Add support for Bash and other shells. Add support for reading from stderr, and for generating the executable from functions. Both were needed to support shell linting.

ale_linters/sh/shell.vim

@@ -0,0 +1,75 @@
+if exists('g:loaded_ale_linters_sh_shell')
+    finish
+endif
+
+let g:loaded_ale_linters_sh_shell = 1
+
+" This option can be changed to change the default shell when the shell
+" cannot be taken from the hashbang line.
+if !exists('g:ale_linters_sh_shell_default_shell')
+    let g:ale_linters_sh_shell_default_shell = 'bash'
+endif
+
+function! ale_linters#sh#shell#GetExecutable(buffer)
+    let shell = g:ale_linters_sh_shell_default_shell
+
+    let banglines = getbufline(a:buffer, 1)
+
+    " Take the shell executable from the hashbang, if we can.
+    if len(banglines) == 1
+        let bangmatch = matchlist(banglines[0], '^#!\([^ ]\+\)')
+
+        if len(bangmatch) > 0
+            let shell = bangmatch[1]
+        endif
+    endif
+
+    return shell
+endfunction
+
+function! ale_linters#sh#shell#GetCommand(buffer)
+    return ale_linters#sh#shell#GetExecutable(a:buffer) . ' -n'
+endfunction
+
+function! ale_linters#sh#shell#Handle(buffer, lines)
+    " Matches patterns line the following:
+    "
+    " bash: line 13: syntax error near unexpected token `d'
+    " sh: 11: Syntax error: "(" unexpected
+    let pattern = '^[^:]\+: \%(line \|\)\(\d\+\): \(.\+\)'
+    let output = []
+
+    for line in a:lines
+        let l:match = matchlist(line, pattern)
+
+        if len(l:match) == 0
+            continue
+        endif
+
+        let line = l:match[1] + 0
+        let column = 1
+        let text = l:match[2]
+        let type = 'E'
+
+        " vcol is Needed to indicate that the column is a character.
+        call add(output, {
+        \   'bufnr': a:buffer,
+        \   'lnum': line,
+        \   'vcol': 0,
+        \   'col': column,
+        \   'text': text,
+        \   'type': type,
+        \   'nr': -1,
+        \})
+    endfor
+
+    return output
+endfunction
+
+call ALEAddLinter('sh', {
+\   'name': 'shell',
+\   'output_stream': 'stderr',
+\   'executable_callback': 'ale_linters#sh#shell#GetExecutable',
+\   'command_callback': 'ale_linters#sh#shell#GetCommand',
+\   'callback': 'ale_linters#sh#shell#Handle',
+\})