Add support for linting less files with lessc

README.md

@@ -109,6 +109,7 @@ formatting.
 | JSON | [jsonlint](http://zaa.ch/jsonlint/), [prettier](https://github.com/prettier/prettier) |
 | Kotlin | [kotlinc](https://kotlinlang.org) !!, [ktlint](https://ktlint.github.io) !! see `:help ale-integration-kotlin` for configuration instructions |
 | LaTeX | [chktex](http://www.nongnu.org/chktex/), [lacheck](https://www.ctan.org/pkg/lacheck), [proselint](http://proselint.com/), [write-good](https://github.com/btford/write-good) |
+| Less | [lessc](https://www.npmjs.com/package/less) |
 | LLVM | [llc](https://llvm.org/docs/CommandGuide/llc.html) |
 | Lua | [luacheck](https://github.com/mpeterv/luacheck) |
 | Mail | [proselint](http://proselint.com/), [vale](https://github.com/ValeLint/vale) |

ale_linters/less/lessc.vim

@@ -0,0 +1,36 @@
+" Author: zanona <https://github.com/zanona>, w0rp <devw0rp@gmail.com>
+" Description: This file adds support for checking Less code with lessc.
+
+call ale#Set('less_lessc_options', '')
+
+function! ale_linters#less#lessc#GetCommand(buffer) abort
+    return 'lessc'
+          \ . ' --no-color --lint '
+          \ . ale#Var(a:buffer, 'less_lessc_options')
+          \ . ' %t'
+endfunction
+
+function! ale_linters#less#lessc#Handle(buffer, lines) abort
+    " Matches patterns like the following:
+    let l:pattern = '^\(\w\+\): \(.\{-}\) in \(.\{-}\) on line \(\d\+\), column \(\d\+\):$'
+    let l:output = []
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        call add(l:output, {
+        \   'lnum': l:match[4] + 0,
+        \   'col': l:match[5] + 0,
+        \   'text': l:match[2],
+        \   'type': 'E',
+        \})
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('less', {
+\   'name': 'lessc',
+\   'executable': 'lessc',
+\   'output_stream': 'stderr',
+\   'command_callback': 'ale_linters#less#lessc#GetCommand',
+\   'callback': 'ale_linters#less#lessc#Handle',
+\})

doc/ale-less.txt

@@ -2,6 +2,17 @@
 ALE Less Integration                                         *ale-less-options*
 
 
+===============================================================================
+lessc                                                          *ale-less-lessc*
+
+g:ale_less_lessc_options                             *g:ale_less_lessc_options*
+                                                     *b:ale_less_lessc_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be set to pass additional options to lessc.
+
+
 ===============================================================================
 prettier                                                    *ale-less-prettier*
 

doc/ale.txt

@@ -105,6 +105,7 @@ CONTENTS                                                         *ale-contents*
     latex.................................|ale-latex-options|
       write-good..........................|ale-latex-write-good|
     less..................................|ale-less-options|
+      lessc...............................|ale-less-lessc-options|
       prettier............................|ale-less-prettier|
     llvm..................................|ale-llvm-options|
       llc.................................|ale-llvm-llc|
@@ -293,6 +294,7 @@ Notes:
 * JSON: `jsonlint`, `prettier`
 * Kotlin: `kotlinc`, `ktlint`
 * LaTeX (tex): `chktex`, `lacheck`, `proselint`, `write-good`
+* Less: `lessc`
 * LLVM: `llc`
 * Lua: `luacheck`
 * Mail: `proselint`, `vale`