Add subcommand completion for YcmCompleter command

autoload/youcompleteme.vim

@@ -609,7 +609,13 @@ function! youcompleteme#OpenGoToList()
   redraw!
 endfunction
 
-command! -nargs=* YcmCompleter call s:CompleterCommand(<f-args>)
+command! -nargs=* -complete=custom,youcompleteme#SubCommandsComplete
+  \ YcmCompleter call s:CompleterCommand(<f-args>)
+
+function! youcompleteme#SubCommandsComplete( arglead, cmdline, cursorpos )
+  return join( pyeval( 'ycm_state.GetFiletypeCompleter().DefinedSubcommands()' ),
+    \ "\n")
+endfunction
 
 function! s:ForceCompile()
   if !pyeval( 'ycm_state.NativeFiletypeCompletionUsable()' )

python/completers/completer.py

@@ -176,6 +176,18 @@ class Completer( object ):
       self.CandidatesForQueryAsyncInner( query, start_column )
 
 
+  def DefinedSubcommands( self ):
+    return []
+
+
+  def UserCommandsHelpMessage( self ):
+    if self.DefinedSubcommands():
+      vimsupport.EchoText( "Supported commands are:\n" +
+                           '\n'.join( self.DefinedSubcommands() )+
+                           "\nSee the docs for information on what they do." )
+    else:
+      vimsupport.EchoText( "No supported subcommands" )
+
   def FilterAndSortCandidates( self, candidates, query ):
     if not candidates:
       return []

python/completers/cpp/clang_completer.py

@@ -28,12 +28,6 @@ from flags import Flags
 CLANG_FILETYPES = set( [ 'c', 'cpp', 'objc', 'objcpp' ] )
 MAX_DIAGNOSTICS_TO_DISPLAY = int( vimsupport.GetVariableValue(
   "g:ycm_max_diagnostics_to_display" ) )
-USER_COMMANDS_HELP_MESSAGE = """
-Supported commands are:
-  GoToDefinition
-  GoToDeclaration
-  GoToDefinitionElseDeclaration
-See the docs for information on what they do."""
 
 
 class ClangCompleter( Completer ):
@@ -130,10 +124,15 @@ class ClangCompleter( Completer ):
     return results
 
 
+  def DefinedSubcommands( self ):
+    return [ "GoToDefinition",
+             "GoToDeclaration",
+             "GoToDefinitionElseDeclaration" ]
+
+
   def OnUserCommand( self, arguments ):
     if not arguments:
-      vimsupport.EchoText( USER_COMMANDS_HELP_MESSAGE )
+      return self.UserCommandsHelpMessage()
-      return
 
     command = arguments[ 0 ]
     if command == 'GoToDefinition':

python/completers/python/jedi_completer.py

@@ -38,13 +38,6 @@ except ImportError:
     'In the YouCompleteMe folder, run "git submodule update --init --recursive"')
 sys.path.pop( 0 )
 
-USER_COMMANDS_HELP_MESSAGE = """
-Supported commands are:
-  GoToDefinition
-  GoToDeclaration
-  GoToDefinitionElseDeclaration
-See the docs for information on what they do."""
-
 
 class JediCompleter( ThreadedCompleter ):
   """
@@ -80,10 +73,15 @@ class JediCompleter( ThreadedCompleter ):
              for completion in script.complete() ]
 
 
+  def DefinedSubcommands( self ):
+    return [ "GoToDefinition",
+             "GoToDeclaration",
+             "GoToDefinitionElseDeclaration" ]
+
+
   def OnUserCommand( self, arguments ):
     if not arguments:
-      vimsupport.EchoText( USER_COMMANDS_HELP_MESSAGE )
+      return self.UserCommandsHelpMessage()
-      return
 
     command = arguments[ 0 ]
     if command == 'GoToDefinition':