Add swiftlint ale checker

Author: keith

ale_linters/swift/swiftlint.vim

@@ -0,0 +1,48 @@
+function! ale_linters#swift#swiftlint#GetExecutable(buffer)
+  if get(g:, 'ale_swift_swiftlint_use_defaults', 0) || filereadable('.swiftlint.yml')
+    return 'swiftlint'
+  endif
+
+  return ''
+endfunction
+
+function! ale_linters#swift#swiftlint#Handle(buffer, lines)
+  " Match and ignore file path (anything but ':')
+  " Match and capture line number
+  " Match and capture optional column number
+  " Match and capture warning level ('error' or 'warning')
+  " Match and capture anything in the message
+  let l:pattern = '^[^:]\+:\(\d\+\):\(\d\+\)\?:\?\s*\(\w\+\):\s*\(.*\)$'
+  let l:output = []
+
+  for l:line in a:lines
+    let l:match = matchlist(l:line, l:pattern)
+
+    if len(l:match) == 0
+      continue
+    endif
+
+    let l:line_number = l:match[1]
+    let l:column = l:match[2]
+    let l:type = toupper(l:match[3][0])
+    let l:text = l:match[4]
+
+    call add(l:output, {
+          \ 'bufnr': a:buffer,
+          \ 'lnum': l:line_number,
+          \ 'vcol': 0,
+          \ 'col': l:column,
+          \ 'text': l:text,
+          \ 'type': l:type,
+        \ })
+  endfor
+
+  return l:output
+endfunction
+
+call ale#linter#Define('swift', {
+      \ 'name': 'swiftlint',
+      \ 'executable_callback': 'ale_linters#swift#swiftlint#GetExecutable',
+      \ 'command': 'swiftlint lint --use-stdin',
+      \ 'callback': 'ale_linters#swift#swiftlint#Handle',
+    \ })