(defun c-macro-expand (beg end) "Display the result of expanding all C macros occurring in the region. The expansion is entirely correct because it uses the C preprocessor." (interactive "r") (let ((outbuf (get-buffer-create "*Macroexpansion*")) (tempfile "%%macroexpand%%") process last-needed) (save-excursion (set-buffer outbuf) (erase-buffer)) (setq process (start-process "macros" outbuf "/lib/cpp")) (set-process-sentinel process '(lambda (&rest x))) (save-restriction (widen) (save-excursion (goto-char beg) (beginning-of-line) (setq last-needed (point)) (if (re-search-backward "^[ \t]*#" nil t) (progn ;; Skip continued lines. (while (progn (end-of-line) (= (preceding-char) ?\\)) (forward-line 1)) ;; Skip the last line of the macro definition we found. (forward-line 1) (setq last-needed (point))))) (write-region (point-min) last-needed tempfile nil 'nomsg) (process-send-string process (concat "#include \"" tempfile "\"\n")) (process-send-string process "\n") (process-send-region process beg end) (process-send-string process "\n") (process-send-eof process)) (while (eq (process-status process) 'run) (accept-process-output)) (delete-file tempfile) (save-excursion (set-buffer outbuf) (goto-char (point-max)) (re-search-backward "\n# [12] \"\"") (forward-line 2) (while (eolp) (delete-char 1)) (delete-region (point-min) (point))) (display-buffer outbuf)))