Auto merge of #2631 - davits:changedtick, r=bstaletic

[READY] Moved change tracking to python. Per buffer diagnostics

Thank you for working on YCM! :)

- [x] I have read and understood YCM's [CONTRIBUTING][cont] document.
- [x] I have read and understood YCM's [CODE_OF_CONDUCT][code] document.
- [x] I have included tests for the changes in my PR. If not, I have included a
  rationale for why I haven't.
- [x] **I understand my PR may be closed if it becomes obvious I didn't
  actually perform all of these steps.**

Adds an emulation of Vim buffer object and moves change tracking into python.
Now diagnostics are stored per buffer, which effectively solves #2165 .

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/valloric/youcompleteme/2631)
<!-- Reviewable:end -->

autoload/youcompleteme.vim

@@ -105,6 +105,9 @@ function! youcompleteme#Enable()
     autocmd CompleteDone * call s:OnCompleteDone()
   augroup END
 
+  " The BufEnter event is not triggered for the first loaded file.
+  exec s:python_command "ycm_state.SetCurrentBuffer()"
+
   " The FileType event is not triggered for the first loaded file. We wait until
   " the server is ready to manually run the s:OnFileTypeSet function.
   let s:pollers.server_ready.id = timer_start(
@@ -431,6 +434,8 @@ endfunction
 
 
 function! s:OnBufferEnter()
+  exec s:python_command "ycm_state.SetCurrentBuffer()"
+
   if !s:VisitedBufferRequiresReparse()
     return
   endif
@@ -460,7 +465,7 @@ endfunction
 
 
 function! s:PollServerReady( timer_id )
-  if !s:Pyeval( 'ycm_state.IsServerReady()' )
+  if !s:Pyeval( 'ycm_state.CheckIfServerIsReady()' )
     let s:pollers.server_ready.id = timer_start(
           \ s:pollers.server_ready.wait_milliseconds,
           \ function( 's:PollServerReady' ) )
@@ -479,15 +484,13 @@ function! s:OnFileReadyToParse( ... )
 
   " We only want to send a new FileReadyToParse event notification if the buffer
   " has changed since the last time we sent one, or if forced.
-  if force_parsing || b:changedtick != get( b:, 'ycm_changedtick', -1 )
+  if force_parsing || s:Pyeval( "ycm_state.NeedsReparse()" )
     exec s:python_command "ycm_state.OnFileReadyToParse()"
 
     call timer_stop( s:pollers.file_parse_response.id )
     let s:pollers.file_parse_response.id = timer_start(
           \ s:pollers.file_parse_response.wait_milliseconds,
           \ function( 's:PollFileParseResponse' ) )
-
-    let b:ycm_changedtick = b:changedtick
   endif
 endfunction
 

python/ycm/buffer.py

@@ -0,0 +1,109 @@
+# Copyright (C) 2016, Davit Samvelyan
+#
+# 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/>.
+
+from __future__ import unicode_literals
+from __future__ import print_function
+from __future__ import division
+from __future__ import absolute_import
+# Not installing aliases from python-future; it's unreliable and slow.
+from builtins import *  # noqa
+
+from ycm import vimsupport
+from ycm.client.event_notification import EventNotification
+from ycm.diagnostic_interface import DiagnosticInterface
+
+
+# Emulates Vim buffer
+# Used to store buffer related information like diagnostics, latest parse
+# request. Stores buffer change tick at the parse request moment, allowing
+# to effectively determine whether reparse is needed for the buffer.
+class Buffer( object ):
+
+  def __init__( self, bufnr, user_options ):
+    self.number = bufnr
+    self._parse_tick = 0
+    self._handled_tick = 0
+    self._parse_request = None
+    self._diag_interface = DiagnosticInterface( user_options )
+
+
+  def FileParseRequestReady( self, block = False ):
+    return bool( self._parse_request and
+                 ( block or self._parse_request.Done() ) )
+
+
+  def SendParseRequest( self, extra_data ):
+    self._parse_request = EventNotification( 'FileReadyToParse',
+                                             extra_data = extra_data )
+    self._parse_request.Start()
+    # Decrement handled tick to ensure correct handling when we are forcing
+    # reparse on buffer visit and changed tick remains the same.
+    self._handled_tick -= 1
+    self._parse_tick = self._ChangedTick()
+
+
+  def NeedsReparse( self ):
+    return self._parse_tick != self._ChangedTick()
+
+
+  def UpdateDiagnostics( self ):
+    self._diag_interface.UpdateWithNewDiagnostics(
+      self._parse_request.Response() )
+
+
+  def PopulateLocationList( self ):
+    return self._diag_interface.PopulateLocationList()
+
+
+  def GetResponse( self ):
+    return self._parse_request.Response()
+
+
+  def IsResponseHandled( self ):
+    return self._handled_tick == self._parse_tick
+
+
+  def MarkResponseHandled( self ):
+    self._handled_tick = self._parse_tick
+
+
+  def OnCursorMoved( self ):
+    self._diag_interface.OnCursorMoved()
+
+
+  def GetErrorCount( self ):
+    return self._diag_interface.GetErrorCount()
+
+
+  def GetWarningCount( self ):
+    return self._diag_interface.GetWarningCount()
+
+
+  def _ChangedTick( self ):
+    return vimsupport.GetBufferChangedTick( self.number )
+
+
+class BufferDict( dict ):
+
+  def __init__( self, user_options ):
+    self._user_options = user_options
+
+
+  def __missing__( self, key ):
+    # Python does not allow to return assignment operation result directly
+    new_value = self[ key ] = Buffer( key, self._user_options )
+    return new_value

python/ycm/diagnostic_interface.py

@@ -32,6 +32,7 @@ import vim
 class DiagnosticInterface( object ):
   def __init__( self, user_options ):
     self._user_options = user_options
+    self._diagnostics = []
     self._diag_filter = DiagnosticFilter.CreateFromOptions( user_options )
     # Line and column numbers are 1-based
     self._buffer_number_to_line_to_diags = defaultdict(
@@ -60,17 +61,18 @@ class DiagnosticInterface( object ):
     return len( self._FilterDiagnostics( _DiagnosticIsWarning ) )
 
 
-  def PopulateLocationList( self, diags ):
+  def PopulateLocationList( self ):
-    vimsupport.SetLocationList(
+    # Do nothing if loc list is already populated by diag_interface
-      vimsupport.ConvertDiagnosticsToQfList(
+    if not self._user_options[ 'always_populate_location_list' ]:
-          self._ApplyDiagnosticFilter( diags ) ) )
+      self._UpdateLocationList()
+    return bool( self._diagnostics )
 
 
   def UpdateWithNewDiagnostics( self, diags ):
-    normalized_diags = [ _NormalizeDiagnostic( x ) for x in
+    self._diagnostics = [ _NormalizeDiagnostic( x ) for x in
                             self._ApplyDiagnosticFilter( diags ) ]
     self._buffer_number_to_line_to_diags = _ConvertDiagListToDict(
-        normalized_diags )
+        self._diagnostics )
 
     if self._user_options[ 'enable_diagnostic_signs' ]:
       self._placed_signs, self._next_sign_id = _UpdateSigns(
@@ -82,7 +84,7 @@ class DiagnosticInterface( object ):
       _UpdateSquiggles( self._buffer_number_to_line_to_diags )
 
     if self._user_options[ 'always_populate_location_list' ]:
-      self.PopulateLocationList( normalized_diags )
+      self._UpdateLocationList()
 
 
   def _ApplyDiagnosticFilter( self, diags, extra_predicate = None ):
@@ -128,6 +130,11 @@ class DiagnosticInterface( object ):
     return matched_diags
 
 
+  def _UpdateLocationList( self ):
+    vimsupport.SetLocationList(
+      vimsupport.ConvertDiagnosticsToQfList( self._diagnostics ) )
+
+
 def _UpdateSquiggles( buffer_number_to_line_to_diags ):
   vimsupport.ClearYcmSyntaxMatches()
   line_to_diags = buffer_number_to_line_to_diags[ vim.current.buffer.number ]

python/ycm/tests/event_notification_test.py

@@ -59,7 +59,7 @@ def UnplaceSign_Call( sign_id, buffer_num ):
 
 
 @contextlib.contextmanager
-def MockArbitraryBuffer( filetype ):
+def MockArbitraryBuffer( filetype, ycm ):
   """Used via the with statement, set up a single buffer with an arbitrary name
   and no contents. Its filetype is set to the supplied filetype."""
 
@@ -68,7 +68,7 @@ def MockArbitraryBuffer( filetype ):
                               window = 1,
                               filetype = filetype )
 
-  with MockVimBuffers( [ current_buffer ], current_buffer ):
+  with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
     yield
 
 
@@ -105,6 +105,9 @@ def MockEventNotification( response_method, native_filetype_completer = True ):
         'ycm.youcompleteme.YouCompleteMe.FiletypeCompleterExistsForFiletype',
         return_value = native_filetype_completer ):
 
+        with patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+                    return_value = True ):
+
           yield
 
 
@@ -121,7 +124,7 @@ def EventNotification_FileReadyToParse_NonDiagnostic_Error_test(
   def ErrorResponse( *args ):
     raise ServerError( ERROR_TEXT )
 
-  with MockArbitraryBuffer( 'javascript' ):
+  with MockArbitraryBuffer( 'javascript', ycm ):
     with MockEventNotification( ErrorResponse ):
       ycm.OnFileReadyToParse()
       ok_( ycm.FileParseRequestReady() )
@@ -153,7 +156,7 @@ def EventNotification_FileReadyToParse_NonDiagnostic_Error_test(
 def EventNotification_FileReadyToParse_NonDiagnostic_Error_NonNative_test(
     ycm, vim_command ):
 
-  with MockArbitraryBuffer( 'javascript' ):
+  with MockArbitraryBuffer( 'javascript', ycm ):
     with MockEventNotification( None, False ):
       ycm.OnFileReadyToParse()
       ycm.HandleFileParseRequest()
@@ -179,7 +182,7 @@ def EventNotification_FileReadyToParse_NonDiagnostic_ConfirmExtraConf_test(
   def UnknownExtraConfResponse( *args ):
     raise UnknownExtraConf( FILE_NAME )
 
-  with MockArbitraryBuffer( 'javascript' ):
+  with MockArbitraryBuffer( 'javascript', ycm ):
     with MockEventNotification( UnknownExtraConfResponse ):
 
       # When the user accepts the extra conf, we load it
@@ -279,7 +282,7 @@ def _Check_FileReadyToParse_Diagnostic_Error( ycm, vim_command ):
     diagnostic = Diagnostic( [], start, extent, 'expected ;', 'ERROR' )
     return [ BuildDiagnosticData( diagnostic ) ]
 
-  with MockArbitraryBuffer( 'cpp' ):
+  with MockArbitraryBuffer( 'cpp', ycm ):
     with MockEventNotification( DiagnosticResponse ):
       ycm.OnFileReadyToParse()
       ok_( ycm.FileParseRequestReady() )
@@ -293,7 +296,6 @@ def _Check_FileReadyToParse_Diagnostic_Error( ycm, vim_command ):
       # Consequent calls to HandleFileParseRequest shouldn't mess with
       # existing diagnostics, when there is no new parse request.
       vim_command.reset_mock()
-      ok_( not ycm.FileParseRequestReady() )
       ycm.HandleFileParseRequest()
       vim_command.assert_not_called()
       eq_( ycm.GetErrorCount(), 1 )
@@ -312,7 +314,7 @@ def _Check_FileReadyToParse_Diagnostic_Warning( ycm, vim_command ):
     diagnostic = Diagnostic( [], start, extent, 'cast', 'WARNING' )
     return [ BuildDiagnosticData( diagnostic ) ]
 
-  with MockArbitraryBuffer( 'cpp' ):
+  with MockArbitraryBuffer( 'cpp', ycm ):
     with MockEventNotification( DiagnosticResponse ):
       ycm.OnFileReadyToParse()
       ok_( ycm.FileParseRequestReady() )
@@ -327,7 +329,6 @@ def _Check_FileReadyToParse_Diagnostic_Warning( ycm, vim_command ):
       # Consequent calls to HandleFileParseRequest shouldn't mess with
       # existing diagnostics, when there is no new parse request.
       vim_command.reset_mock()
-      ok_( not ycm.FileParseRequestReady() )
       ycm.HandleFileParseRequest()
       vim_command.assert_not_called()
       eq_( ycm.GetErrorCount(), 0 )
@@ -339,7 +340,7 @@ def _Check_FileReadyToParse_Diagnostic_Clean( ycm, vim_command ):
   # Tests Vim sign unplacement and error/warning count python API
   # when there are no errors/warnings left.
   # Should be called after _Check_FileReadyToParse_Diagnostic_Warning
-  with MockArbitraryBuffer( 'cpp' ):
+  with MockArbitraryBuffer( 'cpp', ycm ):
     with MockEventNotification( MagicMock( return_value = [] ) ):
       ycm.OnFileReadyToParse()
       ycm.HandleFileParseRequest()
@@ -351,6 +352,8 @@ def _Check_FileReadyToParse_Diagnostic_Clean( ycm, vim_command ):
 
 
 @patch( 'ycm.youcompleteme.YouCompleteMe._AddUltiSnipsDataIfNeeded' )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @YouCompleteMeInstance( { 'collect_identifiers_from_tags_files': 1 } )
 def EventNotification_FileReadyToParse_TagFiles_UnicodeWorkingDirectory_test(
     ycm, *args ):
@@ -363,7 +366,7 @@ def EventNotification_FileReadyToParse_TagFiles_UnicodeWorkingDirectory_test(
   with patch( 'ycm.client.event_notification.EventNotification.'
               'PostDataToHandlerAsync' ) as post_data_to_handler_async:
     with CurrentWorkingDirectory( unicode_dir ):
-      with MockVimBuffers( [ current_buffer ], current_buffer, ( 6, 5 ) ):
+      with MockVimBuffers( [ current_buffer ], current_buffer, ( 6, 5 ), ycm ):
         ycm.OnFileReadyToParse()
 
     assert_that(
@@ -495,6 +498,8 @@ def EventNotification_BufferUnload_BuildRequestForDeletedAndUnsavedBuffers_test(
 
 @patch( 'ycm.syntax_parse.SyntaxKeywordsForCurrentBuffer',
         return_value = [ 'foo', 'bar' ] )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @YouCompleteMeInstance( { 'seed_identifiers_with_syntax': 1 } )
 def EventNotification_FileReadyToParse_SyntaxKeywords_SeedWithCache_test(
     ycm, *args ):
@@ -504,7 +509,7 @@ def EventNotification_FileReadyToParse_SyntaxKeywords_SeedWithCache_test(
 
   with patch( 'ycm.client.event_notification.EventNotification.'
               'PostDataToHandlerAsync' ) as post_data_to_handler_async:
-    with MockVimBuffers( [ current_buffer ], current_buffer ):
+    with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
       ycm.OnFileReadyToParse()
       assert_that(
         # Positional arguments passed to PostDataToHandlerAsync.
@@ -529,6 +534,8 @@ def EventNotification_FileReadyToParse_SyntaxKeywords_SeedWithCache_test(
 
 @patch( 'ycm.syntax_parse.SyntaxKeywordsForCurrentBuffer',
         return_value = [ 'foo', 'bar' ] )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @YouCompleteMeInstance( { 'seed_identifiers_with_syntax': 1 } )
 def EventNotification_FileReadyToParse_SyntaxKeywords_ClearCacheIfRestart_test(
     ycm, *args ):
@@ -538,7 +545,7 @@ def EventNotification_FileReadyToParse_SyntaxKeywords_ClearCacheIfRestart_test(
 
   with patch( 'ycm.client.event_notification.EventNotification.'
               'PostDataToHandlerAsync' ) as post_data_to_handler_async:
-    with MockVimBuffers( [ current_buffer ], current_buffer ):
+    with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
       ycm.OnFileReadyToParse()
       assert_that(
         # Positional arguments passed to PostDataToHandlerAsync.

python/ycm/tests/test_utils.py

@@ -40,7 +40,7 @@ BUFWINNR_REGEX = re.compile( '^bufwinnr\((?P<buffer_number>[0-9]+)\)$' )
 BWIPEOUT_REGEX = re.compile(
   '^(?:silent! )bwipeout!? (?P<buffer_number>[0-9]+)$' )
 GETBUFVAR_REGEX = re.compile(
-  '^getbufvar\((?P<buffer_number>[0-9]+), "&(?P<option>.+)"\)$' )
+  '^getbufvar\((?P<buffer_number>[0-9]+), "(?P<option>.+)"\)$' )
 MATCHADD_REGEX = re.compile(
   '^matchadd\(\'(?P<group>.+)\', \'(?P<pattern>.+)\'\)$' )
 MATCHDELETE_REGEX = re.compile( '^matchdelete\((?P<id>)\)$' )
@@ -85,10 +85,12 @@ def _MockGetBufferWindowNumber( buffer_number ):
 def _MockGetBufferVariable( buffer_number, option ):
   for vim_buffer in VIM_MOCK.buffers:
     if vim_buffer.number == buffer_number:
-      if option == 'mod':
+      if option == '&mod':
         return vim_buffer.modified
-      if option == 'ft':
+      if option == '&ft':
         return vim_buffer.filetype
+      if option == 'changedtick':
+        return vim_buffer.changedtick
       return ''
   return ''
 
@@ -230,6 +232,7 @@ class VimBuffer( object ):
     self.modified = modified
     self.window = window
     self.omnifunc = omnifunc
+    self.changedtick = 1
 
 
   def __getitem__( self, index ):
@@ -268,7 +271,8 @@ class VimMatch( object ):
 
 
 @contextlib.contextmanager
-def MockVimBuffers( buffers, current_buffer, cursor_position = ( 1, 1 ) ):
+def MockVimBuffers( buffers, current_buffer, cursor_position = ( 1, 1 ),
+                    ycm_state = None):
   """Simulates the Vim buffers list |buffers| where |current_buffer| is the
   buffer displayed in the current window and |cursor_position| is the current
   cursor position. All buffers are represented by a VimBuffer object."""
@@ -278,6 +282,8 @@ def MockVimBuffers( buffers, current_buffer, cursor_position = ( 1, 1 ) ):
   with patch( 'vim.buffers', buffers ):
     with patch( 'vim.current.buffer', current_buffer ):
       with patch( 'vim.current.window.cursor', cursor_position ):
+        if ycm_state is not None:
+          ycm_state.SetCurrentBuffer()
         yield
 
 

python/ycm/tests/youcompleteme_test.py

@@ -330,7 +330,7 @@ def YouCompleteMe_ShowDiagnostics_NoDiagnosticsDetected_test(
   ycm, set_location_list, post_vim_message, *args ):
 
   current_buffer = VimBuffer( 'buffer', filetype = 'cpp' )
-  with MockVimBuffers( [ current_buffer ], current_buffer ):
+  with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
     with patch( 'ycm.client.event_notification.EventNotification.Response',
                 return_value = {} ):
       ycm.ShowDiagnostics()
@@ -349,6 +349,8 @@ def YouCompleteMe_ShowDiagnostics_NoDiagnosticsDetected_test(
                           'open_loclist_on_ycm_diags': 0 } )
 @patch( 'ycm.youcompleteme.YouCompleteMe.FiletypeCompleterExistsForFiletype',
         return_value = True )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @patch( 'ycm.vimsupport.PostVimMessage', new_callable = ExtendedMock )
 @patch( 'ycm.vimsupport.SetLocationList', new_callable = ExtendedMock )
 def YouCompleteMe_ShowDiagnostics_DiagnosticsFound_DoNotOpenLocationList_test(
@@ -365,7 +367,7 @@ def YouCompleteMe_ShowDiagnostics_DiagnosticsFound_DoNotOpenLocationList_test(
   }
 
   current_buffer = VimBuffer( 'buffer', filetype = 'cpp', number = 3 )
-  with MockVimBuffers( [ current_buffer ], current_buffer ):
+  with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
     with patch( 'ycm.client.event_notification.EventNotification.Response',
                 return_value = [ diagnostic ] ):
       ycm.ShowDiagnostics()
@@ -388,6 +390,8 @@ def YouCompleteMe_ShowDiagnostics_DiagnosticsFound_DoNotOpenLocationList_test(
 @YouCompleteMeInstance( { 'open_loclist_on_ycm_diags': 1 } )
 @patch( 'ycm.youcompleteme.YouCompleteMe.FiletypeCompleterExistsForFiletype',
         return_value = True )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @patch( 'ycm.vimsupport.PostVimMessage', new_callable = ExtendedMock )
 @patch( 'ycm.vimsupport.SetLocationList', new_callable = ExtendedMock )
 @patch( 'ycm.vimsupport.OpenLocationList', new_callable = ExtendedMock )
@@ -405,7 +409,7 @@ def YouCompleteMe_ShowDiagnostics_DiagnosticsFound_OpenLocationList_test(
   }
 
   current_buffer = VimBuffer( 'buffer', filetype = 'cpp', number = 3 )
-  with MockVimBuffers( [ current_buffer ], current_buffer ):
+  with MockVimBuffers( [ current_buffer ], current_buffer, ycm_state = ycm ):
     with patch( 'ycm.client.event_notification.EventNotification.Response',
                 return_value = [ diagnostic ] ):
       ycm.ShowDiagnostics()
@@ -431,6 +435,8 @@ def YouCompleteMe_ShowDiagnostics_DiagnosticsFound_OpenLocationList_test(
                           'enable_diagnostic_highlighting': 1 } )
 @patch( 'ycm.youcompleteme.YouCompleteMe.FiletypeCompleterExistsForFiletype',
         return_value = True )
+@patch( 'ycm.youcompleteme.YouCompleteMe.IsServerReady',
+        return_value = True )
 @patch( 'ycm.vimsupport.PostVimMessage', new_callable = ExtendedMock )
 @patch( 'vim.command', new_callable = ExtendedMock )
 def YouCompleteMe_UpdateDiagnosticInterface_PrioritizeErrorsOverWarnings_test(
@@ -508,7 +514,7 @@ def YouCompleteMe_UpdateDiagnosticInterface_PrioritizeErrorsOverWarnings_test(
 
   test_utils.VIM_MATCHES = []
 
-  with MockVimBuffers( [ current_buffer ], current_buffer, ( 3, 1 ) ):
+  with MockVimBuffers( [ current_buffer ], current_buffer, ( 3, 1 ), ycm ):
     with patch( 'ycm.client.event_notification.EventNotification.Response',
                 return_value = diagnostics ):
       ycm.OnFileReadyToParse()

python/ycm/vimsupport.py

@@ -147,6 +147,14 @@ def GetBufferFilepath( buffer_object ):
   return os.path.join( GetCurrentDirectory(), str( buffer_object.number ) )
 
 
+def GetCurrentBufferNumber():
+  return vim.current.buffer.number
+
+
+def GetBufferChangedTick( bufnr ):
+  return GetIntValue( 'getbufvar({0}, "changedtick")'.format( bufnr ) )
+
+
 def UnplaceSignInBuffer( buffer_number, sign_id ):
   if buffer_number < 0:
     return

python/ycm/youcompleteme.py

@@ -33,10 +33,10 @@ import vim
 from subprocess import PIPE
 from tempfile import NamedTemporaryFile
 from ycm import base, paths, vimsupport
+from ycm.buffer import BufferDict
 from ycmd import utils
 from ycmd import server_utils
 from ycmd.request_wrap import RequestWrap
-from ycm.diagnostic_interface import DiagnosticInterface
 from ycm.omni_completer import OmniCompleter
 from ycm import syntax_parse
 from ycm.client.ycmd_keepalive import YcmdKeepalive
@@ -49,8 +49,7 @@ from ycm.client.completion_request import ( CompletionRequest,
 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.event_notification import SendEventNotificationAsync
-                                            EventNotification )
 from ycm.client.shutdown_request import SendShutdownRequest
 
 
@@ -114,11 +113,10 @@ class YouCompleteMe( object ):
     self._available_completers = {}
     self._user_options = user_options
     self._user_notified_about_crash = False
-    self._diag_interface = DiagnosticInterface( user_options )
     self._omnicomp = OmniCompleter( user_options )
-    self._latest_file_parse_request = None
+    self._buffers = BufferDict( user_options )
+    self._current_buffer = None
     self._latest_completion_request = None
-    self._latest_diagnostics = []
     self._logger = logging.getLogger( 'ycm' )
     self._client_logfile = None
     self._server_stdout = None
@@ -134,6 +132,7 @@ class YouCompleteMe( object ):
       'cs': lambda self: self._OnCompleteDone_Csharp()
     }
 
+
   def _SetupServer( self ):
     self._available_completers = {}
     self._user_notified_about_crash = False
@@ -222,7 +221,7 @@ class YouCompleteMe( object ):
     return return_code is None
 
 
-  def IsServerReady( self ):
+  def CheckIfServerIsReady( self ):
     if not self._server_is_ready_with_cache and self.IsServerAlive():
       with HandleServerException( display = False ):
         self._server_is_ready_with_cache = BaseRequest.GetDataFromHandler(
@@ -230,6 +229,10 @@ class YouCompleteMe( object ):
     return self._server_is_ready_with_cache
 
 
+  def IsServerReady( self ):
+    return self._server_is_ready_with_cache
+
+
   def _NotifyUserIfServerCrashed( self ):
     if self._user_notified_about_crash or self.IsServerAlive():
       return
@@ -353,11 +356,18 @@ class YouCompleteMe( object ):
              self.NativeFiletypeCompletionAvailable() )
 
 
+  def NeedsReparse( self ):
+    return self._current_buffer.NeedsReparse()
+
+
   def OnFileReadyToParse( self ):
     if not self.IsServerAlive():
       self._NotifyUserIfServerCrashed()
       return
 
+    if not self.IsServerReady():
+      return
+
     self._omnicomp.OnFileReadyToParse( None )
 
     extra_data = {}
@@ -365,9 +375,7 @@ class YouCompleteMe( object ):
     self._AddSyntaxDataIfNeeded( extra_data )
     self._AddExtraConfDataIfNeeded( extra_data )
 
-    self._latest_file_parse_request = EventNotification(
+    self._current_buffer.SendParseRequest( extra_data )
-      'FileReadyToParse', extra_data = extra_data )
-    self._latest_file_parse_request.Start()
 
 
   def OnBufferUnload( self, deleted_buffer_file ):
@@ -380,12 +388,16 @@ class YouCompleteMe( object ):
     SendEventNotificationAsync( 'BufferVisit', extra_data = extra_data )
 
 
+  def SetCurrentBuffer( self ):
+    self._current_buffer = self._buffers[ vimsupport.GetCurrentBufferNumber() ]
+
+
   def OnInsertLeave( self ):
     SendEventNotificationAsync( 'InsertLeave' )
 
 
   def OnCursorMoved( self ):
-    self._diag_interface.OnCursorMoved()
+    self._current_buffer.OnCursorMoved()
 
 
   def _CleanLogfile( self ):
@@ -512,11 +524,11 @@ class YouCompleteMe( object ):
 
 
   def GetErrorCount( self ):
-    return self._diag_interface.GetErrorCount()
+    return self._current_buffer.GetErrorCount()
 
 
   def GetWarningCount( self ):
-    return self._diag_interface.GetWarningCount()
+    return self._current_buffer.GetWarningCount()
 
 
   def DiagnosticUiSupportedForCurrentFiletype( self ):
@@ -530,31 +542,29 @@ class YouCompleteMe( object ):
 
 
   def _PopulateLocationListWithLatestDiagnostics( self ):
-    # Do nothing if loc list is already populated by diag_interface
+    return self._current_buffer.PopulateLocationList()
-    if not self._user_options[ 'always_populate_location_list' ]:
-      self._diag_interface.PopulateLocationList( self._latest_diagnostics )
-    return bool( self._latest_diagnostics )
 
 
-  def UpdateDiagnosticInterface( self ):
+  def FileParseRequestReady( self ):
-    self._diag_interface.UpdateWithNewDiagnostics( self._latest_diagnostics )
+    # Return True if server is not ready yet, to stop repeating check timer.
-
+    return ( not self.IsServerReady() or
-
+             self._current_buffer.FileParseRequestReady() )
-  def FileParseRequestReady( self, block = False ):
-    return bool( self._latest_file_parse_request and
-                 ( block or self._latest_file_parse_request.Done() ) )
 
 
   def HandleFileParseRequest( self, block = False ):
+    if not self.IsServerReady():
+      return
+
+    current_buffer = self._current_buffer
     # Order is important here:
     # FileParseRequestReady has a low cost, while
     # NativeFiletypeCompletionUsable is a blocking server request
-    if ( self.FileParseRequestReady( block ) and
+    if ( not current_buffer.IsResponseHandled() and
+         current_buffer.FileParseRequestReady( block ) and
          self.NativeFiletypeCompletionUsable() ):
 
       if self.ShouldDisplayDiagnostics():
-        self._latest_diagnostics = self._latest_file_parse_request.Response()
+        current_buffer.UpdateDiagnostics()
-        self.UpdateDiagnosticInterface()
       else:
         # YCM client has a hard-coded list of filetypes which are known
         # to support diagnostics, self.DiagnosticUiSupportedForCurrentFiletype()
@@ -563,18 +573,17 @@ class YouCompleteMe( object ):
         # 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.
-        self._latest_file_parse_request.Response()
+        current_buffer.GetResponse()
 
-      # We set the file parse request to None because we want to prevent
+      # We set the file parse request as handled because we want to prevent
-      # repeated issuing of the same warnings/errors/prompts. Setting this to
+      # repeated issuing of the same warnings/errors/prompts. Setting this
-      # None makes FileParseRequestReady return False until the next
+      # makes IsRequestHandled return True until the next request is created.
-      # 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 our responsibility to ensure that we only apply the
+      # it is our responsibility to ensure that we only apply the
       # warning/error/prompt received once (for each event).
-      self._latest_file_parse_request = None
+      current_buffer.MarkResponseHandled()
 
 
   def DebugInfo( self ):