;;; ppindent.el --- Indents C preprocessor directives
;; Copyright (C) 2007 Free Software Foundation, Inc.
;; Author: Craig McDaniel <craigmcd@gmail.com>
;; Keywords: languages, c
;; Maintainer: Craig McDaniel <craigmcd@gmail.com>
;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; PPINDENT indents C-preprocessor statements depending on the current
;; #if..., #el.., #endif level. It only modifies lines with "#" as the
;; first non-blank character and therefore does not conflict with the
;; normal C indentation. Unlike a true indent, it inserts the
;; requisite number of spaces after, rather than before the "#"
;; character. This type of preprocesor indent is commonly used to
;; provide the most compatibility with different C-compilers.
;;
;; Example:
;; #ifdef WOO
;; ....
;; #if defined(X) && !defined(Y)
;; #ifdef Q8
;; ...
;; #else
;; ...
;; ....
;; #elif defined (Z)
;; ....
;; #endif
;; #endif
;; #endif
;; After "M-x ppindent-c" becomes:
;; #ifdef WOO
;; ....
;; #if defined(X) && !defined(Y)
;; #ifdef Q8
;; ...
;; #else
;; ...
;; ....
;; #elif defined (Z)
;; ....
;; #endif
;; #endif
;; #endif
;; Two functions are provided: PPINDENT-C indents as described
;; above. PPINDENT-H does not indent the first level, assuming that
;; .h/.hpp files use an #ifdef guard around the entire file.
;; You can customize PPINDENT-INCREMENT if you want to use something
;; other than 2 spaces for the indent.
;;; History:
;; 2007-01-19 WCM Initial version
;;; Code:
(provide 'ppindent)
(defgroup pp-indent nil
"Indent C preproccessor directives."
:group 'c)
(defcustom ppindent-increment 2
"Number of spaces per indention level.
Used in C pre-processor indent functions ppindent-c and ppindent-h"
:type 'number
:group 'pp-indent)
(defun starts-withp (str prefix)
"str starts with prefix"
(eql (compare-strings prefix nil nil str nil (length prefix)) t))
(defun my-make-string (length init)
"just like make-string, but makes an empty string if length is negative"
(when (minusp length)
(setf length 0))
(make-string length init))
(defun ppindent-aux (start)
(let ((cnt start))
(goto-char (point-min))
(while (re-search-forward "^[ \t]*#[ \t]*\\(.*\\)" nil t)
(cond ((starts-withp (match-string-no-properties 1) "if")
(replace-match (concat (my-make-string cnt ?\s) "#\\1"))
(incf cnt ppindent-increment))
((starts-withp (match-string-no-properties 1) "el")
(when (< (- cnt ppindent-increment) start)
(throw 'err `(,(line-number-at-pos) "Unmatched #else or #elif")))
(replace-match (concat (my-make-string
(- cnt ppindent-increment)
?\s) "#\\1")))
((starts-withp (match-string-no-properties 1) "endif")
(when (< (- cnt ppindent-increment) start)
(throw 'err `(,(line-number-at-pos) "Unmatched #endif")))
(decf cnt ppindent-increment)
(replace-match (concat (my-make-string cnt ?\s) "#\\1")))
(t
(replace-match (concat (my-make-string cnt ?\s) "#\\1")))))))
(defun ppindent-buffer (start)
(let ((result (catch 'err (save-excursion (ppindent-aux start)))))
(when result
(goto-line (car result))
(error "Error: %s" (cadr result)))))
(defun ppindent-c ()
"Indent all C pre-processor statements"
(interactive)
(ppindent-buffer 0))
(defun ppindent-h ()
"Indent C pre-processor statements, keeping first level #ifdef unindented"
(interactive)
(ppindent-buffer (- ppindent-increment)))