text: # -*- coding: utf-8 -*-
  """Displayhook for IPython.
  
  This defines a callable class that IPython uses for `sys.displayhook`.
  """
  
  # Copyright (c) IPython Development Team.
  # Distributed under the terms of the Modified BSD License.
  
  import builtins as builtin_mod
  import sys
  import io as _io
  import tokenize
  
  from traitlets.config.configurable import Configurable
  from traitlets import Instance, Float
  from warnings import warn
  
  # TODO: Move the various attributes (cache_size, [others now moved]). Some
  # of these are also attributes of InteractiveShell. They should be on ONE object
  # only and the other objects should ask that one object for their values.
  
  class DisplayHook(Configurable):
      """The custom IPython displayhook to replace sys.displayhook.
  
      This class does many things, but the basic idea is that it is a callable
      that gets called anytime user code returns a value.
      """
  
      shell = Instance('IPython.core.interactiveshell.InteractiveShellABC',
                       allow_none=True)
      exec_result = Instance('IPython.core.interactiveshell.ExecutionResult',
                             allow_none=True)
      cull_fraction = Float(0.2)
  
      def __init__(self, shell=None, cache_size=1000, **kwargs):
          super(DisplayHook, self).__init__(shell=shell, **kwargs)
          cache_size_min = 3
          if cache_size <= 0:
              self.do_full_cache = 0
              cache_size = 0
          elif cache_size < cache_size_min:
              self.do_full_cache = 0
              cache_size = 0
              warn('caching was disabled (min value for cache size is %s).' %
                   cache_size_min,stacklevel=3)
          else:
              self.do_full_cache = 1
  
          self.cache_size = cache_size
  
          # we need a reference to the user-level namespace
          self.shell = shell
          
          self._,self.__,self.___ = '','',''
  
          # these are deliberately global:
          to_user_ns = {'_':self._,'__':self.__,'___':self.___}
          self.shell.user_ns.update(to_user_ns)
  
      @property
      def prompt_count(self):
          return self.shell.execution_count
  
      #-------------------------------------------------------------------------
      # Methods used in __call__. Override these methods to modify the behavior
      # of the displayhook.
      #-------------------------------------------------------------------------
  
      def check_for_underscore(self):
          """Check if the user has set the '_' variable by hand."""
          # If something injected a '_' variable in __builtin__, delete
          # ipython's automatic one so we don't clobber that.  gettext() in
          # particular uses _, so we need to stay away from it.
          if '_' in builtin_mod.__dict__:
              try:
                  user_value = self.shell.user_ns['_']
                  if user_value is not self._:
                      return
                  del self.shell.user_ns['_']
              except KeyError:
                  pass
  
      def quiet(self):
          """Should we silence the display hook because of ';'?"""
          # do not print output if input ends in ';'
          
          try:
              cell = self.shell.history_manager.input_hist_parsed[-1]
          except IndexError:
              # some uses of ipshellembed may fail here
              return False
          
          sio = _io.StringIO(cell)
          tokens = list(tokenize.generate_tokens(sio.readline))
  
          for token in reversed(tokens):
              if token[0] in (tokenize.ENDMARKER, tokenize.NL, tokenize.NEWLINE, tokenize.COMMENT):
                  continue
              if (token[0] == tokenize.OP) and (token[1] == ';'):
                  return True
              else:
                  return False
  
      def start_displayhook(self):
          """Start the displayhook, initializing resources."""
          pass
  
      def write_output_prompt(self):
          """Write the output prompt.
  
          The default implementation simply writes the prompt to
          ``sys.stdout``.
          """
          # Use write, not print which adds an extra space.
          sys.stdout.write(self.shell.separate_out)
          outprompt = 'Out[{}]: '.format(self.shell.execution_count)
          if self.do_full_cache:
              sys.stdout.write(outprompt)
  
      def compute_format_data(self, result):
          """Compute format data of the object to be displayed.
  
          The format data is a generalization of the :func:`repr` of an object.
          In the default implementation the format data is a :class:`dict` of
          key value pair where the keys are valid MIME types and the values
          are JSON'able data structure containing the raw data for that MIME
          type. It is up to frontends to determine pick a MIME to to use and
          display that data in an appropriate manner.
  
          This method only computes the format data for the object and should
          NOT actually print or write that to a stream.
  
          Parameters
          ----------
          result : object
              The Python object passed to the display hook, whose format will be
              computed.
  
          Returns
          -------
          (format_dict, md_dict) : dict
              format_dict is a :class:`dict` whose keys are valid MIME types and values are
              JSON'able raw data for that MIME type. It is recommended that
              all return values of this should always include the "text/plain"
              MIME type representation of the object.
              md_dict is a :class:`dict` with the same MIME type keys
              of metadata associated with each output.
  
          """
          return self.shell.display_formatter.format(result)
  
      # This can be set to True by the write_output_prompt method in a subclass
      prompt_end_newline = False
  
      def write_format_data(self, format_dict, md_dict=None) -> None:
          """Write the format data dict to the frontend.
  
          This default version of this method simply writes the plain text
          representation of the object to ``sys.stdout``. Subclasses should
          override this method to send the entire `format_dict` to the
          frontends.
  
          Parameters
          ----------
          format_dict : dict
              The format dict for the object passed to `sys.displayhook`.
          md_dict : dict (optional)
              The metadata dict to be associated with the display data.
          """
          if 'text/plain' not in format_dict:
              # nothing to do
              return
          # We want to print because we want to always make sure we have a
          # newline, even if all the prompt separators are ''. This is the
          # standard IPython behavior.
          result_repr = format_dict['text/plain']
          if '\n' in result_repr:
              # So that multi-line strings line up with the left column of
              # the screen, instead of having the output prompt mess up
              # their first line.
              # We use the prompt template instead of the expanded prompt
              # because the expansion may add ANSI escapes that will interfere
              # with our ability to determine whether or not we should add
              # a newline.
              if not self.prompt_end_newline:
                  # But avoid extraneous empty lines.
                  result_repr = '\n' + result_repr
  
          try:
              print(result_repr)
          except UnicodeEncodeError:
              # If a character is not supported by the terminal encoding replace
              # it with its \u or \x representation
              print(result_repr.encode(sys.stdout.encoding,'backslashreplace').decode(sys.stdout.encoding))
  
      def update_user_ns(self, result):
          """Update user_ns with various things like _, __, _1, etc."""
  
          # Avoid recursive reference when displaying _oh/Out
          if self.cache_size and result is not self.shell.user_ns['_oh']:
              if len(self.shell.user_ns['_oh']) >= self.cache_size and self.do_full_cache:
                  self.cull_cache()
  
              # Don't overwrite '_' and friends if '_' is in __builtin__
              # (otherwise we cause buggy behavior for things like gettext). and
              # do not overwrite _, __ or ___ if one of these has been assigned
              # by the user.
              update_unders = True
              for unders in ['_'*i for i in range(1,4)]:
                  if not unders in self.shell.user_ns:
                      continue
                  if getattr(self, unders) is not self.shell.user_ns.get(unders):
                      update_unders = False
  
              self.___ = self.__
              self.__ = self._
              self._ = result
  
              if ('_' not in builtin_mod.__dict__) and (update_unders):
                  self.shell.push({'_':self._,
                                   '__':self.__,
                                  '___':self.___}, interactive=False)
  
              # hackish access to top-level  namespace to create _1,_2... dynamically
              to_main = {}
              if self.do_full_cache:
                  new_result = '_%s' % self.prompt_count
                  to_main[new_result] = result
                  self.shell.push(to_main, interactive=False)
                  self.shell.user_ns['_oh'][self.prompt_count] = result
  
      def fill_exec_result(self, result):
          if self.exec_result is not None:
              self.exec_result.result = result
  
      def log_output(self, format_dict):
          """Log the output."""
          if 'text/plain' not in format_dict:
              # nothing to do
              return
          if self.shell.logger.log_output:
              self.shell.logger.log_write(format_dict['text/plain'], 'output')
          self.shell.history_manager.output_hist_reprs[self.prompt_count] = \
                                                      format_dict['text/plain']
  
      def finish_displayhook(self):
          """Finish up all displayhook activities."""
          sys.stdout.write(self.shell.separate_out2)
          sys.stdout.flush()
  
      def __call__(self, result=None):
          """Printing with history cache management.
  
          This is invoked every time the interpreter needs to print, and is
          activated by setting the variable sys.displayhook to it.
          """
          self.check_for_underscore()
          if result is not None and not self.quiet():
              self.start_displayhook()
              self.write_output_prompt()
              format_dict, md_dict = self.compute_format_data(result)
              self.update_user_ns(result)
              self.fill_exec_result(result)
              if format_dict:
                  self.write_format_data(format_dict, md_dict)
                  self.log_output(format_dict)
              self.finish_displayhook()
  
      def cull_cache(self):
          """Output cache is full, cull the oldest entries"""
          oh = self.shell.user_ns.get('_oh', {})
          sz = len(oh)
          cull_count = max(int(sz * self.cull_fraction), 2)
          warn('Output cache limit (currently {sz} entries) hit.\n'
               'Flushing oldest {cull_count} entries.'.format(sz=sz, cull_count=cull_count))
          
          for i, n in enumerate(sorted(oh)):
              if i >= cull_count:
                  break
              self.shell.user_ns.pop('_%i' % n, None)
              oh.pop(n, None)
          
  
      def flush(self):
          if not self.do_full_cache:
              raise ValueError("You shouldn't have reached the cache flush "
                               "if full caching is not enabled!")
          # delete auto-generated vars from global namespace
  
          for n in range(1,self.prompt_count + 1):
              key = '_'+repr(n)
              try:
                  del self.shell.user_ns[key]
              except: pass
          # In some embedded circumstances, the user_ns doesn't have the
          # '_oh' key set up.
          oh = self.shell.user_ns.get('_oh', None)
          if oh is not None:
              oh.clear()
  
          # Release our own references to objects:
          self._, self.__, self.___ = '', '', ''
  
          if '_' not in builtin_mod.__dict__:
              self.shell.user_ns.update({'_':self._,'__':self.__,'___':self.___})
          import gc
          # TODO: Is this really needed?
          # IronPython blocks here forever
          if sys.platform != "cli":
              gc.collect()
  
  
  class CapturingDisplayHook(object):
      def __init__(self, shell, outputs=None):
          self.shell = shell
          if outputs is None:
              outputs = []
          self.outputs = outputs
  
      def __call__(self, result=None):
          if result is None:
              return
          format_dict, md_dict = self.shell.display_formatter.format(result)
          self.outputs.append({ 'data': format_dict, 'metadata': md_dict })
  