From 19445b6b7bb04e44e39ef2e39a620bd3eadb0acd Mon Sep 17 00:00:00 2001 From: Stefan Monnier Date: Wed, 8 Nov 2023 11:32:27 -0500 Subject: [PATCH] subr.el: Provide a functional API around `derived-mode-parent` The `derived-mode-parent` property should be an implementation detail, so we can change it more easily. To that end, add functions to set and query it. * lisp/subr.el (derived-mode-all-parents): New function. (provided-mode-derived-p): Use it. (derived-mode-set-parent): New function. --- lisp/subr.el | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/lisp/subr.el b/lisp/subr.el index d4173b4daba..6a4c1abfb62 100644 --- a/lisp/subr.el +++ b/lisp/subr.el @@ -2678,20 +2678,27 @@ The variable list SPEC is the same as in `if-let*'." ;; PUBLIC: find if the current mode derives from another. +(defun derived-mode-all-parents (mode &optional known-children) + "Return all the parents of MODE, starting with MODE. +The returned list is not fresh, don't modify it. +\n(fn MODE)" ;`known-children' is for internal use only. + (if (memq mode known-children) + (error "Cycle in the major mode hierarchy: %S" mode) + (push mode known-children)) + (let* ((parent (or (get mode 'derived-mode-parent) + ;; If MODE is an alias, then follow the alias. + (let ((alias (symbol-function mode))) + (and (symbolp alias) alias))))) + (cons mode (if parent (derived-mode-all-parents parent known-children))))) + (defun provided-mode-derived-p (mode &rest modes) "Non-nil if MODE is derived from one of MODES. -Uses the `derived-mode-parent' property of the symbol to trace backwards. If you just want to check `major-mode', use `derived-mode-p'." (declare (side-effect-free t)) - (while - (and - (not (memq mode modes)) - (let* ((parent (get mode 'derived-mode-parent))) - (setq mode (or parent - ;; If MODE is an alias, then follow the alias. - (let ((alias (symbol-function mode))) - (and (symbolp alias) alias))))))) - mode) + (let ((ps (derived-mode-all-parents mode))) + (while (and ps (not (memq (car ps) modes))) + (setq ps (cdr ps))) + (car ps))) (defun derived-mode-p (&rest modes) "Non-nil if the current major mode is derived from one of MODES. @@ -2699,6 +2706,10 @@ Uses the `derived-mode-parent' property of the symbol to trace backwards." (declare (side-effect-free t)) (apply #'provided-mode-derived-p major-mode modes)) +(defun derived-mode-set-parent (mode parent) + "Declare PARENT to be the parent of MODE." + (put mode 'derived-mode-parent parent)) + (defvar-local major-mode--suspended nil) (put 'major-mode--suspended 'permanent-local t) -- 2.39.2