;;; mhtml-mode.el --- HTML editing mode that handles CSS and JS -*- lexical-binding:t -*-
;; Copyright (C) 2017-2024 Free Software Foundation, Inc.
;; Keywords: wp, hypermedia, comm, languages
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
(eval-when-compile (require 'cl-lib))
(eval-when-compile (require 'pcase))
(require 'sgml-mode)
(require 'js)
(require 'css-mode)
(require 'prog-mode)
(defcustom mhtml-tag-relative-indent t
"How <script> and <style> bodies are indented relative to the tag.
When t, indentation looks like:
<script>
code();
</script>
When nil, indentation of the script body starts just below the
tag, like:
<script>
code();
</script>
When `ignore', the script body starts in the first column, like:
<script>
code();
</script>"
:group 'sgml
:type '(choice (const nil) (const t) (const ignore))
:safe 'symbolp
:version "26.1")
(cl-defstruct mhtml--submode
;; Name of this submode.
name
;; HTML end tag.
end-tag
;; Syntax table.
syntax-table
;; Propertize function.
propertize
;; Keymap.
keymap
;; Captured locals that are set when entering a region.
crucial-captured-locals
;; Other captured local variables; these are not set when entering a
;; region but let-bound during certain operations, e.g.,
;; indentation.
captured-locals)
(defconst mhtml--crucial-variable-prefix
(regexp-opt '("comment-" "uncomment-" "electric-indent-"
"smie-" "forward-sexp-function" "completion-" "major-mode"
"adaptive-fill-" "fill-" "normal-auto-fill-function"
"paragraph-"))
"Regexp matching the prefix of \"crucial\" buffer-locals we want to capture.")
(defconst mhtml--variable-prefix
(regexp-opt '("font-lock-" "indent-line-function"))
"Regexp matching the prefix of buffer-locals we want to capture.")
(defun mhtml--construct-submode (mode &rest args)
"A wrapper for make-mhtml--submode that computes the buffer-local variables."
(let ((captured-locals nil)
(crucial-captured-locals nil)
(submode (apply #'make-mhtml--submode args)))
(with-temp-buffer
(funcall mode)
;; Make sure font lock is all set up.
(font-lock-set-defaults)
;; This has to be set to a value other than the mhtml-mode
;; value, to avoid recursion.
(unless (variable-binding-locus 'font-lock-fontify-region-function)
(setq-local font-lock-fontify-region-function
#'font-lock-default-fontify-region))
(dolist (iter (buffer-local-variables))
(when (string-match mhtml--crucial-variable-prefix
(symbol-name (car iter)))
(push iter crucial-captured-locals))
(when (string-match mhtml--variable-prefix (symbol-name (car iter)))
(push iter captured-locals)))
(setf (mhtml--submode-crucial-captured-locals submode)
crucial-captured-locals)
(setf (mhtml--submode-captured-locals submode) captured-locals))
submode))
(defun mhtml--mark-buffer-locals (submode)
(dolist (iter (mhtml--submode-captured-locals submode))
(make-local-variable (car iter))))
(defvar-local mhtml--crucial-variables nil
"List of all crucial variable symbols.")
(defun mhtml--mark-crucial-buffer-locals (submode)
(dolist (iter (mhtml--submode-crucial-captured-locals submode))
(make-local-variable (car iter))
(push (car iter) mhtml--crucial-variables)))
(defconst mhtml--css-submode
(mhtml--construct-submode 'css-mode
:name "CSS"
:end-tag "</style>"
:syntax-table css-mode-syntax-table
:propertize css-syntax-propertize-function
:keymap css-mode-map))
(defconst mhtml--js-submode
(mhtml--construct-submode 'js-mode
:name "JS"
:end-tag "</script>"
:syntax-table js-mode-syntax-table
:propertize #'js-syntax-propertize
:keymap js-mode-map))
(defmacro mhtml--with-locals (submode &rest body)
(declare (indent 1))
`(cl-progv
(when ,submode (mapcar #'car (mhtml--submode-captured-locals ,submode)))
(when ,submode (mapcar #'cdr (mhtml--submode-captured-locals ,submode)))
(cl-progv
(when ,submode (mapcar #'car (mhtml--submode-crucial-captured-locals
,submode)))
(when ,submode (mapcar #'cdr (mhtml--submode-crucial-captured-locals
,submode)))
,@body)))
(defun mhtml--submode-lighter ()
"Mode-line lighter indicating the current submode."
;; The end of the buffer has no text properties, so in this case
;; back up one character, if possible.
(let* ((where (if (and (eobp) (not (bobp)))
(1- (point))
(point)))
(submode (get-text-property where 'mhtml-submode)))
(if submode
(mhtml--submode-name submode)
"")))
(defun mhtml--submode-fontify-one-region (submode beg end &optional loudly)
(if submode
(mhtml--with-locals submode
(save-restriction
(font-lock-fontify-region beg end loudly)))
(font-lock-set-defaults)
(font-lock-default-fontify-region beg end loudly)))
(defun mhtml--submode-fontify-region (beg end loudly)
(syntax-propertize end)
(let ((orig-beg beg)
(orig-end end)
(new-beg beg)
(new-end end))
(while (< beg end)
(let ((submode (get-text-property beg 'mhtml-submode))
(this-end (next-single-property-change beg 'mhtml-submode
nil end)))
(let ((extended (mhtml--submode-fontify-one-region submode beg
this-end loudly)))
;; If the call extended the region, take note. We track the
;; bounds we were passed and take the union of any extended
;; bounds.
(when (and (consp extended)
(eq (car extended) 'jit-lock-bounds))
(setq new-beg (min new-beg (cadr extended)))
;; Make sure that the next region starts where the
;; extension of this region ends.
(setq this-end (cddr extended))
(setq new-end (max new-end this-end))))
(setq beg this-end)))
(when (or (/= orig-beg new-beg)
(/= orig-end new-end))
(cons 'jit-lock-bounds (cons new-beg new-end)))))
(defvar-local mhtml--last-submode nil
"Record the last visited submode.
This is used by `mhtml--pre-command'.")
(defvar-local mhtml--stashed-crucial-variables nil
"Alist of stashed values of the crucial variables.")
(defun mhtml--stash-crucial-variables ()
(setq mhtml--stashed-crucial-variables
(mapcar (lambda (sym)
(cons sym (buffer-local-value sym (current-buffer))))
mhtml--crucial-variables)))
(defun mhtml--map-in-crucial-variables (alist)
(dolist (item alist)
(set (car item) (cdr item))))
(defun mhtml--pre-command ()
(let ((submode (get-text-property (point) 'mhtml-submode)))
(unless (eq submode mhtml--last-submode)
;; If we're entering a submode, and the previous submode was
;; nil, then stash the current values first. This lets the user
;; at least modify some values directly. FIXME maybe always
;; stash into the current mode?
(when (and submode (not mhtml--last-submode))
(mhtml--stash-crucial-variables))
(mhtml--map-in-crucial-variables
(if submode
(mhtml--submode-crucial-captured-locals submode)
mhtml--stashed-crucial-variables))
(setq mhtml--last-submode submode))))
(defun mhtml--syntax-propertize-submode (submode end)
(save-excursion
(when (search-forward (mhtml--submode-end-tag submode) end t)
(setq end (match-beginning 0))))
(set-text-properties (point) end
(list 'mhtml-submode submode
'syntax-table (mhtml--submode-syntax-table submode)
;; We want local-map here so that we act
;; more like the sub-mode and don't
;; override minor mode maps.
'local-map (mhtml--submode-keymap submode)))
(funcall (mhtml--submode-propertize submode) (point) end)
(goto-char end))
(defvar mhtml--syntax-propertize
(syntax-propertize-rules
("<style.*?>"
(0 (ignore
(goto-char (match-end 0))
;; Don't apply in a comment.
(unless (syntax-ppss-context (syntax-ppss))
(mhtml--syntax-propertize-submode mhtml--css-submode end)))))
("<script.*?>"
(0 (ignore
(goto-char (match-end 0))
;; Don't apply in a comment.
(unless (syntax-ppss-context (syntax-ppss))
(mhtml--syntax-propertize-submode mhtml--js-submode end)))))
sgml-syntax-propertize-rules))
(defun mhtml-syntax-propertize (start end)
(let ((submode (get-text-property start 'mhtml-submode)))
;; First remove our special settings from the affected text. They
;; will be re-applied as needed.
(remove-list-of-text-properties start end
'(syntax-table local-map mhtml-submode))
(goto-char start)
(if submode
(mhtml--syntax-propertize-submode submode end)))
(sgml-syntax-propertize (point) end mhtml--syntax-propertize))
(defun mhtml-indent-line ()
"Indent the current line as HTML, JS, or CSS, according to its context."
(interactive)
(let ((submode (save-excursion
(back-to-indentation)
(get-text-property (point) 'mhtml-submode))))
(if submode
(save-restriction
(let* ((region-start
(or (previous-single-property-change (point) 'mhtml-submode)
(point)))
(base-indent (save-excursion
(goto-char region-start)
(sgml-calculate-indent))))
(cond
((eq mhtml-tag-relative-indent nil)
(setq base-indent (- base-indent sgml-basic-offset)))
((eq mhtml-tag-relative-indent 'ignore)
(setq base-indent 0)))
(narrow-to-region region-start (point-max))
(let ((prog-indentation-context (list base-indent)))
(mhtml--with-locals submode
;; indent-line-function was rebound by
;; mhtml--with-locals.
(funcall indent-line-function)))))
;; HTML.
(sgml-indent-line))))
(declare-function flyspell-generic-progmode-verify "flyspell")
(defun mhtml--flyspell-check-word ()
(let ((submode (get-text-property (point) 'mhtml-submode)))
(if submode
(flyspell-generic-progmode-verify)
t)))
;; Support for hideshow.el (see `hs-special-modes-alist').
(defun mhtml-forward (arg)
"Move point forward past a structured expression.
If point is on a tag, move to the end of the tag.
Otherwise, this calls `forward-sexp'.
Prefix arg specifies how many times to move (default 1)."
(interactive "P")
(pcase (get-text-property (point) 'mhtml-submode)
('nil (sgml-skip-tag-forward arg))
(_submode (forward-sexp arg))))
;;;###autoload
(define-derived-mode mhtml-mode html-mode
'((sgml-xml-mode "XHTML+" "HTML+") (:eval (mhtml--submode-lighter)))
"Major mode based on `html-mode', but works with embedded JS and CSS.
Code inside a <script> element is indented using the rules from
`js-mode'; and code inside a <style> element is indented using
the rules from `css-mode'."
(setq-local indent-line-function #'mhtml-indent-line)
(setq-local syntax-propertize-function #'mhtml-syntax-propertize)
(setq-local font-lock-fontify-region-function
#'mhtml--submode-fontify-region)
;; Attach this to both pre- and post- hooks just in case it ever
;; changes a key binding that might be accessed from the menu bar.
(add-hook 'pre-command-hook #'mhtml--pre-command nil t)
(add-hook 'post-command-hook #'mhtml--pre-command nil t)
;; Make any captured variables buffer-local.
(mhtml--mark-buffer-locals mhtml--css-submode)
(mhtml--mark-buffer-locals mhtml--js-submode)
(mhtml--mark-crucial-buffer-locals mhtml--css-submode)
(mhtml--mark-crucial-buffer-locals mhtml--js-submode)
(setq mhtml--crucial-variables (delete-dups mhtml--crucial-variables))
;: Hack
(js--update-quick-match-re)
;; Setup the appropriate js-mode value of auto-fill-function.
(setf (mhtml--submode-crucial-captured-locals mhtml--js-submode)
(push (cons 'auto-fill-function
(if (and (boundp 'auto-fill-function) auto-fill-function)
#'js-do-auto-fill
nil))
(mhtml--submode-crucial-captured-locals mhtml--js-submode)))
;; This mode might be using CC Mode's filling functionality.
(c-foreign-init-lit-pos-cache)
(add-hook 'before-change-functions #'c-foreign-truncate-lit-pos-cache nil t)
;; This is sort of a prog-mode as well as a text mode.
(run-hooks 'prog-mode-hook))
(put 'mhtml-mode 'flyspell-mode-predicate #'mhtml--flyspell-check-word)
(provide 'mhtml-mode)
;;; mhtml-mode.el ends here