text: # The MIT License
  #
  # Copyright (c) 2009-2011 the bpython authors.
  # Copyright (c) 2012-2013,2015 Sebastian Ramacher
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  
  import code
  import inspect
  import os
  import pkgutil
  import pydoc
  import shlex
  import subprocess
  import sys
  import tempfile
  import textwrap
  import time
  import traceback
  from enum import Enum
  from itertools import takewhile
  from pathlib import Path
  from types import ModuleType
  
  from pygments.token import Token
  from pygments.lexers import Python3Lexer
  from . import autocomplete, inspection, simpleeval
  from .clipboard import get_clipboard, CopyFailed
  from .config import getpreferredencoding
  from .formatter import Parenthesis
  from .history import History
  from .lazyre import LazyReCompile
  from .paste import PasteHelper, PastePinnwand, PasteFailed
  from .patch_linecache import filename_for_console_input
  from .translations import _, ngettext
  from .importcompletion import ModuleGatherer
  
  
  class RuntimeTimer:
      """Calculate running time"""
  
      def __init__(self):
          self.reset_timer()
          self.time = time.monotonic if hasattr(time, "monotonic") else time.time
  
      def __enter__(self):
          self.start = self.time()
  
      def __exit__(self, ty, val, tb):
          self.last_command = self.time() - self.start
          self.running_time += self.last_command
          return False
  
      def reset_timer(self):
          self.running_time = 0.0
          self.last_command = 0.0
  
      def estimate(self):
          return self.running_time - self.last_command
  
  
  class Interpreter(code.InteractiveInterpreter):
      """Source code interpreter for use in bpython."""
  
      bpython_input_re = LazyReCompile(r"<bpython-input-\d+>")
  
      def __init__(self, locals=None, encoding=None):
          """Constructor.
  
          The optional 'locals' argument specifies the dictionary in which code
          will be executed; it defaults to a newly created dictionary with key
          "__name__" set to "__main__".
  
          The syntaxerror callback can be set at any time and will be called
          on a caught syntax error. The purpose for this in bpython is so that
          the repl can be instantiated after the interpreter (which it
          necessarily must be with the current factoring) and then an exception
          callback can be added to the Interpreter instance afterwards - more
          specifically, this is so that autoindentation does not occur after a
          traceback.
  
          encoding is only used in Python 2, where it may be necessary to add an
          encoding comment to a source bytestring before running it.
          encoding must be a bytestring in Python 2 because it will be templated
          into a bytestring source as part of an encoding comment.
          """
  
          self.encoding = encoding or getpreferredencoding()
          self.syntaxerror_callback = None
  
          if locals is None:
              # instead of messing with sys.modules, we should modify sys.modules
              # in the interpreter instance
              sys.modules["__main__"] = main_mod = ModuleType("__main__")
              locals = main_mod.__dict__
  
          # Unfortunately code.InteractiveInterpreter is a classic class, so no
          # super()
          code.InteractiveInterpreter.__init__(self, locals)
          self.timer = RuntimeTimer()
  
      def reset_running_time(self):
          self.running_time = 0
  
      def runsource(self, source, filename=None, symbol="single", encode="auto"):
          """Execute Python code.
  
          source, filename and symbol are passed on to
          code.InteractiveInterpreter.runsource. If encode is True,
          an encoding comment will be added to the source.
          On Python 3.X, encode will be ignored.
  
          encode should only be used for interactive interpreter input,
          files should always already have an encoding comment or be ASCII.
          By default an encoding line will be added if no filename is given.
  
          In Python 3, source must be a unicode string
          In Python 2, source may be latin-1 bytestring or unicode string,
          following the interface of code.InteractiveInterpreter.
  
          Because adding an encoding comment to a unicode string in Python 2
          would cause a syntax error to be thrown which would reference code
          the user did not write, setting encoding to True when source is a
          unicode string in Python 2 will throw a ValueError."""
          if encode and filename is not None:
              # files have encoding comments or implicit encoding of ASCII
              if encode != "auto":
                  raise ValueError("shouldn't add encoding line to file contents")
              encode = False
  
          if filename is None:
              filename = filename_for_console_input(source)
          with self.timer:
              return code.InteractiveInterpreter.runsource(
                  self, source, filename, symbol
              )
  
      def showsyntaxerror(self, filename=None):
          """Override the regular handler, the code's copied and pasted from
          code.py, as per showtraceback, but with the syntaxerror callback called
          and the text in a pretty colour."""
          if self.syntaxerror_callback is not None:
              self.syntaxerror_callback()
  
          exc_type, value, sys.last_traceback = sys.exc_info()
          sys.last_type = exc_type
          sys.last_value = value
          if filename and exc_type is SyntaxError:
              # Work hard to stuff the correct filename in the exception
              try:
                  msg, (dummy_filename, lineno, offset, line) = value.args
              except:
                  # Not the format we expect; leave it alone
                  pass
              else:
                  # Stuff in the right filename and right lineno
                  # strip linecache line number
                  if self.bpython_input_re.match(filename):
                      filename = "<input>"
                  value = SyntaxError(msg, (filename, lineno, offset, line))
                  sys.last_value = value
          exc_formatted = traceback.format_exception_only(exc_type, value)
          self.writetb(exc_formatted)
  
      def showtraceback(self):
          """This needs to override the default traceback thing
          so it can put it into a pretty colour and maybe other
          stuff, I don't know"""
          try:
              t, v, tb = sys.exc_info()
              sys.last_type = t
              sys.last_value = v
              sys.last_traceback = tb
              tblist = traceback.extract_tb(tb)
              del tblist[:1]
  
              for i, (fname, lineno, module, something) in enumerate(tblist):
                  # strip linecache line number
                  if self.bpython_input_re.match(fname):
                      fname = "<input>"
                      tblist[i] = (fname, lineno, module, something)
  
              l = traceback.format_list(tblist)
              if l:
                  l.insert(0, "Traceback (most recent call last):\n")
              l[len(l) :] = traceback.format_exception_only(t, v)
          finally:
              pass
  
          self.writetb(l)
  
      def writetb(self, lines):
          """This outputs the traceback and should be overridden for anything
          fancy."""
          for line in lines:
              self.write(line)
  
  
  class MatchesIterator:
      """Stores a list of matches and which one is currently selected if any.
  
      Also responsible for doing the actual replacement of the original line with
      the selected match.
  
      A MatchesIterator can be `clear`ed to reset match iteration, and
      `update`ed to set what matches will be iterated over."""
  
      def __init__(self):
          # word being replaced in the original line of text
          self.current_word = ""
          # possible replacements for current_word
          self.matches = None
          # which word is currently replacing the current word
          self.index = -1
          # cursor position in the original line
          self.orig_cursor_offset = None
          # original line (before match replacements)
          self.orig_line = None
          # class describing the current type of completion
          self.completer = None
  
      def __nonzero__(self):
          """MatchesIterator is False when word hasn't been replaced yet"""
          return self.index != -1
  
      def __bool__(self):
          return self.index != -1
  
      @property
      def candidate_selected(self):
          """True when word selected/replaced, False when word hasn't been
          replaced yet"""
          return bool(self)
  
      def __iter__(self):
          return self
  
      def current(self):
          if self.index == -1:
              raise ValueError("No current match.")
          return self.matches[self.index]
  
      def next(self):
          return self.__next__()
  
      def __next__(self):
          self.index = (self.index + 1) % len(self.matches)
          return self.matches[self.index]
  
      def previous(self):
          if self.index <= 0:
              self.index = len(self.matches)
          self.index -= 1
  
          return self.matches[self.index]
  
      def cur_line(self):
          """Returns a cursor offset and line with the current substitution
          made"""
          return self.substitute(self.current())
  
      def substitute(self, match):
          """Returns a cursor offset and line with match substituted in"""
          start, end, word = self.completer.locate(
              self.orig_cursor_offset, self.orig_line
          )
          return (
              start + len(match),
              self.orig_line[:start] + match + self.orig_line[end:],
          )
  
      def is_cseq(self):
          return bool(
              os.path.commonprefix(self.matches)[len(self.current_word) :]
          )
  
      def substitute_cseq(self):
          """Returns a new line by substituting a common sequence in, and update
          matches"""
          cseq = os.path.commonprefix(self.matches)
          new_cursor_offset, new_line = self.substitute(cseq)
          if len(self.matches) == 1:
              self.clear()
          else:
              self.update(
                  new_cursor_offset, new_line, self.matches, self.completer
              )
              if len(self.matches) == 1:
                  self.clear()
          return new_cursor_offset, new_line
  
      def update(self, cursor_offset, current_line, matches, completer):
          """Called to reset the match index and update the word being replaced
  
          Should only be called if there's a target to update - otherwise, call
          clear"""
  
          if matches is None:
              raise ValueError("Matches may not be None.")
  
          self.orig_cursor_offset = cursor_offset
          self.orig_line = current_line
          self.matches = matches
          self.completer = completer
          self.index = -1
          self.start, self.end, self.current_word = self.completer.locate(
              self.orig_cursor_offset, self.orig_line
          )
  
      def clear(self):
          self.matches = []
          self.cursor_offset = -1
          self.current_line = ""
          self.current_word = ""
          self.start = None
          self.end = None
          self.index = -1
  
  
  class Interaction:
      def __init__(self, config, statusbar=None):
          self.config = config
  
          if statusbar:
              self.statusbar = statusbar
  
      def confirm(self, s):
          raise NotImplementedError
  
      def notify(self, s, n=10, wait_for_keypress=False):
          raise NotImplementedError
  
      def file_prompt(self, s):
          raise NotImplementedError
  
  
  class SourceNotFound(Exception):
      """Exception raised when the requested source could not be found."""
  
  
  class LineTypeTranslator(Enum):
      """Used when adding a tuple to all_logical_lines, to get input / output values
      having to actually type/know the strings"""
  
      INPUT = "input"
      OUTPUT = "output"
  
  
  class Repl:
      """Implements the necessary guff for a Python-repl-alike interface
  
      The execution of the code entered and all that stuff was taken from the
      Python code module, I had to copy it instead of inheriting it, I can't
      remember why. The rest of the stuff is basically what makes it fancy.
  
      It reads what you type, passes it to a lexer and highlighter which
      returns a formatted string. This then gets passed to echo() which
      parses that string and prints to the curses screen in appropriate
      colours and/or bold attribute.
  
      The Repl class also keeps two stacks of lines that the user has typed in:
      One to be used for the undo feature. I am not happy with the way this
      works.  The only way I have been able to think of is to keep the code
      that's been typed in in memory and re-evaluate it in its entirety for each
      "undo" operation. Obviously this means some operations could be extremely
      slow.  I'm not even by any means certain that this truly represents a
      genuine "undo" implementation, but it does seem to be generally pretty
      effective.
  
      If anyone has any suggestions for how this could be improved, I'd be happy
      to hear them and implement it/accept a patch. I researched a bit into the
      idea of keeping the entire Python state in memory, but this really seems
      very difficult (I believe it may actually be impossible to work) and has
      its own problems too.
  
      The other stack is for keeping a history for pressing the up/down keys
      to go back and forth between lines.
  
      XXX Subclasses should implement echo, current_line, cw
      """
  
      def __init__(self, interp, config):
          """Initialise the repl.
  
          interp is a Python code.InteractiveInterpreter instance
  
          config is a populated bpython.config.Struct.
          """
  
          self.config = config
          self.cut_buffer = ""
          self.buffer = []
          self.interp = interp
          self.interp.syntaxerror_callback = self.clear_current_line
          self.match = False
          self.rl_history = History(
              duplicates=config.hist_duplicates, hist_size=config.hist_length
          )
          # all input and output, stored as old style format strings
          # (\x01, \x02, ...) for cli.py
          self.screen_hist = []
          self.history = []  # commands executed since beginning of session
          self.redo_stack = []
          self.evaluating = False
          self.matches_iter = MatchesIterator()
          self.funcprops = None
          self.arg_pos = None
          self.current_func = None
          self.highlighted_paren = None
          self._C = {}
          self.prev_block_finished = 0
          self.interact = Interaction(self.config)
          # previous pastebin content to prevent duplicate pastes, filled on call
          # to repl.pastebin
          self.prev_pastebin_content = ""
          self.prev_pastebin_url = ""
          self.prev_removal_url = ""
          # Necessary to fix mercurial.ui.ui expecting sys.stderr to have this
          # attribute
          self.closed = False
          self.clipboard = get_clipboard()
  
          if self.config.hist_file.exists():
              try:
                  self.rl_history.load(
                      self.config.hist_file, getpreferredencoding() or "ascii"
                  )
              except OSError:
                  pass
  
          self.module_gatherer = ModuleGatherer(
              skiplist=self.config.import_completion_skiplist
          )
          self.completers = autocomplete.get_default_completer(
              config.autocomplete_mode, self.module_gatherer
          )
          if self.config.pastebin_helper:
              self.paster = PasteHelper(self.config.pastebin_helper)
          else:
              self.paster = PastePinnwand(
                  self.config.pastebin_url,
                  self.config.pastebin_expiry,
              )
  
      @property
      def ps1(self):
          try:
              return sys.ps1
          except AttributeError:
              return ">>> "
  
      @property
      def ps2(self):
          try:
              return sys.ps2
          except AttributeError:
              return "... "
  
      def startup(self):
          """
          Execute PYTHONSTARTUP file if it exits. Call this after front
          end-specific initialisation.
          """
          filename = os.environ.get("PYTHONSTARTUP")
          if filename:
              encoding = inspection.get_encoding_file(filename)
              with open(filename, encoding=encoding) as f:
                  source = f.read()
                  self.interp.runsource(source, filename, "exec", encode=False)
  
      def current_string(self, concatenate=False):
          """If the line ends in a string get it, otherwise return ''"""
          tokens = self.tokenize(self.current_line)
          string_tokens = list(
              takewhile(
                  token_is_any_of([Token.String, Token.Text]), reversed(tokens)
              )
          )
          if not string_tokens:
              return ""
          opening = string_tokens.pop()[1]
          string = list()
          for (token, value) in reversed(string_tokens):
              if token is Token.Text:
                  continue
              elif opening is None:
                  opening = value
              elif token is Token.String.Doc:
                  string.append(value[3:-3])
                  opening = None
              elif value == opening:
                  opening = None
                  if not concatenate:
                      string = list()
              else:
                  string.append(value)
  
          if opening is None:
              return ""
          return "".join(string)
  
      def get_object(self, name):
          attributes = name.split(".")
          obj = eval(attributes.pop(0), self.interp.locals)
          while attributes:
              with inspection.AttrCleaner(obj):
                  obj = getattr(obj, attributes.pop(0))
          return obj
  
      @classmethod
      def _funcname_and_argnum(cls, line):
          """Parse out the current function name and arg from a line of code."""
          # each list in stack:
          # [full_expr, function_expr, arg_number, opening]
          # arg_number may be a string if we've encountered a keyword
          # argument so we're done counting
          stack = [["", "", 0, ""]]
          try:
              for (token, value) in Python3Lexer().get_tokens(line):
                  if token is Token.Punctuation:
                      if value in "([{":
                          stack.append(["", "", 0, value])
                      elif value in ")]}":
                          full, _, _, start = stack.pop()
                          expr = start + full + value
                          stack[-1][1] += expr
                          stack[-1][0] += expr
                      elif value == ",":
                          try:
                              stack[-1][2] += 1
                          except TypeError:
                              stack[-1][2] = ""
                          stack[-1][1] = ""
                          stack[-1][0] += value
                      elif value == ":" and stack[-1][3] == "lambda":
                          expr = stack.pop()[0] + ":"
                          stack[-1][1] += expr
                          stack[-1][0] += expr
                      else:
                          stack[-1][1] = ""
                          stack[-1][0] += value
                  elif (
                      token is Token.Number
                      or token in Token.Number.subtypes
                      or token is Token.Name
                      or token in Token.Name.subtypes
                      or token is Token.Operator
                      and value == "."
                  ):
                      stack[-1][1] += value
                      stack[-1][0] += value
                  elif token is Token.Operator and value == "=":
                      stack[-1][2] = stack[-1][1]
                      stack[-1][1] = ""
                      stack[-1][0] += value
                  elif token is Token.Number or token in Token.Number.subtypes:
                      stack[-1][1] = value
                      stack[-1][0] += value
                  elif token is Token.Keyword and value == "lambda":
                      stack.append([value, "", 0, value])
                  else:
                      stack[-1][1] = ""
                      stack[-1][0] += value
              while stack[-1][3] in "[{":
                  stack.pop()
              _, _, arg_number, _ = stack.pop()
              _, func, _, _ = stack.pop()
              return func, arg_number
          except IndexError:
              return None, None
  
      def get_args(self):
          """Check if an unclosed parenthesis exists, then attempt to get the
          argspec() for it. On success, update self.funcprops,self.arg_pos and
          return True, otherwise set self.funcprops to None and return False"""
  
          self.current_func = None
  
          if not self.config.arg_spec:
              return False
  
          func, arg_number = self._funcname_and_argnum(self.current_line)
          if not func:
              return False
  
          try:
              if inspection.is_eval_safe_name(func):
                  f = self.get_object(func)
              else:
                  try:
                      fake_cursor = self.current_line.index(func) + len(func)
                      f = simpleeval.evaluate_current_attribute(
                          fake_cursor, self.current_line, self.interp.locals
                      )
                  except simpleeval.EvaluationError:
                      return False
  
              if inspect.isclass(f):
                  class_f = None
  
                  if hasattr(f, "__init__") and f.__init__ is not object.__init__:
                      class_f = f.__init__
                  if (
                      (not class_f or not inspection.getfuncprops(func, class_f))
                      and hasattr(f, "__new__")
                      and f.__new__ is not object.__new__
                      and
                      # py3
                      f.__new__.__class__ is not object.__new__.__class__
                  ):
  
                      class_f = f.__new__
  
                  if class_f:
                      f = class_f
          except Exception:
              # another case of needing to catch every kind of error
              # since user code is run in the case of descriptors
              # XXX: Make sure you raise here if you're debugging the completion
              # stuff !
              return False
  
          self.current_func = f
          self.funcprops = inspection.getfuncprops(func, f)
          if self.funcprops:
              self.arg_pos = arg_number
              return True
          self.arg_pos = None
          return False
  
      def get_source_of_current_name(self):
          """Return the unicode source code of the object which is bound to the
          current name in the current input line. Throw `SourceNotFound` if the
          source cannot be found."""
  
          obj = self.current_func
          try:
              if obj is None:
                  line = self.current_line
                  if not line.strip():
                      raise SourceNotFound(_("Nothing to get source of"))
                  if inspection.is_eval_safe_name(line):
                      obj = self.get_object(line)
              return inspection.get_source_unicode(obj)
          except (AttributeError, NameError) as e:
              msg = _("Cannot get source: %s") % (e,)
          except OSError as e:
              msg = f"{e}"
          except TypeError as e:
              if "built-in" in f"{e}":
                  msg = _("Cannot access source of %r") % (obj,)
              else:
                  msg = _("No source code found for %s") % (self.current_line,)
          raise SourceNotFound(msg)
  
      def set_docstring(self):
          self.docstring = None
          if not self.get_args():
              self.funcprops = None
          if self.current_func is not None:
              try:
                  self.docstring = pydoc.getdoc(self.current_func)
              except IndexError:
                  self.docstring = None
              else:
                  # pydoc.getdoc() returns an empty string if no
                  # docstring was found
                  if not self.docstring:
                      self.docstring = None
  
      # What complete() does:
      # Should we show the completion box? (are there matches, or is there a
      # docstring to show?)
      #   Some completions should always be shown, other only if tab=True
      # set the current docstring to the "current function's" docstring
      # Populate the matches_iter object with new matches from the current state
      #    if none, clear the matches iterator
      # If exactly one match that is equal to current line, clear matches
      # If example one match and tab=True, then choose that and clear matches
  
      def complete(self, tab=False):
          """Construct a full list of possible completions and
          display them in a window. Also check if there's an available argspec
          (via the inspect module) and bang that on top of the completions too.
          The return value is whether the list_win is visible or not.
  
          If no matches are found, just return whether there's an argspec to show
          If any matches are found, save them and select the first one.
  
          If tab is True exactly one match found, make the replacement and return
            the result of running complete() again on the new line.
          """
  
          self.set_docstring()
  
          matches, completer = autocomplete.get_completer(
              self.completers,
              cursor_offset=self.cursor_offset,
              line=self.current_line,
              locals_=self.interp.locals,
              argspec=self.funcprops,
              current_block="\n".join(self.buffer + [self.current_line]),
              complete_magic_methods=self.config.complete_magic_methods,
              history=self.history,
          )
  
          if len(matches) == 0:
              self.matches_iter.clear()
              return bool(self.funcprops)
  
          self.matches_iter.update(
              self.cursor_offset, self.current_line, matches, completer
          )
  
          if len(matches) == 1:
              if tab:
                  # if this complete is being run for a tab key press, substitute
                  # common sequence
                  (
                      self._cursor_offset,
                      self._current_line,
                  ) = self.matches_iter.substitute_cseq()
                  return Repl.complete(self)  # again for
              elif self.matches_iter.current_word == matches[0]:
                  self.matches_iter.clear()
                  return False
              return completer.shown_before_tab
  
          else:
              return tab or completer.shown_before_tab
  
      def format_docstring(self, docstring, width, height):
          """Take a string and try to format it into a sane list of strings to be
          put into the suggestion box."""
  
          lines = docstring.split("\n")
          out = []
          i = 0
          for line in lines:
              i += 1
              if not line.strip():
                  out.append("\n")
              for block in textwrap.wrap(line, width):
                  out.append("  " + block + "\n")
                  if i >= height:
                      return out
                  i += 1
          # Drop the last newline
          out[-1] = out[-1].rstrip()
          return out
  
      def next_indentation(self):
          """Return the indentation of the next line based on the current
          input buffer."""
          if self.buffer:
              indentation = next_indentation(
                  self.buffer[-1], self.config.tab_length
              )
              if indentation and self.config.dedent_after > 0:
  
                  def line_is_empty(line):
                      return not line.strip()
  
                  empty_lines = takewhile(line_is_empty, reversed(self.buffer))
                  if sum(1 for _ in empty_lines) >= self.config.dedent_after:
                      indentation -= 1
          else:
              indentation = 0
          return indentation
  
      def get_session_formatted_for_file(self):
          """Format the stdout buffer to something suitable for writing to disk,
          i.e. without >>> and ... at input lines and with "# OUT: " prepended to
          output lines and "### " prepended to current line"""
  
          if hasattr(self, "all_logical_lines"):
              # Curtsies
  
              def process():
                  for line, lineType in self.all_logical_lines:
                      if lineType == LineTypeTranslator.INPUT:
                          yield line
                      elif line.rstrip():
                          yield "# OUT: %s" % line
                  yield "### %s" % self.current_line
  
              return "\n".join(process())
  
          else:  # cli and Urwid
              session_output = self.getstdout()
  
              def process():
                  for line in session_output.split("\n"):
                      if line.startswith(self.ps1):
                          yield line[len(self.ps1) :]
                      elif line.startswith(self.ps2):
                          yield line[len(self.ps2) :]
                      elif line.rstrip():
                          yield f"# OUT: {line}"
  
              return "\n".join(process())
  
      def write2file(self):
          """Prompt for a filename and write the current contents of the stdout
          buffer to disk."""
  
          try:
              fn = self.interact.file_prompt(_("Save to file (Esc to cancel): "))
              if not fn:
                  self.interact.notify(_("Save cancelled."))
                  return
          except ValueError:
              self.interact.notify(_("Save cancelled."))
              return
  
          fn = Path(fn).expanduser()
          if fn.suffix != ".py" and self.config.save_append_py:
              # fn.with_suffix(".py") does not append if fn has a non-empty suffix
              fn = Path(f"{fn}.py")
  
          mode = "w"
          if fn.exists():
              mode = self.interact.file_prompt(
                  _(
                      "%s already exists. Do you "
                      "want to (c)ancel, "
                      " (o)verwrite or "
                      "(a)ppend? "
                  )
                  % (fn,)
              )
              if mode in ("o", "overwrite", _("overwrite")):
                  mode = "w"
              elif mode in ("a", "append", _("append")):
                  mode = "a"
              else:
                  self.interact.notify(_("Save cancelled."))
                  return
  
          stdout_text = self.get_session_formatted_for_file()
  
          try:
              with open(fn, mode) as f:
                  f.write(stdout_text)
          except OSError as e:
              self.interact.notify(_("Error writing file '%s': %s") % (fn, e))
          else:
              self.interact.notify(_("Saved to %s.") % (fn,))
  
      def copy2clipboard(self):
          """Copy current content to clipboard."""
  
          if self.clipboard is None:
              self.interact.notify(_("No clipboard available."))
              return
  
          content = self.get_session_formatted_for_file()
          try:
              self.clipboard.copy(content)
          except CopyFailed:
              self.interact.notify(_("Could not copy to clipboard."))
          else:
              self.interact.notify(_("Copied content to clipboard."))
  
      def pastebin(self, s=None):
          """Upload to a pastebin and display the URL in the status bar."""
  
          if s is None:
              s = self.getstdout()
  
          if self.config.pastebin_confirm and not self.interact.confirm(
              _("Pastebin buffer? (y/N) ")
          ):
              self.interact.notify(_("Pastebin aborted."))
              return
          return self.do_pastebin(s)
  
      def do_pastebin(self, s):
          """Actually perform the upload."""
          if s == self.prev_pastebin_content:
              self.interact.notify(
                  _("Duplicate pastebin. Previous URL: %s. " "Removal URL: %s")
                  % (self.prev_pastebin_url, self.prev_removal_url),
                  10,
              )
              return self.prev_pastebin_url
  
          self.interact.notify(_("Posting data to pastebin..."))
          try:
              paste_url, removal_url = self.paster.paste(s)
          except PasteFailed as e:
              self.interact.notify(_("Upload failed: %s") % e)
              return
  
          self.prev_pastebin_content = s
          self.prev_pastebin_url = paste_url
          self.prev_removal_url = removal_url
  
          if removal_url is not None:
              self.interact.notify(
                  _("Pastebin URL: %s - Removal URL: %s")
                  % (paste_url, removal_url),
                  10,
              )
          else:
              self.interact.notify(_("Pastebin URL: %s") % (paste_url,), 10)
  
          return paste_url
  
      def push(self, s, insert_into_history=True):
          """Push a line of code onto the buffer so it can process it all
          at once when a code block ends"""
          # This push method is used by cli and urwid, but not curtsies
          s = s.rstrip("\n")
          self.buffer.append(s)
  
          if insert_into_history:
              self.insert_into_history(s)
  
          more = self.interp.runsource("\n".join(self.buffer))
  
          if not more:
              self.buffer = []
  
          return more
  
      def insert_into_history(self, s):
          try:
              self.rl_history.append_reload_and_write(
                  s, self.config.hist_file, getpreferredencoding()
              )
          except RuntimeError as e:
              self.interact.notify(f"{e}")
  
      def prompt_undo(self):
          """Returns how many lines to undo, 0 means don't undo"""
          if (
              self.config.single_undo_time < 0
              or self.interp.timer.estimate() < self.config.single_undo_time
          ):
              return 1
          est = self.interp.timer.estimate()
          n = self.interact.file_prompt(
              _("Undo how many lines? (Undo will take up to ~%.1f seconds) [1]")
              % (est,)
          )
          try:
              if n == "":
                  n = "1"
              n = int(n)
          except ValueError:
              self.interact.notify(_("Undo canceled"), 0.1)
              return 0
          else:
              if n == 0:
                  self.interact.notify(_("Undo canceled"), 0.1)
                  return 0
              else:
                  message = ngettext(
                      "Undoing %d line... (est. %.1f seconds)",
                      "Undoing %d lines... (est. %.1f seconds)",
                      n,
                  )
                  self.interact.notify(message % (n, est), 0.1)
              return n
  
      def undo(self, n=1):
          """Go back in the undo history n steps and call reevaluate()
          Note that in the program this is called "Rewind" because I
          want it to be clear that this is by no means a true undo
          implementation, it is merely a convenience bonus."""
          if not self.history:
              return None
  
          self.interp.timer.reset_timer()
  
          if len(self.history) < n:
              n = len(self.history)
  
          entries = list(self.rl_history.entries)
  
          # Most recently undone command
          last_entries = self.history[-n:]
          last_entries.reverse()
          self.redo_stack += last_entries
          self.history = self.history[:-n]
          self.reevaluate()
  
          self.rl_history.entries = entries
  
      def flush(self):
          """Olivier Grisel brought it to my attention that the logging
          module tries to call this method, since it makes assumptions
          about stdout that may not necessarily be true. The docs for
          sys.stdout say:
  
          "stdout and stderr needn't be built-in file objects: any
           object is acceptable as long as it has a write() method
           that takes a string argument."
  
          So I consider this to be a bug in logging, and this is a hack
          to fix it, unfortunately. I'm sure it's not the only module
          to do it."""
  
      def close(self):
          """See the flush() method docstring."""
  
      def tokenize(self, s, newline=False):
          """Tokenizes a line of code, returning pygments tokens
          with side effects/impurities:
          - reads self.cpos to see what parens should be highlighted
          - reads self.buffer to see what came before the passed in line
          - sets self.highlighted_paren to (buffer_lineno, tokens_for_that_line)
            for buffer line that should replace that line to unhighlight it,
            or None if no paren is currently highlighted
          - calls reprint_line with a buffer's line's tokens and the buffer
            lineno that has changed if line other than the current line changes
          """
          highlighted_paren = None
  
          source = "\n".join(self.buffer + [s])
          cursor = len(source) - self.cpos
          if self.cpos:
              cursor += 1
          stack = list()
          all_tokens = list(Python3Lexer().get_tokens(source))
          # Unfortunately, Pygments adds a trailing newline and strings with
          # no size, so strip them
          while not all_tokens[-1][1]:
              all_tokens.pop()
          all_tokens[-1] = (all_tokens[-1][0], all_tokens[-1][1].rstrip("\n"))
          line = pos = 0
          parens = dict(zip("{([", "})]"))
          line_tokens = list()
          saved_tokens = list()
          search_for_paren = True
          for (token, value) in split_lines(all_tokens):
              pos += len(value)
              if token is Token.Text and value == "\n":
                  line += 1
                  # Remove trailing newline
                  line_tokens = list()
                  saved_tokens = list()
                  continue
              line_tokens.append((token, value))
              saved_tokens.append((token, value))
              if not search_for_paren:
                  continue
              under_cursor = pos == cursor
              if token is Token.Punctuation:
                  if value in parens:
                      if under_cursor:
                          line_tokens[-1] = (Parenthesis.UnderCursor, value)
                          # Push marker on the stack
                          stack.append((Parenthesis, value))
                      else:
                          stack.append(
                              (line, len(line_tokens) - 1, line_tokens, value)
                          )
                  elif value in parens.values():
                      saved_stack = list(stack)
                      try:
                          while True:
                              opening = stack.pop()
                              if parens[opening[-1]] == value:
                                  break
                      except IndexError:
                          # SyntaxError.. more closed parentheses than
                          # opened or a wrong closing paren
                          opening = None
                          if not saved_stack:
                              search_for_paren = False
                          else:
                              stack = saved_stack
                      if opening and opening[0] is Parenthesis:
                          # Marker found
                          line_tokens[-1] = (Parenthesis, value)
                          search_for_paren = False
                      elif opening and under_cursor and not newline:
                          if self.cpos:
                              line_tokens[-1] = (Parenthesis.UnderCursor, value)
                          else:
                              # The cursor is at the end of line and next to
                              # the paren, so it doesn't reverse the paren.
                              # Therefore, we insert the Parenthesis token
                              # here instead of the Parenthesis.UnderCursor
                              # token.
                              line_tokens[-1] = (Parenthesis, value)
                          (lineno, i, tokens, opening) = opening
                          if lineno == len(self.buffer):
                              highlighted_paren = (lineno, saved_tokens)
                              line_tokens[i] = (Parenthesis, opening)
                          else:
                              highlighted_paren = (lineno, list(tokens))
                              # We need to redraw a line
                              tokens[i] = (Parenthesis, opening)
                              self.reprint_line(lineno, tokens)
                          search_for_paren = False
                  elif under_cursor:
                      search_for_paren = False
          self.highlighted_paren = highlighted_paren
          if line != len(self.buffer):
              return list()
          return line_tokens
  
      def clear_current_line(self):
          """This is used as the exception callback for the Interpreter instance.
          It prevents autoindentation from occurring after a traceback."""
  
      def send_to_external_editor(self, text):
          """Returns modified text from an editor, or the original text if editor
          exited with non-zero"""
  
          encoding = getpreferredencoding()
          editor_args = shlex.split(self.config.editor)
          with tempfile.NamedTemporaryFile(suffix=".py") as temp:
              temp.write(text.encode(encoding))
              temp.flush()
  
              args = editor_args + [temp.name]
              if subprocess.call(args) == 0:
                  with open(temp.name) as f:
                      return f.read()
              else:
                  return text
  
      def open_in_external_editor(self, filename):
          editor_args = shlex.split(self.config.editor)
          args = editor_args + [filename]
          return subprocess.call(args) == 0
  
      def edit_config(self):
          if not self.config.config_path.is_file():
              if self.interact.confirm(
                  _(
                      "Config file does not exist - create "
                      "new from default? (y/N)"
                  )
              ):
                  try:
                      default_config = pkgutil.get_data(
                          "bpython", "sample-config"
                      )
                      # Py3  files need unicode
                      default_config = default_config.decode("ascii")
                      containing_dir = self.config.config_path.parent
                      if not containing_dir.exists():
                          containing_dir.mkdir(parents=True)
                      with open(self.config.config_path, "w") as f:
                          f.write(default_config)
                  except OSError as e:
                      self.interact.notify(
                          _("Error writing file '%s': %s")
                          % (self.config.config_path, e)
                      )
                      return False
              else:
                  return False
  
          try:
              if self.open_in_external_editor(self.config.config_path):
                  self.interact.notify(
                      _(
                          "bpython config file edited. Restart "
                          "bpython for changes to take effect."
                      )
                  )
          except OSError as e:
              self.interact.notify(_("Error editing config file: %s") % e)
  
  
  def next_indentation(line, tab_length):
      """Given a code line, return the indentation of the next line."""
      line = line.expandtabs(tab_length)
      indentation = (len(line) - len(line.lstrip(" "))) // tab_length
      if line.rstrip().endswith(":"):
          indentation += 1
      elif indentation >= 1:
          if line.lstrip().startswith(("return", "pass", "raise", "yield")):
              indentation -= 1
      return indentation
  
  
  def next_token_inside_string(code_string, inside_string):
      """Given a code string s and an initial state inside_string, return
      whether the next token will be inside a string or not."""
      for token, value in Python3Lexer().get_tokens(code_string):
          if token is Token.String:
              value = value.lstrip("bBrRuU")
              if value in ('"""', "'''", '"', "'"):
                  if not inside_string:
                      inside_string = value
                  elif value == inside_string:
                      inside_string = False
      return inside_string
  
  
  def split_lines(tokens):
      for (token, value) in tokens:
          if not value:
              continue
          while value:
              head, newline, value = value.partition("\n")
              yield (token, head)
              if newline:
                  yield (Token.Text, newline)
  
  
  def token_is(token_type):
      """Return a callable object that returns whether a token is of the
      given type `token_type`."""
  
      def token_is_type(token):
          """Return whether a token is of a certain type or not."""
          token = token[0]
          while token is not token_type and token.parent:
              token = token.parent
          return token is token_type
  
      return token_is_type
  
  
  def token_is_any_of(token_types):
      """Return a callable object that returns whether a token is any of the
      given types `token_types`."""
      is_token_types = tuple(map(token_is, token_types))
  
      def token_is_any_of(token):
          return any(check(token) for check in is_token_types)
  
      return token_is_any_of
  
  
  def extract_exit_value(args):
      """Given the arguments passed to `SystemExit`, return the value that
      should be passed to `sys.exit`.
      """
      if len(args) == 0:
          return None
      elif len(args) == 1:
          return args[0]
      else:
          return args
  