YouCompleteMe/python/ycm/youcompleteme.py

# Copyright (C) 2011-2018 YouCompleteMe contributors
#
# This file is part of YouCompleteMe.
#
# YouCompleteMe is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# YouCompleteMe is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.

import base64
import json
import logging
import os
import signal
import vim
from subprocess import PIPE
from tempfile import NamedTemporaryFile
from ycm import base, paths, signature_help, vimsupport
from ycm.buffer import BufferDict
from ycmd import utils
from ycmd.request_wrap import RequestWrap
from ycm.omni_completer import OmniCompleter
from ycm import syntax_parse
from ycm.client.ycmd_keepalive import YcmdKeepalive
from ycm.client.base_request import BaseRequest, BuildRequestData
from ycm.client.completer_available_request import SendCompleterAvailableRequest
from ycm.client.command_request import ( SendCommandRequest,
                                         SendCommandRequestAsync,
                                         GetCommandResponse )
from ycm.client.completion_request import CompletionRequest
from ycm.client.resolve_completion_request import ResolveCompletionItem
from ycm.client.signature_help_request import ( SignatureHelpRequest,
                                                SigHelpAvailableByFileType )
from ycm.client.debug_info_request import ( SendDebugInfoRequest,
                                            FormatDebugInfoResponse )
from ycm.client.omni_completion_request import OmniCompletionRequest
from ycm.client.event_notification import SendEventNotificationAsync
from ycm.client.shutdown_request import SendShutdownRequest
from ycm.client.messages_request import MessagesPoll


def PatchNoProxy():
  current_value = os.environ.get( 'no_proxy', '' )
  additions = '127.0.0.1,localhost'
  os.environ[ 'no_proxy' ] = ( additions if not current_value
                               else current_value + ',' + additions )


# We need this so that Requests doesn't end up using the local HTTP proxy when
# talking to ycmd. Users should actually be setting this themselves when
# configuring a proxy server on their machine, but most don't know they need to
# or how to do it, so we do it for them.
# Relevant issues:
#  https://github.com/Valloric/YouCompleteMe/issues/641
#  https://github.com/kennethreitz/requests/issues/879
PatchNoProxy()

# Force the Python interpreter embedded in Vim (in which we are running) to
# ignore the SIGINT signal. This helps reduce the fallout of a user pressing
# Ctrl-C in Vim.
signal.signal( signal.SIGINT, signal.SIG_IGN )

HMAC_SECRET_LENGTH = 16
SERVER_SHUTDOWN_MESSAGE = (
  "The ycmd server SHUT DOWN (restart with ':YcmRestartServer')." )
EXIT_CODE_UNEXPECTED_MESSAGE = (
  "Unexpected exit code {code}. "
  "Type ':YcmToggleLogs {logfile}' to check the logs." )
CORE_UNEXPECTED_MESSAGE = (
  "Unexpected error while loading the YCM core library. "
  "Type ':YcmToggleLogs {logfile}' to check the logs." )
CORE_MISSING_MESSAGE = (
  'YCM core library not detected; you need to compile YCM before using it. '
  'Follow the instructions in the documentation.' )
CORE_OUTDATED_MESSAGE = (
  'YCM core library too old; PLEASE RECOMPILE by running the install.py '
  'script. See the documentation for more details.' )
NO_PYTHON2_SUPPORT_MESSAGE = (
  'YCM has dropped support for python2. '
  'You need to recompile it with python3 instead.' )
SERVER_IDLE_SUICIDE_SECONDS = 1800  # 30 minutes
CLIENT_LOGFILE_FORMAT = 'ycm_'
SERVER_LOGFILE_FORMAT = 'ycmd_{port}_{std}_'

# Flag to set a file handle inheritable by child processes on Windows. See
# https://msdn.microsoft.com/en-us/library/ms724935.aspx
HANDLE_FLAG_INHERIT = 0x00000001


class YouCompleteMe:
  def __init__( self, default_options = {} ):
    self._logger = logging.getLogger( 'ycm' )
    self._client_logfile = None
    self._server_stdout = None
    self._server_stderr = None
    self._server_popen = None
    self._default_options = default_options
    self._ycmd_keepalive = YcmdKeepalive()
    self._SetUpLogging()
    self._SetUpServer()
    self._ycmd_keepalive.Start()


  def _SetUpServer( self ):
    self._available_completers = {}
    self._user_notified_about_crash = False
    self._filetypes_with_keywords_loaded = set()
    self._server_is_ready_with_cache = False
    self._message_poll_requests = {}

    self._latest_completion_request = None
    self._latest_signature_help_request = None
    self._signature_help_available_requests = SigHelpAvailableByFileType()
    self._latest_command_reqeust = None

    self._signature_help_state = signature_help.SignatureHelpState()
    self._user_options = base.GetUserOptions( self._default_options )
    self._omnicomp = OmniCompleter( self._user_options )
    self._buffers = BufferDict( self._user_options )

    self._SetLogLevel()

    hmac_secret = os.urandom( HMAC_SECRET_LENGTH )
    options_dict = dict( self._user_options )
    options_dict[ 'hmac_secret' ] = utils.ToUnicode(
      base64.b64encode( hmac_secret ) )
    options_dict[ 'server_keep_logfiles' ] = self._user_options[
      'keep_logfiles' ]

    # The temp options file is deleted by ycmd during startup.
    with NamedTemporaryFile( delete = False, mode = 'w+' ) as options_file:
      json.dump( options_dict, options_file )

    server_port = utils.GetUnusedLocalhostPort()

    BaseRequest.server_location = 'http://127.0.0.1:' + str( server_port )
    BaseRequest.hmac_secret = hmac_secret

    try:
      python_interpreter = paths.PathToPythonInterpreter()
    except RuntimeError as error:
      error_message = (
        f"Unable to start the ycmd server. { str( error ).rstrip( '.' ) }. "
        "Correct the error then restart the server "
        "with ':YcmRestartServer'." )
      self._logger.exception( error_message )
      vimsupport.PostVimMessage( error_message )
      return

    args = [ python_interpreter,
             paths.PathToServerScript(),
             f'--port={ server_port }',
             f'--options_file={ options_file.name }',
             f'--log={ self._user_options[ "log_level" ] }',
             f'--idle_suicide_seconds={ SERVER_IDLE_SUICIDE_SECONDS }' ]

    self._server_stdout = utils.CreateLogfile(
        SERVER_LOGFILE_FORMAT.format( port = server_port, std = 'stdout' ) )
    self._server_stderr = utils.CreateLogfile(
        SERVER_LOGFILE_FORMAT.format( port = server_port, std = 'stderr' ) )
    args.append( f'--stdout={ self._server_stdout }' )
    args.append( f'--stderr={ self._server_stderr }' )

    if self._user_options[ 'keep_logfiles' ]:
      args.append( '--keep_logfiles' )

    self._server_popen = utils.SafePopen( args, stdin_windows = PIPE,
                                          stdout = PIPE, stderr = PIPE )


  def _SetUpLogging( self ):
    def FreeFileFromOtherProcesses( file_object ):
      if utils.OnWindows():
        from ctypes import windll
        import msvcrt

        file_handle = msvcrt.get_osfhandle( file_object.fileno() )
        windll.kernel32.SetHandleInformation( file_handle,
                                              HANDLE_FLAG_INHERIT,
                                              0 )

    self._client_logfile = utils.CreateLogfile( CLIENT_LOGFILE_FORMAT )

    handler = logging.FileHandler( self._client_logfile )

    # On Windows and Python prior to 3.4, file handles are inherited by child
    # processes started with at least one replaced standard stream, which is the
    # case when we start the ycmd server (we are redirecting all standard
    # outputs into a pipe). These files cannot be removed while the child
    # processes are still up. This is not desirable for a logfile because we
    # want to remove it at Vim exit without having to wait for the ycmd server
    # to be completely shut down. We need to make the logfile handle
    # non-inheritable. See https://www.python.org/dev/peps/pep-0446 for more
    # details.
    FreeFileFromOtherProcesses( handler.stream )

    formatter = logging.Formatter( '%(asctime)s - %(levelname)s - %(message)s' )
    handler.setFormatter( formatter )

    self._logger.addHandler( handler )


  def _SetLogLevel( self ):
    log_level = self._user_options[ 'log_level' ]
    numeric_level = getattr( logging, log_level.upper(), None )
    if not isinstance( numeric_level, int ):
      raise ValueError( f'Invalid log level: { log_level }' )
    self._logger.setLevel( numeric_level )


  def IsServerAlive( self ):
    # When the process hasn't finished yet, poll() returns None.
    return bool( self._server_popen ) and self._server_popen.poll() is None


  def CheckIfServerIsReady( self ):
    if not self._server_is_ready_with_cache and self.IsServerAlive():
      self._server_is_ready_with_cache = BaseRequest().GetDataFromHandler(
          'ready', display_message = False )
    return self._server_is_ready_with_cache


  def IsServerReady( self ):
    return self._server_is_ready_with_cache


  def NotifyUserIfServerCrashed( self ):
    if ( not self._server_popen or self._user_notified_about_crash or
         self.IsServerAlive() ):
      return
    self._user_notified_about_crash = True

    return_code = self._server_popen.poll()
    logfile = os.path.basename( self._server_stderr )
    # See https://github.com/Valloric/ycmd#exit-codes for the list of exit
    # codes.
    if return_code == 3:
      error_message = CORE_UNEXPECTED_MESSAGE.format( logfile = logfile )
    elif return_code == 4:
      error_message = CORE_MISSING_MESSAGE
    elif return_code == 7:
      error_message = CORE_OUTDATED_MESSAGE
    elif return_code == 8:
      error_message = NO_PYTHON2_SUPPORT_MESSAGE
    else:
      error_message = EXIT_CODE_UNEXPECTED_MESSAGE.format( code = return_code,
                                                           logfile = logfile )

    if return_code != 8:
      error_message = SERVER_SHUTDOWN_MESSAGE + ' ' + error_message
    self._logger.error( error_message )
    vimsupport.PostVimMessage( error_message )


  def ServerPid( self ):
    if not self._server_popen:
      return -1
    return self._server_popen.pid


  def _ShutdownServer( self ):
    SendShutdownRequest()


  def RestartServer( self ):
    vimsupport.PostVimMessage( 'Restarting ycmd server...' )
    self._ShutdownServer()
    self._SetUpServer()


  def SendCompletionRequest( self, force_semantic = False ):
    request_data = BuildRequestData()
    request_data[ 'force_semantic' ] = force_semantic

    if not self.NativeFiletypeCompletionUsable():
      wrapped_request_data = RequestWrap( request_data )
      if self._omnicomp.ShouldUseNow( wrapped_request_data ):
        self._latest_completion_request = OmniCompletionRequest(
            self._omnicomp, wrapped_request_data )
        self._latest_completion_request.Start()
        return

    self._AddExtraConfDataIfNeeded( request_data )
    self._latest_completion_request = CompletionRequest( request_data )
    self._latest_completion_request.Start()


  def CompletionRequestReady( self ):
    return bool( self._latest_completion_request and
                 self._latest_completion_request.Done() )


  def GetCompletionResponse( self ):
    return self._latest_completion_request.Response()


  def SignatureHelpAvailableRequestComplete( self, filetype, send_new=True ):
    """Triggers or polls signature help available request. Returns whether or
    not the request is complete. When send_new is False, won't send a new
    request, only return the current status (This is used by the tests)"""
    if not send_new and filetype not in self._signature_help_available_requests:
      return False

    return self._signature_help_available_requests[ filetype ].Done()


  def SendSignatureHelpRequest( self ):
    """Send a signature help request, if we're ready to. Return whether or not a
    request was sent (and should be checked later)"""
    if not self.NativeFiletypeCompletionUsable():
      return False

    for filetype in vimsupport.CurrentFiletypes():
      if not self.SignatureHelpAvailableRequestComplete( filetype ):
        continue

      sig_help_available = self._signature_help_available_requests[
          filetype ].Response()
      if sig_help_available == 'NO':
        continue

      if sig_help_available == 'PENDING':
        # Send another /signature_help_available request
        self._signature_help_available_requests[ filetype ].Start( filetype )
        continue

      if not self._latest_completion_request:
        return False

      request_data = self._latest_completion_request.request_data.copy()
      request_data[ 'signature_help_state' ] = self._signature_help_state.state

      self._AddExtraConfDataIfNeeded( request_data )

      self._latest_signature_help_request = SignatureHelpRequest( request_data )
      self._latest_signature_help_request.Start()
      return True

    return False


  def SignatureHelpRequestReady( self ):
    return bool( self._latest_signature_help_request and
                 self._latest_signature_help_request.Done() )


  def GetSignatureHelpResponse( self ):
    return self._latest_signature_help_request.Response()


  def ClearSignatureHelp( self ):
    self.UpdateSignatureHelp( {} )
    if self._latest_signature_help_request:
      self._latest_signature_help_request.Reset()


  def UpdateSignatureHelp( self, signature_info ):
    self._signature_help_state = signature_help.UpdateSignatureHelp(
      self._signature_help_state,
      signature_info )


  def _GetCommandRequestArguments( self,
                                   arguments,
                                   has_range,
                                   start_line,
                                   end_line ):
    final_arguments = []
    for argument in arguments:
      # The ft= option which specifies the completer when running a command is
      # ignored because it has not been working for a long time. The option is
      # still parsed to not break users that rely on it.
      if argument.startswith( 'ft=' ):
        continue
      final_arguments.append( argument )

    extra_data = {
      'options': {
        'tab_size': vimsupport.GetIntValue( 'shiftwidth()' ),
        'insert_spaces': vimsupport.GetBoolValue( '&expandtab' )
      }
    }
    if has_range:
      extra_data.update( vimsupport.BuildRange( start_line, end_line ) )
    self._AddExtraConfDataIfNeeded( extra_data )

    return final_arguments, extra_data



  def SendCommandRequest( self,
                          arguments,
                          modifiers,
                          has_range,
                          start_line,
                          end_line ):
    final_arguments, extra_data = self._GetCommandRequestArguments(
      arguments,
      has_range,
      start_line,
      end_line )
    return SendCommandRequest(
      final_arguments,
      modifiers,
      self._user_options[ 'goto_buffer_command' ],
      extra_data )


  def GetCommandResponse( self, arguments ):
    final_arguments, extra_data = self._GetCommandRequestArguments(
      arguments,
      False,
      0,
      0 )
    return GetCommandResponse( final_arguments, extra_data )


  def SendCommandRequestAsync( self, arguments ):
    final_arguments, extra_data = self._GetCommandRequestArguments(
      arguments,
      False,
      0,
      0 )
    self._latest_command_reqeust = SendCommandRequestAsync( final_arguments,
                                                            extra_data )


  def GetCommandRequest( self ):
    return self._latest_command_reqeust


  def GetDefinedSubcommands( self ):
    request = BaseRequest()
    subcommands = request.PostDataToHandler( BuildRequestData(),
                                             'defined_subcommands' )
    return subcommands if subcommands else []


  def GetCurrentCompletionRequest( self ):
    return self._latest_completion_request


  def GetOmniCompleter( self ):
    return self._omnicomp


  def FiletypeCompleterExistsForFiletype( self, filetype ):
    try:
      return self._available_completers[ filetype ]
    except KeyError:
      pass

    exists_completer = SendCompleterAvailableRequest( filetype )
    if exists_completer is None:
      return False

    self._available_completers[ filetype ] = exists_completer
    return exists_completer


  def NativeFiletypeCompletionAvailable( self ):
    return any( self.FiletypeCompleterExistsForFiletype( x ) for x in
                vimsupport.CurrentFiletypes() )


  def NativeFiletypeCompletionUsable( self ):
    disabled_filetypes = self._user_options[
      'filetype_specific_completion_to_disable' ]
    return ( vimsupport.CurrentFiletypesEnabled( disabled_filetypes ) and
             self.NativeFiletypeCompletionAvailable() )


  def NeedsReparse( self ):
    return self.CurrentBuffer().NeedsReparse()


  def UpdateWithNewDiagnosticsForFile( self, filepath, diagnostics ):
    if not self._user_options[ 'show_diagnostics_ui' ]:
      return

    bufnr = vimsupport.GetBufferNumberForFilename( filepath )
    if bufnr in self._buffers and vimsupport.BufferIsVisible( bufnr ):
      # Note: We only update location lists, etc. for visible buffers, because
      # otherwise we default to using the current location list and the results
      # are that non-visible buffer errors clobber visible ones.
      self._buffers[ bufnr ].UpdateWithNewDiagnostics( diagnostics )
    else:
      # The project contains errors in file "filepath", but that file is not
      # open in any buffer. This happens for Language Server Protocol-based
      # completers, as they return diagnostics for the entire "project"
      # asynchronously (rather than per-file in the response to the parse
      # request).
      #
      # There are a number of possible approaches for
      # this, but for now we simply ignore them. Other options include:
      # - Use the QuickFix list to report project errors?
      # - Use a special buffer for project errors
      # - Put them in the location list of whatever the "current" buffer is
      # - Store them in case the buffer is opened later
      # - add a :YcmProjectDiags command
      # - Add them to errror/warning _counts_ but not any actual location list
      #   or other
      # - etc.
      #
      # However, none of those options are great, and lead to their own
      # complexities. So for now, we just ignore these diagnostics for files not
      # open in any buffer.
      pass


  def OnPeriodicTick( self ):
    if not self.IsServerAlive():
      # Server has died. We'll reset when the server is started again.
      return False
    elif not self.IsServerReady():
      # Try again in a jiffy
      return True

    for w in vim.windows:
      for filetype in vimsupport.FiletypesForBuffer( w.buffer ):
        if filetype not in self._message_poll_requests:
          self._message_poll_requests[ filetype ] = MessagesPoll( w.buffer )

        # None means don't poll this filetype
        if ( self._message_poll_requests[ filetype ] and
             not self._message_poll_requests[ filetype ].Poll( self ) ):
          self._message_poll_requests[ filetype ] = None

    return any( self._message_poll_requests.values() )


  def OnFileReadyToParse( self ):
    if not self.IsServerAlive():
      self.NotifyUserIfServerCrashed()
      return

    if not self.IsServerReady():
      return

    extra_data = {}
    self._AddTagsFilesIfNeeded( extra_data )
    self._AddSyntaxDataIfNeeded( extra_data )
    self._AddExtraConfDataIfNeeded( extra_data )

    self.CurrentBuffer().SendParseRequest( extra_data )


  def OnFileSave( self, saved_buffer_number ):
    SendEventNotificationAsync( 'FileSave', saved_buffer_number )


  def OnBufferUnload( self, deleted_buffer_number ):
    SendEventNotificationAsync( 'BufferUnload', deleted_buffer_number )


  def UpdateMatches( self ):
    self.CurrentBuffer().UpdateMatches()


  def OnFileTypeSet( self ):
    buffer_number = vimsupport.GetCurrentBufferNumber()
    filetypes = vimsupport.CurrentFiletypes()
    self._buffers[ buffer_number ].UpdateFromFileTypes( filetypes )
    self.OnBufferVisit()


  def OnBufferVisit( self ):
    for filetype in vimsupport.CurrentFiletypes():
      # Send the signature help available request for these filetypes if we need
      # to (as a side effect of checking if it is complete)
      self.SignatureHelpAvailableRequestComplete( filetype, True )

    extra_data = {}
    self._AddUltiSnipsDataIfNeeded( extra_data )
    SendEventNotificationAsync( 'BufferVisit', extra_data = extra_data )


  def CurrentBuffer( self ):
    return self._buffers[ vimsupport.GetCurrentBufferNumber() ]


  def OnInsertLeave( self ):
    SendEventNotificationAsync( 'InsertLeave' )


  def OnCursorMoved( self ):
    self.CurrentBuffer().OnCursorMoved()


  def _CleanLogfile( self ):
    logging.shutdown()
    if not self._user_options[ 'keep_logfiles' ]:
      if self._client_logfile:
        utils.RemoveIfExists( self._client_logfile )


  def OnVimLeave( self ):
    self._ShutdownServer()
    self._CleanLogfile()


  def OnCurrentIdentifierFinished( self ):
    SendEventNotificationAsync( 'CurrentIdentifierFinished' )


  def OnCompleteDone( self ):
    completion_request = self.GetCurrentCompletionRequest()
    if completion_request:
      completion_request.OnCompleteDone()


  def ResolveCompletionItem( self, item ):
    # Note: As mentioned elsewhere, we replace the current completion request
    # with a resolve request. It's not valid to have simultaneous resolve and
    # completion requests, because the resolve request uses the request data
    # from the last completion request and is therefore dependent on it not
    # having changed.
    #
    # The result of this is that self.GetCurrentCompletionRequest() might return
    # either a completion request of a resolve request and it's the
    # responsibility of the vimscript code to ensure that it only does one at a
    # time. This is handled by re-using the same poller for completions and
    # resolves.
    completion_request = self.GetCurrentCompletionRequest()
    if not completion_request:
      return False

    request  = ResolveCompletionItem( completion_request, item )
    if not request:
      return False

    self._latest_completion_request = request
    return True


  def GetErrorCount( self ):
    return self.CurrentBuffer().GetErrorCount()


  def GetWarningCount( self ):
    return self.CurrentBuffer().GetWarningCount()


  def _PopulateLocationListWithLatestDiagnostics( self ):
    return self.CurrentBuffer().PopulateLocationList()


  def FileParseRequestReady( self ):
    # Return True if server is not ready yet, to stop repeating check timer.
    return ( not self.IsServerReady() or
             self.CurrentBuffer().FileParseRequestReady() )


  def HandleFileParseRequest( self, block = False ):
    if not self.IsServerReady():
      return

    current_buffer = self.CurrentBuffer()
    # Order is important here:
    # FileParseRequestReady has a low cost, while
    # NativeFiletypeCompletionUsable is a blocking server request
    if ( not current_buffer.IsResponseHandled() and
         current_buffer.FileParseRequestReady( block ) and
         self.NativeFiletypeCompletionUsable() ):

      if self._user_options[ 'show_diagnostics_ui' ]:
        # Forcefuly update the location list, etc. from the parse request when
        # doing something like :YcmDiags
        current_buffer.UpdateDiagnostics( block )
      else:
        # If the user disabled diagnostics, we just want to check
        # the _latest_file_parse_request for any exception or UnknownExtraConf
        # response, to allow the server to raise configuration warnings, etc.
        # to the user. We ignore any other supplied data.
        current_buffer.GetResponse()

      # We set the file parse request as handled because we want to prevent
      # repeated issuing of the same warnings/errors/prompts. Setting this
      # makes IsRequestHandled return True until the next request is created.
      #
      # Note: it is the server's responsibility to determine the frequency of
      # error/warning/prompts when receiving a FileReadyToParse event, but
      # it is our responsibility to ensure that we only apply the
      # warning/error/prompt received once (for each event).
      current_buffer.MarkResponseHandled()


  def ShouldResendFileParseRequest( self ):
    return self.CurrentBuffer().ShouldResendParseRequest()


  def DebugInfo( self ):
    debug_info = ''
    if self._client_logfile:
      debug_info += f'Client logfile: { self._client_logfile }\n'
    extra_data = {}
    self._AddExtraConfDataIfNeeded( extra_data )
    debug_info += FormatDebugInfoResponse( SendDebugInfoRequest( extra_data ) )
    debug_info += f'Server running at: { BaseRequest.server_location }\n'
    if self._server_popen:
      debug_info += f'Server process ID: { self._server_popen.pid }\n'
    if self._server_stdout and self._server_stderr:
      debug_info += ( 'Server logfiles:\n'
                      f'  { self._server_stdout }\n'
                      f'  { self._server_stderr }' )
    return debug_info


  def GetLogfiles( self ):
    logfiles_list = [ self._client_logfile,
                      self._server_stdout,
                      self._server_stderr ]

    extra_data = {}
    self._AddExtraConfDataIfNeeded( extra_data )
    debug_info = SendDebugInfoRequest( extra_data )
    if debug_info:
      completer = debug_info[ 'completer' ]
      if completer:
        for server in completer[ 'servers' ]:
          logfiles_list.extend( server[ 'logfiles' ] )

    logfiles = {}
    for logfile in logfiles_list:
      logfiles[ os.path.basename( logfile ) ] = logfile
    return logfiles


  def _OpenLogfile( self, size, mods, logfile ):
    # Open log files in a horizontal window with the same behavior as the
    # preview window (same height and winfixheight enabled). Automatically
    # watch for changes. Set the cursor position at the end of the file.
    if not size:
      size = vimsupport.GetIntValue( '&previewheight' )

    options = {
      'size': size,
      'fix': True,
      'focus': False,
      'watch': True,
      'position': 'end',
      'mods': mods
    }

    vimsupport.OpenFilename( logfile, options )


  def _CloseLogfile( self, logfile ):
    vimsupport.CloseBuffersForFilename( logfile )


  def ToggleLogs( self, size, mods, *filenames ):
    logfiles = self.GetLogfiles()
    if not filenames:
      sorted_logfiles = sorted( logfiles )
      try:
        logfile_index = vimsupport.SelectFromList(
          'Which logfile do you wish to open (or close if already open)?',
          sorted_logfiles )
      except RuntimeError as e:
        vimsupport.PostVimMessage( str( e ) )
        return

      logfile = logfiles[ sorted_logfiles[ logfile_index ] ]
      if not vimsupport.BufferIsVisibleForFilename( logfile ):
        self._OpenLogfile( size, mods, logfile )
      else:
        self._CloseLogfile( logfile )
      return

    for filename in set( filenames ):
      if filename not in logfiles:
        continue

      logfile = logfiles[ filename ]

      if not vimsupport.BufferIsVisibleForFilename( logfile ):
        self._OpenLogfile( size, mods, logfile )
        continue

      self._CloseLogfile( logfile )


  def ShowDetailedDiagnostic( self ):
    detailed_diagnostic = BaseRequest().PostDataToHandler(
        BuildRequestData(), 'detailed_diagnostic' )

    if detailed_diagnostic and 'message' in detailed_diagnostic:
      vimsupport.PostVimMessage( detailed_diagnostic[ 'message' ],
                                 warning = False )


  def ForceCompileAndDiagnostics( self ):
    if not self.NativeFiletypeCompletionUsable():
      vimsupport.PostVimMessage(
          'Native filetype completion not supported for current file, '
          'cannot force recompilation.', warning = False )
      return False
    vimsupport.PostVimMessage(
        'Forcing compilation, this will block Vim until done.',
        warning = False )
    self.OnFileReadyToParse()
    self.HandleFileParseRequest( block = True )
    vimsupport.PostVimMessage( 'Diagnostics refreshed', warning = False )
    return True


  def ShowDiagnostics( self ):
    if not self.ForceCompileAndDiagnostics():
      return

    if not self._PopulateLocationListWithLatestDiagnostics():
      vimsupport.PostVimMessage( 'No warnings or errors detected.',
                                 warning = False )
      return

    if self._user_options[ 'open_loclist_on_ycm_diags' ]:
      vimsupport.OpenLocationList( focus = True )


  def _AddSyntaxDataIfNeeded( self, extra_data ):
    if not self._user_options[ 'seed_identifiers_with_syntax' ]:
      return
    filetype = vimsupport.CurrentFiletypes()[ 0 ]
    if filetype in self._filetypes_with_keywords_loaded:
      return

    if self.IsServerReady():
      self._filetypes_with_keywords_loaded.add( filetype )
    extra_data[ 'syntax_keywords' ] = list(
       syntax_parse.SyntaxKeywordsForCurrentBuffer() )


  def _AddTagsFilesIfNeeded( self, extra_data ):
    def GetTagFiles():
      tag_files = vim.eval( 'tagfiles()' )
      return [ os.path.join( utils.GetCurrentDirectory(), tag_file )
               for tag_file in tag_files ]

    if not self._user_options[ 'collect_identifiers_from_tags_files' ]:
      return
    extra_data[ 'tag_files' ] = GetTagFiles()


  def _AddExtraConfDataIfNeeded( self, extra_data ):
    def BuildExtraConfData( extra_conf_vim_data ):
      extra_conf_data = {}
      for expr in extra_conf_vim_data:
        try:
          extra_conf_data[ expr ] = vimsupport.VimExpressionToPythonType( expr )
        except vim.error:
          message = (
            f"Error evaluating '{ expr }' in the 'g:ycm_extra_conf_vim_data' "
            "option." )
          vimsupport.PostVimMessage( message, truncate = True )
          self._logger.exception( message )
      return extra_conf_data

    extra_conf_vim_data = self._user_options[ 'extra_conf_vim_data' ]
    if extra_conf_vim_data:
      extra_data[ 'extra_conf_data' ] = BuildExtraConfData(
        extra_conf_vim_data )


  def _AddUltiSnipsDataIfNeeded( self, extra_data ):
    # See :h UltiSnips#SnippetsInCurrentScope.
    try:
      vim.eval( 'UltiSnips#SnippetsInCurrentScope( 1 )' )
    except vim.error:
      return

    snippets = vimsupport.GetVariableValue( 'g:current_ulti_dict_info' )
    extra_data[ 'ultisnips_snippets' ] = [
      { 'trigger': trigger,
        'description': snippet[ 'description' ] }
      for trigger, snippet in snippets.items()
    ]