Path-specific style switching for Emacs

define-new-c-style.el

((defmacro define-new-c-style (name derived-from style-alists tabs-p path-list)
  `(progn
     (add-hook 'c-mode-common-hook
	       (lambda ()
		 (c-add-style ,name
			      '(,derived-from (c-offsets-alist
					       ,style-alists)))))
     (add-hook 'c-mode-hook
	       (lambda ()
		 (let ((filename (buffer-file-name)))
		   (when (and filename
			      (delq nil
				    (mapcar (lambda (path)
					      (string-match (expand-file-name path)
							    filename))
					    ',path-list)))
		     (setq indent-tabs-mode ,tabs-p)
		     (c-set-style ,name)))))))

(defun c-lineup-arglist-tabs-only (ignored)
  "Line up argument lists with tabs, not spaces"
  (let* ((anchor (c-langelem-pos c-syntactic-element))
         (column (c-langelem-2nd-pos c-syntactic-element))
         (offset (- (1+ column) anchor))
         (steps (floor offset c-basic-offset)))
    (* (max steps 1)
       c-basic-offset)))

;; Syntax for define-new-c-style:
;; <style name> <derived from> <style alist> <tabs-p> <list of paths to apply to>

(define-new-c-style "linux-tabs-only" "linux" (arglist-cont-nonempty
					       c-lineup-gcc-asm-reg
					       c-lineup-arglist-tabs-only) t
					       ("~/src/linux" "~/src/git"))

(define-new-c-style "subversion" "gnu" (inextern-lang 0) nil ("~/svn"))