;; Indentation commands for Emacs
;; Copyright (C) 1985 Free Software Foundation, Inc.

;; This file is part of GNU Emacs.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY.  No author or distributor
;; accepts responsibility to anyone for the consequences of using it
;; or for whether it serves any particular purpose or works at all,
;; unless he says so in writing.  Refer to the GNU Emacs General Public
;; License for full details.

;; Everyone is granted permission to copy, modify and redistribute
;; GNU Emacs, but only under the conditions described in the
;; GNU Emacs General Public License.   A copy of this license is
;; supposed to have been given to you along with GNU Emacs so you
;; can know your rights and responsibilities.  It should be in a
;; file named COPYING.  Among other things, the copyright notice
;; and this notice must be preserved on all copies.


;Now in loaddefs.el
;(defvar indent-line-function
;  'indent-to-left-margin
;  "Function to indent current line.")

(defun indent-according-to-mode ()
  "Indent line in proper way for current major mode."
  (interactive)
  (funcall indent-line-function))

(defun indent-for-tab-command ()
  "Indent line in proper way for current major mode."
  (interactive)
  (if (eq indent-line-function 'indent-to-left-margin)
      (insert-tab)
    (funcall indent-line-function)))

(defun insert-tab ()
  (if abbrev-mode
      (expand-abbrev))
  (if indent-tabs-mode
      (insert ?\t)
    (indent-to (* tab-width (1+ (/ (current-column) tab-width))))))

(defun indent-rigidly (start end arg)
  "Indent all lines starting in the region sideways by ARG columns.
Called from a program, takes three arguments, START, END and ARG."
  (interactive "r\np")
  (save-excursion
    (goto-char end)
    (setq end (point-marker))
    (goto-char start)
    (or (bolp) (forward-line 1))
    (while (< (point) end)
      (let ((indent (current-indentation)))
	(delete-region (point) (progn (skip-chars-forward " \t") (point)))
	(or (eolp)
	    (indent-to (max 0 (+ indent arg)) 0)))
      (forward-line 1))
    (move-marker end nil)))

;; This is the default indent-line-function,
;; used in Fundamental Mode, Text Mode, etc.
(defun indent-to-left-margin ()
  (or (= (current-indentation) left-margin)
      (let (epos)
	(save-excursion
	 (beginning-of-line)
	 (delete-region (point)
			(progn (skip-chars-forward " \t")
			       (point)))
	 (indent-to left-margin)
	 (setq epos (point)))
	(if (< (point) epos)
	    (goto-char epos)))))

(defvar indent-region-function nil
  "Function which is short cut to indent each line in region with Tab.
nil means really call Tab on each line.")

(defun indent-region (start end arg)
  "Indent each nonblank line in the region.
With no argument, indent each line with Tab.
With argument COLUMN, indent each line to that column.
Called from a program, takes three args: START, END and COLUMN."
  (interactive "r\nP")
  (if (null arg)
      (if indent-region-function
	  (funcall indent-region-function start end)
	(save-excursion
	 (goto-char end)
	 (setq end (point-marker))
	 (goto-char start)
	 (or (bolp) (forward-line 1))
	 (while (< (point) end)
	   (funcall indent-line-function)
	   (forward-line 1))
	 (move-marker end nil)))
    (setq arg (prefix-numeric-value arg))
  (save-excursion
   (goto-char end)
   (setq end (point-marker))
   (goto-char start)
   (or (bolp) (forward-line 1))
   (while (< (point) end)
     (delete-region (point) (progn (skip-chars-forward " \t") (point)))
     (or (eolp)
	 (indent-to arg 0))
     (forward-line 1))
   (move-marker end nil))))

(defun indent-relative-maybe ()
  "Indent a new line like previous nonblank line."
  (interactive)
  (indent-relative t))

(defun indent-relative (&optional unindented-ok)
  "Space out to under next indent point in previous nonblank line.
An indent point is a non-whitespace character following whitespace.
If the previous nonblank line has no indent points beyond
the column point starts at,  tab-to-tab-stop  is done instead."
  (interactive "P")
  (if abbrev-mode (expand-abbrev))
  (let ((start-column (current-column))
	indent)
    (save-excursion
      (beginning-of-line)
      (if (re-search-backward "^[^\n]" nil t)
	  (let ((end (save-excursion (forward-line 1) (point))))
	    (move-to-column start-column)
	    ;; Is start-column inside a tab on this line?
	    (if (> (current-column) start-column)
		(backward-char 1))
	    (or (looking-at "[ \t]")
		unindented-ok
		(skip-chars-forward "^ \t" end))
	    (skip-chars-forward " \t" end)
	    (or (= (point) end) (setq indent (current-column))))))
    (if indent
	(let ((opoint (point-marker)))
	  (delete-region (point) (progn (skip-chars-backward " \t") (point)))
	  (indent-to indent 0)
	  (if (> opoint (point))
	      (goto-char opoint))
	  (move-marker opoint nil))
      (tab-to-tab-stop))))

(defvar tab-stop-list
  '(8 16 24 32 40 48 56 64 72 80 88 96 104 112 120)
  "*List of tab stop positions used by tab-to-tab-stops.")

(defvar edit-tab-stops-map nil "Keymap used in edit-tab-stops.")
(if edit-tab-stops-map
    nil
  (setq edit-tab-stops-map (make-sparse-keymap))
  (define-key edit-tab-stops-map "\C-x\C-s" 'edit-tab-stops-note-changes)
  (define-key edit-tab-stops-map "\C-c\C-c" 'edit-tab-stops-note-changes))

(defvar edit-tab-stops-buffer nil
  "Buffer whose tab stops are being edited--in case
the variable tab-stop-list is local in that buffer.")

(defun edit-tab-stops ()
  "Edit the tab stops used by tab-to-tab-stop.
Creates a buffer *Tab Stops* containing text describing the tab stops.
A colon indicates a column where there is a tab stop.
You can add or remove colons and then do C-c C-c to make changes take effect."
  (interactive)
  (setq edit-tab-stops-buffer (current-buffer))
  (switch-to-buffer (get-buffer-create "*Tab Stops*"))
  (use-local-map edit-tab-stops-map)
  (make-local-variable 'indent-tabs-mode)
  (setq indent-tabs-mode nil)
  (overwrite-mode 1)
  (setq truncate-lines t)
  (erase-buffer)
  (let ((tabs tab-stop-list))
    (while tabs
      (indent-to (car tabs) 0)
      (insert ?:)
      (setq tabs (cdr tabs))))
  (let ((count 0))
    (insert ?\n)
    (while (< count 8)
      (insert (+ count ?0))
    (insert "         ")
      (setq count (1+ count)))
    (insert ?\n)
    (while (> count 0)
      (insert "0123456789")
      (setq count (1- count))))
  (insert "\nTo install changes, type C-c C-c")
  (goto-char (point-min)))

(defun edit-tab-stops-note-changes ()
  "Put edited tab stops into effect."
  (interactive)
    (let (tabs)
      (save-excursion
	(goto-char 1)
	(end-of-line)
	(while (search-backward ":" nil t)
	  (setq tabs (cons (current-column) tabs))))
      (bury-buffer (prog1 (current-buffer)
			  (switch-to-buffer edit-tab-stops-buffer)))
      (setq tab-stop-list tabs))
  (message "Tab stops installed"))

(defun tab-to-tab-stop ()
  "Insert spaces or tabs to next defined tab-stop column.
The variable tab-stop-list is a list of columns at which there are tab stops.
Use \\[edit-tab-stops] to edit them interactively."
  (interactive)
  (if abbrev-mode (expand-abbrev))
  (let ((tabs tab-stop-list))
    (while (and tabs (>= (current-column) (car tabs)))
      (setq tabs (cdr tabs)))
    (if tabs
	(indent-to (car tabs))
      (insert ? ))))

(define-key global-map "\t" 'indent-for-tab-command)
(define-key esc-map "\034" 'indent-region)
(define-key ctl-x-map "\t" 'indent-rigidly)
(define-key esc-map "i" 'tab-to-tab-stop)
