iedit-lib.el

;;; iedit-lib.el --- APIs for editing multiple regions in the same way
;;; simultaneously.

;; Copyright (C) 2010, 2011, 2012 Victor Ren

;; Time-stamp: <2013-03-02 22:41:36 Victor Ren>
;; Author: Victor Ren <victorhge@gmail.com>
;; Keywords: occurrence region simultaneous rectangle refactoring
;; Version: 0.97
;; X-URL: http://www.emacswiki.org/emacs/Iedit
;; Compatibility: GNU Emacs: 22.x, 23.x, 24.x

;; This file is not part of GNU Emacs, but it is distributed under
;; the same terms as 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This package is iedit APIs library that allow you to write your own minor mode.

;;; todo:
;; - Update comments for APIs
;; - Add more easy access keys for whole occurrence
;; - More APIs: extend occurrences,

;;; Code:

(eval-when-compile (require 'cl))

(defgroup iedit nil
  "Edit multiple regions in the same way simultaneously."
  :prefix "iedit-"
  :group 'replace
  :group 'convenience)

(defface iedit-occurrence
  '((t :inherit highlight))
  "*Face used for the occurrences' default values."
  :group 'iedit)

(defface iedit-read-only-occurrence
  '((t :inherit region))
  "*Face used for the read-only occurrences' default values."
  :group 'iedit)

(defcustom iedit-case-sensitive-default t
  "If no-nil, matching is case sensitive."
  :type 'boolean
  :group 'iedit)

(defcustom iedit-unmatched-lines-invisible-default nil
  "If no-nil, hide lines that do not cover any occurrences by default."
  :type 'boolean
  :group 'iedit)

(defcustom iedit-transient-mark-sensitive t
  "If no-nil, Iedit mode is sensitive to the Transient Mark mode.
It means Iedit works as expected only when regions are
highlighted.  If you want to use iedit without Transient Mark
mode, set it as nil."
  :type 'boolean
  :group 'iedit)

(defcustom iedit-overlay-priority 200
  "The priority of the overlay used to indicate matches."
  :type 'integer
  :group 'iedit)

(defvar iedit-occurrences-overlays nil
  "The occurrences slot contains a list of overlays used to
indicate the position of each editable occurrence.  In addition, the
occurrence overlay is used to provide a different face
configurable via `iedit-occurrence'.")

(defvar iedit-read-only-occurrences-overlays nil
  "The occurrences slot contains a list of overlays used to
indicate the position of each read-only occurrence.  In addition, the
occurrence overlay is used to provide a different face
configurable via `iedit-ready-only-occurrence'.")

(defvar iedit-case-sensitive iedit-case-sensitive-default
  "This is buffer local variable.
If no-nil, matching is case sensitive.")

(defvar iedit-unmatched-lines-invisible nil
  "This is buffer local variable which indicates whether
unmatched lines are hided.")

(defvar iedit-forward-success t
  "This is buffer local variable which indicates the moving
forward or backward successful")

(defvar iedit-before-modification-string ""
  "This is buffer local variable which is the buffer substring
that is going to be changed.")

(defvar iedit-before-modification-undo-list nil
  "This is buffer local variable which is the buffer undo list before modification.")

;; `iedit-occurrence-update-hook' gets called twice when change==0 and
;; occurrence is zero-width (beg==end) -- for front and back insertion.
(defvar iedit-skip-modification-once t
  "Variable used to skip first modification hook run when
insertion against a zero-width occurrence.")

(defvar iedit-aborting nil
  "This is buffer local variable which indicates Iedit mode is aborting.")

(defvar iedit-aborting-hook nil
  "Functions to call before iedit-abort.  Normally it should be mode exit function.")

(defvar iedit-post-undo-hook-installed nil
  "This is buffer local variable which indicated if
`iedit-post-undo-hook' is installed in `post-command-hook'.")

(defvar iedit-buffering nil
  "This is buffer local variable which indicates iedit-mode is
buffering, which means the modification to the current occurrence
is not applied to other occurrences when it is true.")

(defvar iedit-occurrence-context-lines 1
  "The number of lines before or after the occurrence.")

(make-variable-buffer-local 'iedit-occurrences-overlays)
(make-variable-buffer-local 'iedit-read-only-occurrences-overlays)
(make-variable-buffer-local 'iedit-unmatched-lines-invisible)
(make-local-variable 'iedit-case-sensitive)
(make-variable-buffer-local 'iedit-forward-success)
(make-variable-buffer-local 'iedit-before-modification-string)
(make-variable-buffer-local 'iedit-before-modification-undo-list)
(make-variable-buffer-local 'iedit-skip-modification-once)
(make-variable-buffer-local 'iedit-aborting)
(make-variable-buffer-local 'iedit-buffering)
(make-variable-buffer-local 'iedit-post-undo-hook-installed)
(make-variable-buffer-local 'iedit-occurrence-context-lines)

(defconst iedit-occurrence-overlay-name 'iedit-occurrence-overlay-name)
(defconst iedit-invisible-overlay-name 'iedit-invisible-overlay-name)

;;; Define Iedit mode map
(defvar iedit-lib-keymap
  (let ((map (make-sparse-keymap)))
    ;; Default key bindings
    (define-key map (kbd "TAB") 'iedit-next-occurrence)
    (define-key map (kbd "<S-tab>") 'iedit-prev-occurrence)
    (define-key map (kbd "<S-iso-lefttab>") 'iedit-prev-occurrence)
    (define-key map (kbd "<backtab>") 'iedit-prev-occurrence)
    (define-key map (kbd "C-'") 'iedit-toggle-unmatched-lines-visible)
    map)
  "Keymap used while Iedit mode is enabled.")

(defvar iedit-occurrence-keymap-default
  (let ((map (make-sparse-keymap)))
;;  (set-keymap-parent map iedit-lib-keymap)
    (define-key map (kbd "M-U") 'iedit-upcase-occurrences)
    (define-key map (kbd "M-L") 'iedit-downcase-occurrences)
    (define-key map (kbd "M-R") 'iedit-replace-occurrences)
    (define-key map (kbd "M-SPC") 'iedit-blank-occurrences)
    (define-key map (kbd "M-D") 'iedit-delete-occurrences)
    (define-key map (kbd "M-N") 'iedit-number-occurrences)
    (define-key map (kbd "M-B") 'iedit-toggle-buffering)
    (define-key map (kbd "M-<") 'iedit-goto-first-occurrence)
    (define-key map (kbd "M->") 'iedit-goto-last-occurrence)
    (define-key map (kbd "C-?") 'iedit-help-for-occurrences)
    map)
  "Default keymap used within occurrence overlays.")

(defvar iedit-occurrence-keymap 'iedit-occurrence-keymap-default
  "Keymap used within occurrence overlays.
It should be set before occurrence overlay is created.")
(make-local-variable 'iedit-occurrence-keymap)

(defun iedit-help-for-occurrences ()
  "Display `iedit-occurrence-keymap-default'"
  (interactive)
  (message (concat (substitute-command-keys "\\[iedit-upcase-occurrences]") "/"
                   (substitute-command-keys "\\[iedit-downcase-occurrences]") ":up/downcase "
                   (substitute-command-keys "\\[iedit-replace-occurrences]") ":replace "
                   (substitute-command-keys "\\[iedit-blank-occurrences]") ":blank "
                   (substitute-command-keys "\\[iedit-delete-occurrences]") ":delete "
                   (substitute-command-keys "\\[iedit-number-occurrences]") ":number "
                   (substitute-command-keys "\\[iedit-toggle-buffering]") ":buffering "
                   (substitute-command-keys "\\[iedit-goto-first-occurrence]") "/"
                   (substitute-command-keys "\\[iedit-goto-last-occurrence]") ":first/last "
                   )))

(defun iedit-make-occurrences-overlays (occurrence-regexp beg end)
  "Create occurrence overlays for `occurrence-regexp' in a region.
Return the number of occurrences."
  (setq iedit-aborting nil)
  (setq iedit-occurrences-overlays nil)
  (setq iedit-read-only-occurrences-overlays nil)
  ;; Find and record each occurrence's markers and add the overlay to the occurrences
  (let ((counter 0)
        (case-fold-search (not iedit-case-sensitive)))
    (save-excursion
      (save-window-excursion
        (goto-char end)
        ;; todo: figure out why re-search-forward is slow without "recenter"
        (recenter)
        (goto-char beg)
        (while (re-search-forward occurrence-regexp end t)
          (let ((beginning (match-beginning 0))
                (ending (match-end 0)))
            (if (text-property-not-all beginning ending 'read-only nil)
                (push (iedit-make-read-only-occurrence-overlay beginning ending)
                      iedit-read-only-occurrences-overlays)
              (push (iedit-make-occurrence-overlay beginning ending)
                    iedit-occurrences-overlays))
            (setq counter (1+ counter))))
        (message "%d matches for \"%s\"" counter (iedit-printable occurrence-regexp))
        (when (/= 0 counter)
          (if iedit-unmatched-lines-invisible
              (iedit-hide-unmatched-lines iedit-occurrence-context-lines))))
      counter)))

(defun iedit-add-next-occurrence-overlay (occurrence-exp &optional point)
  "Create next occurrence overlay for `occurrence-exp'."
  (iedit-add-occurrence-overlay occurrence-exp point t))

(defun iedit-add-previous-occurrence-overlay (occurrence-exp &optional point)
  "Create previous occurrence overlay for `occurrence-exp'."
  (iedit-add-occurrence-overlay occurrence-exp point nil))

(defun iedit-add-occurrence-overlay (occurrence-exp point forward)
  "Create next or previous occurrence overlay for `occurrence-exp'."
  (or point
      (setq point (point)))
  (let ((case-fold-search (not iedit-case-sensitive)))
    (save-excursion
      (goto-char point)
      (if (not (if forward
                   (re-search-forward occurrence-exp nil t)
                 (re-search-backward occurrence-exp nil t)))
          (message "No matches.")
        (if (or (iedit-find-overlay-at-point (match-beginning 0) 'iedit-occurrence-overlay-name)
                (iedit-find-overlay-at-point (match-end 0) 'iedit-occurrence-overlay-name))
            (error "Conflict region"))
        (push (iedit-make-occurrence-overlay (match-beginning 0)
                                             (match-end 0))
              iedit-occurrences-overlays)
        (message "Add one match for \"%s\"" (iedit-printable occurrence-exp))
        (if iedit-unmatched-lines-invisible
            (iedit-hide-unmatched-lines iedit-occurrence-context-lines))))))

(defun iedit-add-region-as-occurrence (beg end)
  "Add region as an occurrence.
The length of the region must the same as other occurrences if
there are."
  (or (= beg end)
      (error "No region"))
  (if (null iedit-occurrences-overlays)
      (push
       (iedit-make-occurrence-overlay beg end)
       iedit-occurrences-overlays)
    (or (= (- end beg) (iedit-occurrence-string-length))
        (error "Wrong region"))
    (if (or (iedit-find-overlay-at-point beg 'iedit-occurrence-overlay-name)
            (iedit-find-overlay-at-point end 'iedit-occurrence-overlay-name))
        (error "Conflict region"))
    (push (iedit-make-occurrence-overlay beg end)
          iedit-occurrences-overlays)
    )) ;; todo test this function

(defun iedit-cleanup ()
  "Clean up occurrence overlay, invisible overlay and local variables."
  (remove-overlays nil nil iedit-occurrence-overlay-name t)
  (iedit-show-all)
  (setq iedit-occurrences-overlays nil)
  (setq iedit-read-only-occurrences-overlays nil)
  (setq iedit-aborting nil)
  (setq iedit-before-modification-string "")
  (setq iedit-before-modification-undo-list nil))

(defun iedit-make-occurrence-overlay (begin end)
  "Create an overlay for an occurrence in Iedit mode.
Add the properties for the overlay: a face used to display a
occurrence's default value, and modification hooks to update
occurrences if the user starts typing."
  (let ((occurrence (make-overlay begin end (current-buffer) nil t)))
    (overlay-put occurrence iedit-occurrence-overlay-name t)
    (overlay-put occurrence 'face 'iedit-occurrence)
    (overlay-put occurrence 'keymap iedit-occurrence-keymap)
    (overlay-put occurrence 'insert-in-front-hooks '(iedit-occurrence-update-hook))
    (overlay-put occurrence 'insert-behind-hooks '(iedit-occurrence-update-hook))
    (overlay-put occurrence 'modification-hooks '(iedit-occurrence-update-hook))
    (overlay-put occurrence 'priority iedit-overlay-priority)
    occurrence))

(defun iedit-make-read-only-occurrence-overlay (begin end)
  "Create an overlay for an read-only occurrence in Iedit mode."
  (let ((occurrence (make-overlay begin end (current-buffer) nil t)))
    (overlay-put occurrence iedit-occurrence-overlay-name t)
    (overlay-put occurrence 'face 'iedit-read-only-occurrence)
    occurrence))

(defun iedit-make-unmatched-lines-overlay (begin end)
  "Create an overlay for lines between two occurrences in Iedit mode."
  (let ((unmatched-lines-overlay (make-overlay begin end (current-buffer) nil t)))
    (overlay-put unmatched-lines-overlay iedit-invisible-overlay-name t)
    (overlay-put unmatched-lines-overlay 'invisible 'iedit-invisible-overlay-name)
    ;;    (overlay-put unmatched-lines-overlay 'intangible t)
    unmatched-lines-overlay))

(defun iedit-post-undo-hook ()
  "Check if it is time to abort iedit after undo command is executed.

This is added to `post-command-hook' when undo command is executed
in occurrences."
  (if (iedit-same-length)
      nil
    (run-hooks 'iedit-aborting-hook))
  (remove-hook 'post-command-hook 'iedit-post-undo-hook t)
  (setq iedit-post-undo-hook-installed nil))

(defun iedit-reset-aborting ()
  "Turning Iedit mode off and reset `iedit-aborting'.

This is added to `post-command-hook' when aborting Iedit mode is
decided.  `iedit-aborting-hook' is postponed after the current
command is executed for avoiding `iedit-occurrence-update-hook'
is called for a removed overlay."
  (run-hooks 'iedit-aborting-hook)
  (remove-hook 'post-command-hook 'iedit-reset-aborting t)
  (setq iedit-aborting nil))

;; There are two ways to update all occurrences.  One is to redefine all key
;; stroke map for overlay, the other is to figure out three basic modification
;; in the modification hook.  This function chooses the latter.
(defun iedit-occurrence-update-hook (occurrence after beg end &optional change)
  "Update all occurrences.
This modification hook is triggered when a user edits any
occurrence and is responsible for updating all other
occurrences. Refer to `modification-hooks' for more details.
Current supported edits are insertion, yank, deletion and
replacement.  If this modification is going out of the
occurrence, it will abort Iedit mode."
  (if undo-in-progress
      ;; If the "undo" change make occurrences different, it is going to mess up
      ;; occurrences.  So a check will be done after undo command is executed.
      (when (not iedit-post-undo-hook-installed)
        (add-hook 'post-command-hook 'iedit-post-undo-hook nil t)
        (setq iedit-post-undo-hook-installed t))
    (when (not iedit-aborting)
    ;; before modification
    (if (null after)
        (if (or (< beg (overlay-start occurrence))
                (> end (overlay-end occurrence)))
            (progn (setq iedit-aborting t) ; abort iedit-mode
                   (add-hook 'post-command-hook 'iedit-reset-aborting nil t))
          (setq iedit-before-modification-string
                (buffer-substring-no-properties beg end))
          ;; Check if this is called twice before modification. When inserting
          ;; into zero-width occurrence or between two conjoined occurrences,
          ;; both insert-in-front-hooks and insert-behind-hooks will be
          ;; called.  Two calls will make `iedit-skip-modification-once' true.
          (setq iedit-skip-modification-once (not iedit-skip-modification-once)))
      ;; after modification
      (when (not iedit-buffering)
        (if iedit-skip-modification-once
            ;; Skip the first hook
            (setq iedit-skip-modification-once nil)
          (setq iedit-skip-modification-once t)
          (when (or (eq 0 change) ;; insertion
                    (eq beg end)  ;; deletion
                    (not (string= iedit-before-modification-string
                                  (buffer-substring-no-properties beg end))))
            (iedit-update-occurrences  occurrence after beg end change))))))))

(defun iedit-update-occurrences (occurrence after beg end &optional change)
  ""
  (let ((inhibit-modification-hooks t)
        (offset (- beg (overlay-start occurrence)))
        (value (buffer-substring-no-properties beg end)))
    (save-excursion
      ;; insertion or yank
      (if (= 0 change)
          (dolist (another-occurrence iedit-occurrences-overlays)
            (let* ((beginning (+ (overlay-start another-occurrence) offset))
                   (ending (+ beginning (- end beg))))
              (when (not (eq another-occurrence occurrence))
                (goto-char beginning)
                (insert-and-inherit value)
                ;; todo: reconsider this change Quick fix for
                ;; multi-occur occur-edit-mode: multi-occur depend on
                ;; after-change-functions to update original
                ;; buffer. Since inhibit-modification-hooks is set to
                ;; non-nil, after-change-functions hooks are not going
                ;; to be called for the changes of other occurrences.
                ;; So run the hook here.
                (run-hook-with-args 'after-change-functions
                                    beginning
                                    ending
                                    change))
              (iedit-move-conjoined-overlays another-occurrence)))
        ;; deletion
        (dolist (another-occurrence (remove occurrence iedit-occurrences-overlays))
          (let ((beginning (+ (overlay-start another-occurrence) offset)))
            (delete-region beginning (+ beginning change))
            (unless (eq beg end) ;; replacement
              (goto-char beginning)
              (insert-and-inherit value))
            (run-hook-with-args 'after-change-functions
                                beginning
                                (+ beginning (- beg end))
                                change)))))))

(defun iedit-next-occurrence ()
  "Move forward to the next occurrence in the `iedit'.
If the point is already in the last occurrences, you are asked to type
another `iedit-next-occurrence', it starts again from the
beginning of the buffer."
  (interactive)
  (let ((pos (point))
        (in-occurrence (get-char-property (point) 'iedit-occurrence-overlay-name)))
    (when in-occurrence
      (setq pos (next-single-char-property-change pos 'iedit-occurrence-overlay-name)))
    (setq pos (next-single-char-property-change pos 'iedit-occurrence-overlay-name))
    (if (/= pos (point-max))
        (setq iedit-forward-success t)
      (if (and iedit-forward-success in-occurrence)
          (progn (message "This is the last occurrence.")
                 (setq iedit-forward-success nil))
        (progn
          (if (get-char-property (point-min) 'iedit-occurrence-overlay-name)
              (setq pos (point-min))
            (setq pos (next-single-char-property-change
                       (point-min)
                       'iedit-occurrence-overlay-name)))
          (setq iedit-forward-success t)
          (message "Located the first occurrence."))))
    (when iedit-forward-success
      (goto-char pos))))

(defun iedit-prev-occurrence ()
  "Move backward to the previous occurrence in the `iedit'.
If the point is already in the first occurrences, you are asked to type
another `iedit-prev-occurrence', it starts again from the end of
the buffer."
  (interactive)
  (let ((pos (point))
        (in-occurrence (get-char-property (point) 'iedit-occurrence-overlay-name)))
    (when in-occurrence
      (setq pos (previous-single-char-property-change pos 'iedit-occurrence-overlay-name)))
    (setq pos (previous-single-char-property-change pos 'iedit-occurrence-overlay-name))
    ;; At the start of the first occurrence
    (if (or (and (eq pos (point-min))
                 (not (get-char-property (point-min) 'iedit-occurrence-overlay-name)))
            (and (eq (point) (point-min))
                 in-occurrence))
        (if (and iedit-forward-success in-occurrence)
            (progn (message "This is the first occurrence.")
                   (setq iedit-forward-success nil))
          (progn
            (setq pos (previous-single-char-property-change (point-max) 'iedit-occurrence-overlay-name))
            (if (not (get-char-property (- (point-max) 1) 'iedit-occurrence-overlay-name))
                (setq pos (previous-single-char-property-change pos 'iedit-occurrence-overlay-name)))
            (setq iedit-forward-success t)
            (message "Located the last occurrence.")))
      (setq iedit-forward-success t))
    (when iedit-forward-success
      (goto-char pos))))

(defun iedit-goto-first-occurrence ()
  "Move to the first occurrence."
  (interactive)
  (goto-char (iedit-first-occurrence))
  (setq iedit-forward-success t)
  (message "Located the first occurrence."))

(defun iedit-first-occurrence ()
  "return the position of the first occurrence."
  (if (get-char-property (point-min) 'iedit-occurrence-overlay-name)
      (point-min)
    (next-single-char-property-change
     (point-min) 'iedit-occurrence-overlay-name)))

(defun iedit-goto-last-occurrence ()
  "Move to the last occurrence."
  (interactive)
  (goto-char (iedit-last-occurrence))
  (setq iedit-forward-success t)
  (message "Located the last occurrence."))

(defun iedit-last-occurrence ()
  "return the position of the last occurrence."
  (let ((pos (previous-single-char-property-change (point-max) 'iedit-occurrence-overlay-name)))
    (if (not (get-char-property (- (point-max) 1) 'iedit-occurrence-overlay-name))
        (setq pos (previous-single-char-property-change pos 'iedit-occurrence-overlay-name)))
    pos))

(defun iedit-toggle-unmatched-lines-visible (&optional arg)
  "Toggle whether to display unmatched lines.
A prefix ARG specifies how many lines before and after the
occurrences are not hided; negative is treated the same as zero.

If no prefix argument, the prefix argument last time or default
value of `iedit-occurrence-context-lines' is used for this time."
  (interactive "P")
  (if (null arg)
      ;; toggle visible
      (progn (setq iedit-unmatched-lines-invisible (not iedit-unmatched-lines-invisible))
             (if iedit-unmatched-lines-invisible
                 (iedit-hide-unmatched-lines iedit-occurrence-context-lines)
               (iedit-show-all)))
    ;; reset invisible lines
    (setq arg (prefix-numeric-value arg))
    (if (< arg 0)
        (setq arg 0))
    (unless (and iedit-unmatched-lines-invisible
                 (= arg iedit-occurrence-context-lines))
      (when iedit-unmatched-lines-invisible
        (remove-overlays nil nil iedit-invisible-overlay-name t))
      (setq iedit-occurrence-context-lines arg)
      (setq iedit-unmatched-lines-invisible t)
      (iedit-hide-unmatched-lines iedit-occurrence-context-lines))))

(defun iedit-show-all()
  "Show hided lines."
  (setq line-move-ignore-invisible nil)
  (remove-from-invisibility-spec '(iedit-invisible-overlay-name . t))
  (remove-overlays nil nil iedit-invisible-overlay-name t))

(defun iedit-hide-unmatched-lines (context-lines)
  "Hide unmatched lines using invisible overlay."
  (let ((prev-occurrence-end 1)
        (unmatched-lines nil))
    (save-excursion
      (goto-char (iedit-first-occurrence))
      (while (/= (point) (point-max))
        ;; Now at the beginning of an occurrence
        (let ((current-start (point)))
          (forward-line (- context-lines))
          (let ((line-beginning (line-beginning-position)))
            (if (> line-beginning prev-occurrence-end)
                (push  (list prev-occurrence-end (1- line-beginning)) unmatched-lines)))
          ;; goto the end of the occurrence
          (goto-char (next-single-char-property-change current-start 'iedit-occurrence-overlay-name)))
        (let ((current-end (point)))
          (forward-line context-lines)
          (setq prev-occurrence-end (1+ (line-end-position)))
          ;; goto the beginning of next occurrence
          (goto-char (next-single-char-property-change current-end 'iedit-occurrence-overlay-name))))
      (if (< prev-occurrence-end (point-max))
          (push (list prev-occurrence-end (point-max)) unmatched-lines))
      (when unmatched-lines
        (set (make-local-variable 'line-move-ignore-invisible) t)
        (add-to-invisibility-spec '(iedit-invisible-overlay-name . t))
        (dolist (unmatch unmatched-lines)
          (iedit-make-unmatched-lines-overlay (car unmatch) (cadr unmatch)))))
    unmatched-lines))

;;;; functions for overlay keymap
(defun iedit-apply-on-occurrences (function &rest args)
  "Call function for each occurrence."
  (let ((inhibit-modification-hooks t))
      (save-excursion
        (dolist (occurrence iedit-occurrences-overlays)
          (apply function (overlay-start occurrence) (overlay-end occurrence) args)))))

(defun iedit-upcase-occurrences ()
  "Covert occurrences to upper case."
  (interactive "*")
  (iedit-barf-if-buffering)
  (iedit-apply-on-occurrences 'upcase-region))

(defun iedit-downcase-occurrences()
  "Covert occurrences to lower case."
  (interactive "*")
  (iedit-barf-if-buffering)
  (iedit-apply-on-occurrences 'downcase-region))

(defun iedit-replace-occurrences(to-string)
  "Replace occurrences with STRING.
This function preserves case."
  (interactive "*sReplace with: ")
  (iedit-barf-if-buffering)
  (let* ((ov (iedit-find-current-occurrence-overlay))
         (offset (- (point) (overlay-start ov)))
         (from-string (downcase (buffer-substring-no-properties
                                 (overlay-start ov)
                                 (overlay-end ov)))))
    (iedit-apply-on-occurrences
     (lambda (beg end from-string to-string)
       (goto-char beg)
       (search-forward from-string end)
       (replace-match to-string nil))
     from-string to-string)
    (goto-char (+ (overlay-start ov) offset))))

(defun iedit-blank-occurrences()
  "Replace occurrences with blank spaces."
  (interactive "*")
  (iedit-barf-if-buffering)
  (let* ((ov (car iedit-occurrences-overlays))
         (offset (- (point) (overlay-start ov)))
         (count (- (overlay-end ov) (overlay-start ov))))
    (iedit-apply-on-occurrences
     (lambda (beg end )
       (delete-region beg end)
       (goto-char beg)
       (insert-and-inherit (make-string count 32))))
    (goto-char (+ (overlay-start ov) offset))))

(defun iedit-delete-occurrences()
  "Delete occurrences."
  (interactive "*")
  (iedit-barf-if-buffering)
  (iedit-apply-on-occurrences 'delete-region))

;; todo: add cancel buffering function
(defun iedit-toggle-buffering ()
  "Toggle buffering.
This is intended to improve iedit's response time.  If the number
of occurrences are huge, it might be slow to update all the
occurrences for each key stoke.  When buffering is on,
modification is only applied to the current occurrence and will
be applied to other occurrences when buffering is off."
  (interactive "*")
  (if iedit-buffering
      (iedit-stop-buffering)
    (iedit-start-buffering))
  (message (concat "Modification Buffering "
                   (if iedit-buffering
                       "started."
                     "stopped."))))

(defun iedit-start-buffering ()
  "Start buffering."
  (setq iedit-buffering t)
  (setq iedit-before-modification-string (iedit-current-occurrence-string))
  (setq iedit-before-modification-undo-list buffer-undo-list)
  (message "Start buffering editing..."))

(defun iedit-stop-buffering ()
  "Stop buffering and apply the modification to other occurrences.
If current point is not at any occurrence, the buffered
modification is not going to be applied to other occurrences."
  (let ((ov (iedit-find-current-occurrence-overlay)))
    (when ov
      (let* ((beg (overlay-start ov))
             (end (overlay-end ov))
             (modified-string (buffer-substring-no-properties beg end))
             (offset (- (point) beg)) ;; delete-region moves cursor
             (inhibit-modification-hooks t))
        (when (not (string= iedit-before-modification-string modified-string))
          (save-excursion
            ;; Rollback the current modification and buffer-undo-list. This is
            ;; to avoid the inconsistency if user undoes modifications
            (delete-region beg end)
            (goto-char beg)
            (insert-and-inherit iedit-before-modification-string)
            (setq buffer-undo-list iedit-before-modification-undo-list)
            (dolist (occurrence iedit-occurrences-overlays) ; todo:extract as a function
              (let ((beginning (overlay-start occurrence))
                    (ending (overlay-end occurrence)))
                (delete-region beginning ending)
                (unless (eq beg end) ;; replacement
                  (goto-char beginning)
                  (insert-and-inherit modified-string))
                (iedit-move-conjoined-overlays occurrence))))
          (goto-char (+ (overlay-start ov) offset))))))
  (setq iedit-buffering nil)
  (message "Buffered modification applied.")
  (setq iedit-before-modification-undo-list nil))

(defun iedit-move-conjoined-overlays (occurrence)
  "This function keeps overlays conjoined after modification.
After modification, conjoined overlays may be overlapped."
  (let ((beginning (overlay-start occurrence))
        (ending (overlay-end occurrence)))
    (unless (= beginning (point-min))
      (let ((previous-overlay (iedit-find-overlay-at-point
                               (1- beginning)
                               'iedit-occurrence-overlay-name)))
        (if previous-overlay ; two conjoined occurrences
            (move-overlay previous-overlay
                          (overlay-start previous-overlay)
                          beginning))))
    (unless (= ending (point-max))
      (let ((next-overlay (iedit-find-overlay-at-point
                           ending
                           'iedit-occurrence-overlay-name)))
        (if next-overlay ; two conjoined occurrences
            (move-overlay next-overlay ending (overlay-end next-overlay)))))))

(defvar iedit-number-line-counter 1
  "Occurrence number for 'iedit-number-occurrences.")

(defun iedit-default-occurrence-number-format (start-at)
  (concat "%"
          (int-to-string
           (length (int-to-string
                    (1- (+ (length iedit-occurrences-overlays) start-at)))))
          "d "))

(defun iedit-number-occurrences (start-at &optional format-string)
  "Insert numbers in front of the occurrences.
START-AT, if non-nil, should be a number from which to begin
counting.  FORMAT, if non-nil, should be a format string to pass
to `format-string' along with the line count.  When called
interactively with a prefix argument, prompt for START-AT and
FORMAT."
  (interactive
   (if current-prefix-arg
       (let* ((start-at (read-number "Number to count from: " 1)))
         (list start-at
               (read-string "Format string: "
                            (iedit-default-occurrence-number-format
                             start-at))))
     (list 1 nil)))
  (iedit-barf-if-buffering)
  (unless format-string
    (setq format-string (iedit-default-occurrence-number-format start-at)))
  (let ((iedit-number-occurrence-counter start-at)
        (inhibit-modification-hooks t))
    (save-excursion
      (goto-char (iedit-first-occurrence))
      (while (/= (point) (point-max))
        (insert (format format-string iedit-number-occurrence-counter))
        (iedit-move-conjoined-overlays (iedit-find-current-occurrence-overlay))
        (setq iedit-number-occurrence-counter
              (1+ iedit-number-occurrence-counter))
        (goto-char (next-single-char-property-change (point) 'iedit-occurrence-overlay-name))
        (goto-char (next-single-char-property-change (point) 'iedit-occurrence-overlay-name))))))


;;; help functions
(defun iedit-find-current-occurrence-overlay ()
  "Return the current occurrence overlay  at point or point - 1.
This function is supposed to be called in overlay keymap."
  (or (iedit-find-overlay-at-point (point) 'iedit-occurrence-overlay-name)
      (iedit-find-overlay-at-point (1- (point)) 'iedit-occurrence-overlay-name)))

(defun iedit-find-overlay-at-point (point property)
  "Return the overlay with PROPERTY at POINT."
  (let ((overlays (overlays-at point))
        found)
    (while (and overlays (not found))
      (let ((overlay (car overlays)))
        (if (overlay-get overlay property)
            (setq found overlay)
          (setq overlays (cdr overlays)))))
    found))

(defun iedit-same-column ()
  "Return t if all occurrences are at the same column."
  (save-excursion
    (let ((column (progn (goto-char (overlay-start (car iedit-occurrences-overlays)))
                         (current-column)))
          (overlays (cdr  iedit-occurrences-overlays))
          (same t))
      (while (and overlays same)
        (let ((overlay (car overlays)))
          (if (/= (progn (goto-char (overlay-start overlay))
                         (current-column))
                  column)
              (setq same nil)
            (setq overlays (cdr overlays)))))
      same)))

(defun iedit-same-length ()
  "Return t if all occurrences are the same length."
  (save-excursion
    (let ((length (iedit-occurrence-string-length))
          (overlays (cdr iedit-occurrences-overlays))
          (same t))
      (while (and overlays same)
        (let ((ov (car overlays)))
          (if (/= (- (overlay-end ov) (overlay-start ov))
                  length)
              (setq same nil)
            (setq overlays (cdr overlays)))))
      same)))

;; This function might be called out of any occurrence
(defun iedit-current-occurrence-string ()
  "Return current occurrence string.
Return nil if occurrence string is empty string."
  (let ((ov (or (iedit-find-current-occurrence-overlay)
                 (car iedit-occurrences-overlays))))
    (if ov
        (let ((beg (overlay-start ov))
              (end (overlay-end ov)))
          (if (/=  beg end)
              (buffer-substring-no-properties beg end)
            nil))
      nil)))

(defun iedit-occurrence-string-length ()
  "Return the length of current occurrence string."
  (let ((ov (car iedit-occurrences-overlays)))
    (- (overlay-end ov) (overlay-start ov))))

(defun iedit-find-overlay (beg end property &optional exclusive)
  "Return a overlay with property in region, or out of the region if EXCLUSIVE is not nil."
  (if exclusive
      (or (iedit-find-overlay-in-region (point-min) beg property)
          (iedit-find-overlay-in-region end (point-max) property))
    (iedit-find-overlay-in-region beg end property)))

(defun iedit-find-overlay-in-region (beg end property)
  "Return a overlay with property in region."
  (let ((overlays (overlays-in beg end))
        found)
    (while (and overlays (not found))
      (let ((overlay (car overlays)))
        (if (and (overlay-get overlay property)
                 (>= (overlay-start overlay) beg)
                 (<= (overlay-end overlay) end))
            (setq found overlay)
          (setq overlays (cdr overlays)))))
    found))

(defun iedit-cleanup-occurrences-overlays (beg end &optional inclusive)
  "Remove deleted overlays from list `iedit-occurrences-overlays'."
  (if inclusive
      (remove-overlays beg end iedit-occurrence-overlay-name t)
    (remove-overlays (point-min) beg iedit-occurrence-overlay-name t)
    (remove-overlays end (point-max) iedit-occurrence-overlay-name t))
  (let (overlays)
    (dolist (overlay iedit-occurrences-overlays)
      (if (overlay-buffer overlay)
          (push overlay overlays)))
    (setq iedit-occurrences-overlays overlays)))

(defun iedit-printable (string)
  "Return a omitted substring that is not longer than 50.
STRING is already `regexp-quote'ed"
  (let ((first-newline-index (string-match "$" string))
        (length (length string)))
    (if (and first-newline-index
             (/= first-newline-index length))
        (if (< first-newline-index 50)
            (concat (substring string 0 first-newline-index) "...")
          (concat (substring string 0 50) "..."))
      (if (> length 50)
          (concat (substring string 0 50) "...")
        string))))

(defun iedit-char-at-bol (&optional N)
  "Get char position of the beginning of the current line. If `N'
is given, move forward (or backward) that many lines (using
`forward-line') and get the char position at the beginning of
that line."
  (save-excursion
    (forward-line (if N N 0))
    (point)))

(defun iedit-char-at-eol (&optional N)
  "Get char position of the end of the current line. If `N' is
given, move forward (or backward) that many lines (using
`forward-line') and get the char position at the end of that
line."
  (save-excursion
    (forward-line (if N N 0))
    (end-of-line)
    (point)))

(defun iedit-region-active ()
  "Return t if region is active and not empty.
If variable `iedit-transient-mark-sensitive' is t, active region
means `transient-mark-mode' is on and mark is active. Otherwise,
it just means mark is active."
  (and (if iedit-transient-mark-sensitive
           transient-mark-mode
         t)
       mark-active (not (equal (mark) (point)))))

(defun iedit-barf-if-lib-active()
  "Signal error if Iedit lib is active."
  (or (and (null iedit-occurrences-overlays)
           (null iedit-read-only-occurrences-overlays))
      (error "Iedit lib is active")))

(defun iedit-barf-if-buffering()
  "Signal error if Iedit lib is buffering."
  (or  (null iedit-buffering)
      (error "Iedit is buffering")))

(provide 'iedit-lib)

;;; iedit-lib.el ends here

;;  LocalWords:  iedit el MERCHANTABILITY kbd isearch todo ert Lindberg Tassilo
;;  LocalWords:  eval rect defgroup defcustom boolean defvar assq alist nconc
;;  LocalWords:  substring cadr keymap defconst purecopy bkm defun princ prev
;;  LocalWords:  iso lefttab backtab upcase downcase concat setq autoload arg
;;  LocalWords:  refactoring propertize cond goto nreverse progn rotatef eq elp
;;  LocalWords:  dolist pos unmatch args ov sReplace iedit's cdr quote'ed