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+;;; Array editing commands for Gnu Emacs
+;;;  Written by dmb%morgoth@harvard.harvard.edu (address is old)
+;;;   (David M. Brown at Goldberg-Zoino & Associates, Inc.)
+;;;  Thanks to cph@kleph.ai.mit.edu for assistance
+
+;; Copyright (C) 1987 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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 1, or (at your option)
+;; any later version.
+
+;; GNU Emacs 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, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+;;; To do:
+;;;   Smooth initialization process by grokking local variables list
+;;;     at end of buffer or parsing buffer using whitespace as delimiters.
+;;;   Make 'array-copy-column-right faster.
+
+
+
+;;; Internal information functions.
+  
+(defun array-cursor-in-array-range ()
+  "Returns t if the cursor is in a valid array cell.
+Its ok to be on a row number line."
+  (let ((columns-last-line (% max-column columns-per-line)))
+    ;; Requires buffer-line and buffer-column to be current.
+    (not (or
+          ;; The cursor is too far to the right.
+          (>= buffer-column line-length)
+          ;; The cursor is below the last row.
+          (>= buffer-line (* lines-per-row max-row))
+          ;; The cursor is on the last line of the row, the line is smaller
+          ;;  than the others, and the cursor is after the last array column
+          ;;  on the line.
+          (and (zerop (% (1+ buffer-line) lines-per-row))
+               (not (zerop columns-last-line))
+               (>= buffer-column (* columns-last-line field-width)))))))
+
+(defun array-current-row ()
+  "Return the array row of the field in which the cursor is located."
+  ;; Requires buffer-line and buffer-column to be current.
+  (and (array-cursor-in-array-range)
+       (1+ (floor buffer-line lines-per-row))))
+
+(defun array-current-column ()
+  "Return the array column of the field in which the cursor is located."
+  ;; Requires buffer-line and buffer-column to be current.
+  (and (array-cursor-in-array-range)
+       ;; It's not okay to be on a row number line.
+       (not (and rows-numbered
+                 (zerop (% buffer-line lines-per-row))))
+       (+
+        ;; Array columns due to line differences.
+        (* columns-per-line
+           (if rows-numbered
+               (1- (% buffer-line lines-per-row))
+             (% buffer-line lines-per-row)))
+        ;; Array columns on the current line.
+        (ceiling (1+ buffer-column) field-width))))
+
+(defun array-update-array-position (&optional a-row a-column)
+  "Set `array-row' and `array-column' to their current values or
+to the optional arguments A-ROW and A-COLUMN."
+  ;; Requires that buffer-line and buffer-column be current.
+  (setq array-row (or a-row (array-current-row))
+        array-column (or a-column (array-current-column))))
+
+(defun array-update-buffer-position ()
+  "Set buffer-line and buffer-column to their current values."
+  (setq buffer-line (current-line)
+        buffer-column (current-column)))
+
+
+
+;;; Information commands.
+
+(defun array-what-position ()
+  "Display the row and column in which the cursor is positioned."
+  (interactive)
+  (let ((buffer-line (current-line))
+        (buffer-column (current-column)))
+    (message (format "Array row: %s  Array column: %s" 
+                     (prin1-to-string (array-current-row))
+                     (prin1-to-string (array-current-column))))))
+
+(defun array-display-local-variables ()
+  "Display the current state of the local variables in the minibuffer."
+  (interactive)
+  (let ((buf (buffer-name (current-buffer))))
+    (with-output-to-temp-buffer "*Local Variables*"
+      (buffer-disable-undo standard-output)
+      (terpri)
+      (princ (format " Buffer:             %s\n\n" buf))
+      (princ (format "  max-row:           %s\n"
+                     (prin1-to-string max-row)))
+      (princ (format "  max-column:        %s\n"
+                     (prin1-to-string max-column)))
+      (princ (format "  columns-per-line:  %s\n"
+                     (prin1-to-string columns-per-line)))
+      (princ (format "  field-width:       %s\n"
+                     (prin1-to-string field-width)))
+      (princ (format "  rows-numbered:     %s\n"
+                     (prin1-to-string rows-numbered)))
+      (princ (format "  lines-per-row:     %s\n"
+                     (prin1-to-string lines-per-row)))
+      (princ (format "  line-length:       %s\n"
+                     (prin1-to-string line-length))))))
+
+
+
+;;; Internal movement functions.
+
+(defun array-beginning-of-field (&optional go-there)
+   "Return the column of the beginning of the current field.
+Optional argument GO-THERE, if non-nil, means go there too."
+   ;; Requires that buffer-column be current.
+   (let ((goal-column (- buffer-column (% buffer-column field-width))))
+     (if go-there
+         (move-to-column-untabify goal-column)
+       goal-column)))
+
+(defun array-end-of-field (&optional go-there)
+  "Return the column of the end of the current array field.
+If optional argument GO-THERE is non-nil, go there too."
+  ;; Requires that buffer-column be current.
+  (let ((goal-column (+ (- buffer-column (% buffer-column field-width))
+                        field-width)))
+    (if go-there
+        (move-to-column-untabify goal-column)
+      goal-column)))
+
+(defun array-move-to-cell (a-row a-column)
+  "Move to array row A-ROW and array column A-COLUMN.  
+Leave point at the beginning of the field and return the new buffer column."
+  (let ((goal-line (+ (* lines-per-row (1- a-row))
+                      (if rows-numbered 1 0)
+                      (floor (1- a-column) columns-per-line)))
+        (goal-column (* field-width (% (1- a-column) columns-per-line))))
+    (goto-char (point-min))
+    (forward-line goal-line)
+    (move-to-column-untabify goal-column)))
+
+(defun array-move-to-row (a-row)
+  "Move to array row A-ROW preserving the current array column.
+Leave point at the beginning of the field and return the new array row."
+  ;; Requires that buffer-line and buffer-column be current.
+  (let ((goal-line (+ (* lines-per-row (1- a-row))
+                      (% buffer-line lines-per-row)))
+        (goal-column (- buffer-column (% buffer-column field-width))))
+    (forward-line (- goal-line buffer-line))
+    (move-to-column-untabify goal-column)
+    a-row))
+
+(defun array-move-to-column (a-column)
+  "Move to array column A-COLUMN preserving the current array row.
+Leave point at the beginning of the field and return the new array column."
+  ;; Requires that buffer-line and buffer-column be current.
+  (let ((goal-line (+ (- buffer-line (% buffer-line lines-per-row))
+                      (if rows-numbered 1 0)
+                      (floor (1- a-column) columns-per-line)))
+        (goal-column (* field-width (% (1- a-column) columns-per-line))))
+    (forward-line (- goal-line buffer-line))
+    (move-to-column-untabify goal-column)
+    a-column))
+
+(defun array-move-one-row (sign)
+  "Move one array row in direction SIGN (1 or -1).
+Leave point at the beginning of the field and return the new array row.
+If requested to move beyond the array bounds, signal an error."
+  ;; Requires that buffer-line and buffer-column be current.
+  (let ((goal-column (array-beginning-of-field))
+        (array-row (or (array-current-row)
+                       (error "Cursor is not in a valid array cell."))))
+    (cond ((and (= array-row max-row) (= sign 1))
+           (error "End of array."))
+          ((and (= array-row 1) (= sign -1))
+           (error "Beginning of array."))
+          (t
+           (progn
+             (forward-line (* sign lines-per-row))
+             (move-to-column-untabify goal-column)
+             (+ array-row sign))))))
+
+(defun array-move-one-column (sign)
+  "Move one array column in direction SIGN (1 or -1).
+Leave point at the beginning of the field and return the new array column.
+If requested to move beyond the array bounds, signal an error."
+  ;; Requires that buffer-line and buffer-column be current.
+  (let ((array-column (or (array-current-column)
+                      (error "Cursor is not in a valid array cell."))))
+    (cond ((and (= array-column max-column) (= sign 1))
+           (error "End of array."))
+          ((and (= array-column 1) (= sign -1))
+           (error "Beginning of array."))
+          (t
+           (cond 
+            ;; Going backward from first column on the line.
+            ((and (= sign -1) (= 1 (% array-column columns-per-line)))
+             (forward-line -1)
+             (move-to-column-untabify
+              (* field-width (1- columns-per-line))))
+            ;; Going forward from last column on the line.
+            ((and (= sign 1) (zerop (% array-column columns-per-line)))
+             (forward-line 1))
+            ;; Somewhere in the middle of the line.
+            (t
+             (move-to-column-untabify (+ (array-beginning-of-field)
+                                         (* field-width sign)))))
+           (+ array-column sign)))))
+
+(defun array-normalize-cursor ()
+  "Move the cursor to the first non-whitespace character in the field and,
+if necessary, scroll horizontally to keep the cursor in view."
+  ;; Assumes point is at the beginning of the field.
+  (let ((buffer-column (current-column)))
+    (skip-chars-forward " \t"
+                        (1- (save-excursion (array-end-of-field t) (point))))
+    (array-maybe-scroll-horizontally)))
+
+(defun array-maybe-scroll-horizontally ()
+  "If necessary, scroll horizontally to keep the cursor in view."
+  ;; This is only called from array-normalize-cursor so
+  ;;  buffer-column will always be current.
+  (let ((w-hscroll (window-hscroll))
+        (w-width (window-width)))
+    (cond
+     ((and (>= buffer-column w-hscroll)
+           (<= buffer-column (+ w-hscroll w-width)))
+      ;; It's already visible.  Do nothing.
+      nil)
+     ((> buffer-column (+ w-hscroll w-width))
+      ;; It's to the right.  Scroll left.
+      (scroll-left (- (- buffer-column w-hscroll)
+                      (/ w-width 2))))
+     (t
+      ;; It's to the left.  Scroll right.
+      (scroll-right (+ (- w-hscroll buffer-column)
+                       (/ w-width 2)))))))
+
+
+
+;;; Movement commands.
+
+(defun array-next-row (&optional arg)
+  "Move down one array row, staying in the current array column.
+If optional ARG is given, move down ARG array rows."
+  (interactive "p")
+  (let ((buffer-line (current-line))
+        (buffer-column (current-column)))
+    (if (= (abs arg) 1)
+        (array-move-one-row arg)
+      (array-move-to-row
+       (limit-index (+ (or (array-current-row)
+                           (error "Cursor is not in an array cell."))
+                       arg)
+                    max-row))))
+  (array-normalize-cursor))
+
+(defun array-previous-row (&optional arg)
+  "Move up one array row, staying in the current array column.
+If optional ARG is given, move up ARG array rows."
+  (interactive "p")
+  (array-next-row (- arg)))
+
+(defun array-forward-column (&optional arg)
+  "Move forward one field, staying in the current array row.
+If optional ARG is given, move forward ARG array columns.
+If necessary, keep the cursor in the window by scrolling right or left."
+  (interactive "p")
+  (let ((buffer-line (current-line))
+        (buffer-column (current-column)))
+    (if (= (abs arg) 1)
+        (array-move-one-column arg)
+      (array-move-to-column
+       (limit-index (+ (or (array-current-column)
+                           (error "Cursor is not in an array cell."))
+                       arg)
+                    max-column))))
+  (array-normalize-cursor))
+
+(defun array-backward-column (&optional arg)
+  "Move backward one field, staying in the current array row.
+If optional ARG is given, move backward ARG array columns.
+If necessary, keep the cursor in the window by scrolling right or left."
+  (interactive "p")
+  (array-forward-column (- arg)))
+
+(defun array-goto-cell (a-row a-column)
+  "Go to array row A-ROW and array column A-COLUMN."
+  (interactive "nArray row: \nnArray column: ")
+  (array-move-to-cell
+   (limit-index a-row max-row)
+   (limit-index a-column max-column))
+  (array-normalize-cursor))
+
+
+
+;;; Internal copying functions.
+
+(defun array-field-string ()
+  "Return the field string at the current cursor location."
+  ;; Requires that buffer-column be current.
+  (buffer-substring
+   (save-excursion (array-beginning-of-field t) (point))
+   (save-excursion (array-end-of-field t) (point))))
+
+(defun array-copy-once-vertically (sign)
+  "Copy the current field into one array row in direction SIGN (1 or -1).
+Leave point at the beginning of the field and return the new array row.
+If requested to move beyond the array bounds, signal an error."
+  ;; Requires that buffer-line, buffer-column, and copy-string be current.
+  (let ((a-row (array-move-one-row sign)))
+    (let ((inhibit-quit t))
+      (delete-region (point) (save-excursion (array-end-of-field t) (point)))
+      (insert copy-string))
+    (move-to-column buffer-column)
+    a-row))
+
+(defun array-copy-once-horizontally (sign)
+  "Copy the current field into one array column in direction SIGN (1 or -1).
+Leave point at the beginning of the field and return the new array column.
+If requested to move beyond the array bounds, signal an error."
+  ;; Requires that buffer-line, buffer-column, and copy-string be current.
+  (let ((a-column (array-move-one-column sign)))
+    (array-update-buffer-position)
+    (let ((inhibit-quit t))
+      (delete-region (point) (save-excursion (array-end-of-field t) (point)))
+      (insert copy-string))
+    (move-to-column buffer-column)
+    a-column))
+
+(defun array-copy-to-row (a-row)
+  "Copy the current field vertically into every cell up to and including A-ROW.
+Leave point at the beginning of the field."
+  ;; Requires that buffer-line, buffer-column, array-row, and
+  ;;  copy-string be current.
+  (let* ((num (- a-row array-row))
+         (count (abs num))
+         (sign (if (zerop count) () (/ num count))))
+    (while (> count 0)
+      (array-move-one-row sign)
+      (array-update-buffer-position)
+      (let ((inhibit-quit t))
+        (delete-region (point) (save-excursion (array-end-of-field t) (point)))
+        (insert copy-string))
+      (move-to-column buffer-column)
+      (setq count (1- count)))))
+        
+(defun array-copy-to-column (a-column)
+  "Copy the current field horizontally into every cell up to and including
+A-COLUMN.  Leave point at the beginning of the field."
+  ;; Requires that buffer-line, buffer-column, array-column, and
+  ;;  copy-string be current.
+  (let* ((num (- a-column array-column))
+         (count (abs num))
+         (sign (if (zerop count) () (/ num count))))
+    (while (> count 0)
+      (array-move-one-column sign)
+      (array-update-buffer-position)
+      (let ((inhibit-quit t))
+        (delete-region (point) (save-excursion (array-end-of-field t) (point)))
+        (insert copy-string))
+      (move-to-column buffer-column)
+      (setq count (1- count)))))
+
+(defun array-copy-to-cell (a-row a-column)
+  "Copy the current field into the cell at A-ROW, A-COLUMN.
+Leave point at the beginning of the field."
+  ;; Requires that copy-string be current.
+  (array-move-to-cell a-row a-column)
+  (array-update-buffer-position)
+  (delete-region (point) (save-excursion (array-end-of-field t) (point)))
+  (insert copy-string)
+  (move-to-column buffer-column))
+
+
+
+;;; Commands for copying.
+
+(defun array-copy-down (&optional arg)
+  "Copy the current field one array row down.
+If optional ARG is given, copy down through ARG array rows."
+  (interactive "p")
+  (let* ((buffer-line (current-line))
+         (buffer-column (current-column))
+         (array-row (or (array-current-row)
+                           (error "Cursor is not in a valid array cell.")))
+         (copy-string (array-field-string)))
+    (if (= (abs arg) 1)
+        (array-copy-once-vertically arg)
+      (array-copy-to-row
+       (limit-index (+ array-row arg) max-row))))
+  (array-normalize-cursor))
+
+(defun array-copy-up (&optional arg)
+  "Copy the current field one array row up.
+If optional ARG is given, copy up through ARG array rows."
+  (interactive "p")
+  (array-copy-down (- arg)))
+
+(defun array-copy-forward (&optional arg)
+  "Copy the current field one array column to the right.
+If optional ARG is given, copy through ARG array columns to the right."
+  (interactive "p")
+  (let* ((buffer-line (current-line))
+         (buffer-column (current-column))
+         (array-column (or (array-current-column)
+                           (error "Cursor is not in a valid array cell.")))
+         (copy-string (array-field-string)))
+    (if (= (abs arg) 1)
+        (array-copy-once-horizontally arg)
+      (array-copy-to-column
+       (limit-index (+ array-column arg) max-column))))
+  (array-normalize-cursor))
+
+(defun array-copy-backward (&optional arg)
+  "Copy the current field one array column to the left.
+If optional ARG is given, copy through ARG array columns to the left."
+  (interactive "p")
+  (array-copy-forward (- arg)))
+
+(defun array-copy-column-forward (&optional arg)
+  "Copy the entire current column in to the column to the right.
+If optional ARG is given, copy through ARG array columns to the right."
+  (interactive "p")
+  (array-update-buffer-position)
+  (array-update-array-position)
+  (if (not array-column)
+      (error "Cursor is not in a valid array cell."))
+  (message "Working...")
+  (let ((this-row 0))
+    (while (< this-row max-row)
+      (setq this-row (1+ this-row))
+      (array-move-to-cell this-row array-column)
+      (array-update-buffer-position)
+      (let ((copy-string (array-field-string)))
+        (if (= (abs arg) 1)
+            (array-copy-once-horizontally arg)
+          (array-copy-to-column
+           (limit-index (+ array-column arg) max-column))))))
+  (message "Working...done")
+  (array-move-to-row array-row)
+  (array-normalize-cursor))
+
+(defun array-copy-column-backward (&optional arg)
+  "Copy the entire current column one column to the left.
+If optional ARG is given, copy through ARG columns to the left."
+  (interactive "p")
+  (array-copy-column-forward (- arg)))
+
+(defun array-copy-row-down (&optional arg)
+  "Copy the entire current row one row down.
+If optional ARG is given, copy through ARG rows down."
+  (interactive "p")
+  (array-update-buffer-position)
+  (array-update-array-position)
+  (if (not array-row)
+      (error "Cursor is not in a valid array cell."))
+  (cond
+   ((and (= array-row 1) (= arg -1))
+    (error "Beginning of array."))
+   ((and (= array-row max-row) (= arg 1))
+    (error "End of array."))
+   (t
+    (let* ((copy-string
+            (buffer-substring
+             (save-excursion (array-move-to-cell array-row 1)
+                             (point))
+             (save-excursion (array-move-to-cell array-row max-column)
+                             (forward-line 1)
+                             (point))))
+           (this-row array-row)
+           (goal-row (limit-index (+ this-row arg) max-row))
+           (num (- goal-row this-row))
+           (count (abs num))
+           (sign (if (not (zerop count)) (/ num count))))
+      (while (> count 0)
+        (setq this-row (+ this-row sign))
+        (array-move-to-cell this-row 1)
+        (let ((inhibit-quit t))
+          (delete-region (point)
+                         (save-excursion
+                           (array-move-to-cell this-row max-column)
+                           (forward-line 1)
+                           (point)))
+          (insert copy-string))
+        (setq count (1- count)))
+      (array-move-to-cell goal-row (or array-column 1)))))
+  (array-normalize-cursor))
+
+(defun array-copy-row-up (&optional arg)
+  "Copy the entire current array row into the row above.
+If optional ARG is given, copy through ARG rows up."
+  (interactive "p")
+  (array-copy-row-down (- arg)))
+
+(defun array-fill-rectangle ()
+  "Copy the field at mark into every cell between mark and point."
+  (interactive)
+  ;; Bind arguments.
+  (array-update-buffer-position)
+  (let ((p-row (or (array-current-row)
+                   (error "Cursor is not in a valid array cell.")))
+        (p-column (or (array-current-column)
+                      (error "Cursor is not in a valid array cell.")))
+        (m-row
+         (save-excursion
+           (exchange-point-and-mark)
+           (array-update-buffer-position)
+           (or (array-current-row)
+               (error "Mark is not in a valid array cell."))))
+        (m-column 
+         (save-excursion
+           (exchange-point-and-mark)
+           (array-update-buffer-position)
+           (or (array-current-column)
+               (error "Mark is not in a valid array cell.")))))
+    (message "Working...")
+    (let ((top-row (min m-row p-row))
+          (bottom-row (max m-row p-row))
+          (left-column (min m-column p-column))
+          (right-column (max m-column p-column)))
+      ;; Do the first row.
+      (let ((copy-string
+             (save-excursion
+               (array-move-to-cell m-row m-column)
+               (array-update-buffer-position)
+               (array-field-string))))
+        (array-copy-to-cell top-row left-column)
+        (array-update-array-position top-row left-column)
+        (array-update-buffer-position)
+        (array-copy-to-column right-column))
+      ;; Do the rest of the rows.
+      (array-move-to-cell top-row left-column)
+      (let ((copy-string
+             (buffer-substring
+              (point)
+              (save-excursion
+                (array-move-to-cell top-row right-column)
+                (setq buffer-column (current-column))
+                (array-end-of-field t)
+                (point))))
+            (this-row top-row))
+        (while (/= this-row bottom-row)
+          (setq this-row (1+ this-row))
+          (array-move-to-cell this-row left-column)
+          (let ((inhibit-quit t))
+            (delete-region
+             (point)
+             (save-excursion
+               (array-move-to-cell this-row right-column)
+               (setq buffer-column (current-column))
+               (array-end-of-field t)
+               (point)))
+            (insert copy-string)))))
+    (message "Working...done")
+    (array-goto-cell p-row p-column)))
+
+
+
+;;; Reconfiguration of the array.
+
+(defun array-make-template ()
+  "Create the template of an array."
+  (interactive)
+  ;; If there is a conflict between field-width and init-string, resolve it.
+  (let ((check t)
+        (len))
+    (while check
+      (setq init-field (read-input "Initial field value: "))
+      (setq len (length init-field))
+      (if (/= len field-width)
+          (if (y-or-n-p (format "Change field width to %d? " len))
+              (progn (setq field-width len)
+                     (setq check nil)))
+        (setq check nil))))
+  (goto-char (point-min))
+  (message "Working...")
+  (let ((this-row 1))
+    ;; Loop through the rows.
+    (while (<= this-row max-row)
+      (if rows-numbered
+          (insert (format "%d:\n" this-row)))
+      (let ((this-column 1))
+        ;; Loop through the columns.
+        (while (<= this-column max-column)
+          (insert init-field)
+          (if (and (zerop (% this-column columns-per-line))
+                   (/= this-column max-column))
+              (newline))
+          (setq this-column (1+ this-column))))
+      (setq this-row (1+ this-row))
+      (newline)))
+  (message "Working...done")
+  (array-goto-cell 1 1))
+
+(defun array-reconfigure-rows (new-columns-per-line new-rows-numbered)
+  "Reconfigure the state of `rows-numbered' and `columns-per-line'.
+NEW-COLUMNS-PER-LINE is the desired value of `columns-per-line' and
+NEW-ROWS-NUMBERED (a character, either ?y or ?n) is the desired value
+of rows-numbered."
+  (interactive "nColumns per line: \ncRows numbered? (y or n) ")
+  ;; Check on new-columns-per-line
+  (let ((check t))
+    (while check
+      (if (and (>= new-columns-per-line 1)
+               (<= new-columns-per-line max-column))
+          (setq check nil)
+        (setq new-columns-per-line
+              (string-to-int 
+               (read-input 
+                (format "Columns per line (1 - %d): " max-column)))))))
+  ;; Check on new-rows-numbered.  It has to be done this way
+  ;;  because interactive does not have y-or-n-p.
+  (cond
+   ((eq new-rows-numbered ?y)
+    (setq new-rows-numbered t))
+   ((eq new-rows-numbered ?n)
+    (setq new-rows-numbered nil))
+   (t
+    (setq new-rows-numbered (y-or-n-p "Rows numbered? "))))
+  (message "Working...")
+  (array-update-buffer-position)
+  (let* ((main-buffer (buffer-name (current-buffer)))
+         (temp-buffer (make-temp-name "Array"))
+         (temp-max-row max-row)
+         (temp-max-column max-column)
+         (old-rows-numbered rows-numbered)
+         (old-columns-per-line columns-per-line)
+         (old-lines-per-row lines-per-row)
+         (old-field-width field-width)
+         (old-line-length line-length)
+         (this-row 1))
+    (array-update-array-position)
+    ;; Do the cutting in a temporary buffer.
+    (copy-to-buffer temp-buffer (point-min) (point-max))
+    (set-buffer temp-buffer)
+    (goto-char (point-min))
+    (while (<= this-row temp-max-row)
+      ;; Deal with row number.
+      (cond
+       ((or (and old-rows-numbered new-rows-numbered)
+            (and (not old-rows-numbered) (not new-rows-numbered)))
+        ;; Nothing is changed.
+        ())
+       ((and old-rows-numbered (not new-rows-numbered))
+        ;; Delete the row number.
+        (kill-line 1))
+       (t
+        ;; Add the row number.
+        (insert-string (format "%d:\n" this-row))))
+      ;; Deal with the array columns in this row.
+      (cond
+       ((= old-columns-per-line new-columns-per-line)
+        ;; Nothing is changed.  Go to the next row.
+        (forward-line (- old-lines-per-row (if old-rows-numbered 1 0))))
+       (t
+        ;; First expand the row.  Then cut it up into new pieces.
+        (let ((newlines-to-be-removed
+               (floor (1- temp-max-column) old-columns-per-line))
+              (newlines-removed 0)
+              (newlines-to-be-added
+               (floor (1- temp-max-column) new-columns-per-line))
+              (newlines-added 0))
+          (while (< newlines-removed newlines-to-be-removed)
+            (move-to-column-untabify
+             (* (1+ newlines-removed) old-line-length))
+            (kill-line 1)
+            (setq newlines-removed (1+ newlines-removed)))
+          (beginning-of-line)
+          (while (< newlines-added newlines-to-be-added)
+            (move-to-column-untabify (* old-field-width new-columns-per-line))
+            (newline)
+            (setq newlines-added (1+ newlines-added)))
+          (forward-line 1))))
+      (setq this-row (1+ this-row)))
+    (let ((inhibit-quit t))
+      (set-buffer main-buffer)
+      (erase-buffer)
+      (insert-buffer temp-buffer) 
+      ;; Update local variables.
+      (setq columns-per-line new-columns-per-line)
+      (setq rows-numbered new-rows-numbered)
+      (setq line-length (* old-field-width new-columns-per-line))
+      (setq lines-per-row 
+            (+ (ceiling temp-max-column new-columns-per-line)
+               (if new-rows-numbered 1 0)))
+      (array-goto-cell (or array-row 1) (or array-column 1)))
+    (kill-buffer temp-buffer))
+  (message "Working...done"))
+
+(defun array-expand-rows ()
+  "Expand the rows so each fits on one line and remove row numbers."
+  (interactive)
+  (array-reconfigure-rows max-column ?n))
+
+
+
+;;; Utilities.
+
+(defun limit-index (index limit)
+  (cond ((< index 1) 1)
+        ((> index limit) limit)
+        (t index)))
+
+(defun abs (int)
+  "Return the absolute value of INT."
+  (if (< int 0) (- int) int))
+
+
+(defun floor (int1 int2)
+  "Returns the floor of INT1 divided by INT2.
+INT1 may be negative.  INT2 must be positive."
+  (if (< int1 0)
+      (- (ceiling (- int1) int2))
+      (/ int1 int2)))
+
+(defun ceiling (int1 int2)
+  "Returns the ceiling of INT1 divided by INT2.
+Assumes that both arguments are nonnegative."
+  (+ (/ int1 int2)
+     (if (zerop (mod int1 int2))
+         0
+         1)))
+
+(defun xor (pred1 pred2)
+  "Returns the logical exclusive or of predicates PRED1 and PRED2."
+  (and (or pred1 pred2)
+       (not (and pred1 pred2))))
+
+(defun current-line ()
+  "Return the current buffer line at point.  The first line is 0." 
+  (save-excursion
+    (beginning-of-line)
+    (count-lines (point-min) (point))))
+
+(defun move-to-column-untabify (column)
+  "Move to COLUMN on the current line, untabifying if necessary.
+Return COLUMN."
+  (or (and (= column (move-to-column column))
+           column)
+      ;; There is a tab in the way.
+      (if respect-tabs
+          (error "There is a TAB character in the way.")
+        (progn
+          (untabify-backward)
+          (move-to-column column)))))
+
+(defun untabify-backward ()
+  "Untabify the preceding tab."
+  (save-excursion
+    (let ((start (point)))
+      (backward-char 1)
+      (untabify (point) start))))
+
+
+
+;;; Array mode.
+
+(defvar array-mode-map nil 
+  "Keymap used in array mode.")
+
+(if array-mode-map
+    ()
+  (setq array-mode-map (make-keymap))
+  ;; Bind keys.
+  (define-key array-mode-map "\M-ad"   'array-display-local-variables)
+  (define-key array-mode-map "\M-am"   'array-make-template)
+  (define-key array-mode-map "\M-ae"   'array-expand-rows)
+  (define-key array-mode-map "\M-ar"   'array-reconfigure-rows)
+  (define-key array-mode-map "\M-a="   'array-what-position)
+  (define-key array-mode-map "\M-ag"   'array-goto-cell)
+  (define-key array-mode-map "\M-af"   'array-fill-rectangle)
+  (define-key array-mode-map "\C-n"    'array-next-row)
+  (define-key array-mode-map "\C-p"    'array-previous-row)
+  (define-key array-mode-map "\C-f"    'array-forward-column)
+  (define-key array-mode-map "\C-b"    'array-backward-column)
+  (define-key array-mode-map "\M-n"    'array-copy-down)
+  (define-key array-mode-map "\M-p"    'array-copy-up)
+  (define-key array-mode-map "\M-f"    'array-copy-forward)
+  (define-key array-mode-map "\M-b"    'array-copy-backward)
+  (define-key array-mode-map "\M-\C-n" 'array-copy-row-down)
+  (define-key array-mode-map "\M-\C-p" 'array-copy-row-up)
+  (define-key array-mode-map "\M-\C-f" 'array-copy-column-forward)
+  (define-key array-mode-map "\M-\C-b" 'array-copy-column-backward))
+
+(put 'array-mode 'mode-class 'special)
+
+(defun array-mode ()
+  "Major mode for editing arrays.
+
+  Array mode is a specialized mode for editing arrays.  An array is
+considered to be a two-dimensional set of strings.  The strings are
+NOT recognized as integers or real numbers.
+
+  The array MUST reside at the top of the buffer.  
+
+  TABs are not respected, and may be converted into spaces at any time.
+Setting the variable 'respect-tabs to non-nil will prevent TAB conversion,
+but will cause many functions to give errors if they encounter one.
+
+  Upon entering array mode, you will be prompted for the values of
+several variables.  Others will be calculated based on the values you
+supply.  These variables are all local the the buffer.  Other buffer
+in array mode may have different values assigned to the variables.
+The variables are:
+
+Variables you assign:
+     max-row:          The number of rows in the array.
+     max-column:       The number of columns in the array. 
+     columns-per-line: The number of columns in the array per line of buffer.
+     field-width:      The width of each field, in characters.
+     rows-numbered:    A logical variable describing whether to ignore
+                       row numbers in the buffer.
+
+Variables which are calculated:
+     line-length:      The number of characters in a buffer line.
+     lines-per-row:    The number of buffer lines used to display each row.
+
+  The following commands are available (an asterisk indicates it may
+take a numeric prefix argument):
+
+    *   \\<array-mode-map>\\[array-forward-column]        Move forward one column.
+    *   \\[array-backward-column]         Move backward one column.
+    *   \\[array-next-row]        Move down one row.
+    *   \\[array-previous-row]    Move up one row.
+
+    *   \\[array-copy-forward]    Copy the current field into the column to the right.
+    *   \\[array-copy-backward]   Copy the current field into the column to the left.
+    *   \\[array-copy-down]       Copy the current field into the row below.
+    *   \\[array-copy-up]         Copy the current field into the row above.
+
+    *   \\[array-copy-column-forward]   Copy the current column into the column to the right.
+    *   \\[array-copy-column-backward]   Copy the current column into the column to the left.
+    *   \\[array-copy-row-down]   Copy the current row into the row below.
+    *   \\[array-copy-row-up]   Copy the current row into the row above.
+
+        \\[array-fill-rectangle]   Copy the field at mark into every cell with row and column
+                  between that of point and mark.
+
+        \\[array-what-position]   Display the current array row and column.
+        \\[array-goto-cell]       Go to a particular array cell.
+
+        \\[array-make-template]   Make a template for a new array.
+        \\[array-reconfigure-rows]        Reconfigure the array.
+        \\[array-expand-rows]   Expand the array (remove row numbers and
+                  newlines inside rows)
+
+        \\[array-display-local-variables]   Display the current values of local variables.
+
+Entering array mode calls the function `array-mode-hook'."
+
+  (interactive)
+  ;; Number of rows in the array.
+  (make-local-variable 'max-row)    
+  ;; Number of columns in the array.
+  (make-local-variable 'max-column)    
+  ;; Number of array columns per line.
+  (make-local-variable 'columns-per-line) 
+  ;; Width of a field in the array.
+  (make-local-variable 'field-width)   
+  ;; Are rows numbered in the buffer?
+  (make-local-variable 'rows-numbered) 
+  ;; Length of a line in the array.
+  (make-local-variable 'line-length)   
+  ;; Number of lines per array row.
+  (make-local-variable 'lines-per-row) 
+  ;; Current line number of point in the buffer.
+  (make-local-variable 'buffer-line)
+  ;; Current column number of point in the buffer.
+  (make-local-variable 'buffer-column)
+  ;; Current array row location of point.
+  (make-local-variable 'array-row)
+  ;; Current array column location of point.
+  (make-local-variable 'array-column)
+  ;; Current field string being copied.
+  (make-local-variable 'copy-string)
+  ;; Should TAB conversion be prevented?
+  (make-local-variable 'respect-tabs)
+  (setq respect-tabs nil)
+  (array-init-local-variables)
+  (setq major-mode 'array-mode)
+  (setq mode-name "Array")
+  ;; Update mode-line.
+  (progn (save-excursion (set-buffer (other-buffer)))
+         (set-buffer-modified-p (buffer-modified-p))
+         (sit-for 0))
+  (make-variable-buffer-local 'truncate-lines)
+  (setq truncate-lines t)
+  (setq overwrite-mode t)
+  (use-local-map array-mode-map)
+  (run-hooks 'array-mode-hook))
+
+
+
+;;; Initialization functions.  These are not interactive.
+
+(defun array-init-local-variables ()
+  "Initialize the variables associated with the
+array in this buffer."
+  (array-init-max-row)
+  (array-init-max-column)
+  (array-init-columns-per-line)
+  (array-init-field-width)
+  (array-init-rows-numbered)
+  (array-init-line-length)
+  (array-init-lines-per-row)
+  (message ""))
+
+(defun array-init-max-row (&optional arg)
+  "Initialize the value of max-row."
+  (setq max-row
+        (or arg (string-to-int (read-input "Number of array rows: ")))))
+
+(defun array-init-max-column (&optional arg)
+  "Initialize the value of max-column."
+  (setq max-column
+        (or arg (string-to-int (read-input "Number of array columns: ")))))
+
+(defun array-init-columns-per-line (&optional arg)
+  "Initialize the value of columns-per-line."
+  (setq columns-per-line 
+        (or arg (string-to-int (read-input "Array columns per line: ")))))
+
+(defun array-init-field-width (&optional arg)
+  "Initialize the value of field-width."
+  (setq field-width 
+        (or arg (string-to-int (read-input "Field width: ")))))
+
+(defun array-init-rows-numbered (&optional arg)
+  "Initialize the value of rows-numbered."
+  (setq rows-numbered 
+        (or arg (y-or-n-p "Rows numbered? "))))
+
+(defun array-init-line-length (&optional arg)
+  "Initialize the value of line-length."
+  (setq line-length
+        (or arg
+          (* field-width columns-per-line))))
+
+(defun array-init-lines-per-row (&optional arg)
+  "Initialize the value of lines-per-row."
+  (setq lines-per-row
+        (or arg
+          (+ (ceiling max-column columns-per-line)
+             (if rows-numbered 1 0)))))