Chanege behavior od Emacs search

search.el

;;;; Search.

;; Automatically wrapping I-search.
;; https://stackoverflow.com/questions/285660/automatically-wrapping-i-search
;; TODO: Still not perfect: does not distinguish overwrapped I-search anymore.
(defadvice isearch-search (after isearch-no-fail activate)
  (unless isearch-success
    ;; Avoid recursive loop
    (ad-disable-advice 'isearch-search 'after 'isearch-no-fail)
    (ad-activate 'isearch-search) ;; ad-activate to reflect the above change
    ;; Repeat the search (in the appropriate direction)
    (isearch-repeat (if isearch-forward 'forward))
    ;; Restore advice
    (ad-enable-advice 'isearch-search 'after 'isearch-no-fail)
    (ad-activate 'isearch-search)))

;; The above solution has a serious problem: it creates a spurious "input event"
;; when it implicitly repeats the search. This means you have to type DEL
;; *twice* to undo the last command. I should find a proper solution to this,
;; but the fact is that I don't generally want DEL to undo last event anyway, I
;; want it to remove the last characher from the search (what C-M-w does (yeah,
;; really). So instead I'll redefine DEL (which apparently has to be called
;; <backspace> for the graphical Emacs) to remove last character from search
;; query, and the undo key to undo the last search event. This leaves the undo
;; key with the aforementioned bug, but whatever.

(define-key isearch-mode-map (kbd "<backspace>") 'isearch-del-char)
(define-key isearch-mode-map (kbd "DEL") 'isearch-del-char)
(define-key isearch-mode-map (kbd "C-/") 'isearch-delete-char)
(define-key isearch-mode-map (kbd "C-_") 'isearch-delete-char)