;;; Code: (defvar find-file-existed-complementary-alist (mapc (lambda (elt) (cons (purecopy (car elt)) (cdr elt))) '(("\\.html$" . "\\.php$") ("\\.c$" . "\\.h$"))) "*Alist of complementary pair of extension patterns in filename.")
(defun extension-from-pattern (pattern) "Return true extension which is included period from search pattern." (let ((beg (string-match "\\." pattern)) (end (string-match "\\$" pattern))) (substring pattern beg end)))