Add support for linting git commit message files (#1233)

ale_linters/gitcommit/gitlint.vim

@@ -0,0 +1,51 @@
+" Author: Nick Yamane <nick.diego@gmail.com>
+" Description: gitlint for git commit message files
+
+let g:ale_gitcommit_gitlint_executable =
+\   get(g:, 'ale_gitcommit_gitlint_executable', 'gitlint')
+let g:ale_gitcommit_gitlint_options = get(g:, 'ale_gitcommit_gitlint_options', '')
+let g:ale_gitcommit_gitlint_use_global = get(g:, 'ale_gitcommit_gitlint_use_global', 0)
+
+
+function! ale_linters#gitcommit#gitlint#GetExecutable(buffer) abort
+    return ale#python#FindExecutable(a:buffer, 'gitcommit_gitlint', ['gitlint'])
+endfunction
+
+function! ale_linters#gitcommit#gitlint#GetCommand(buffer) abort
+    let l:options = ale#Var(a:buffer, 'gitcommit_gitlint_options')
+    let l:executable = ale_linters#gitcommit#gitlint#GetExecutable(a:buffer)
+    return ale#Escape(l:executable)
+    \   . (!empty(l:options) ? ' ' . l:options : '')
+    \   . ' lint'
+endfunction
+
+
+function! ale_linters#gitcommit#gitlint#Handle(buffer, lines) abort
+    " Matches patterns line the following:
+    let l:pattern = '\v^(\d+): (\w+) (.*)$'
+    let l:output = []
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        let l:code = l:match[2]
+
+        let l:item = {
+        \   'lnum': l:match[1] + 0,
+        \   'text': l:code . ': ' . l:match[3],
+        \   'type': 'E',
+        \}
+
+        call add(l:output, l:item)
+    endfor
+
+    return l:output
+endfunction
+
+
+call ale#linter#Define('gitcommit', {
+\   'name': 'gitlint',
+\   'output_stream': 'stderr',
+\   'executable_callback': 'ale_linters#gitcommit#gitlint#GetExecutable',
+\   'command_callback': 'ale_linters#gitcommit#gitlint#GetCommand',
+\   'callback': 'ale_linters#gitcommit#gitlint#Handle',
+\})
+