lisp/textmodes/less-css-mode.el

   1 ;;; less-css-mode.el --- Major mode for editing Less CSS files  -*- lexical-binding: t; -*-
   2
   3 ;; Copyright (C) 2011-2018 Free Software Foundation, Inc.
   4
   5 ;; Author: Steve Purcell <steve@sanityinc.com>
   6 ;; Maintainer: Simen Heggestøyl <simenheg@gmail.com>
   7 ;; Keywords: hypermedia
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; This mode provides syntax highlighting for Less CSS files
  27 ;; (http://lesscss.org/), plus optional support for compilation of
  28 ;; .less files to .css files at the time they are saved: use
  29 ;; `less-css-compile-at-save' to enable this.
  30 ;;
  31 ;; Command line utility "lessc" is required if setting
  32 ;; `less-css-compile-at-save' to t.  To install "lessc" using the
  33 ;; Node.js package manager, run "npm install less".
  34 ;;
  35 ;; Also make sure the "lessc" executable is in Emacs' PATH, example:
  36 ;; (push (expand-file-name "~/.gem/ruby/1.8/bin") exec-path)
  37 ;; or customize `less-css-lessc-command' to point to your "lessc"
  38 ;; executable.
  39 ;;
  40 ;; We target lessc >= 1.4.0, and thus use the `--no-color' flag by
  41 ;; default.  You may want to adjust `less-css-lessc-options' for
  42 ;; compatibility with older versions.
  43 ;;
  44 ;; `less-css-mode' is derived from `css-mode', and indentation of
  45 ;; nested blocks may not work correctly with versions of `css-mode'
  46 ;; other than that bundled with recent Emacs.
  47 ;;
  48 ;; You can specify per-file values for `less-css-compile-at-save',
  49 ;; `less-css-output-file-name' or `less-css-output-directory' using a
  50 ;; variables header at the top of your .less file, e.g.:
  51 ;;
  52 ;; // -*- less-css-compile-at-save: t; less-css-output-directory: "../css" -*-
  53 ;;
  54 ;; Alternatively, you can use directory local variables to set the
  55 ;; default value of `less-css-output-directory' for your project.
  56 ;;
  57 ;; In the case of files which are included in other .less files, you
  58 ;; may want to trigger the compilation of a "master" .less file on
  59 ;; save: you can accomplish this with `less-css-input-file-name',
  60 ;; which is probably best set using directory local variables.
  61 ;;
  62 ;; If you don't need CSS output but would like to be warned of any
  63 ;; syntax errors in your .less source, consider using `flymake-less':
  64 ;; https://github.com/purcell/flymake-less.
  65
  66 ;;; Credits
  67
  68 ;; The original code for this mode was, in large part, written using
  69 ;; Anton Johansson's scss-mode as a template -- thanks Anton!
  70 ;; https://github.com/antonj
  71
  72 ;;; Code:
  73
  74 (require 'compile)
  75 (require 'css-mode)
  76 (require 'derived)
  77 (eval-when-compile (require 'subr-x))
  78
  79 (defgroup less-css nil
  80   "Less CSS mode."
  81   :version "26.1"
  82   :prefix "less-css-"
  83   :group 'css)
  84
  85 (defcustom less-css-lessc-command "lessc"
  86   "Command used to compile Less files.
  87 Should be \"lessc\" or the complete path to your lessc
  88 executable, e.g.: \"~/.gem/ruby/1.8/bin/lessc\"."
  89   :type 'file)
  90
  91 (defcustom less-css-compile-at-save nil
  92   "If non-nil, Less buffers are compiled to CSS after each save."
  93   :type 'boolean)
  94 ;;;###autoload
  95 (put 'less-css-compile-at-save 'safe-local-variable 'booleanp)
  96
  97 (defcustom less-css-lessc-options '("--no-color")
  98   "Command line options for Less executable.
  99 Use \"-x\" to minify output."
 100   :type '(repeat string))
 101 ;;;###autoload
 102 (put 'less-css-lessc-options 'safe-local-variable t)
 103
 104 (defcustom less-css-output-directory nil
 105   "Directory in which to save CSS, or nil to use the Less file's directory.
 106 This path is expanded relative to the directory of the Less file
 107 using `expand-file-name', so both relative and absolute paths
 108 will work as expected."
 109   :type '(choice (const :tag "Same as Less file" nil) directory))
 110 ;;;###autoload
 111 (put 'less-css-output-directory 'safe-local-variable 'stringp)
 112
 113 (defcustom less-css-output-file-name nil
 114   "File name in which to save CSS, or nil to use <name>.css for <name>.less.
 115 This can be also be set to a full path, or a relative path.  If
 116 the path is relative, it will be relative to the value of
 117 `less-css-output-dir', if set, or the current directory by
 118 default."
 119   :type '(choice (const :tag "Default" nil) file))
 120 (make-variable-buffer-local 'less-css-output-file-name)
 121
 122 (defcustom less-css-input-file-name nil
 123   "File name which will be compiled to CSS.
 124 When the current buffer is saved `less-css-input-file-name' file
 125 will be compiled to CSS instead of the current file.
 126
 127 Set this in order to trigger compilation of a \"master\" .less
 128 file which includes the current file.  The best way to set this
 129 variable in most cases is likely to be via directory local
 130 variables.
 131
 132 This can be also be set to a full path, or a relative path.  If
 133 the path is relative, it will be relative to the current
 134 directory by default."
 135   :type '(choice (const nil) file))
 136 ;;;###autoload
 137 (put 'less-css-input-file-name 'safe-local-variable 'stringp)
 138 (make-variable-buffer-local 'less-css-input-file-name)
 139
 140 (defconst less-css-default-error-regex
 141   "^\\(?:\e\\[31m\\)?\\([^\e\n]*\\|FileError:.*\n\\)\\(?:\e\\[39m\e\\[31m\\)? in \\(?:\e\\[39m\\)?\\([^ \r\n\t\e]+\\)\\(?:\e\\[90m\\)?\\(?::\\| on line \\)\\([0-9]+\\)\\(?::\\|, column \\)\\([0-9]+\\):?\\(?:\e\\[39m\\)?")
 142
 143 ;;; Compilation to CSS
 144
 145 (add-to-list 'compilation-error-regexp-alist-alist
 146              (list 'less-css less-css-default-error-regex 2 3 4 nil 1))
 147 (add-to-list 'compilation-error-regexp-alist 'less-css)
 148
 149 (defun less-css-compile-maybe ()
 150   "Run `less-css-compile' if `less-css-compile-at-save' is non-nil."
 151   (when less-css-compile-at-save
 152     (less-css-compile)))
 153
 154 (defun less-css--output-path ()
 155   "Return the path to use for the compiled CSS file."
 156   (expand-file-name
 157    (or less-css-output-file-name
 158        (concat
 159         (file-name-nondirectory
 160          (file-name-sans-extension buffer-file-name))
 161         ".css"))
 162    (or less-css-output-directory default-directory)))
 163
 164 (defun less-css-compile ()
 165   "Compile the current buffer to CSS using `less-css-lessc-command'."
 166   (interactive)
 167   (message "Compiling Less to CSS")
 168   (let ((compilation-buffer-name-function
 169          (lambda (_) "*less-css-compilation*")))
 170     (save-window-excursion
 171       (with-current-buffer
 172           (compile
 173            (string-join
 174             (append
 175              (list less-css-lessc-command)
 176              (mapcar #'shell-quote-argument less-css-lessc-options)
 177              (list (shell-quote-argument
 178                     (or less-css-input-file-name buffer-file-name))
 179                    (shell-quote-argument (less-css--output-path))))
 180             " "))
 181         (add-hook 'compilation-finish-functions
 182                   (lambda (buf msg)
 183                     (unless (string-match-p "^finished" msg)
 184                       (display-buffer buf)))
 185                   nil
 186                   t)))))
 187
 188 ;;; Major mode
 189
 190 ;; TODO:
 191 ;; - interpolation ("@{val}")
 192 ;; - escaped values (~"...")
 193 ;; - JS eval (~`...`)
 194 ;; - custom faces.
 195 (defconst less-css-font-lock-keywords
 196   '(;; Variables
 197     ("@[a-z_-][a-z-_0-9]*" . font-lock-variable-name-face)
 198     ("&" . font-lock-preprocessor-face)
 199     ;; Mixins
 200     ("\\(?:[ \t{;]\\|^\\)\\(\\.[a-z_-][a-z-_0-9]*\\)[ \t]*;" .
 201      (1 font-lock-keyword-face))))
 202
 203 (defvar less-css-mode-syntax-table
 204   (let ((st (make-syntax-table css-mode-syntax-table)))
 205     ;; C++-style comments.
 206     (modify-syntax-entry ?/ ". 124b" st)
 207     (modify-syntax-entry ?* ". 23" st)
 208     (modify-syntax-entry ?\n "> b" st)
 209     ;; Special chars that sometimes come at the beginning of words.
 210     (modify-syntax-entry ?. "'" st)
 211     st))
 212
 213 (defvar less-css-mode-map
 214   (let ((map (make-sparse-keymap)))
 215     (define-key map "\C-c\C-c" 'less-css-compile)
 216     map))
 217
 218 ;;;###autoload (add-to-list 'auto-mode-alist '("\\.less\\'" . less-css-mode))
 219 ;;;###autoload
 220 (define-derived-mode less-css-mode css-mode "Less"
 221   "Major mode for editing Less files (http://lesscss.org/).
 222 Special commands:
 223 \\{less-css-mode-map}"
 224   (font-lock-add-keywords nil less-css-font-lock-keywords)
 225   (setq-local comment-start "//")
 226   (setq-local comment-end "")
 227   (setq-local comment-continue " *")
 228   (setq-local comment-start-skip "/[*/]+[ \t]*")
 229   (setq-local comment-end-skip "[ \t]*\\(?:\n\\|\\*+/\\)")
 230   (add-hook 'after-save-hook 'less-css-compile-maybe nil t))
 231
 232 (provide 'less-css-mode)
 233 ;;; less-css-mode.el ends here