__dict__ if locals is None: locals = globals self.reset() sys.settrace(self.trace_dispatch) if not isinstance(expr, types.CodeType): expr = expr+'\n' try: return eval(expr, globals, locals) except BdbQuit: pass finally: self.quitting = 1 sys.settrace(None) def runctx(self, cmd, globals, locals): # B/W compatibility self.run(cmd, globals, locals) # This method is more useful to debug a single function call. def runcall(self, func, *args, **kwds): self.reset() sys.settrace(self.trace_dispatch) res = None try: res = func(*args, **kwds) except BdbQuit: pass finally: self.quitting = 1 sys.settrace(None) return res def set_trace(): Bdb().set_trace() class Breakpoint: """Breakpoint class Implements temporary breakpoints, ignore counts, disabling and (re)-enabling, and conditionals. Breakpoints are indexed by number through bpbynumber and by the file,line tuple using bplist. The former points to a single instance of class Breakpoint. The latter points to a list of such instances since there may be more than one breakpoint per line. """ # XXX Keeping state in the class is a mistake -- this means # you cannot have more than one active Bdb instance. next = 1 # Next bp to be assigned bplist = {} # indexed by (file, lineno) tuple bpbynumber = [None] # Each entry is None or an instance of Bpt # index 0 is unused, except for marking an # effective break .... see effective() def __init__(self, file, line, temporary=0, cond=None, funcname=None): self.funcname = funcname # Needed if funcname is not None. self.func_first_executable_line = None self.file = file # This better be in canonical form! self.line = line self.temporary = temporary self.cond = cond self.enabled = 1 self.ignore = 0 self.hits = 0 self.number = Breakpoint.next Breakpoint.next = Breakpoint.next + 1 # Build the two lists self.bpbynumber.append(self) if self.bplist.has_key((file, line)): self.bplist[file, line].append(self) else: self.bplist[file, line] = [self] def deleteMe(self): index = (self.file, self.line) self.bpbynumber[self.number] = None # No longer in list self.bplist[index].remove(self) if not self.bplist[index]: # No more bp for this f:l combo del self.bplist[index] def enable(self): self.enabled = 1 def disable(self): self.enabled = 0 def bpprint(self, out=None): if out is None: out = sys.stdout if self.temporary: disp = 'del ' else: disp = 'keep ' if self.enabled: disp = disp + 'yes ' else: disp = disp + 'no ' print >>out, '%-4dbreakpoint %s at %s:%d' % (self.number, disp, self.file, self.line) if self.cond: print >>out, '\tstop only if %s' % (self.cond,) if self.ignore: print >>out, '\tignore next %d hits' % (self.ignore) if (self.hits): if (self.hits > 1): ss = 's' else: ss = '' print >>out, ('\tbreakpoint already hit %d time%s' % (self.hits, ss)) # -----------end of Breakpoint class---------- def checkfuncname(b, frame): """Check whether we should break here because of `b.funcname`.""" if not b.funcname: # Breakpoint was set via line number. if b.line != frame.f_lineno: # Breakpoint was set at a line with a def statement and the function # defined is called: don't break. return False return True # Breakpoint set via function name. if frame.f_code.co_name != b.funcname: # It's not a function call, but rather execution of def statement. return False # We are in the right frame. if not b.func_first_executable_line: # The function is entered for the 1st time. b.func_first_executable_line = frame.f_lineno if b.func_first_executable_line != frame.f_lineno: # But we are not at the first line number: don't break. return False return True # Determines if there is an effective (active) breakpoint at this # line of code. Returns breakpoint number or 0 if none def effective(file, line, frame): """Determine which breakpoint for this file:line is to be acted upon. Called only if we know there is a bpt at this location. Returns breakpoint that was triggered and a flag that indicates if it is ok to delete a temporary bp. """ possibles = Breakpoint.bplist[file,line] for i in range(0, len(possibles)): b = possibles[i] if b.enabled == 0: continue if not checkfuncname(b, frame): continue # Count every hit when bp is enabled b.hits = b.hits + 1 if not b.cond: # If unconditional, and ignoring, # go on to next, else break if b.ignore > 0: b.ignore = b.ignore -1 continue else: # breakpoint and marker that's ok # to delete if temporary return (b,1) else: # Conditional bp. # Ignore count applies only to those bpt hits where the # condition evaluates to true. try: val = eval(b.cond, frame.f_globals, frame.f_locals) if val: if b.ignore > 0: b.ignore = b.ignore -1 # continue else: return (b,1) # else: # continue except: # if eval fails, most conservative # thing is to stop on breakpoint # regardless of ignore count. # Don't delete temporary, # as another hint to user. return (b,0) return (None, None) # -------------------- testing -------------------- class Tdb(Bdb): def user_call(self, frame, args): name = frame.f_code.co_name if not name: name = '???' print '+++ call', name, args def user_line(self, frame): import linecache name = frame.f_code.co_name if not name: name = '???' fn = self.canonic(frame.f_code.co_filename) line = linecache.getline(fn, frame.f_lineno, frame.f_globals) print '+++', fn, frame.f_lineno, name, ':', line.strip() def user_return(self, frame, retval): print '+++ return', retval def user_exception(self, frame, exc_stuff): print '+++ exception', exc_stuff self.set_continue() def foo(n): print 'foo(', n, ')' x = bar(n*10) print 'bar returned', x def bar(a): print 'bar(', a, ')' return a/2 def test(): t = Tdb() t.run('import bdb; bdb.foo(10)') # end