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;;; dabbrev.el --- dynamic abbreviation package
;; Copyright (C) 1985, 1986, 1992, 1994 Free Software Foundation, Inc.

;; Author: Don Morrison
;; Maintainer: Lars Lindberg <Lars.Lindberg@sypro.cap.se>
;; Created: 16 Mars 1992
;; Lindberg's last update version: 5.2
;; Keywords: abbrev expand completion

;; This program 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 of the License, or
;; (at your option) any later version.
;;
;; This program 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 this program; if not, write to the Free Software
;; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Commentary:

;; The purpose with this package is to let you write just a few
;; characters of words you've written earlier to be able to expand
;; them.
;;
;; To expand a word, just put the point right after the word and press
;; M-/ (dabbrev-expand) or M-C-/ (dabbrev-completion).
;;
;; There are powerful things in this package that aren't turned on by
;; default.  I recommend you to do the following.
;;
;; Put the following 2 lines in your .emacs file:
;; (setq dabbrev-always-check-other-buffers t)
;; (setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
;;
;; Dabbrev will now search in all buffers with the same major mode for
;; your expansions.  It will also search for complete symbols, the old
;; dabbrev package only looked half-heartedly for symbols.
;;
;; Check out the customizable variables below to learn about all the
;; features of this package.

;;; Hints and tips for major modes writers:

;; Recommended values           C/Lisp etc      text
;; dabbrev-case-fold-search     nil             t
;; dabbrev-case-replace         nil             t
;;
;; Set the variables you want special for your mode like this:
;; (set (make-local-variable 'dabbrev-case-replace) nil)
;; Then you don't interfer with other modes.
;;
;; If your mode handles buffers that refers to other buffers
;; (i.e. compilation-mode, gud-mode), then try to set
;; `dabbrev-select-buffers-function' or `dabbrev-friend-buffer-function'
;; to a function that point out those buffers.

;; Same goes for major-modes that are connected to other modes.  There
;; are for instance a number of mail-modes.  One for reading, one for
;; creating a new mail etc.  Maybe those should be connected.

;; Example for GNUS (when we write a reply, we want dabbrev to look in
;; the article for expansion):
;; (set (make-local-variable 'dabbrev-friend-buffer-function)
;;      (lambda (buffer)
;;         (save-excursion
;;           (set-buffer buffer)
;;           (memq major-mode '(news-reply-mode gnus-article-mode)))))


;; Known bugs and limitations.
;; - Possible to do several levels of `dabbrev-completion' in the
;;   minibuffer.
;; - dabbrev-completion doesn't handle resetting the globals variables
;;   right.  It resets them after finding the abbrev.

;; Future enhancements
;;  - Check the tags-files? Like tags-complete?
;;  - Add the possibility of searching both forward and backward to
;;    the nearest expansion.
;;  - Check the kill-ring when everything else fails.  (Maybe something
;;  for hippie-expand?).  [Bng] <boris@cs.rochester.edu>

;;; Thanks goes to
;;  [hymie]     Hyman Rosen <marks!hymie@jyacc.jyacc.com>
;;  [burgett]   Steve Burgett <burgett@bizet.eecs.berkeley.edu>
;;  [jules]     Julian Gosnell <jules@x.co.uk>
;;  [kifer]     Michael Kifer <kifer@sbcs.sunysb.edu>
;;  [ake]       Ake Stenhoff <extaksf@aom.ericsson.se>
;;  [alon]      Alon Albert <al%imercury@uunet.uu.net>
;;  [tromey]    Tom Tromey <tromey@busco.lanl.gov>
;;  [Rolf]      Rolf Schreiber <rolf@mathematik.uni-stuttgart.de>
;;  [Petri]     Petri Raitio <per@tekla.fi>
;;  [ejb]       Jay Berkenbilt <ejb@ERA.COM>
;;  [hawley]    Bob Hawley <rth1@quartet.mt.att.com>
;;  ... and to all the people who have participated in the beta tests.

;;; Code:

;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
;;; Customization variables
;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
(defvar dabbrev-backward-only nil
  "*If non-nil, `dabbrev-expand' only looks backwards.")

(defvar dabbrev-limit nil
  "*Limits region searched by `dabbrev-expand' to this many chars away.")

(defvar dabbrev-abbrev-skip-leading-regexp nil
  "*Regexp for skipping leading characters of an abbreviation.

Example: Set this to \"\\\\$\" for programming languages
in which variable names may appear with or without a leading `$'.
(For example, in Makefiles.)

Set this to nil if no characters should be skipped.")

;; I recommend that you set this to nil.
(defvar dabbrev-case-fold-search 'case-fold-search
  "*Non-nil if dabbrev searches should ignore case.
A value of nil means case is significant.

The value of this variable is an expression; it is evaluated
and the resulting value determines the decision.
For example: setting this to `case-fold-search' means evaluate that
variable to see whether its value is nil.")

(defvar dabbrev-upcase-means-case-search nil
  "*The significance of an uppercase character in an abbreviation.
nil means case fold search, non-nil means case sensitive search.

This variable has an effect only when the value of
`dabbrev-case-fold-search' evaluates to t.")

;; I recommend that you set this to nil.
(defvar dabbrev-case-replace 'case-replace
  "*Non-nil means dabbrev should preserve case when expanding the abbreviation.
The value of this variable is an expression; it is evaluated
and the resulting value determines the decision.
For example, setting this to `case-replace' means evaluate that
variable to see if its value is t or nil.

This variable has an effect only when the value of
`dabbrev-case-fold-search' evaluates to t.")

(defvar dabbrev-abbrev-char-regexp "\\sw\\|\\s_"
  "*Regexp to recognize a character in an abbreviation or expansion.
This regexp will be surrounded with \\\\( ... \\\\) when actually used.

Set this variable to \"\\\\sw\" if you want ordinary words or
\"\\\\sw\\\\|\\\\s_\" if you want symbols.

You can also set it to nil if you want old-style dabbrev searching
\(the abbreviation is from point to previous word-start, the
search is for symbols).

For instance, if you are programming in Lisp, `yes-or-no-p' is a symbol,
while `yes', `or', `no' and `p' are considered words.  If you set this
variable to nil, then expanding `yes-or-no-' looks for a symbol
starting with or containing `no-'.  If you set this variable to
\"\\\\sw\\\\|\\\\s_\", that expansion looks for a symbol starting with
`yes-or-no-'.  Finally, if you set this variable to \"\\\\sw\", then
expanding `yes-or-no-' signals an error because `-' is not part of a word;
but expanding `yes-or-no' looks for a word starting with `no'.

The recommended value is \"\\\\sw\\\\|\\\\s_\".")

(defvar dabbrev-check-rest-of-buffers t
  "*Non-nil means dabbrev package should search in all buffers.
It searches the buffers pointed out by `dabbrev-select-buffers-function'
first; afterward it looks in the rest of the buffers.")


;; I recommend that you set this to t.
(defvar dabbrev-always-check-other-buffers nil
  "*Should \\[dabbrev-expand] look in other buffers?\
nil = Don't look in other buffers.\n\
t = Look in other buffers.\n\
Value other than nil and t = ask the user if he want's to look in
other buffers.

The recommended value is t.")

;; I guess setting this to a function that selects all C- or C++-
;; mode buffers would be a good choice for a debugging buffer,
;; when debugging C- or C++-code.
(defvar dabbrev-select-buffers-function 'dabbrev--select-buffers
  "A function that selects buffers that should be searched by dabbrev.

The function should take no arguments and return a list of buffers to
search for expansions.  Have a look at `dabbrev--select-buffers' for
an example.

A mode setting this variable should make it buffer local.")

(defvar dabbrev-friend-buffer-function 'dabbrev--same-major-mode-p
  "*A function to check if OTHER-BUFFER should be searched by dabbrev.

The function should take one argument, OTHER-BUFFER, and return
non-nil if that buffer should be searched.  Have a look at
`dabbrev--same-major-mode-p' for an example.

The value of `dabbrev-friend-buffer-function' has an effect only if
the value of `dabbrev-select-buffers-function' uses it.  The function
`dabbrev--select-buffers' is one function you can use here.

A mode setting this variable should make it buffer local.")

(defvar dabbrev-search-these-buffers-only nil
  "If non-nil, a list of buffers which dabbrev should search.
If this variable is non-nil, dabbrev will only look in these buffers.
It will not even look in the current buffer if it is not a member of
this list.")

;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
;;; Internal variables
;;;----------------------------------------------------------------
;;;----------------------------------------------------------------

;; Last obarray of completions in `dabbrev-completion'
(defvar dabbrev--last-obarray nil)

;; Table of expansions seen so far
(defvar dabbrev--last-table nil)

;; Last string we tried to expand.
(defvar dabbrev--last-abbreviation nil)

;; Location last abbreviation began
(defvar dabbrev--last-abbrev-location nil)

;; Direction of last dabbrevs search
(defvar dabbrev--last-direction 0)

;; Last expansion of an abbreviation.
(defvar dabbrev--last-expansion nil)

;; Location the last expansion was found.
(defvar dabbrev--last-expansion-location nil)

;; The list of remaining buffers with the same mode as current buffer.
(defvar dabbrev--friend-buffer-list nil)

;; The buffer we looked in last.
(defvar dabbrev--last-buffer nil)

;; The buffer we found the expansion last time.
(defvar dabbrev--last-buffer-found nil)

;; The buffer we last did a completion in.
(defvar dabbrev--last-completion-buffer nil)

;; Same as dabbrev-always-check-other-buffers, but is set for every expand.
(defvar dabbrev--check-other-buffers dabbrev-always-check-other-buffers)

;; The regexp for recognizing a character in an abbreviation.
(defvar dabbrev--abbrev-char-regexp nil)

;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
;;; Macros
;;;----------------------------------------------------------------
;;;----------------------------------------------------------------

;;; Get the buffer that mini-buffer was activated from
(defsubst dabbrev--minibuffer-origin ()
  (car (cdr (buffer-list))))

;; Make a list of some of the elements of LIST.
;; Check each element of LIST, storing it temporarily in the
;; variable ELEMENT, and include it in the result
;; if CONDITION evaluates non-nil.
(defmacro dabbrev-filter-elements (element list condition)
  (` (let (dabbrev-result dabbrev-tail (, element))
       (setq dabbrev-tail (, list))
       (while dabbrev-tail
         (setq (, element) (car dabbrev-tail))
         (if (, condition)
             (setq dabbrev-result (cons (, element) dabbrev-result)))
         (setq dabbrev-tail (cdr dabbrev-tail)))
       (nreverse dabbrev-result))))

;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
;;; Exported functions
;;;----------------------------------------------------------------
;;;----------------------------------------------------------------

;;;###autoload
(define-key esc-map "/" 'dabbrev-expand)
;;;??? Do we want this?
;;;###autoload
(define-key esc-map [?\C-/] 'dabbrev-completion)

;;;###autoload
(defun dabbrev-completion (&optional arg)
  "Completion on current word.
Like \\[dabbrev-expand] but finds all expansions in the current buffer
and presents suggestions for completion.

With a prefix argument, it searches all buffers accepted by the
function pointed out by `dabbrev-friend-buffer-function' to find the
completions.

If the prefix argument is 16 (which comes from C-u C-u),
then it searches *all* buffers.

With no prefix argument, it reuses an old completion list
if there is a suitable one already."

  (interactive "*P")
  (let* ((dabbrev-always-check-other-buffers (and arg t))
         (dabbrev-check-rest-of-buffers
          (and arg (= (prefix-numeric-value arg) 16)))
         (abbrev (dabbrev--abbrev-at-point))
         (ignore-case-p  (and (eval dabbrev-case-fold-search)
                                (or (not dabbrev-upcase-means-case-search)
                                    (string= abbrev (downcase abbrev)))))
         (my-obarray dabbrev--last-obarray)
         init)
    (save-excursion
      (if (and (null arg)
               my-obarray
               (or (eq dabbrev--last-completion-buffer (current-buffer))
                   (and (window-minibuffer-p (selected-window))
                        (eq dabbrev--last-completion-buffer
                            (dabbrev--minibuffer-origin))))
               dabbrev--last-abbreviation
               (>= (length abbrev) (length dabbrev--last-abbreviation))
               (string= dabbrev--last-abbreviation
                        (substring abbrev 0
                                   (length dabbrev--last-abbreviation)))
               (setq init (try-completion abbrev my-obarray)))
          ;; We can reuse the existing completion list.
          nil
        ;;--------------------------------
        ;; New abbreviation to expand.
        ;;--------------------------------
        (dabbrev--reset-global-variables)
        (setq dabbrev--last-abbreviation abbrev)
        ;; Find all expansion
        (let ((completion-list
               (dabbrev--find-all-expansions abbrev ignore-case-p)))
          ;; Make an obarray with all expansions
          (setq my-obarray (make-vector (length completion-list) 0))
          (or (> (length my-obarray) 0)
              (error "No dynamic expansion for \"%s\" found%s"
                     abbrev
                     (if dabbrev--check-other-buffers "" " in this-buffer")))
          (cond
           ((or (not ignore-case-p)
                (not dabbrev-case-replace))
            (mapc (function (lambda (string)
                              (intern string my-obarray)))
                  completion-list))
           ((string= abbrev (upcase abbrev))
            (mapc (function (lambda (string)
                              (intern (upcase string) my-obarray)))
                  completion-list))
           ((string= (substring abbrev 0 1)
                     (upcase (substring abbrev 0 1)))
            (mapc (function (lambda (string)
                              (intern (dabbrev--capitalize string) my-obarray)))
                  completion-list))
           (t
            (mapc (function (lambda (string)
                              (intern (downcase string) my-obarray)))
                  completion-list)))
          (setq dabbrev--last-obarray my-obarray)
          (setq dabbrev--last-completion-buffer (current-buffer))
          ;; Find the longest common string.
          (setq init (try-completion abbrev my-obarray)))))
    ;;--------------------------------
    ;; Let the user choose between the expansions
    ;;--------------------------------
    (or (stringp init)
        (setq init abbrev))
    (cond
     ;; * Replace string fragment with matched common substring completion.
     ((and (not (string-equal init ""))
           (not (string-equal (downcase init) (downcase abbrev))))
      (if (> (length (all-completions init my-obarray)) 1)
          (message "Repeat `%s' to see all completions"
                   (key-description (this-command-keys)))
        (message "The only possible completion"))
      (dabbrev--substitute-expansion nil abbrev init))
     (t
      ;; * String is a common substring completion already.  Make list.
      (message "Making completion list...")
      (with-output-to-temp-buffer " *Completions*"
        (display-completion-list (all-completions init my-obarray)))
      (message "Making completion list...done")))
    (and (window-minibuffer-p (selected-window))
         (message nil))))

;;;###autoload
(defun dabbrev-expand (arg)
  "Expand previous word \"dynamically\".

Expands to the most recent, preceding word for which this is a prefix.
If no suitable preceding word is found, words following point are
considered.  If still no suitable word is found, then look in the
buffers accepted by the function pointed out by variable
`dabbrev-friend-buffer-function'.

A positive prefix argument, N, says to take the Nth backward *distinct*
possibility.  A negative argument says search forward.

If the cursor has not moved from the end of the previous expansion and
no argument is given, replace the previously-made expansion
with the next possible expansion not yet tried.

The variable `dabbrev-backward-only' may be used to limit the
direction of search to backward if set non-nil.

???
To make it more powerful, make sure that
`dabbrev-always-check-other-buffers' is set to t.

See also `dabbrev-abbrev-char-regexp' and \\[dabbrev-completion]."
  (interactive "*P")
  (let (abbrev expansion old direction)
    ;; abbrev -- the abbrev to expand
    ;; expansion -- the expansion found (eventually) or nil until then
    ;; old -- the text currently in the buffer
    ;;    (the abbrev, or the previously-made expansion)
    (save-excursion
      (if (and (null arg)
               dabbrev--last-abbrev-location
               (or (eq last-command this-command)
                   (and (window-minibuffer-p (selected-window))
                        (= dabbrev--last-abbrev-location
                           (point)))))
          ;; Find a different expansion for the same abbrev as last time.
          (progn
            (setq abbrev dabbrev--last-abbreviation)
            (setq old dabbrev--last-expansion)
            (setq direction dabbrev--last-direction))
        ;; We have a different abbrev to expand.
        (dabbrev--reset-global-variables)
        (setq direction (if (null arg)
                            (if dabbrev-backward-only 1 0)
                          (prefix-numeric-value arg)))
        (setq abbrev (dabbrev--abbrev-at-point))
        (setq old nil))

      ;;--------------------------------
      ;; Find the expansion
      ;;--------------------------------
      (setq expansion
            (dabbrev--find-expansion abbrev direction
                                     (and (eval dabbrev-case-fold-search)
                                          (or (not dabbrev-upcase-means-case-search)
                                              (string= abbrev (downcase abbrev)))))))
    (cond
     ((not expansion)
      (dabbrev--reset-global-variables)
      (if old
          (save-excursion
            (search-backward (substring old (length abbrev)))
            (delete-region (match-beginning 0) (match-end 0))))
      (error "No%s dynamic expansion for `%s' found"
             (if old " further" "") abbrev))
     (t
      (if (not (eq dabbrev--last-buffer dabbrev--last-buffer-found))
          (progn
            (message "Expansion found in '%s'"
                     (buffer-name dabbrev--last-buffer))
            (setq dabbrev--last-buffer-found dabbrev--last-buffer))
        (message nil))
      ;; Success: stick it in and return.
      (dabbrev--substitute-expansion old abbrev expansion)
      ;; Save state for re-expand.
      (setq dabbrev--last-expansion expansion)  
      (setq dabbrev--last-abbreviation abbrev)
      (setq dabbrev--last-abbrev-location (point-marker))))))

;;;----------------------------------------------------------------
;;;----------------------------------------------------------------
;;; Local functions
;;;----------------------------------------------------------------
;;;----------------------------------------------------------------

(defun dabbrev--capitalize (string)
  ;; Capitalize STRING (See capitalize-word)
  (let ((new-string ""))
    (save-match-data
      (while (string-match "\\w+" string)
        (let* ((mb (match-beginning 0))
               (me (match-end 0))
               (ms (substring string mb me)))
          (setq new-string
                (concat new-string
                        (substring string 0 mb)
                        (upcase (substring ms 0 1))
                        (downcase (substring ms 1))))
          (setq string (substring string me)))))
    new-string))

;;; Checks if OTHER-BUFFER has the same major mode as current buffer.
(defun dabbrev--same-major-mode-p (other-buffer)
  (eq major-mode
      (save-excursion
        (set-buffer other-buffer)
        major-mode)))

;;; Back over all abbrev type characters and then moves forward over
;;; all skip characters.
(defun dabbrev--goto-start-of-abbrev ()
  ;; Move backwards over abbrev chars
  (save-match-data
    (if (not (bobp))
        (progn
          (forward-char -1)
          (while (and (looking-at dabbrev--abbrev-char-regexp)
                      (not (bobp)))
            (forward-char -1))
          (or (looking-at dabbrev--abbrev-char-regexp)
              (forward-char 1))))
    (and dabbrev-abbrev-skip-leading-regexp
         (while (looking-at dabbrev-abbrev-skip-leading-regexp)
           (forward-char 1)))))

;;; Extract the symbol at point to serve as abbreviation.
(defun dabbrev--abbrev-at-point ()
  ;; Check for error
  (save-excursion
    (save-match-data
      (if (or (bobp)
              (progn 
                (forward-char -1)
                (not (looking-at (concat "\\("
                                         (or dabbrev-abbrev-char-regexp
                                             "\\sw\\|\\s_")
                                         "\\)+")))))
          (error "Not positioned immediately after an abbreviation"))))
  ;; Return abbrev at point
  (save-excursion
    (setq dabbrev--last-abbrev-location (point))
    (buffer-substring (point) 
                      (progn (dabbrev--goto-start-of-abbrev)
                             (point)))))
        
;;; Initializes all global variables
(defun dabbrev--reset-global-variables ()
  ;; dabbrev--last-obarray and dabbrev--last-completion-buffer
  ;; must not be reset here.
  (setq dabbrev--last-table nil
        dabbrev--last-abbreviation nil
        dabbrev--last-abbrev-location nil
        dabbrev--last-direction nil
        dabbrev--last-expansion nil
        dabbrev--last-expansion-location nil
        dabbrev--friend-buffer-list nil
        dabbrev--last-buffer nil
        dabbrev--last-buffer-found nil
        dabbrev--abbrev-char-regexp (or dabbrev-abbrev-char-regexp
                                        "\\sw\\|\\s_")
        dabbrev--check-other-buffers dabbrev-always-check-other-buffers))

;;; Find all buffers that are considered "friends" according to the
;;; function pointed out by dabbrev-friend-buffer-function.
(defun dabbrev--select-buffers ()
  (save-excursion
    (and (window-minibuffer-p (selected-window))
         (set-buffer (dabbrev--minibuffer-origin)))
    (let ((orig-buffer (current-buffer)))
      (dabbrev-filter-elements
       buffer (buffer-list)
       (and (not (eq orig-buffer buffer))
            (boundp 'dabbrev-friend-buffer-function)
            (funcall dabbrev-friend-buffer-function buffer))))))

;;; Search for ABBREV, N times, normally looking forward,
;;; but looking in reverse instead if REVERSE is non-nil.
(defun dabbrev--try-find (abbrev reverse n ignore-case)
  (save-excursion
    (let ((expansion nil))
      (and dabbrev--last-expansion-location
           (goto-char dabbrev--last-expansion-location))
      (let ((case-fold-search ignore-case)
            (count n))
        (while (and (> count 0)
                    (setq expansion (dabbrev--search abbrev
                                                     reverse
                                                     ignore-case)))
          (setq count (1- count))))
      (and expansion
           (setq dabbrev--last-expansion-location (point)))
      expansion)))

;;; Find all expansions of ABBREV
(defun dabbrev--find-all-expansions (abbrev ignore-case)
  (let ((all-expansions nil)
        expansion)
    (save-excursion
      (goto-char (point-min))
      (while (setq expansion (dabbrev--find-expansion abbrev -1 ignore-case))
        (push expansion all-expansions)))
    all-expansions))

(defun dabbrev--scanning-message ()
  (message "Scanning `%s'" (buffer-name (current-buffer))))

;;; Find one occasion of ABBREV.
;;; DIRECTION > 0 means look that many times backwards.
;;; DIRECTION < 0 means look that many times forward.
;;; DIRECTION = 0 means try both backward and forward.
;;; IGNORE-CASE non-nil means ignore case when searching.
(defun dabbrev--find-expansion (abbrev direction ignore-case)
  (let (expansion)
    (save-excursion
      (cond
       (dabbrev--last-buffer
        (set-buffer dabbrev--last-buffer)
        (dabbrev--scanning-message))
       ((and (not dabbrev-search-these-buffers-only)
             (window-minibuffer-p (selected-window)))
        (set-buffer (dabbrev--minibuffer-origin))
        ;; In the minibuffer-origin buffer we will only search from
        ;; the top and down.
        (goto-char (point-min))
        (setq direction -1)
        (dabbrev--scanning-message)))
      (cond
       ;; ------------------------------------------
       ;; Look backwards
       ;; ------------------------------------------
       ((and (not dabbrev-search-these-buffers-only)
             (>= direction 0)
             (setq dabbrev--last-direction (min 1 direction))
             (setq expansion (dabbrev--try-find abbrev t
                                                (max 1 direction)
                                                ignore-case)))
        expansion)
       ;; ------------------------------------------
       ;; Look forward
       ;; ------------------------------------------
       ((and (or (not dabbrev-search-these-buffers-only)
                 dabbrev--last-buffer)
             (<= direction 0)
             (setq dabbrev--last-direction -1)
             (setq expansion (dabbrev--try-find abbrev nil
                                                (max 1 (- direction))
                                                ignore-case)))
        expansion)
       ;; ------------------------------------------
       ;; Look in other buffers.
       ;; Start at (point-min) and look forward.
       ;; ------------------------------------------
       (t
        (setq dabbrev--last-direction -1)
        ;; Make sure that we should check other buffers
        (or dabbrev--friend-buffer-list
            dabbrev--last-buffer
            (setq dabbrev--friend-buffer-list
                  (mapcar (function get-buffer)
                          dabbrev-search-these-buffers-only))
            (not dabbrev--check-other-buffers)
            (not (or (eq dabbrev--check-other-buffers t)
                     (progn
                       (setq dabbrev--check-other-buffers
                             (y-or-n-p "Scan other buffers also? ")))))
            (let* (friend-buffer-list non-friend-buffer-list)
              (setq dabbrev--friend-buffer-list
                    (funcall dabbrev-select-buffers-function))
              (if dabbrev-check-rest-of-buffers
                  (setq non-friend-buffer-list
                        (nreverse
                         (dabbrev-filter-elements
                          buffer (buffer-list)
                          (not (memq buffer dabbrev--friend-buffer-list))))
                        dabbrev--friend-buffer-list
                        (append dabbrev--friend-buffer-list
                                non-friend-buffer-list)))))
        ;; Walk through the buffers
        (while (and (not expansion) dabbrev--friend-buffer-list)
          (setq dabbrev--last-buffer
                (car dabbrev--friend-buffer-list))
          (setq dabbrev--friend-buffer-list
                (cdr dabbrev--friend-buffer-list))
          (set-buffer dabbrev--last-buffer)
          (dabbrev--scanning-message)
          (setq dabbrev--last-expansion-location (point-min))
          (setq expansion (dabbrev--try-find abbrev nil 1 ignore-case)))
        expansion)))))

(defun dabbrev--safe-replace-match (string &optional fixedcase literal)
  (if (eq major-mode 'picture-mode)
      (picture-replace-match string fixedcase literal)
    (replace-match string fixedcase literal)))

;;;----------------------------------------------------------------
;;; Substitute the current string in buffer with the expansion
;;; OLD is nil or the last expansion substring.
;;; ABBREV is the abbreviation we are working with.
;;; EXPANSION is the expansion substring.
(defun dabbrev--substitute-expansion (old abbrev expansion)
  ;;(undo-boundary)
  (let ((use-case-replace (and (eval dabbrev-case-fold-search)
                               (or (not dabbrev-upcase-means-case-search)
                                   (string= abbrev (downcase abbrev)))
                               (eval dabbrev-case-replace))))
    (and nil use-case-replace
         (setq old (concat abbrev (or old "")))
         (setq expansion (concat abbrev expansion)))
    (if old
        (save-excursion
          (search-backward old))
      ;;(store-match-data (list (point-marker) (point-marker)))
      (search-backward abbrev))
    ;; Make case of replacement conform to case of abbreviation
    ;; provided (1) that kind of thing is enabled in this buffer
    ;; and (2) the replacement itself is all lower case.
    (dabbrev--safe-replace-match expansion
                                 (not use-case-replace)
                                 t)))


;;;----------------------------------------------------------------
;;; Search function used by dabbrevs library.

;;; ABBREV is string to find as prefix of word.  Second arg, REVERSE,
;;; is t for reverse search, nil for forward.  Variable dabbrev-limit
;;; controls the maximum search region size.  Third argment IGNORE-CASE
;;; non-nil means treat case as insignificant while looking for a match
;;; and when comparing with previous matches.  Also if that's non-nil
;;; and the match is found at the beginning of a sentence and is in
;;; lower case except for the initial then it is converted to all lower
;;; case for return.

;;; Table of expansions already seen is examined in buffer
;;; `dabbrev--last-table' so that only distinct possibilities are found
;;; by dabbrev-re-expand.

;;; Value is the expansion, or nil if not found.

(defun dabbrev--search (abbrev reverse ignore-case)
  (save-match-data
    (let ((pattern1 (concat (regexp-quote abbrev)
                            "\\(" dabbrev--abbrev-char-regexp "\\)"))
          (pattern2 (concat (regexp-quote abbrev)
                           "\\(\\(" dabbrev--abbrev-char-regexp "\\)+\\)"))
          (found-string nil))
      ;; Limited search.
      (save-restriction
        (and dabbrev-limit
             (narrow-to-region dabbrev--last-expansion-location
                               (+ (point)
                                  (if reverse (- dabbrev-limit) dabbrev-limit))))
        ;;--------------------------------
        ;; Look for a distinct expansion, using dabbrev--last-table.
        ;;--------------------------------
        (while (and (not found-string)
                    (if reverse
                        (re-search-backward pattern1 nil t)
                      (re-search-forward pattern1 nil t)))
          (cond
           ((progn
              (goto-char (match-beginning 0))
              (dabbrev--goto-start-of-abbrev)
              (/= (point) (match-beginning 0)))
            ;; Prefix of found abbreviation not OK
            nil)
           (t
            (goto-char (match-beginning 0))
            (re-search-forward pattern2)
            (setq found-string
                  (buffer-substring (match-beginning 1) (match-end 1)))
            (and ignore-case (setq found-string (downcase found-string)))
            ;; Throw away if found in table
            (if (dabbrev-filter-elements
                 table-string dabbrev--last-table
                 (string= found-string table-string))
                (setq found-string nil))))
          (if reverse
              (goto-char (match-beginning 0))
            (goto-char (match-end 0))))
        (cond
         (found-string
          ;;--------------------------------
          ;; Put in `dabbrev--last-table' and decide if we should return
          ;; result or (downcase result)
          ;;--------------------------------
          (push found-string dabbrev--last-table)
          (let ((result (buffer-substring (match-beginning 0) (match-end 0))))
            (if (and ignore-case (eval dabbrev-case-replace))
                (downcase result)
              result))))))))

(provide 'dabbrev)

;; dabbrev.el ends here