new_contents: import os
  import ycm_core
  from clang_helpers import PrepareClangFlags
  
  # Set this to the absolute path to the folder (NOT the file!) containing the
  # compile_commands.json file to use that instead of 'flags'. See here for
  # more details: http://clang.llvm.org/docs/JSONCompilationDatabase.html
  # Most projects will NOT need to set this to anything; you can just change the
  # 'flags' list of compilation flags. Notice that YCM itself uses that approach.
  compilation_database_folder = ''
  
  # These are the compilation flags that will be used in case there's no
  # compilation database set.
  flags = [
      '-Wall',
      '-std=c++11',
      '-stdlib=libc++',
      '-x',
      'c++',
      '-I',
      '.',
      '-Ilib',
      '-Isrc',
      '-isystem',
      '/usr/lib/c++/v1'
  ]
  
  if compilation_database_folder:
      database = ycm_core.CompilationDatabase(compilation_database_folder)
  else:
      database = None
  
  
  def DirectoryOfThisScript():
      return os.path.dirname(os.path.abspath(__file__))
  
  
  def MakeRelativePathsInFlagsAbsolute(flags, working_directory):
      if not working_directory:
          return flags
      new_flags = []
      make_next_absolute = False
      path_flags = ['-isystem', '-I', '-iquote', '--sysroot=']
      for flag in flags:
          new_flag = flag
  
          if make_next_absolute:
              make_next_absolute = False
              if not flag.startswith('/'):
                  new_flag = os.path.join(working_directory, flag)
  
          for path_flag in path_flags:
              if flag == path_flag:
                  make_next_absolute = True
                  break
  
              if flag.startswith(path_flag):
                  path = flag[len(path_flag):]
                  new_flag = path_flag + os.path.join(working_directory, path)
                  break
  
          if new_flag:
              new_flags.append(new_flag)
      return new_flags
  
  
  def FlagsForFile(filename):
      if database:
          # Bear in mind that compilation_info.compiler_flags_ does NOT return a
          # python list, but a "list-like" StringVec object
          compilation_info = database.GetCompilationInfoForFile(filename)
          final_flags = PrepareClangFlags(
              MakeRelativePathsInFlagsAbsolute(
                  compilation_info.compiler_flags_,
                  compilation_info.compiler_working_dir_),
              filename)
      else:
          relative_to = DirectoryOfThisScript()
          final_flags = MakeRelativePathsInFlagsAbsolute(flags, relative_to)
  
      return {
          'flags': final_flags,
          'do_cache': True}
  
subject: add YouCompleteMe config