puppet: Add puppet-languageserver linter

ale_linters/puppet/languageserver.vim

@@ -0,0 +1,35 @@
+" Author: Alexander Olofsson <alexander.olofsson@liu.se>
+" Description: Puppet Language Server integration for ALE
+
+call ale#Set('puppet_languageserver_executable', 'puppet-languageserver')
+
+function! ale_linters#puppet#languageserver#GetExecutable(buffer) abort
+    return ale#Var(a:buffer, 'puppet_languageserver_executable')
+endfunction
+
+function! ale_linters#puppet#languageserver#GetCommand(buffer) abort
+    let l:exe = ale#Escape(ale_linters#puppet#languageserver#GetExecutable(a:buffer))
+
+    return l:exe . ' --stdio'
+endfunction
+
+function! ale_linters#puppet#languageserver#GetProjectRoot(buffer) abort
+    " Note: while manifest.json is a strong recommendation, the only
+    " *required* path for a Puppet module is the manifests folder.
+    let l:root_path = ale#path#FindNearestFile(a:buffer, 'metadata.json')
+
+    if empty(l:root_path)
+        let l:root_path = ale#path#FindNearestDirectory(a:buffer, 'manifests')
+    endif
+
+    return !empty(l:root_path) ? fnamemodify(l:root_path, ':h') : ''
+endfunction
+
+call ale#linter#Define('puppet', {
+\   'name': 'languageserver',
+\   'lsp': 'stdio',
+\   'executable_callback': 'ale_linters#puppet#languageserver#GetExecutable',
+\   'command_callback': 'ale_linters#puppet#languageserver#GetCommand',
+\   'language': 'puppet',
+\   'project_root_callback': 'ale_linters#puppet#languageserver#GetProjectRoot',
+\})