Lib/pdb.py - external/github.com/python/cpython - Git at Google

 #! /usr/bin/env python3

 """
 The Python Debugger Pdb
 =======================

 To use the debugger in its simplest form:

         >>> import pdb
         >>> pdb.run('<a statement>')

 The debugger's prompt is '(Pdb) '.  This will stop in the first
 function call in <a statement>.

 Alternatively, if a statement terminated with an unhandled exception,
 you can use pdb's post-mortem facility to inspect the contents of the
 traceback:

         >>> <a statement>
         <exception traceback>
         >>> import pdb
         >>> pdb.pm()

 The commands recognized by the debugger are listed in the next
 section.  Most can be abbreviated as indicated; e.g., h(elp) means
 that 'help' can be typed as 'h' or 'help' (but not as 'he' or 'hel',
 nor as 'H' or 'Help' or 'HELP').  Optional arguments are enclosed in
 square brackets.  Alternatives in the command syntax are separated
 by a vertical bar (|).

 A blank line repeats the previous command literally, except for
 'list', where it lists the next 11 lines.

 Commands that the debugger doesn't recognize are assumed to be Python
 statements and are executed in the context of the program being
 debugged.  Python statements can also be prefixed with an exclamation
 point ('!').  This is a powerful way to inspect the program being
 debugged; it is even possible to change variables or call functions.
 When an exception occurs in such a statement, the exception name is
 printed but the debugger's state is not changed.

 The debugger supports aliases, which can save typing.  And aliases can
 have parameters (see the alias help entry) which allows one a certain
 level of adaptability to the context under examination.

 Multiple commands may be entered on a single line, separated by the
 pair ';;'.  No intelligence is applied to separating the commands; the
 input is split at the first ';;', even if it is in the middle of a
 quoted string.

 If a file ".pdbrc" exists in your home directory or in the current
 directory, it is read in and executed as if it had been typed at the
 debugger prompt.  This is particularly useful for aliases.  If both
 files exist, the one in the home directory is read first and aliases
 defined there can be overridden by the local file.  This behavior can be
 disabled by passing the "readrc=False" argument to the Pdb constructor.

 Aside from aliases, the debugger is not directly programmable; but it
 is implemented as a class from which you can derive your own debugger
 class, which you can make as fancy as you like.


 Debugger commands
 =================

 """
 # NOTE: the actual command documentation is collected from docstrings of the
 # commands and is appended to __doc__ after the class has been defined.

 import os
 import io
 import re
 import sys
 import cmd
 import bdb
 import dis
 import code
 import glob
 import token
 import types
 import codeop
 import pprint
 import signal
 import inspect
 import textwrap
 import tokenize
 import traceback
 import linecache
 import _colorize

 from contextlib import contextmanager
 from rlcompleter import Completer
 from types import CodeType


 class Restart(Exception):
     """Causes a debugger to be restarted for the debugged python program."""
     pass

 __all__ = ["run", "pm", "Pdb", "runeval", "runctx", "runcall", "set_trace",
            "post_mortem", "help"]


 def find_first_executable_line(code):
     """ Try to find the first executable line of the code object.

     Equivalently, find the line number of the instruction that's
     after RESUME

     Return code.co_firstlineno if no executable line is found.
     """
     prev = None
     for instr in dis.get_instructions(code):
         if prev is not None and prev.opname == 'RESUME':
             if instr.positions.lineno is not None:
                 return instr.positions.lineno
             return code.co_firstlineno
         prev = instr
     return code.co_firstlineno

 def find_function(funcname, filename):
     cre = re.compile(r'def\s+%s\s*[(]' % re.escape(funcname))
     try:
         fp = tokenize.open(filename)
     except OSError:
         lines = linecache.getlines(filename)
         if not lines:
             return None
         fp = io.StringIO(''.join(lines))
     funcdef = ""
     funcstart = None
     # consumer of this info expects the first line to be 1
     with fp:
         for lineno, line in enumerate(fp, start=1):
             if cre.match(line):
                 funcstart, funcdef = lineno, line
             elif funcdef:
                 funcdef += line

             if funcdef:
                 try:
                     funccode = compile(funcdef, filename, 'exec').co_consts[0]
                 except SyntaxError:
                     continue
                 lineno_offset = find_first_executable_line(funccode)
                 return funcname, filename, funcstart + lineno_offset - 1
     return None

 def lasti2lineno(code, lasti):
     linestarts = list(dis.findlinestarts(code))
     linestarts.reverse()
     for i, lineno in linestarts:
         if lasti >= i:
             return lineno
     return 0


 class _rstr(str):
     """String that doesn't quote its repr."""
     def __repr__(self):
         return self


 class _ExecutableTarget:
     filename: str
     code: CodeType | str
     namespace: dict


 class _ScriptTarget(_ExecutableTarget):
     def __init__(self, target):
         self._target = os.path.realpath(target)

         if not os.path.exists(self._target):
             print(f'Error: {target} does not exist')
             sys.exit(1)
         if os.path.isdir(self._target):
             print(f'Error: {target} is a directory')
             sys.exit(1)

         # If safe_path(-P) is not set, sys.path[0] is the directory
         # of pdb, and we should replace it with the directory of the script
         if not sys.flags.safe_path:
             sys.path[0] = os.path.dirname(self._target)

     def __repr__(self):
         return self._target

     @property
     def filename(self):
         return self._target

     @property
     def code(self):
         # Open the file each time because the file may be modified
         with io.open_code(self._target) as fp:
             return f"exec(compile({fp.read()!r}, {self._target!r}, 'exec'))"

     @property
     def namespace(self):
         return dict(
             __name__='__main__',
             __file__=self._target,
             __builtins__=__builtins__,
             __spec__=None,
         )


 class _ModuleTarget(_ExecutableTarget):
     def __init__(self, target):
         self._target = target

         import runpy
         try:
             _, self._spec, self._code = runpy._get_module_details(self._target)
         except ImportError as e:
             print(f"ImportError: {e}")
             sys.exit(1)
         except Exception:
             traceback.print_exc()
             sys.exit(1)

     def __repr__(self):
         return self._target

     @property
     def filename(self):
         return self._code.co_filename

     @property
     def code(self):
         return self._code

     @property
     def namespace(self):
         return dict(
             __name__='__main__',
             __file__=os.path.normcase(os.path.abspath(self.filename)),
             __package__=self._spec.parent,
             __loader__=self._spec.loader,
             __spec__=self._spec,
             __builtins__=__builtins__,
         )


 class _ZipTarget(_ExecutableTarget):
     def __init__(self, target):
         import runpy

         self._target = os.path.realpath(target)
         sys.path.insert(0, self._target)
         try:
             _, self._spec, self._code = runpy._get_main_module_details()
         except ImportError as e:
             print(f"ImportError: {e}")
             sys.exit(1)
         except Exception:
             traceback.print_exc()
             sys.exit(1)

     def __repr__(self):
         return self._target

     @property
     def filename(self):
         return self._code.co_filename

     @property
     def code(self):
         return self._code

     @property
     def namespace(self):
         return dict(
             __name__='__main__',
             __file__=os.path.normcase(os.path.abspath(self.filename)),
             __package__=self._spec.parent,
             __loader__=self._spec.loader,
             __spec__=self._spec,
             __builtins__=__builtins__,
         )


 class _PdbInteractiveConsole(code.InteractiveConsole):
     def __init__(self, ns, message):
         self._message = message
         super().__init__(locals=ns, local_exit=True)

     def write(self, data):
         self._message(data, end='')


 # Interaction prompt line will separate file and call info from code
 # text using value of line_prefix string.  A newline and arrow may
 # be to your liking.  You can set it once pdb is imported using the
 # command "pdb.line_prefix = '\n% '".
 # line_prefix = ': '    # Use this to get the old situation back
 line_prefix = '\n-> '   # Probably a better default


 class Pdb(bdb.Bdb, cmd.Cmd):
     _previous_sigint_handler = None

     # Limit the maximum depth of chained exceptions, we should be handling cycles,
     # but in case there are recursions, we stop at 999.
     MAX_CHAINED_EXCEPTION_DEPTH = 999

     _file_mtime_table = {}

     def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
                  nosigint=False, readrc=True):
         bdb.Bdb.__init__(self, skip=skip)
         cmd.Cmd.__init__(self, completekey, stdin, stdout)
         sys.audit("pdb.Pdb")
         if stdout:
             self.use_rawinput = 0
         self.prompt = '(Pdb) '
         self.aliases = {}
         self.displaying = {}
         self.mainpyfile = ''
         self._wait_for_mainpyfile = False
         self.tb_lineno = {}
         # Try to load readline if it exists
         try:
             import readline
             # remove some common file name delimiters
             readline.set_completer_delims(' \t\n`@#%^&*()=+[{]}\\|;:\'",<>?')
         except ImportError:
             pass
         self.allow_kbdint = False
         self.nosigint = nosigint
         # Consider these characters as part of the command so when the users type
         # c.a or c['a'], it won't be recognized as a c(ontinue) command
         self.identchars = cmd.Cmd.identchars + '=.[](),"\'+-*/%@&|<>~^'

         # Read ~/.pdbrc and ./.pdbrc
         self.rcLines = []
         if readrc:
             try:
                 with open(os.path.expanduser('~/.pdbrc'), encoding='utf-8') as rcFile:
                     self.rcLines.extend(rcFile)
             except OSError:
                 pass
             try:
                 with open(".pdbrc", encoding='utf-8') as rcFile:
                     self.rcLines.extend(rcFile)
             except OSError:
                 pass

         self.commands = {} # associates a command list to breakpoint numbers
         self.commands_doprompt = {} # for each bp num, tells if the prompt
                                     # must be disp. after execing the cmd list
         self.commands_silent = {} # for each bp num, tells if the stack trace
                                   # must be disp. after execing the cmd list
         self.commands_defining = False # True while in the process of defining
                                        # a command list
         self.commands_bnum = None # The breakpoint number for which we are
                                   # defining a list

         self._chained_exceptions = tuple()
         self._chained_exception_index = 0

     def sigint_handler(self, signum, frame):
         if self.allow_kbdint:
             raise KeyboardInterrupt
         self.message("\nProgram interrupted. (Use 'cont' to resume).")
         self.set_step()
         self.set_trace(frame)

     def reset(self):
         bdb.Bdb.reset(self)
         self.forget()

     def forget(self):
         self.lineno = None
         self.stack = []
         self.curindex = 0
         if hasattr(self, 'curframe') and self.curframe:
             self.curframe.f_globals.pop('__pdb_convenience_variables', None)
         self.curframe = None
         self.tb_lineno.clear()

     def setup(self, f, tb):
         self.forget()
         self.stack, self.curindex = self.get_stack(f, tb)
         while tb:
             # when setting up post-mortem debugging with a traceback, save all
             # the original line numbers to be displayed along the current line
             # numbers (which can be different, e.g. due to finally clauses)
             lineno = lasti2lineno(tb.tb_frame.f_code, tb.tb_lasti)
             self.tb_lineno[tb.tb_frame] = lineno
             tb = tb.tb_next
         self.curframe = self.stack[self.curindex][0]
         # The f_locals dictionary used to be updated from the actual frame
         # locals whenever the .f_locals accessor was called, so it was
         # cached here to ensure that modifications were not overwritten. While
         # the caching is no longer required now that f_locals is a direct proxy
         # on optimized frames, it's also harmless, so the code structure has
         # been left unchanged.
         self.curframe_locals = self.curframe.f_locals
         self.set_convenience_variable(self.curframe, '_frame', self.curframe)

         if self._chained_exceptions:
             self.set_convenience_variable(
                 self.curframe,
                 '_exception',
                 self._chained_exceptions[self._chained_exception_index],
             )

         if self.rcLines:
             self.cmdqueue = [
                 line for line in self.rcLines
                 if line.strip() and not line.strip().startswith("#")
             ]
             self.rcLines = []

     # Override Bdb methods

     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."""
         if self._wait_for_mainpyfile:
             return
         if self.stop_here(frame):
             self.message('--Call--')
             self.interaction(frame, None)

     def user_line(self, frame):
         """This function is called when we stop or break at this line."""
         if self._wait_for_mainpyfile:
             if (self.mainpyfile != self.canonic(frame.f_code.co_filename)
                 or frame.f_lineno <= 0):
                 return
             self._wait_for_mainpyfile = False
         if self.bp_commands(frame):
             self.interaction(frame, None)

     user_opcode = user_line

     def bp_commands(self, frame):
         """Call every command that was set for the current active breakpoint
         (if there is one).

         Returns True if the normal interaction function must be called,
         False otherwise."""
         # self.currentbp is set in bdb in Bdb.break_here if a breakpoint was hit
         if getattr(self, "currentbp", False) and \
                self.currentbp in self.commands:
             currentbp = self.currentbp
             self.currentbp = 0
             lastcmd_back = self.lastcmd
             self.setup(frame, None)
             for line in self.commands[currentbp]:
                 self.onecmd(line)
             self.lastcmd = lastcmd_back
             if not self.commands_silent[currentbp]:
                 self.print_stack_entry(self.stack[self.curindex])
             if self.commands_doprompt[currentbp]:
                 self._cmdloop()
             self.forget()
             return
         return 1

     def user_return(self, frame, return_value):
         """This function is called when a return trap is set here."""
         if self._wait_for_mainpyfile:
             return
         frame.f_locals['__return__'] = return_value
         self.set_convenience_variable(frame, '_retval', return_value)
         self.message('--Return--')
         self.interaction(frame, None)

     def user_exception(self, frame, exc_info):
         """This function is called if an exception occurs,
         but only if we are to stop at or just below this level."""
         if self._wait_for_mainpyfile:
             return
         exc_type, exc_value, exc_traceback = exc_info
         frame.f_locals['__exception__'] = exc_type, exc_value
         self.set_convenience_variable(frame, '_exception', exc_value)

         # An 'Internal StopIteration' exception is an exception debug event
         # issued by the interpreter when handling a subgenerator run with
         # 'yield from' or a generator controlled by a for loop. No exception has
         # actually occurred in this case. The debugger uses this debug event to
         # stop when the debuggee is returning from such generators.
         prefix = 'Internal ' if (not exc_traceback
                                     and exc_type is StopIteration) else ''
         self.message('%s%s' % (prefix, self._format_exc(exc_value)))
         self.interaction(frame, exc_traceback)

     # General interaction function
     def _cmdloop(self):
         while True:
             try:
                 # keyboard interrupts allow for an easy way to cancel
                 # the current command, so allow them during interactive input
                 self.allow_kbdint = True
                 self.cmdloop()
                 self.allow_kbdint = False
                 break
             except KeyboardInterrupt:
                 self.message('--KeyboardInterrupt--')

     def _validate_file_mtime(self):
         """Check if the source file of the current frame has been modified since
         the last time we saw it. If so, give a warning."""
         try:
             filename = self.curframe.f_code.co_filename
             mtime = os.path.getmtime(filename)
         except Exception:
             return
         if (filename in self._file_mtime_table and
             mtime != self._file_mtime_table[filename]):
             self.message(f"*** WARNING: file '{filename}' was edited, "
                          "running stale code until the program is rerun")
         self._file_mtime_table[filename] = mtime

     # Called before loop, handles display expressions
     # Set up convenience variable containers
     def _show_display(self):
         displaying = self.displaying.get(self.curframe)
         if displaying:
             for expr, oldvalue in displaying.items():
                 newvalue = self._getval_except(expr)
                 # check for identity first; this prevents custom __eq__ to
                 # be called at every loop, and also prevents instances whose
                 # fields are changed to be displayed
                 if newvalue is not oldvalue and newvalue != oldvalue:
                     displaying[expr] = newvalue
                     self.message('display %s: %s  [old: %s]' %
                                  (expr, self._safe_repr(newvalue, expr),
                                   self._safe_repr(oldvalue, expr)))

     def _get_tb_and_exceptions(self, tb_or_exc):
         """
         Given a tracecack or an exception, return a tuple of chained exceptions
         and current traceback to inspect.

         This will deal with selecting the right ``__cause__`` or ``__context__``
         as well as handling cycles, and return a flattened list of exceptions we
         can jump to with do_exceptions.

         """
         _exceptions = []
         if isinstance(tb_or_exc, BaseException):
             traceback, current = tb_or_exc.__traceback__, tb_or_exc

             while current is not None:
                 if current in _exceptions:
                     break
                 _exceptions.append(current)
                 if current.__cause__ is not None:
                     current = current.__cause__
                 elif (
                     current.__context__ is not None and not current.__suppress_context__
                 ):
                     current = current.__context__

                 if len(_exceptions) >= self.MAX_CHAINED_EXCEPTION_DEPTH:
                     self.message(
                         f"More than {self.MAX_CHAINED_EXCEPTION_DEPTH}"
                         " chained exceptions found, not all exceptions"
                         "will be browsable with `exceptions`."
                     )
                     break
         else:
             traceback = tb_or_exc
         return tuple(reversed(_exceptions)), traceback

     @contextmanager
     def _hold_exceptions(self, exceptions):
         """
         Context manager to ensure proper cleaning of exceptions references

         When given a chained exception instead of a traceback,
         pdb may hold references to many objects which may leak memory.

         We use this context manager to make sure everything is properly cleaned

         """
         try:
             self._chained_exceptions = exceptions
             self._chained_exception_index = len(exceptions) - 1
             yield
         finally:
             # we can't put those in forget as otherwise they would
             # be cleared on exception change
             self._chained_exceptions = tuple()
             self._chained_exception_index = 0

     def interaction(self, frame, tb_or_exc):
         # Restore the previous signal handler at the Pdb prompt.
         if Pdb._previous_sigint_handler:
             try:
                 signal.signal(signal.SIGINT, Pdb._previous_sigint_handler)
             except ValueError:  # ValueError: signal only works in main thread
                 pass
             else:
                 Pdb._previous_sigint_handler = None

         _chained_exceptions, tb = self._get_tb_and_exceptions(tb_or_exc)
         if isinstance(tb_or_exc, BaseException):
             assert tb is not None, "main exception must have a traceback"
         with self._hold_exceptions(_chained_exceptions):
             self.setup(frame, tb)
             # We should print the stack entry if and only if the user input
             # is expected, and we should print it right before the user input.
             # We achieve this by appending _pdbcmd_print_frame_status to the
             # command queue. If cmdqueue is not exausted, the user input is
             # not expected and we will not print the stack entry.
             self.cmdqueue.append('_pdbcmd_print_frame_status')
             self._cmdloop()
             # If _pdbcmd_print_frame_status is not used, pop it out
             if self.cmdqueue and self.cmdqueue[-1] == '_pdbcmd_print_frame_status':
                 self.cmdqueue.pop()
             self.forget()

     def displayhook(self, obj):
         """Custom displayhook for the exec in default(), which prevents
         assignment of the _ variable in the builtins.
         """
         # reproduce the behavior of the standard displayhook, not printing None
         if obj is not None:
             self.message(repr(obj))

     @contextmanager
     def _disable_command_completion(self):
         completenames = self.completenames
         try:
             self.completenames = self.completedefault
             yield
         finally:
             self.completenames = completenames
         return

     def _exec_in_closure(self, source, globals, locals):
         """ Run source code in closure so code object created within source
             can find variables in locals correctly

             returns True if the source is executed, False otherwise
         """

         # Determine if the source should be executed in closure. Only when the
         # source compiled to multiple code objects, we should use this feature.
         # Otherwise, we can just raise an exception and normal exec will be used.

         code = compile(source, "<string>", "exec")
         if not any(isinstance(const, CodeType) for const in code.co_consts):
             return False

         # locals could be a proxy which does not support pop
         # copy it first to avoid modifying the original locals
         locals_copy = dict(locals)

         locals_copy["__pdb_eval__"] = {
             "result": None,
             "write_back": {}
         }

         # If the source is an expression, we need to print its value
         try:
             compile(source, "<string>", "eval")
         except SyntaxError:
             pass
         else:
             source = "__pdb_eval__['result'] = " + source

         # Add write-back to update the locals
         source = ("try:\n" +
                   textwrap.indent(source, "  ") + "\n" +
                   "finally:\n" +
                   "  __pdb_eval__['write_back'] = locals()")

         # Build a closure source code with freevars from locals like:
         # def __pdb_outer():
         #   var = None
         #   def __pdb_scope():  # This is the code object we want to execute
         #     nonlocal var
         #     <source>
         #   return __pdb_scope.__code__
         source_with_closure = ("def __pdb_outer():\n" +
                                "\n".join(f"  {var} = None" for var in locals_copy) + "\n" +
                                "  def __pdb_scope():\n" +
                                "\n".join(f"    nonlocal {var}" for var in locals_copy) + "\n" +
                                textwrap.indent(source, "    ") + "\n" +
                                "  return __pdb_scope.__code__"
                                )

         # Get the code object of __pdb_scope()
         # The exec fills locals_copy with the __pdb_outer() function and we can call
         # that to get the code object of __pdb_scope()
         ns = {}
         try:
             exec(source_with_closure, {}, ns)
         except Exception:
             return False
         code = ns["__pdb_outer"]()

         cells = tuple(types.CellType(locals_copy.get(var)) for var in code.co_freevars)

         try:
             exec(code, globals, locals_copy, closure=cells)
         except Exception:
             return False

         # get the data we need from the statement
         pdb_eval = locals_copy["__pdb_eval__"]

         # __pdb_eval__ should not be updated back to locals
         pdb_eval["write_back"].pop("__pdb_eval__")

         # Write all local variables back to locals
         locals.update(pdb_eval["write_back"])
         eval_result = pdb_eval["result"]
         if eval_result is not None:
             print(repr(eval_result))

         return True

     def default(self, line):
         if line[:1] == '!': line = line[1:].strip()
         locals = self.curframe_locals
         globals = self.curframe.f_globals
         try:
             buffer = line
             if (code := codeop.compile_command(line + '\n', '<stdin>', 'single')) is None:
                 # Multi-line mode
                 with self._disable_command_completion():
                     buffer = line
                     continue_prompt = "...   "
                     while (code := codeop.compile_command(buffer, '<stdin>', 'single')) is None:
                         if self.use_rawinput:
                             try:
                                 line = input(continue_prompt)
                             except (EOFError, KeyboardInterrupt):
                                 self.lastcmd = ""
                                 print('\n')
                                 return
                         else:
                             self.stdout.write(continue_prompt)
                             self.stdout.flush()
                             line = self.stdin.readline()
                             if not len(line):
                                 self.lastcmd = ""
                                 self.stdout.write('\n')
                                 self.stdout.flush()
                                 return
                             else:
                                 line = line.rstrip('\r\n')
                         buffer += '\n' + line
             save_stdout = sys.stdout
             save_stdin = sys.stdin
             save_displayhook = sys.displayhook
             try:
                 sys.stdin = self.stdin
                 sys.stdout = self.stdout
                 sys.displayhook = self.displayhook
                 if not self._exec_in_closure(buffer, globals, locals):
                     exec(code, globals, locals)
             finally:
                 sys.stdout = save_stdout
                 sys.stdin = save_stdin
                 sys.displayhook = save_displayhook
         except:
             self._error_exc()

     def _replace_convenience_variables(self, line):
         """Replace the convenience variables in 'line' with their values.
            e.g. $foo is replaced by __pdb_convenience_variables["foo"].
            Note: such pattern in string literals will be skipped"""

         if "$" not in line:
             return line

         dollar_start = dollar_end = -1
         replace_variables = []
         try:
             for t in tokenize.generate_tokens(io.StringIO(line).readline):
                 token_type, token_string, start, end, _ = t
                 if token_type == token.OP and token_string == '$':
                     dollar_start, dollar_end = start, end
                 elif start == dollar_end and token_type == token.NAME:
                     # line is a one-line command so we only care about column
                     replace_variables.append((dollar_start[1], end[1], token_string))
         except tokenize.TokenError:
             return line

         if not replace_variables:
             return line

         last_end = 0
         line_pieces = []
         for start, end, name in replace_variables:
             line_pieces.append(line[last_end:start] + f'__pdb_convenience_variables["{name}"]')
             last_end = end
         line_pieces.append(line[last_end:])

         return ''.join(line_pieces)

     def precmd(self, line):
         """Handle alias expansion and ';;' separator."""
         if not line.strip():
             return line
         args = line.split()
         while args[0] in self.aliases:
             line = self.aliases[args[0]]
             for idx in range(1, 10):
                 if f'%{idx}' in line:
                     if idx >= len(args):
                         self.error(f"Not enough arguments for alias '{args[0]}'")
                         # This is a no-op
                         return "!"
                     line = line.replace(f'%{idx}', args[idx])
                 elif '%*' not in line:
                     if idx < len(args):
                         self.error(f"Too many arguments for alias '{args[0]}'")
                         # This is a no-op
                         return "!"
                     break

             line = line.replace("%*", ' '.join(args[1:]))
             args = line.split()
         # split into ';;' separated commands
         # unless it's an alias command
         if args[0] != 'alias':
             marker = line.find(';;')
             if marker >= 0:
                 # queue up everything after marker
                 next = line[marker+2:].lstrip()
                 self.cmdqueue.insert(0, next)
                 line = line[:marker].rstrip()

         # Replace all the convenience variables
         line = self._replace_convenience_variables(line)

         return line

     def onecmd(self, line):
         """Interpret the argument as though it had been typed in response
         to the prompt.

         Checks whether this line is typed at the normal prompt or in
         a breakpoint command list definition.
         """
         if not self.commands_defining:
             self._validate_file_mtime()
             if line.startswith('_pdbcmd'):
                 command, arg, line = self.parseline(line)
                 if hasattr(self, command):
                     return getattr(self, command)(arg)
             return cmd.Cmd.onecmd(self, line)
         else:
             return self.handle_command_def(line)

     def handle_command_def(self, line):
         """Handles one command line during command list definition."""
         cmd, arg, line = self.parseline(line)
         if not cmd:
             return False
         if cmd == 'silent':
             self.commands_silent[self.commands_bnum] = True
             return False  # continue to handle other cmd def in the cmd list
         elif cmd == 'end':
             return True  # end of cmd list
         cmdlist = self.commands[self.commands_bnum]
         if arg:
             cmdlist.append(cmd+' '+arg)
         else:
             cmdlist.append(cmd)
         # Determine if we must stop
         try:
             func = getattr(self, 'do_' + cmd)
         except AttributeError:
             func = self.default
         # one of the resuming commands
         if func.__name__ in self.commands_resuming:
             self.commands_doprompt[self.commands_bnum] = False
             return True
         return False

     # interface abstraction functions

     def message(self, msg, end='\n'):
         print(msg, end=end, file=self.stdout)

     def error(self, msg):
         print('***', msg, file=self.stdout)

     # convenience variables

     def set_convenience_variable(self, frame, name, value):
         if '__pdb_convenience_variables' not in frame.f_globals:
             frame.f_globals['__pdb_convenience_variables'] = {}
         frame.f_globals['__pdb_convenience_variables'][name] = value

     # Generic completion functions.  Individual complete_foo methods can be
     # assigned below to one of these functions.

     def completenames(self, text, line, begidx, endidx):
         # Overwrite completenames() of cmd so for the command completion,
         # if no current command matches, check for expressions as well
         commands = super().completenames(text, line, begidx, endidx)
         for alias in self.aliases:
             if alias.startswith(text):
                 commands.append(alias)
         if commands:
             return commands
         else:
             expressions = self._complete_expression(text, line, begidx, endidx)
             if expressions:
                 return expressions
             return self.completedefault(text, line, begidx, endidx)

     def _complete_location(self, text, line, begidx, endidx):
         # Complete a file/module/function location for break/tbreak/clear.
         if line.strip().endswith((':', ',')):
             # Here comes a line number or a condition which we can't complete.
             return []
         # First, try to find matching functions (i.e. expressions).
         try:
             ret = self._complete_expression(text, line, begidx, endidx)
         except Exception:
             ret = []
         # Then, try to complete file names as well.
         globs = glob.glob(glob.escape(text) + '*')
         for fn in globs:
             if os.path.isdir(fn):
                 ret.append(fn + '/')
             elif os.path.isfile(fn) and fn.lower().endswith(('.py', '.pyw')):
                 ret.append(fn + ':')
         return ret

     def _complete_bpnumber(self, text, line, begidx, endidx):
         # Complete a breakpoint number.  (This would be more helpful if we could
         # display additional info along with the completions, such as file/line
         # of the breakpoint.)
         return [str(i) for i, bp in enumerate(bdb.Breakpoint.bpbynumber)
                 if bp is not None and str(i).startswith(text)]

     def _complete_expression(self, text, line, begidx, endidx):
         # Complete an arbitrary expression.
         if not self.curframe:
             return []
         # Collect globals and locals.  It is usually not really sensible to also
         # complete builtins, and they clutter the namespace quite heavily, so we
         # leave them out.
         ns = {**self.curframe.f_globals, **self.curframe_locals}
         if text.startswith("$"):
             # Complete convenience variables
             conv_vars = self.curframe.f_globals.get('__pdb_convenience_variables', {})
             return [f"${name}" for name in conv_vars if name.startswith(text[1:])]
         if '.' in text:
             # Walk an attribute chain up to the last part, similar to what
             # rlcompleter does.  This will bail if any of the parts are not
             # simple attribute access, which is what we want.
             dotted = text.split('.')
             try:
                 obj = ns[dotted[0]]
                 for part in dotted[1:-1]:
                     obj = getattr(obj, part)
             except (KeyError, AttributeError):
                 return []
             prefix = '.'.join(dotted[:-1]) + '.'
             return [prefix + n for n in dir(obj) if n.startswith(dotted[-1])]
         else:
             # Complete a simple name.
             return [n for n in ns.keys() if n.startswith(text)]

     def completedefault(self, text, line, begidx, endidx):
         if text.startswith("$"):
             # Complete convenience variables
             conv_vars = self.curframe.f_globals.get('__pdb_convenience_variables', {})
             return [f"${name}" for name in conv_vars if name.startswith(text[1:])]

         # Use rlcompleter to do the completion
         state = 0
         matches = []
         completer = Completer(self.curframe.f_globals | self.curframe_locals)
         while (match := completer.complete(text, state)) is not None:
             matches.append(match)
             state += 1
         return matches

     # Pdb meta commands, only intended to be used internally by pdb

     def _pdbcmd_print_frame_status(self, arg):
         self.print_stack_entry(self.stack[self.curindex])
         self._show_display()

     # Command definitions, called by cmdloop()
     # The argument is the remaining string on the command line
     # Return true to exit from the command loop

     def do_commands(self, arg):
         """(Pdb) commands [bpnumber]
         (com) ...
         (com) end
         (Pdb)

         Specify a list of commands for breakpoint number bpnumber.
         The commands themselves are entered on the following lines.
         Type a line containing just 'end' to terminate the commands.
         The commands are executed when the breakpoint is hit.

         To remove all commands from a breakpoint, type commands and
         follow it immediately with end; that is, give no commands.

         With no bpnumber argument, commands refers to the last
         breakpoint set.

         You can use breakpoint commands to start your program up
         again.  Simply use the continue command, or step, or any other
         command that resumes execution.

         Specifying any command resuming execution (currently continue,
         step, next, return, jump, quit and their abbreviations)
         terminates the command list (as if that command was
         immediately followed by end).  This is because any time you
         resume execution (even with a simple next or step), you may
         encounter another breakpoint -- which could have its own
         command list, leading to ambiguities about which list to
         execute.

         If you use the 'silent' command in the command list, the usual
         message about stopping at a breakpoint is not printed.  This
         may be desirable for breakpoints that are to print a specific
         message and then continue.  If none of the other commands
         print anything, you will see no sign that the breakpoint was
         reached.
         """
         if not arg:
             bnum = len(bdb.Breakpoint.bpbynumber) - 1
         else:
             try:
                 bnum = int(arg)
             except:
                 self._print_invalid_arg(arg)
                 return
         try:
             self.get_bpbynumber(bnum)
         except ValueError as err:
             self.error('cannot set commands: %s' % err)
             return

         self.commands_bnum = bnum
         # Save old definitions for the case of a keyboard interrupt.
         if bnum in self.commands:
             old_command_defs = (self.commands[bnum],
                                 self.commands_doprompt[bnum],
                                 self.commands_silent[bnum])
         else:
             old_command_defs = None
         self.commands[bnum] = []
         self.commands_doprompt[bnum] = True
         self.commands_silent[bnum] = False

         prompt_back = self.prompt
         self.prompt = '(com) '
         self.commands_defining = True
         try:
             self.cmdloop()
         except KeyboardInterrupt:
             # Restore old definitions.
             if old_command_defs:
                 self.commands[bnum] = old_command_defs[0]
                 self.commands_doprompt[bnum] = old_command_defs[1]
                 self.commands_silent[bnum] = old_command_defs[2]
             else:
                 del self.commands[bnum]
                 del self.commands_doprompt[bnum]
                 del self.commands_silent[bnum]
             self.error('command definition aborted, old commands restored')
         finally:
             self.commands_defining = False
             self.prompt = prompt_back

     complete_commands = _complete_bpnumber

     def do_break(self, arg, temporary = 0):
         """b(reak) [ ([filename:]lineno | function) [, condition] ]

         Without argument, list all breaks.

         With a line number argument, set a break at this line in the
         current file.  With a function name, set a break at the first
         executable line of that function.  If a second argument is
         present, it is a string specifying an expression which must
         evaluate to true before the breakpoint is honored.

         The line number may be prefixed with a filename and a colon,
         to specify a breakpoint in another file (probably one that
         hasn't been loaded yet).  The file is searched for on
         sys.path; the .py suffix may be omitted.
         """
         if not arg:
             if self.breaks:  # There's at least one
                 self.message("Num Type         Disp Enb   Where")
                 for bp in bdb.Breakpoint.bpbynumber:
                     if bp:
                         self.message(bp.bpformat())
             return
         # parse arguments; comma has lowest precedence
         # and cannot occur in filename
         filename = None
         lineno = None
         cond = None
         comma = arg.find(',')
         if comma > 0:
             # parse stuff after comma: "condition"
             cond = arg[comma+1:].lstrip()
             if err := self._compile_error_message(cond):
                 self.error('Invalid condition %s: %r' % (cond, err))
                 return
             arg = arg[:comma].rstrip()
         # parse stuff before comma: [filename:]lineno | function
         colon = arg.rfind(':')
         funcname = None
         if colon >= 0:
             filename = arg[:colon].rstrip()
             f = self.lookupmodule(filename)
             if not f:
                 self.error('%r not found from sys.path' % filename)
                 return
             else:
                 filename = f
             arg = arg[colon+1:].lstrip()
             try:
                 lineno = int(arg)
             except ValueError:
                 self.error('Bad lineno: %s' % arg)
                 return
         else:
             # no colon; can be lineno or function
             try:
                 lineno = int(arg)
             except ValueError:
                 try:
                     func = eval(arg,
                                 self.curframe.f_globals,
                                 self.curframe_locals)
                 except:
                     func = arg
                 try:
                     if hasattr(func, '__func__'):
                         func = func.__func__
                     code = func.__code__
                     #use co_name to identify the bkpt (function names
                     #could be aliased, but co_name is invariant)
                     funcname = code.co_name
                     lineno = find_first_executable_line(code)
                     filename = code.co_filename
                 except:
                     # last thing to try
                     (ok, filename, ln) = self.lineinfo(arg)
                     if not ok:
                         self.error('The specified object %r is not a function '
                                    'or was not found along sys.path.' % arg)
                         return
                     funcname = ok # ok contains a function name
                     lineno = int(ln)
         if not filename:
             filename = self.defaultFile()
         # Check for reasonable breakpoint
         line = self.checkline(filename, lineno)
         if line:
             # now set the break point
             err = self.set_break(filename, line, temporary, cond, funcname)
             if err:
                 self.error(err)
             else:
                 bp = self.get_breaks(filename, line)[-1]
                 self.message("Breakpoint %d at %s:%d" %
                              (bp.number, bp.file, bp.line))

     # To be overridden in derived debuggers
     def defaultFile(self):
         """Produce a reasonable default."""
         filename = self.curframe.f_code.co_filename
         if filename == '<string>' and self.mainpyfile:
             filename = self.mainpyfile
         return filename

     do_b = do_break

     complete_break = _complete_location
     complete_b = _complete_location

     def do_tbreak(self, arg):
         """tbreak [ ([filename:]lineno | function) [, condition] ]

         Same arguments as break, but sets a temporary breakpoint: it
         is automatically deleted when first hit.
         """
         self.do_break(arg, 1)

     complete_tbreak = _complete_location

     def lineinfo(self, identifier):
         failed = (None, None, None)
         # Input is identifier, may be in single quotes
         idstring = identifier.split("'")
         if len(idstring) == 1:
             # not in single quotes
             id = idstring[0].strip()
         elif len(idstring) == 3:
             # quoted
             id = idstring[1].strip()
         else:
             return failed
         if id == '': return failed
         parts = id.split('.')
         # Protection for derived debuggers
         if parts[0] == 'self':
             del parts[0]
             if len(parts) == 0:
                 return failed
         # Best first guess at file to look at
         fname = self.defaultFile()
         if len(parts) == 1:
             item = parts[0]
         else:
             # More than one part.
             # First is module, second is method/class
             f = self.lookupmodule(parts[0])
             if f:
                 fname = f
             item = parts[1]
         answer = find_function(item, self.canonic(fname))
         return answer or failed

     def checkline(self, filename, lineno):
         """Check whether specified line seems to be executable.

         Return `lineno` if it is, 0 if not (e.g. a docstring, comment, blank
         line or EOF). Warning: testing is not comprehensive.
         """
         # this method should be callable before starting debugging, so default
         # to "no globals" if there is no current frame
         frame = getattr(self, 'curframe', None)
         globs = frame.f_globals if frame else None
         line = linecache.getline(filename, lineno, globs)
         if not line:
             self.message('End of file')
             return 0
         line = line.strip()
         # Don't allow setting breakpoint at a blank line
         if (not line or (line[0] == '#') or
              (line[:3] == '"""') or line[:3] == "'''"):
             self.error('Blank or comment')
             return 0
         return lineno

     def do_enable(self, arg):
         """enable bpnumber [bpnumber ...]

         Enables the breakpoints given as a space separated list of
         breakpoint numbers.
         """
         args = arg.split()
         for i in args:
             try:
                 bp = self.get_bpbynumber(i)
             except ValueError as err:
                 self.error(err)
             else:
                 bp.enable()
                 self.message('Enabled %s' % bp)

     complete_enable = _complete_bpnumber

     def do_disable(self, arg):
         """disable bpnumber [bpnumber ...]

         Disables the breakpoints given as a space separated list of
         breakpoint numbers.  Disabling a breakpoint means it cannot
         cause the program to stop execution, but unlike clearing a
         breakpoint, it remains in the list of breakpoints and can be
         (re-)enabled.
         """
         args = arg.split()
         for i in args:
             try:
                 bp = self.get_bpbynumber(i)
             except ValueError as err:
                 self.error(err)
             else:
                 bp.disable()
                 self.message('Disabled %s' % bp)

     complete_disable = _complete_bpnumber

     def do_condition(self, arg):
         """condition bpnumber [condition]

         Set a new condition for the breakpoint, an expression which
         must evaluate to true before the breakpoint is honored.  If
         condition is absent, any existing condition is removed; i.e.,
         the breakpoint is made unconditional.
         """
         args = arg.split(' ', 1)
         try:
             cond = args[1]
             if err := self._compile_error_message(cond):
                 self.error('Invalid condition %s: %r' % (cond, err))
                 return
         except IndexError:
             cond = None
         try:
             bp = self.get_bpbynumber(args[0].strip())
         except IndexError:
             self.error('Breakpoint number expected')
         except ValueError as err:
             self.error(err)
         else:
             bp.cond = cond
             if not cond:
                 self.message('Breakpoint %d is now unconditional.' % bp.number)
             else:
                 self.message('New condition set for breakpoint %d.' % bp.number)

     complete_condition = _complete_bpnumber

     def do_ignore(self, arg):
         """ignore bpnumber [count]

         Set the ignore count for the given breakpoint number.  If
         count is omitted, the ignore count is set to 0.  A breakpoint
         becomes active when the ignore count is zero.  When non-zero,
         the count is decremented each time the breakpoint is reached
         and the breakpoint is not disabled and any associated
         condition evaluates to true.
         """
         args = arg.split()
         if not args:
             self.error('Breakpoint number expected')
             return
         if len(args) == 1:
             count = 0
         elif len(args) == 2:
             try:
                 count = int(args[1])
             except ValueError:
                 self._print_invalid_arg(arg)
                 return
         else:
             self._print_invalid_arg(arg)
             return
         try:
             bp = self.get_bpbynumber(args[0].strip())
         except ValueError as err:
             self.error(err)
         else:
             bp.ignore = count
             if count > 0:
                 if count > 1:
                     countstr = '%d crossings' % count
                 else:
                     countstr = '1 crossing'
                 self.message('Will ignore next %s of breakpoint %d.' %
                              (countstr, bp.number))
             else:
                 self.message('Will stop next time breakpoint %d is reached.'
                              % bp.number)

     complete_ignore = _complete_bpnumber

     def do_clear(self, arg):
         """cl(ear) [filename:lineno | bpnumber ...]

         With a space separated list of breakpoint numbers, clear
         those breakpoints.  Without argument, clear all breaks (but
         first ask confirmation).  With a filename:lineno argument,
         clear all breaks at that line in that file.
         """
         if not arg:
             try:
                 reply = input('Clear all breaks? ')
             except EOFError:
                 reply = 'no'
             reply = reply.strip().lower()
             if reply in ('y', 'yes'):
                 bplist = [bp for bp in bdb.Breakpoint.bpbynumber if bp]
                 self.clear_all_breaks()
                 for bp in bplist:
                     self.message('Deleted %s' % bp)
             return
         if ':' in arg:
             # Make sure it works for "clear C:\foo\bar.py:12"
             i = arg.rfind(':')
             filename = arg[:i]
             arg = arg[i+1:]
             try:
                 lineno = int(arg)
             except ValueError:
                 err = "Invalid line number (%s)" % arg
             else:
                 bplist = self.get_breaks(filename, lineno)[:]
                 err = self.clear_break(filename, lineno)
             if err:
                 self.error(err)
             else:
                 for bp in bplist:
                     self.message('Deleted %s' % bp)
             return
         numberlist = arg.split()
         for i in numberlist:
             try:
                 bp = self.get_bpbynumber(i)
             except ValueError as err:
                 self.error(err)
             else:
                 self.clear_bpbynumber(i)
                 self.message('Deleted %s' % bp)
     do_cl = do_clear # 'c' is already an abbreviation for 'continue'

     complete_clear = _complete_location
     complete_cl = _complete_location

     def do_where(self, arg):
         """w(here)

         Print a stack trace, with the most recent frame at the bottom.
         An arrow indicates the "current frame", which determines the
         context of most commands.  'bt' is an alias for this command.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         self.print_stack_trace()
     do_w = do_where
     do_bt = do_where

     def _select_frame(self, number):
         assert 0 <= number < len(self.stack)
         self.curindex = number
         self.curframe = self.stack[self.curindex][0]
         self.curframe_locals = self.curframe.f_locals
         self.set_convenience_variable(self.curframe, '_frame', self.curframe)
         self.print_stack_entry(self.stack[self.curindex])
         self.lineno = None

     def do_exceptions(self, arg):
         """exceptions [number]

         List or change current exception in an exception chain.

         Without arguments, list all the current exception in the exception
         chain. Exceptions will be numbered, with the current exception indicated
         with an arrow.

         If given an integer as argument, switch to the exception at that index.
         """
         if not self._chained_exceptions:
             self.message(
                 "Did not find chained exceptions. To move between"
                 " exceptions, pdb/post_mortem must be given an exception"
                 " object rather than a traceback."
             )
             return
         if not arg:
             for ix, exc in enumerate(self._chained_exceptions):
                 prompt = ">" if ix == self._chained_exception_index else " "
                 rep = repr(exc)
                 if len(rep) > 80:
                     rep = rep[:77] + "..."
                 indicator = (
                     "  -"
                     if self._chained_exceptions[ix].__traceback__ is None
                     else f"{ix:>3}"
                 )
                 self.message(f"{prompt} {indicator} {rep}")
         else:
             try:
                 number = int(arg)
             except ValueError:
                 self.error("Argument must be an integer")
                 return
             if 0 <= number < len(self._chained_exceptions):
                 if self._chained_exceptions[number].__traceback__ is None:
                     self.error("This exception does not have a traceback, cannot jump to it")
                     return

                 self._chained_exception_index = number
                 self.setup(None, self._chained_exceptions[number].__traceback__)
                 self.print_stack_entry(self.stack[self.curindex])
             else:
                 self.error("No exception with that number")

     def do_up(self, arg):
         """u(p) [count]

         Move the current frame count (default one) levels up in the
         stack trace (to an older frame).
         """
         if self.curindex == 0:
             self.error('Oldest frame')
             return
         try:
             count = int(arg or 1)
         except ValueError:
             self.error('Invalid frame count (%s)' % arg)
             return
         if count < 0:
             newframe = 0
         else:
             newframe = max(0, self.curindex - count)
         self._select_frame(newframe)
     do_u = do_up

     def do_down(self, arg):
         """d(own) [count]

         Move the current frame count (default one) levels down in the
         stack trace (to a newer frame).
         """
         if self.curindex + 1 == len(self.stack):
             self.error('Newest frame')
             return
         try:
             count = int(arg or 1)
         except ValueError:
             self.error('Invalid frame count (%s)' % arg)
             return
         if count < 0:
             newframe = len(self.stack) - 1
         else:
             newframe = min(len(self.stack) - 1, self.curindex + count)
         self._select_frame(newframe)
     do_d = do_down

     def do_until(self, arg):
         """unt(il) [lineno]

         Without argument, continue execution until the line with a
         number greater than the current one is reached.  With a line
         number, continue execution until a line with a number greater
         or equal to that is reached.  In both cases, also stop when
         the current frame returns.
         """
         if arg:
             try:
                 lineno = int(arg)
             except ValueError:
                 self.error('Error in argument: %r' % arg)
                 return
             if lineno <= self.curframe.f_lineno:
                 self.error('"until" line number is smaller than current '
                            'line number')
                 return
         else:
             lineno = None
         self.set_until(self.curframe, lineno)
         return 1
     do_unt = do_until

     def do_step(self, arg):
         """s(tep)

         Execute the current line, stop at the first possible occasion
         (either in a function that is called or in the current
         function).
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         self.set_step()
         return 1
     do_s = do_step

     def do_next(self, arg):
         """n(ext)

         Continue execution until the next line in the current function
         is reached or it returns.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         self.set_next(self.curframe)
         return 1
     do_n = do_next

     def do_run(self, arg):
         """run [args...]

         Restart the debugged python program. If a string is supplied
         it is split with "shlex", and the result is used as the new
         sys.argv.  History, breakpoints, actions and debugger options
         are preserved.  "restart" is an alias for "run".
         """
         if arg:
             import shlex
             argv0 = sys.argv[0:1]
             try:
                 sys.argv = shlex.split(arg)
             except ValueError as e:
                 self.error('Cannot run %s: %s' % (arg, e))
                 return
             sys.argv[:0] = argv0
         # this is caught in the main debugger loop
         raise Restart

     do_restart = do_run

     def do_return(self, arg):
         """r(eturn)

         Continue execution until the current function returns.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         self.set_return(self.curframe)
         return 1
     do_r = do_return

     def do_continue(self, arg):
         """c(ont(inue))

         Continue execution, only stop when a breakpoint is encountered.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         if not self.nosigint:
             try:
                 Pdb._previous_sigint_handler = \
                     signal.signal(signal.SIGINT, self.sigint_handler)
             except ValueError:
                 # ValueError happens when do_continue() is invoked from
                 # a non-main thread in which case we just continue without
                 # SIGINT set. Would printing a message here (once) make
                 # sense?
                 pass
         self.set_continue()
         return 1
     do_c = do_cont = do_continue

     def do_jump(self, arg):
         """j(ump) lineno

         Set the next line that will be executed.  Only available in
         the bottom-most frame.  This lets you jump back and execute
         code again, or jump forward to skip code that you don't want
         to run.

         It should be noted that not all jumps are allowed -- for
         instance it is not possible to jump into the middle of a
         for loop or out of a finally clause.
         """
         if self.curindex + 1 != len(self.stack):
             self.error('You can only jump within the bottom frame')
             return
         try:
             arg = int(arg)
         except ValueError:
             self.error("The 'jump' command requires a line number")
         else:
             try:
                 # Do the jump, fix up our copy of the stack, and display the
                 # new position
                 self.curframe.f_lineno = arg
                 self.stack[self.curindex] = self.stack[self.curindex][0], arg
                 self.print_stack_entry(self.stack[self.curindex])
             except ValueError as e:
                 self.error('Jump failed: %s' % e)
     do_j = do_jump

     def do_debug(self, arg):
         """debug code

         Enter a recursive debugger that steps through the code
         argument (which is an arbitrary expression or statement to be
         executed in the current environment).
         """
         sys.settrace(None)
         globals = self.curframe.f_globals
         locals = self.curframe_locals
         p = Pdb(self.completekey, self.stdin, self.stdout)
         p.prompt = "(%s) " % self.prompt.strip()
         self.message("ENTERING RECURSIVE DEBUGGER")
         try:
             sys.call_tracing(p.run, (arg, globals, locals))
         except Exception:
             self._error_exc()
         self.message("LEAVING RECURSIVE DEBUGGER")
         sys.settrace(self.trace_dispatch)
         self.lastcmd = p.lastcmd

     complete_debug = _complete_expression

     def do_quit(self, arg):
         """q(uit) | exit

         Quit from the debugger. The program being executed is aborted.
         """
         self._user_requested_quit = True
         self.set_quit()
         return 1

     do_q = do_quit
     do_exit = do_quit

     def do_EOF(self, arg):
         """EOF

         Handles the receipt of EOF as a command.
         """
         self.message('')
         self._user_requested_quit = True
         self.set_quit()
         return 1

     def do_args(self, arg):
         """a(rgs)

         Print the argument list of the current function.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         co = self.curframe.f_code
         dict = self.curframe_locals
         n = co.co_argcount + co.co_kwonlyargcount
         if co.co_flags & inspect.CO_VARARGS: n = n+1
         if co.co_flags & inspect.CO_VARKEYWORDS: n = n+1
         for i in range(n):
             name = co.co_varnames[i]
             if name in dict:
                 self.message('%s = %s' % (name, self._safe_repr(dict[name], name)))
             else:
                 self.message('%s = *** undefined ***' % (name,))
     do_a = do_args

     def do_retval(self, arg):
         """retval

         Print the return value for the last return of a function.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         if '__return__' in self.curframe_locals:
             self.message(self._safe_repr(self.curframe_locals['__return__'], "retval"))
         else:
             self.error('Not yet returned!')
     do_rv = do_retval

     def _getval(self, arg):
         try:
             return eval(arg, self.curframe.f_globals, self.curframe_locals)
         except:
             self._error_exc()
             raise

     def _getval_except(self, arg, frame=None):
         try:
             if frame is None:
                 return eval(arg, self.curframe.f_globals, self.curframe_locals)
             else:
                 return eval(arg, frame.f_globals, frame.f_locals)
         except BaseException as exc:
             return _rstr('** raised %s **' % self._format_exc(exc))

     def _error_exc(self):
         exc = sys.exception()
         self.error(self._format_exc(exc))

     def _msg_val_func(self, arg, func):
         try:
             val = self._getval(arg)
         except:
             return  # _getval() has displayed the error
         try:
             self.message(func(val))
         except:
             self._error_exc()

     def _safe_repr(self, obj, expr):
         try:
             return repr(obj)
         except Exception as e:
             return _rstr(f"*** repr({expr}) failed: {self._format_exc(e)} ***")

     def do_p(self, arg):
         """p expression

         Print the value of the expression.
         """
         self._msg_val_func(arg, repr)

     def do_pp(self, arg):
         """pp expression

         Pretty-print the value of the expression.
         """
         self._msg_val_func(arg, pprint.pformat)

     complete_print = _complete_expression
     complete_p = _complete_expression
     complete_pp = _complete_expression

     def do_list(self, arg):
         """l(ist) [first[, last] | .]

         List source code for the current file.  Without arguments,
         list 11 lines around the current line or continue the previous
         listing.  With . as argument, list 11 lines around the current
         line.  With one argument, list 11 lines starting at that line.
         With two arguments, list the given range; if the second
         argument is less than the first, it is a count.

         The current line in the current frame is indicated by "->".
         If an exception is being debugged, the line where the
         exception was originally raised or propagated is indicated by
         ">>", if it differs from the current line.
         """
         self.lastcmd = 'list'
         last = None
         if arg and arg != '.':
             try:
                 if ',' in arg:
                     first, last = arg.split(',')
                     first = int(first.strip())
                     last = int(last.strip())
                     if last < first:
                         # assume it's a count
                         last = first + last
                 else:
                     first = int(arg.strip())
                     first = max(1, first - 5)
             except ValueError:
                 self.error('Error in argument: %r' % arg)
                 return
         elif self.lineno is None or arg == '.':
             first = max(1, self.curframe.f_lineno - 5)
         else:
             first = self.lineno + 1
         if last is None:
             last = first + 10
         filename = self.curframe.f_code.co_filename
         # gh-93696: stdlib frozen modules provide a useful __file__
         # this workaround can be removed with the closure of gh-89815
         if filename.startswith("<frozen"):
             tmp = self.curframe.f_globals.get("__file__")
             if isinstance(tmp, str):
                 filename = tmp
         breaklist = self.get_file_breaks(filename)
         try:
             lines = linecache.getlines(filename, self.curframe.f_globals)
             self._print_lines(lines[first-1:last], first, breaklist,
                               self.curframe)
             self.lineno = min(last, len(lines))
             if len(lines) < last:
                 self.message('[EOF]')
         except KeyboardInterrupt:
             pass
     do_l = do_list

     def do_longlist(self, arg):
         """ll | longlist

         List the whole source code for the current function or frame.
         """
         if arg:
             self._print_invalid_arg(arg)
             return
         filename = self.curframe.f_code.co_filename
         breaklist = self.get_file_breaks(filename)
         try:
             lines, lineno = self._getsourcelines(self.curframe)
         except OSError as err:
             self.error(err)
             return
         self._print_lines(lines, lineno, breaklist, self.curframe)
     do_ll = do_longlist

     def do_source(self, arg):
         """source expression

         Try to get source code for the given object and display it.
         """
         try:
             obj = self._getval(arg)
         except:
             return
         try:
             lines, lineno = self._getsourcelines(obj)
         except (OSError, TypeError) as err:
             self.error(err)
             return
         self._print_lines(lines, lineno)

     complete_source = _complete_expression

     def _print_lines(self, lines, start, breaks=(), frame=None):
         """Print a range of lines."""
         if frame:
             current_lineno = frame.f_lineno
             exc_lineno = self.tb_lineno.get(frame, -1)
         else:
             current_lineno = exc_lineno = -1
         for lineno, line in enumerate(lines, start):
             s = str(lineno).rjust(3)
             if len(s) < 4:
                 s += ' '
             if lineno in breaks:
                 s += 'B'
             else:
                 s += ' '
             if lineno == current_lineno:
                 s += '->'
             elif lineno == exc_lineno:
                 s += '>>'
             self.message(s + '\t' + line.rstrip())

     def do_whatis(self, arg):
         """whatis expression

         Print the type of the argument.
         """
         try:
             value = self._getval(arg)
         except:
             # _getval() already printed the error
             return
         code = None
         # Is it an instance method?
         try:
             code = value.__func__.__code__
         except Exception:
             pass
         if code:
             self.message('Method %s' % code.co_name)
             return
         # Is it a function?
         try:
             code = value.__code__
         except Exception:
             pass
         if code:
             self.message('Function %s' % code.co_name)
             return
         # Is it a class?
         if value.__class__ is type:
             self.message('Class %s.%s' % (value.__module__, value.__qualname__))
             return
         # None of the above...
         self.message(type(value))

     complete_whatis = _complete_expression

     def do_display(self, arg):
         """display [expression]

         Display the value of the expression if it changed, each time execution
         stops in the current frame.

         Without expression, list all display expressions for the current frame.
         """
         if not arg:
             if self.displaying:
                 self.message('Currently displaying:')
                 for key, val in self.displaying.get(self.curframe, {}).items():
                     self.message('%s: %s' % (key, self._safe_repr(val, key)))
             else:
                 self.message('No expression is being displayed')
         else:
             if err := self._compile_error_message(arg):
                 self.error('Unable to display %s: %r' % (arg, err))
             else:
                 val = self._getval_except(arg)
                 self.displaying.setdefault(self.curframe, {})[arg] = val
                 self.message('display %s: %s' % (arg, self._safe_repr(val, arg)))

     complete_display = _complete_expression

     def do_undisplay(self, arg):
         """undisplay [expression]

         Do not display the expression any more in the current frame.

         Without expression, clear all display expressions for the current frame.
         """
         if arg:
             try:
                 del self.displaying.get(self.curframe, {})[arg]
             except KeyError:
                 self.error('not displaying %s' % arg)
         else:
             self.displaying.pop(self.curframe, None)

     def complete_undisplay(self, text, line, begidx, endidx):
         return [e for e in self.displaying.get(self.curframe, {})
                 if e.startswith(text)]

     def do_interact(self, arg):
         """interact

         Start an interactive interpreter whose global namespace
         contains all the (global and local) names found in the current scope.
         """
         ns = {**self.curframe.f_globals, **self.curframe_locals}
         console = _PdbInteractiveConsole(ns, message=self.message)
         console.interact(banner="*pdb interact start*",
                          exitmsg="*exit from pdb interact command*")

     def do_alias(self, arg):
         """alias [name [command]]

         Create an alias called 'name' that executes 'command'.  The
         command must *not* be enclosed in quotes.  Replaceable
         parameters can be indicated by %1, %2, and so on, while %* is
         replaced by all the parameters.  If no command is given, the
         current alias for name is shown. If no name is given, all
         aliases are listed.

         Aliases may be nested and can contain anything that can be
         legally typed at the pdb prompt.  Note!  You *can* override
         internal pdb commands with aliases!  Those internal commands
         are then hidden until the alias is removed.  Aliasing is
         recursively applied to the first word of the command line; all
         other words in the line are left alone.

         As an example, here are two useful aliases (especially when
         placed in the .pdbrc file):

         # Print instance variables (usage "pi classInst")
         alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k])
         # Print instance variables in self
         alias ps pi self
         """
         args = arg.split()
         if len(args) == 0:
             keys = sorted(self.aliases.keys())
             for alias in keys:
                 self.message("%s = %s" % (alias, self.aliases[alias]))
             return
         if len(args) == 1:
             if args[0] in self.aliases:
                 self.message("%s = %s" % (args[0], self.aliases[args[0]]))
             else:
                 self.error(f"Unknown alias '{args[0]}'")
         else:
             # Do a validation check to make sure no replaceable parameters
             # are skipped if %* is not used.
             alias = ' '.join(args[1:])
             if '%*' not in alias:
                 consecutive = True
                 for idx in range(1, 10):
                     if f'%{idx}' not in alias:
                         consecutive = False
                     if f'%{idx}' in alias and not consecutive:
                         self.error("Replaceable parameters must be consecutive")
                         return
             self.aliases[args[0]] = alias

     def do_unalias(self, arg):
         """unalias name

         Delete the specified alias.
         """
         args = arg.split()
         if len(args) == 0:
             self._print_invalid_arg(arg)
             return
         if args[0] in self.aliases:
             del self.aliases[args[0]]

     def complete_unalias(self, text, line, begidx, endidx):
         return [a for a in self.aliases if a.startswith(text)]

     # List of all the commands making the program resume execution.
     commands_resuming = ['do_continue', 'do_step', 'do_next', 'do_return',
                          'do_quit', 'do_jump']

     # Print a traceback starting at the top stack frame.
     # The most recently entered frame is printed last;
     # this is different from dbx and gdb, but consistent with
     # the Python interpreter's stack trace.
     # It is also consistent with the up/down commands (which are
     # compatible with dbx and gdb: up moves towards 'main()'
     # and down moves towards the most recent stack frame).

     def print_stack_trace(self):
         try:
             for frame_lineno in self.stack:
                 self.print_stack_entry(frame_lineno)
         except KeyboardInterrupt:
             pass

     def print_stack_entry(self, frame_lineno, prompt_prefix=line_prefix):
         frame, lineno = frame_lineno
         if frame is self.curframe:
             prefix = '> '
         else:
             prefix = '  '
         self.message(prefix +
                      self.format_stack_entry(frame_lineno, prompt_prefix))

     # Provide help

     def do_help(self, arg):
         """h(elp)

         Without argument, print the list of available commands.
         With a command name as argument, print help about that command.
         "help pdb" shows the full pdb documentation.
         "help exec" gives help on the ! command.
         """
         if not arg:
             return cmd.Cmd.do_help(self, arg)
         try:
             try:
                 topic = getattr(self, 'help_' + arg)
                 return topic()
             except AttributeError:
                 command = getattr(self, 'do_' + arg)
         except AttributeError:
             self.error('No help for %r' % arg)
         else:
             if sys.flags.optimize >= 2:
                 self.error('No help for %r; please do not run Python with -OO '
                            'if you need command help' % arg)
                 return
             if command.__doc__ is None:
                 self.error('No help for %r; __doc__ string missing' % arg)
                 return
             self.message(self._help_message_from_doc(command.__doc__))

     do_h = do_help

     def help_exec(self):
         """(!) statement

         Execute the (one-line) statement in the context of the current
         stack frame.  The exclamation point can be omitted unless the
         first word of the statement resembles a debugger command, e.g.:
         (Pdb) ! n=42
         (Pdb)

         To assign to a global variable you must always prefix the command with
         a 'global' command, e.g.:
         (Pdb) global list_options; list_options = ['-l']
         (Pdb)
         """
         self.message((self.help_exec.__doc__ or '').strip())

     def help_pdb(self):
         help()

     # other helper functions

     def lookupmodule(self, filename):
         """Helper function for break/clear parsing -- may be overridden.

         lookupmodule() translates (possibly incomplete) file or module name
         into an absolute file name.

         filename could be in format of:
             * an absolute path like '/path/to/file.py'
             * a relative path like 'file.py' or 'dir/file.py'
             * a module name like 'module' or 'package.module'

         files and modules will be searched in sys.path.
         """
         if not filename.endswith('.py'):
             # A module is passed in so convert it to equivalent file
             filename = filename.replace('.', os.sep) + '.py'

         if os.path.isabs(filename):
             if os.path.exists(filename):
                 return filename
             return None

         for dirname in sys.path:
             while os.path.islink(dirname):
                 dirname = os.readlink(dirname)
             fullname = os.path.join(dirname, filename)
             if os.path.exists(fullname):
                 return fullname
         return None

     def _run(self, target: _ExecutableTarget):
         # When bdb sets tracing, a number of call and line events happen
         # BEFORE debugger even reaches user's code (and the exact sequence of
         # events depends on python version). Take special measures to
         # avoid stopping before reaching the main script (see user_line and
         # user_call for details).
         self._wait_for_mainpyfile = True
         self._user_requested_quit = False

         self.mainpyfile = self.canonic(target.filename)

         # The target has to run in __main__ namespace (or imports from
         # __main__ will break). Clear __main__ and replace with
         # the target namespace.
         import __main__
         __main__.__dict__.clear()
         __main__.__dict__.update(target.namespace)

         # Clear the mtime table for program reruns, assume all the files
         # are up to date.
         self._file_mtime_table.clear()

         self.run(target.code)

     def _format_exc(self, exc: BaseException):
         return traceback.format_exception_only(exc)[-1].strip()

     def _compile_error_message(self, expr):
         """Return the error message as string if compiling `expr` fails."""
         try:
             compile(expr, "<stdin>", "eval")
         except SyntaxError as exc:
             return _rstr(self._format_exc(exc))
         return ""

     def _getsourcelines(self, obj):
         # GH-103319
         # inspect.getsourcelines() returns lineno = 0 for
         # module-level frame which breaks our code print line number
         # This method should be replaced by inspect.getsourcelines(obj)
         # once this bug is fixed in inspect
         lines, lineno = inspect.getsourcelines(obj)
         lineno = max(1, lineno)
         return lines, lineno

     def _help_message_from_doc(self, doc, usage_only=False):
         lines = [line.strip() for line in doc.rstrip().splitlines()]
         if not lines:
             return "No help message found."
         if "" in lines:
             usage_end = lines.index("")
         else:
             usage_end = 1
         formatted = []
         indent = " " * len(self.prompt)
         for i, line in enumerate(lines):
             if i == 0:
                 prefix = "Usage: "
             elif i < usage_end:
                 prefix = "       "
             else:
                 if usage_only:
                     break
                 prefix = ""
             formatted.append(indent + prefix + line)
         return "\n".join(formatted)

     def _print_invalid_arg(self, arg):
         """Return the usage string for a function."""

         self.error(f"Invalid argument: {arg}")

         # Yes it's a bit hacky. Get the caller name, get the method based on
         # that name, and get the docstring from that method.
         # This should NOT fail if the caller is a method of this class.
         doc = inspect.getdoc(getattr(self, sys._getframe(1).f_code.co_name))
         if doc is not None:
             self.message(self._help_message_from_doc(doc, usage_only=True))

 # Collect all command help into docstring, if not run with -OO

 if __doc__ is not None:
     # unfortunately we can't guess this order from the class definition
     _help_order = [
         'help', 'where', 'down', 'up', 'break', 'tbreak', 'clear', 'disable',
         'enable', 'ignore', 'condition', 'commands', 'step', 'next', 'until',
         'jump', 'return', 'retval', 'run', 'continue', 'list', 'longlist',
         'args', 'p', 'pp', 'whatis', 'source', 'display', 'undisplay',
         'interact', 'alias', 'unalias', 'debug', 'quit',
     ]

     for _command in _help_order:
         __doc__ += getattr(Pdb, 'do_' + _command).__doc__.strip() + '\n\n'
     __doc__ += Pdb.help_exec.__doc__

     del _help_order, _command


 # Simplified interface

 def run(statement, globals=None, locals=None):
     """Execute the *statement* (given as a string or a code object)
     under debugger control.

     The debugger prompt appears before any code is executed; you can set
     breakpoints and type continue, or you can step through the statement
     using step or next.

     The optional *globals* and *locals* arguments specify the
     environment in which the code is executed; by default the
     dictionary of the module __main__ is used (see the explanation of
     the built-in exec() or eval() functions.).
     """
     Pdb().run(statement, globals, locals)

 def runeval(expression, globals=None, locals=None):
     """Evaluate the *expression* (given as a string or a code object)
     under debugger control.

     When runeval() returns, it returns the value of the expression.
     Otherwise this function is similar to run().
     """
     return Pdb().runeval(expression, globals, locals)

 def runctx(statement, globals, locals):
     # B/W compatibility
     run(statement, globals, locals)

 def runcall(*args, **kwds):
     """Call the function (a function or method object, not a string)
     with the given arguments.

     When runcall() returns, it returns whatever the function call
     returned. The debugger prompt appears as soon as the function is
     entered.
     """
     return Pdb().runcall(*args, **kwds)

 def set_trace(*, header=None):
     """Enter the debugger at the calling stack frame.

     This is useful to hard-code a breakpoint at a given point in a
     program, even if the code is not otherwise being debugged (e.g. when
     an assertion fails). If given, *header* is printed to the console
     just before debugging begins.
     """
     pdb = Pdb()
     if header is not None:
         pdb.message(header)
     pdb.set_trace(sys._getframe().f_back)

 # Post-Mortem interface

 def post_mortem(t=None):
     """Enter post-mortem debugging of the given *traceback*, or *exception*
     object.

     If no traceback is given, it uses the one of the exception that is
     currently being handled (an exception must be being handled if the
     default is to be used).

     If `t` is an exception object, the `exceptions` command makes it possible to
     list and inspect its chained exceptions (if any).
     """
     return _post_mortem(t, Pdb())


 def _post_mortem(t, pdb_instance):
     """
     Private version of post_mortem, which allow to pass a pdb instance
     for testing purposes.
     """
     # handling the default
     if t is None:
         exc = sys.exception()
         if exc is not None:
             t = exc.__traceback__

     if t is None or (isinstance(t, BaseException) and t.__traceback__ is None):
         raise ValueError("A valid traceback must be passed if no "
                          "exception is being handled")

     pdb_instance.reset()
     pdb_instance.interaction(None, t)


 def pm():
     """Enter post-mortem debugging of the traceback found in sys.last_exc."""
     post_mortem(sys.last_exc)


 # Main program for testing

 TESTCMD = 'import x; x.main()'

 def test():
     run(TESTCMD)

 # print help
 def help():
     import pydoc
     pydoc.pager(__doc__)

 _usage = """\
 Debug the Python program given by pyfile. Alternatively,
 an executable module or package to debug can be specified using
 the -m switch.

 Initial commands are read from .pdbrc files in your home directory
 and in the current directory, if they exist.  Commands supplied with
 -c are executed after commands from .pdbrc files.

 To let the script run until an exception occurs, use "-c continue".
 To let the script run up to a given line X in the debugged file, use
 "-c 'until X'"."""


 def main():
     import argparse

     parser = argparse.ArgumentParser(prog="pdb",
                                      usage="%(prog)s [-h] [-c command] (-m module | pyfile) [args ...]",
                                      description=_usage,
                                      formatter_class=argparse.RawDescriptionHelpFormatter,
                                      allow_abbrev=False)

     # We need to maunally get the script from args, because the first positional
     # arguments could be either the script we need to debug, or the argument
     # to the -m module
     parser.add_argument('-c', '--command', action='append', default=[], metavar='command', dest='commands',
                         help='pdb commands to execute as if given in a .pdbrc file')
     parser.add_argument('-m', metavar='module', dest='module')
     parser.add_argument('args', nargs='*',
                         help="when -m is not specified, the first arg is the script to debug")

     if len(sys.argv) == 1:
         # If no arguments were given (python -m pdb), print the whole help message.
         # Without this check, argparse would only complain about missing required arguments.
         parser.print_help()
         sys.exit(2)

     opts = parser.parse_args()

     if opts.module:
         file = opts.module
         target = _ModuleTarget(file)
     else:
         if not opts.args:
             parser.error("no module or script to run")
         file = opts.args.pop(0)
         if file.endswith('.pyz'):
             target = _ZipTarget(file)
         else:
             target = _ScriptTarget(file)

     sys.argv[:] = [file] + opts.args  # Hide "pdb.py" and pdb options from argument list

     # Note on saving/restoring sys.argv: it's a good idea when sys.argv was
     # modified by the script being debugged. It's a bad idea when it was
     # changed by the user from the command line. There is a "restart" command
     # which allows explicit specification of command line arguments.
     pdb = Pdb()
     pdb.rcLines.extend(opts.commands)
     while True:
         try:
             pdb._run(target)
         except Restart:
             print("Restarting", target, "with arguments:")
             print("\t" + " ".join(sys.argv[1:]))
         except SystemExit as e:
             # In most cases SystemExit does not warrant a post-mortem session.
             print("The program exited via sys.exit(). Exit status:", end=' ')
             print(e)
         except BaseException as e:
             traceback.print_exception(e, colorize=_colorize.can_colorize())
             print("Uncaught exception. Entering post mortem debugging")
             print("Running 'cont' or 'step' will restart the program")
             try:
                 pdb.interaction(None, e)
             except Restart:
                 print("Restarting", target, "with arguments:")
                 print("\t" + " ".join(sys.argv[1:]))
                 continue
         if pdb._user_requested_quit:
             break
         print("The program finished and will be restarted")


 # When invoked as main program, invoke the debugger on a script
 if __name__ == '__main__':
     import pdb
     pdb.main()