tombi: support its LSP (#5022)

* tombi: support its LSP
* tombi: support linting and formatting

ale_linters/toml/tombi.vim

@@ -0,0 +1,45 @@
+" Author: Ben Boeckel <github@me.benboeckel.net>
+" Description: TOML Formatter / Linter / Language Server
+
+call ale#Set('toml_tombi_executable', 'tombi')
+call ale#Set('toml_tombi_lsp_options', '')
+
+function! ale_linters#toml#tombi#GetCommand(buffer) abort
+    let l:options = ale#Var(a:buffer, 'toml_tombi_lsp_options')
+
+    return '%e lsp'
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+endfunction
+
+function! ale_linters#toml#tombi#GetProjectRoot(buffer) abort
+    " Try to find nearest tombi.toml
+    let l:tombiconfig_file = ale#path#FindNearestFile(a:buffer, 'tombi.toml')
+
+    if !empty(l:tombiconfig_file)
+        return fnamemodify(l:tombiconfig_file . '/', ':p:h:h')
+    endif
+
+    " Try to find nearest pyproject.toml
+    let l:pyproject_file = ale#path#FindNearestFile(a:buffer, 'pyproject.toml')
+
+    if !empty(l:pyproject_file)
+        return fnamemodify(l:pyproject_file . '/', ':p:h:h')
+    endif
+
+    " Try to find nearest `git` directory
+    let l:gitdir = ale#path#FindNearestFile(a:buffer, '.git')
+
+    if !empty(l:gitdir)
+        return fnamemodify(l:gitdir . '/', ':p:h:h')
+    endif
+
+    return ''
+endfunction
+
+call ale#linter#Define('toml', {
+\   'name': 'tombi',
+\   'lsp': 'stdio',
+\   'executable': {b -> ale#Var(b, 'toml_tombi_executable')},
+\   'command': function('ale_linters#toml#tombi#GetCommand'),
+\   'project_root': function('ale_linters#toml#tombi#GetProjectRoot'),
+\})