Auto merge of #1814 - kennykaye:error-warning-count, r=vheon

Expose functions to get error and warning counts

@Valloric I've implemented two functions which resolve #1011

The interface exposed to Vim is:

```viml
youcompleteme#GetErrorCount()
youcompleteme#GetWarningCount()
```

Below is a rough example of how these methods can be used to integrate with other plugins. In this case Lightline has been extended to show the error and warning count as red and yellow sections on the end of the status line, respectively.

![animation](https://cloud.githubusercontent.com/assets/3267574/11604073/078cb98e-9a9d-11e5-9fa3-c9b4bb6a6e82.gif)

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README.md

@@ -1122,6 +1122,35 @@ provides a list of implementations to choose from.
 
 Supported in filetypes: `cs`
 
+Functions
+--------
+
+### The `youcompleteme#GetErrorCount` function
+
+Get the number of YCM Diagnostic errors. If no errors are present, this function
+returns 0.
+
+For example:
+```viml
+  call youcompleteme#GetErrorCount()
+```
+
+Both this function and `youcompleteme#GetWarningCount` can be useful when
+integrating YCM with other Vim plugins. For example, a [lightline][] user could
+add a diagnostics section to their statusline which would display the number of
+errors and warnings.
+
+### The `youcompleteme#GetWarningCount` function
+
+Get the number of YCM Diagnostic warnings. If no warnings are present, this
+function returns 0.
+
+For example:
+```viml
+  call youcompleteme#GetWarningCount()
+```
+
+
 Options
 -------
 
@@ -2349,6 +2378,7 @@ This software is licensed under the [GPL v3 license][gpl].
 [gpl]: http://www.gnu.org/copyleft/gpl.html
 [vim]: http://www.vim.org/
 [syntastic]: https://github.com/scrooloose/syntastic
+[lightline]: https://github.com/itchyny/lightline.vim
 [flags_example]: https://github.com/Valloric/ycmd/blob/master/cpp/ycm/.ycm_extra_conf.py
 [compdb]: http://clang.llvm.org/docs/JSONCompilationDatabase.html
 [subsequence]: https://en.wikipedia.org/wiki/Subsequence

autoload/youcompleteme.vim

@@ -111,6 +111,16 @@ function! youcompleteme#DisableCursorMovedAutocommands()
 endfunction
 
 
+function! youcompleteme#GetErrorCount()
+  return pyeval( 'ycm_state.GetErrorCount()' )
+endfunction
+
+
+function! youcompleteme#GetWarningCount()
+  return pyeval( 'ycm_state.GetWarningCount()' )
+endfunction
+
+
 function! s:SetUpPython() abort
 python << EOF
 import sys

doc/youcompleteme.txt

@@ -55,7 +55,10 @@ Contents ~
   14. The |ReloadSolution| subcommand
   15. The |GoToImplementation| subcommand
   16. The |GoToImplementationElseDeclaration| subcommand
- 8. Options                                             |youcompleteme-options|
+ 8. Functions                                         |youcompleteme-functions|
+  1. The |youcompleteme#GetErrorCount| function
+  2. The |youcompleteme#GetWarningCount| function
+ 9. Options                                             |youcompleteme-options|
   1. The |g:ycm_min_num_of_chars_for_completion| option
   2. The |g:ycm_min_num_identifier_candidate_chars| option
   3. The |g:ycm_auto_trigger| option
@@ -101,7 +104,7 @@ Contents ~
   43. The |g:ycm_use_ultisnips_completer| option
   44. The |g:ycm_goto_buffer_command| option
   45. The |g:ycm_disable_for_files_larger_than_kb| option
- 9. FAQ                                                     |youcompleteme-faq|
+ 10. FAQ                                                    |youcompleteme-faq|
   1. I used to be able to 'import vim' in '.ycm_extra_conf.py', but now can't |import-vim|
   2. On very rare occasions Vim crashes when I tab through the completion menu |youcompleteme-on-very-rare-occasions-vim-crashes-when-i-tab-through-completion-menu|
   3. I get a linker warning regarding |libpython| on Mac when compiling YCM
@@ -1346,6 +1349,35 @@ provides a list of implementations to choose from.
 
 Supported in filetypes: 'cs'
 
+===============================================================================
+                                                      *youcompleteme-functions*
+Functions ~
+
+-------------------------------------------------------------------------------
+The *youcompleteme#GetErrorCount* function
+
+Get the number of YCM Diagnostic errors. If no errors are present, this
+function returns 0.
+
+For example:
+>
+  call youcompleteme#GetErrorCount()
+<
+Both this function and |youcompleteme#GetWarningCount| can be useful when
+integrating YCM with other Vim plugins. For example, a lightline [48] user
+could add a diagnostics section to their statusline which would display the
+number of errors and warnings.
+
+-------------------------------------------------------------------------------
+The *youcompleteme#GetWarningCount* function
+
+Get the number of YCM Diagnostic warnings. If no warnings are present, this
+function returns 0.
+
+For example:
+>
+  call youcompleteme#GetWarningCount()
+<
 ===============================================================================
                                                         *youcompleteme-options*
 Options ~
@@ -2600,5 +2632,6 @@ References ~
 [45] http://www.gnu.org/copyleft/gpl.html
 [46] https://bitdeli.com/free
 [47] https://d2weczhvl823v0.cloudfront.net/Valloric/youcompleteme/trend.png
+[48] https://github.com/itchyny/lightline.vim
 
 vim: ft=help

python/ycm/diagnostic_interface.py

@@ -43,6 +43,15 @@ class DiagnosticInterface( object ):
       if self._user_options[ 'echo_current_diagnostic' ]:
         self._EchoDiagnosticForLine( line )
 
+
+  def GetErrorCount( self ):
+    return len( self._FilterDiagnostics( _DiagnosticIsError ) )
+
+
+  def GetWarningCount( self ):
+    return len( self._FilterDiagnostics( _DiagnosticIsWarning ) )
+
+
   def UpdateWithNewDiagnostics( self, diags ):
     normalized_diags = [ _NormalizeDiagnostic( x ) for x in diags ]
     self._buffer_number_to_line_to_diags = _ConvertDiagListToDict(
@@ -79,6 +88,16 @@ class DiagnosticInterface( object ):
     self._diag_message_needs_clearing = True
 
 
+  def _FilterDiagnostics( self, predicate ):
+    matched_diags = []
+    line_to_diags = self._buffer_number_to_line_to_diags[
+      vim.current.buffer.number ]
+
+    for diags in line_to_diags.itervalues():
+      matched_diags.extend( filter( predicate, diags ) )
+    return matched_diags
+
+
 def _UpdateSquiggles( buffer_number_to_line_to_diags ):
   vimsupport.ClearYcmSyntaxMatches()
   line_to_diags = buffer_number_to_line_to_diags[ vim.current.buffer.number ]
@@ -209,6 +228,10 @@ def _DiagnosticIsError( diag ):
   return diag[ 'kind' ] == 'ERROR'
 
 
+def _DiagnosticIsWarning( diag ):
+  return diag[ 'kind' ] == 'WARNING'
+
+
 def _NormalizeDiagnostic( diag ):
   def ClampToOne( value ):
     return value if value > 0 else 1

python/ycm/youcompleteme.py

@@ -451,6 +451,11 @@ class YouCompleteMe( object ):
       return None
     return completion[ "extra_data" ][ "required_namespace_import" ]
 
+  def GetErrorCount( self ):
+    return self._diag_interface.GetErrorCount()
+
+  def GetWarningCount( self ):
+    return self._diag_interface.GetWarningCount()
 
   def DiagnosticsForCurrentFileReady( self ):
     return bool( self._latest_file_parse_request and