Rewrite completion system

Bring fully asynchronous completion by polling for completions with a timer
then calling completefunc once the completions are ready. Use the start column
returned by the server in completefunc. Immediately display the last completion
on the TextChangedI event to prevent the popup menu disappearing while waiting
for the completions. Handle the TextChangedI event not being triggered while
the completion menu is open by closing the menu when inserting a character
through the InsertCharPre event, and when deleting a character on the <BS> and
<C-h> keys.

autoload/youcompleteme.vim

@@ -21,12 +21,18 @@ set cpo&vim
 
 " This needs to be called outside of a function
 let s:script_folder_path = escape( expand( '<sfile>:p:h' ), '\' )
-let s:omnifunc_mode = 0
-
-let s:old_cursor_position = []
-let s:cursor_moved = 0
+let s:force_semantic = 0
+let s:default_completion = {
+      \   'start_column': -1,
+      \   'candidates': []
+      \ }
+let s:completion = s:default_completion
 let s:previous_allowed_buffer_number = 0
 let s:pollers = {
+      \   'completion': {
+      \     'id': -1,
+      \     'wait_milliseconds': 10
+      \   },
       \   'file_parse_response': {
       \     'id': -1,
       \     'wait_milliseconds': 100
@@ -100,7 +106,6 @@ function! youcompleteme#Enable()
     autocmd BufEnter * call s:OnBufferEnter()
     autocmd BufUnload * call s:OnBufferUnload()
     autocmd InsertLeave * call s:OnInsertLeave()
-    autocmd InsertEnter * call s:OnInsertEnter()
     autocmd VimLeave * call s:OnVimLeave()
     autocmd CompleteDone * call s:OnCompleteDone()
   augroup END
@@ -119,6 +124,10 @@ function! youcompleteme#EnableCursorMovedAutocommands()
     autocmd CursorMoved * call s:OnCursorMovedNormalMode()
     autocmd TextChanged * call s:OnTextChangedNormalMode()
     autocmd TextChangedI * call s:OnTextChangedInsertMode()
+    " The TextChangedI event is not triggered when inserting a character while
+    " the completion menu is open. We handle this by closing the completion menu
+    " just before inserting a character.
+    autocmd InsertCharPre * call s:OnInsertChar()
   augroup END
 endfunction
 
@@ -221,15 +230,22 @@ function! s:SetUpKeyMappings()
       imap <Nul> <C-Space>
     endif
 
-    " <c-x><c-o> trigger omni completion, <c-p> deselects the first completion
-    " candidate that vim selects by default
-    silent! exe 'inoremap <unique> ' . invoke_key .  ' <C-X><C-O><C-P>'
+    silent! exe 'inoremap <unique> <silent> ' . invoke_key .
+          \ ' <C-R>=<SID>InvokeSemanticCompletion()<CR>'
   endif
 
   if !empty( g:ycm_key_detailed_diagnostics )
     silent! exe 'nnoremap <unique> ' . g:ycm_key_detailed_diagnostics .
-          \ ' :YcmShowDetailedDiagnostic<cr>'
+          \ ' :YcmShowDetailedDiagnostic<CR>'
   endif
+
+  " The TextChangedI event is not triggered when deleting a character while the
+  " completion menu is open. We handle this by closing the completion menu on
+  " the keys that delete a character in insert mode.
+  for key in [ "<BS>", "<C-h>" ]
+    silent! exe 'inoremap <unique> <expr> ' . key .
+          \ ' <SID>OnDeleteChar( "\' . key . '" )'
+  endfor
 endfunction
 
 
@@ -406,6 +422,11 @@ function! s:SetUpCompleteopt()
 endfunction
 
 
+function! s:SetCompleteFunc()
+  let &completefunc = 'youcompleteme#CompleteFunc'
+endfunction
+
+
 function! s:OnVimLeave()
   exec s:python_command "ycm_state.OnVimLeave()"
 endfunction
@@ -423,7 +444,6 @@ function! s:OnFileTypeSet()
 
   call s:SetUpCompleteopt()
   call s:SetCompleteFunc()
-  call s:SetOmnicompleteFunc()
 
   exec s:python_command "ycm_state.OnBufferVisit()"
   call s:OnFileReadyToParse( 1 )
@@ -437,7 +457,6 @@ function! s:OnBufferEnter()
 
   call s:SetUpCompleteopt()
   call s:SetCompleteFunc()
-  call s:SetOmnicompleteFunc()
 
   exec s:python_command "ycm_state.OnBufferVisit()"
   " Last parse may be outdated because of changes from other buffers. Force a
@@ -502,24 +521,20 @@ function! s:PollFileParseResponse( ... )
 endfunction
 
 
-function! s:SetCompleteFunc()
-  let &completefunc = 'youcompleteme#Complete'
-  let &l:completefunc = 'youcompleteme#Complete'
+function! s:OnInsertChar()
+  call timer_stop( s:pollers.completion.id )
+  if pumvisible()
+    call feedkeys( "\<C-e>", 'n' )
+  endif
 endfunction
 
 
-function! s:SetOmnicompleteFunc()
-  if s:Pyeval( 'ycm_state.NativeFiletypeCompletionUsable()' )
-    let &omnifunc = 'youcompleteme#OmniComplete'
-    let &l:omnifunc = 'youcompleteme#OmniComplete'
-
-  " If we don't have native filetype support but the omnifunc is set to YCM's
-  " omnifunc because the previous file the user was editing DID have native
-  " support, we remove our omnifunc.
-  elseif &omnifunc == 'youcompleteme#OmniComplete'
-    let &omnifunc = ''
-    let &l:omnifunc = ''
+function! s:OnDeleteChar( key )
+  call timer_stop( s:pollers.completion.id )
+  if pumvisible()
+    return "\<C-y>" . a:key
   endif
+  return a:key
 endfunction
 
 
@@ -546,23 +561,28 @@ function! s:OnTextChangedInsertMode()
     return
   endif
 
-  exec s:python_command "ycm_state.OnCursorMoved()"
-  call s:UpdateCursorMoved()
-
   call s:IdentifierFinishedOperations()
-  if g:ycm_autoclose_preview_window_after_completion
-    call s:ClosePreviewWindowIfNeeded()
+
+  " We have to make sure we correctly leave semantic mode even when the user
+  " inserts something like a "operator[]" candidate string which fails
+  " CurrentIdentifierFinished check.
+  if s:force_semantic && !s:Pyeval( 'base.LastEnteredCharIsIdentifierChar()' )
+    let s:force_semantic = 0
   endif
 
-  if g:ycm_auto_trigger || s:omnifunc_mode
+  if &completefunc == "youcompleteme#CompleteFunc" &&
+        \ ( g:ycm_auto_trigger || s:force_semantic ) &&
+        \ !s:InsideCommentOrStringAndShouldStop() &&
+        \ !s:OnBlankLine()
+    " Immediately call previous completion to avoid flickers.
+    call s:Complete()
     call s:InvokeCompletion()
   endif
 
-  " We have to make sure we correctly leave omnifunc mode even when the user
-  " inserts something like a "operator[]" candidate string which fails
-  " CurrentIdentifierFinished check.
-  if s:omnifunc_mode && !s:Pyeval( 'base.LastEnteredCharIsIdentifierChar()')
-    let s:omnifunc_mode = 0
+  exec s:python_command "ycm_state.OnCursorMoved()"
+
+  if g:ycm_autoclose_preview_window_after_completion
+    call s:ClosePreviewWindowIfNeeded()
   endif
 endfunction
 
@@ -572,7 +592,8 @@ function! s:OnInsertLeave()
     return
   endif
 
-  let s:omnifunc_mode = 0
+  let s:force_semantic = 0
+  let s:completion = s:default_completion
   call s:OnFileReadyToParse()
   exec s:python_command "ycm_state.OnInsertLeave()"
   if g:ycm_autoclose_preview_window_after_completion ||
@@ -582,22 +603,6 @@ function! s:OnInsertLeave()
 endfunction
 
 
-function! s:OnInsertEnter()
-  if !s:AllowedToCompleteInCurrentBuffer()
-    return
-  endif
-
-  let s:old_cursor_position = []
-endfunction
-
-
-function! s:UpdateCursorMoved()
-  let current_position = getpos('.')
-  let s:cursor_moved = current_position != s:old_cursor_position
-  let s:old_cursor_position = current_position
-endfunction
-
-
 function! s:ClosePreviewWindowIfNeeded()
   let current_buffer_name = bufname('')
 
@@ -619,7 +624,8 @@ function! s:IdentifierFinishedOperations()
     return
   endif
   exec s:python_command "ycm_state.OnCurrentIdentifierFinished()"
-  let s:omnifunc_mode = 0
+  let s:force_semantic = 0
+  let s:completion = s:default_completion
 endfunction
 
 
@@ -662,28 +668,45 @@ endfunction
 
 
 function! s:InvokeCompletion()
-  if &completefunc != "youcompleteme#Complete"
-    return
-  endif
+  exec s:python_command "ycm_state.SendCompletionRequest(" .
+        \ "vimsupport.GetBoolValue( 's:force_semantic' ) )"
 
-  if s:InsideCommentOrStringAndShouldStop() || s:OnBlankLine()
-    return
-  endif
+  call s:PollCompletion()
+endfunction
+
+
+function! s:InvokeSemanticCompletion()
+  let s:force_semantic = 1
+  exec s:python_command "ycm_state.SendCompletionRequest( True )"
 
-  " This is tricky. First, having 'refresh' set to 'always' in the dictionary
-  " that our completion function returns makes sure that our completion function
-  " is called on every keystroke. Second, when the sequence of characters the
-  " user typed produces no results in our search an infinite loop can occur. The
-  " problem is that our feedkeys call triggers the OnCursorMovedI event which we
-  " are tied to. We prevent this infinite loop from starting by making sure that
-  " the user has moved the cursor since the last time we provided completion
-  " results.
-  if !s:cursor_moved
+  call s:PollCompletion()
+  " Since this function is called in a mapping through the expression register
+  " <C-R>=, its return value is inserted (see :h c_CTRL-R_=). We don't want to
+  " insert anything so we return an empty string.
+  return ''
+endfunction
+
+
+function! s:PollCompletion( ... )
+  if !s:Pyeval( 'ycm_state.CompletionRequestReady()' )
+    let s:pollers.completion.id = timer_start(
+          \ s:pollers.completion.wait_milliseconds,
+          \ function( 's:PollCompletion' ) )
     return
   endif
 
+  let response = s:Pyeval( 'ycm_state.GetCompletionResponse()' )
+  let s:completion = {
+        \   'start_column': response.completion_start_column,
+        \   'candidates': response.completions
+        \ }
+  call s:Complete()
+endfunction
+
+
+function! s:Complete()
   " <c-x><c-u> invokes the user's completion function (which we have set to
-  " youcompleteme#Complete), and <c-p> tells Vim to select the previous
+  " youcompleteme#CompleteFunc), and <c-p> tells Vim to select the previous
   " completion candidate. This is necessary because by default, Vim selects the
   " first candidate when completion is invoked, and selecting a candidate
   " automatically replaces the current text with it. Calling <c-p> forces Vim to
@@ -693,43 +716,17 @@ function! s:InvokeCompletion()
 endfunction
 
 
-" This is our main entry point. This is what vim calls to get completions.
-function! youcompleteme#Complete( findstart, base )
-  " After the user types one character after the call to the omnifunc, the
-  " completefunc will be called because of our mapping that calls the
-  " completefunc on every keystroke. Therefore we need to delegate the call we
-  " 'stole' back to the omnifunc
-  if s:omnifunc_mode
-    return youcompleteme#OmniComplete( a:findstart, a:base )
-  endif
-
+function! youcompleteme#CompleteFunc( findstart, base )
   if a:findstart
-    " InvokeCompletion has this check but we also need it here because of random
-    " Vim bugs and unfortunate interactions with the autocommands of other
-    " plugins
-    if !s:cursor_moved
-      " for vim, -2 means not found but don't trigger an error message
-      " see :h complete-functions
+    if s:completion.start_column > col( '.' ) ||
+          \ empty( s:completion.candidates )
+      " For vim, -2 means not found but don't trigger an error message.
+      " See :h complete-functions.
       return -2
     endif
-
-    exec s:python_command "ycm_state.CreateCompletionRequest()"
-    return s:Pyeval( 'base.CompletionStartColumn()' )
-  else
-    return s:Pyeval( 'ycm_state.GetCompletions()' )
-  endif
-endfunction
-
-
-function! youcompleteme#OmniComplete( findstart, base )
-  if a:findstart
-    let s:omnifunc_mode = 1
-    exec s:python_command "ycm_state.CreateCompletionRequest(" .
-          \ "force_semantic = True )"
-    return s:Pyeval( 'base.CompletionStartColumn()' )
-  else
-    return s:Pyeval( 'ycm_state.GetCompletions()' )
+    return s:completion.start_column - 1
   endif
+  return s:completion.candidates
 endfunction
 
 

python/ycm/base.py

@@ -25,7 +25,6 @@
 from future.utils import iteritems
 from ycm import vimsupport
 from ycmd import user_options_store
-from ycmd import request_wrap
 from ycmd import identifier_utils
 
 YCM_VAR_PREFIX = 'ycm_'
@@ -57,13 +56,6 @@ def LoadJsonDefaultsIntoVim():
       vimsupport.SetVariableValue( new_key, value )
 
 
-def CompletionStartColumn():
-  return ( request_wrap.CompletionStartColumn(
-      vimsupport.CurrentLineContents(),
-      vimsupport.CurrentColumn() + 1,
-      vimsupport.CurrentFiletypes()[ 0 ] ) - 1 )
-
-
 def CurrentIdentifierFinished():
   line, current_column = vimsupport.CurrentLineContentsAndCodepointColumn()
   previous_char_index = current_column - 1