[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: exposing the effective mode in a multi-mode
From: |
Tom Tromey |
Subject: |
Re: exposing the effective mode in a multi-mode |
Date: |
Tue, 19 Sep 2017 22:21:13 -0600 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
>>>>> "Alan" == Alan Mackenzie <address@hidden> writes:
Alan> The facility will surely be needed by modes which aren't derived from
Alan> prog-mode.
That's a good point, and I've updated the patch accordingly. It's
appended; let me know what you think.
Alan> Is the current implementation going to be applicable to all
Alan> these various ways of doing multi-mode? Would it not be better to have
Alan> this as a hook function (in global namespace), where the pertinent
Alan> multi-mode could set the hook to its own function?
I don't really understand this critique, because that's what the patch
did. Is there something I should change?
Tom
diff --git a/lisp/subr.el b/lisp/subr.el
index 79ae1f4..5c63f4f 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1906,6 +1906,24 @@ derived-mode-p
"Non-nil if the current major mode is derived from one of MODES.
Uses the `derived-mode-parent' property of the symbol to trace backwards."
(apply #'provided-mode-derived-p major-mode modes))
+
+(defvar-local effective-major-mode-function nil
+ "When non-nil, provides the effective mode at point for embedded chunks.
+When non-nil, this is a function that will be called by
+`effective-major-mode' to find the effective major mode at point.
+This function should return a symbol naming a major mode, e.g. `css-mode'.
+It may return nil to mean the \"outer\" major mode.")
+
+(defun effective-major-mode ()
+ "Returns the effective mode at point.
+
+There are languages where part of the code is actually written in
+a sub language, e.g., a Yacc/Bison or ANTLR grammar also consists
+of plain C code. This function returns the effective value of
+`major-mode' at point."
+ (or (if effective-major-mode-function
+ (funcall effective-major-mode-function))
+ major-mode))
;;;; Minor modes.
diff --git a/lisp/textmodes/mhtml-mode.el b/lisp/textmodes/mhtml-mode.el
index b6cd157..326cee4 100644
--- a/lisp/textmodes/mhtml-mode.el
+++ b/lisp/textmodes/mhtml-mode.el
@@ -56,7 +56,9 @@ mhtml-tag-relative-indent
:version "26.1")
(cl-defstruct mhtml--submode
- ;; Name of this submode.
+ ;; The submode's symbol, like 'css-mode.
+ mode
+ ;; Name of this submode, a string. Used for the mode-line lighter.
name
;; HTML end tag.
end-tag
@@ -86,7 +88,7 @@ mhtml--construct-submode
"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)))
+ (submode (apply #'make-mhtml--submode :mode mode args)))
(with-temp-buffer
(funcall mode)
;; Make sure font lock is all set up.
@@ -348,6 +350,13 @@ mhtml--flyspell-check-word
(flyspell-generic-progmode-verify)
t)))
+(defun mhtml--effective-mode ()
+ "Return the current mode (a symbol) at point.
+If point is not in a submode section, returns 'html-mode."
+ (let ((submode (get-text-property (point) 'mhtml-submode)))
+ (when submode
+ (mhtml--submode-mode submode))))
+
;;;###autoload
(define-derived-mode mhtml-mode html-mode
'((sgml-xml-mode "XHTML+" "HTML+") (:eval (mhtml--submode-lighter)))
@@ -365,6 +374,7 @@ mhtml-mode
(setq-local font-lock-extend-region-functions
'(mhtml--extend-font-lock-region
font-lock-extend-region-multiline))
+ (setq-local effective-major-mode-function 'mhtml--effective-mode)
;; 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.