Fix 4246 - Add ansible language-server (#4355)

ale_linters/ansible/ansible_language_server.vim

@@ -0,0 +1,46 @@
+" Author: Horacio Sanson <https://github.com/hsanson>
+" Description: Support ansible language server https://github.com/ansible/ansible-language-server/
+
+call ale#Set('ansible_language_server_executable', 'ansible-language-server')
+call ale#Set('ansible_language_server_config', {})
+
+function! ale_linters#ansible#ansible_language_server#Executable(buffer) abort
+    return ale#Var(a:buffer, 'ansible_language_server_executable')
+endfunction
+
+function! ale_linters#ansible#ansible_language_server#GetCommand(buffer) abort
+    let l:executable = ale_linters#ansible#ansible_language_server#Executable(a:buffer)
+
+    return ale#Escape(l:executable) . ' --stdio'
+endfunction
+
+function! ale_linters#ansible#ansible_language_server#FindProjectRoot(buffer) abort
+    let l:dir = fnamemodify(
+    \   ale#path#FindNearestFile(a:buffer, 'ansible.cfg'),
+    \   ':h'
+    \)
+
+    if l:dir isnot# '.' && isdirectory(l:dir)
+        return l:dir
+    endif
+
+    let l:dir = fnamemodify(
+    \   ale#path#FindNearestDirectory(a:buffer, '.git'),
+    \   ':h:h'
+    \)
+
+    if l:dir isnot# '.' && isdirectory(l:dir)
+        return l:dir
+    endif
+
+    return ''
+endfunction
+
+call ale#linter#Define('ansible', {
+\   'name': 'ansible-language-server',
+\   'lsp': 'stdio',
+\   'executable': function('ale_linters#ansible#ansible_language_server#Executable'),
+\   'command': function('ale_linters#ansible#ansible_language_server#GetCommand'),
+\   'project_root': function('ale_linters#ansible#ansible_language_server#FindProjectRoot'),
+\   'lsp_config': {b -> ale#Var(b, 'ansible_language_server_config')}
+\})