Implement extension to report errors and warnings from LanguageClient plugin

autoload/airline/extensions.vim

@@ -254,6 +254,11 @@ function! airline#extensions#load()
     call add(loaded_ext, 'ale')
   endif
 
+  if (get(g:, 'airline#extensions#languageclient#enabled', 1) && exists(':LanguageClientStart'))
+    call airline#extensions#languageclient#init(s:ext)
+    call add(loaded_ext, 'languageclient')
+  endif
+
   if get(g:, 'airline#extensions#whitespace#enabled', 1)
     call airline#extensions#whitespace#init(s:ext)
     call add(loaded_ext, 'whitespace')

autoload/airline/extensions/languageclient.vim

@@ -0,0 +1,101 @@
+" MIT License. Copyright (c) 2013-2018 Bjorn Neergaard, w0rp, hallettj et al.
+" vim: et ts=2 sts=2 sw=2
+
+scriptencoding utf-8
+
+let s:error_symbol = get(g:, 'airline#extensions#languageclient#error_symbol', 'E:')
+let s:warning_symbol = get(g:, 'airline#extensions#languageclient#warning_symbol', 'W:')
+let s:show_line_numbers = get(g:, 'airline#extensions#languageclient#show_line_numbers', 1)
+
+" Severity codes from the LSP spec
+let s:severity_error = 1
+let s:severity_warning = 2
+let s:severity_info = 3
+let s:severity_hint = 4
+
+" After each LanguageClient state change `s:diagnostics` will be populated with
+" a map from file names to lists of errors, warnings, informational messages,
+" and hints.
+let s:diagnostics = {}
+
+function! s:languageclient_refresh()
+  if get(g:, 'airline_skip_empty_sections', 0)
+    exe ':AirlineRefresh'
+  endif
+endfunction
+
+function! s:record_diagnostics(state)
+  let result = json_decode(a:state.result)
+  let s:diagnostics = result.diagnostics
+  call s:languageclient_refresh()
+endfunction
+
+function! s:get_diagnostics()
+  call LanguageClient#getState(function("s:record_diagnostics"))
+endfunction
+
+function! s:diagnostics_for_buffer()
+  return get(s:diagnostics, expand('%:p'), [])
+endfunction
+
+function! s:airline_languageclient_count(cnt, symbol)
+  return a:cnt ? a:symbol. a:cnt : ''
+endfunction
+
+function! s:airline_languageclient_get_line_number(type) abort
+  let linenumber_of_first_problem = 0
+  for d in s:diagnostics_for_buffer()
+    if d.severity == a:type
+      let linenumber_of_first_problem = d.range.start.line
+      break
+    endif
+  endfor
+
+  if linenumber_of_first_problem == 0
+    return ''
+  endif
+
+  let open_lnum_symbol  = get(g:, 'airline#extensions#languageclient#open_lnum_symbol', '(L')
+  let close_lnum_symbol = get(g:, 'airline#extensions#languageclient#close_lnum_symbol', ')')
+
+  return open_lnum_symbol . linenumber_of_first_problem . close_lnum_symbol
+endfunction
+
+function! airline#extensions#languageclient#get(type)
+  let is_err = a:type == s:severity_error
+  let symbol = is_err ? s:error_symbol : s:warning_symbol
+
+  let count = 0
+  for d in s:diagnostics_for_buffer()
+    if d.severity == a:type
+      let count += 1
+    endif
+  endfor
+
+  if count == 0
+    return ''
+  endif
+
+  if s:show_line_numbers == 1
+    return s:airline_languageclient_count(count, symbol) . <sid>airline_languageclient_get_line_number(a:type)
+  else
+    return s:airline_languageclient_count(count, symbol)
+  endif
+endfunction
+
+function! airline#extensions#languageclient#get_warning()
+  return airline#extensions#languageclient#get(s:severity_warning)
+endfunction
+
+function! airline#extensions#languageclient#get_error()
+  return airline#extensions#languageclient#get(s:severity_error)
+endfunction
+
+function! airline#extensions#languageclient#init(ext)
+  call airline#parts#define_function('languageclient_error_count', 'airline#extensions#languageclient#get_error')
+  call airline#parts#define_function('languageclient_warning_count', 'airline#extensions#languageclient#get_warning')
+  augroup airline_languageclient
+    autocmd!
+    autocmd User LanguageClientDiagnosticsChanged call <sid>get_diagnostics()
+  augroup END
+endfunction

autoload/airline/init.vim

@@ -148,7 +148,8 @@ function! airline#init#bootstrap()
   call airline#parts#define_empty(['hunks', 'branch', 'obsession', 'tagbar',
         \ 'syntastic-warn', 'syntastic-err', 'eclim', 'whitespace','windowswap',
         \ 'ycm_error_count', 'ycm_warning_count', 'neomake_error_count',
-        \ 'neomake_warning_count', 'ale_error_count', 'ale_warning_count'])
+        \ 'neomake_warning_count', 'ale_error_count', 'ale_warning_count',
+        \ 'languageclient_error_count', 'languageclient_warning_count'])
   call airline#parts#define_text('capslock', '')
   call airline#parts#define_text('gutentags', '')
   call airline#parts#define_text('grepper', '')
@@ -194,9 +195,9 @@ function! airline#init#sections()
     endif
   endif
   if !exists('g:airline_section_error')
-    let g:airline_section_error = airline#section#create(['ycm_error_count', 'syntastic-err', 'eclim', 'neomake_error_count', 'ale_error_count'])
+    let g:airline_section_error = airline#section#create(['ycm_error_count', 'syntastic-err', 'eclim', 'neomake_error_count', 'ale_error_count', 'languageclient_error_count'])
   endif
   if !exists('g:airline_section_warning')
-    let g:airline_section_warning = airline#section#create(['ycm_warning_count',  'syntastic-warn', 'neomake_warning_count', 'ale_warning_count', 'whitespace'])
+    let g:airline_section_warning = airline#section#create(['ycm_warning_count',  'syntastic-warn', 'neomake_warning_count', 'ale_warning_count', 'languageclient_warning_count', 'whitespace'])
   endif
 endfunction