evil-search.el

;;; evil-search.el --- Search and substitute -*- lexical-binding: t -*-

;; Author: Vegard Øye <vegard_oye at hotmail.com>
;; Maintainer: Vegard Øye <vegard_oye at hotmail.com>

;; Version: 1.15.0

;;
;; This file is NOT part of GNU Emacs.

;;; License:

;; This file is part of Evil.
;;
;; Evil 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.
;;
;; Evil 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 Evil.  If not, see <http://www.gnu.org/licenses/>.

(require 'evil-core)
(require 'evil-common)
(require 'evil-ex)

;;; Code:

(defun evil-select-search-module (option module)
  "Change the search module according to MODULE.
If MODULE is `isearch', then Emacs' isearch module is used.
If MODULE is `evil-search', then Evil's own interactive
search module is used."
  (let ((search-functions
         '(forward
           backward
           word-forward
           word-backward
           unbounded-word-forward
           unbounded-word-backward
           next
           previous)))
    (dolist (fun search-functions)
      (let ((isearch (intern (format "evil-search-%s" fun)))
            (evil-search (intern (format "evil-ex-search-%s" fun))))
        (if (eq module 'isearch)
            (substitute-key-definition
             evil-search isearch evil-motion-state-map)
          (substitute-key-definition
           isearch evil-search evil-motion-state-map)))))
  (set-default option module))

;; this customization is here because it requires
;; the knowledge of `evil-select-search-mode'
(defcustom evil-search-module 'isearch
  "The search module to be used.  May be either `isearch', for
Emacs' isearch module, or `evil-search', for Evil's own
interactive search module.  N.b. changing this will not affect keybindings.
To swap out relevant keybindings, see `evil-select-search-module' function."
  :type '(radio (const :tag "Emacs built-in isearch." :value isearch)
                (const :tag "Evil interactive search." :value evil-search))
  :group 'evil
  :set 'evil-select-search-module
  :initialize 'evil-custom-initialize-pending-reset)

(defun evil-push-search-history (string forward)
  "Push STRING into the appropriate search history (determined by FORWARD)."
  (let* ((history-var (if forward
                          'evil-search-forward-history
                        'evil-search-backward-history))
         (history (symbol-value history-var)))
    (unless (equal (car-safe history) string)
      (set history-var (cons string history)))))

(defun evil-search-incrementally (forward regexp-p)
  "Search incrementally for user-entered text."
  (let ((evil-search-prompt (evil-search-prompt forward))
        (isearch-search-fun-function 'evil-isearch-function)
        (point (point))
        search-nonincremental-instead)
    (setq isearch-forward forward)
    (evil-save-echo-area
      (evil-without-input-method-hooks
       ;; set the input method locally rather than globally to ensure that
       ;; isearch clears the input method when it's finished
       (setq current-input-method evil-input-method)
       (if forward
           (isearch-forward regexp-p)
         (isearch-backward regexp-p))
       (evil-push-search-history isearch-string forward)
       (setq current-input-method nil))
      (when (/= (point) point)
        ;; position the point at beginning of the match only if the call to
        ;; `isearch' has really moved the point. `isearch' doesn't move the
        ;; point only if "C-g" is hit twice to exit the search, in which case we
        ;; shouldn't move the point either.
        (when (and forward isearch-other-end)
          (goto-char isearch-other-end))
        (when (and (eq point (point))
                   (not (string= isearch-string "")))
          (if forward
              (isearch-repeat-forward)
            (isearch-repeat-backward))
          (isearch-exit)
          (when (and forward isearch-other-end)
            (goto-char isearch-other-end)))
        (evil-flash-search-pattern
         (evil-search-message isearch-string forward))))))

(defun evil-flash-search-pattern (string &optional all)
  "Flash last search matches for duration of `evil-flash-delay'.
If ALL is non-nil, flash all matches. STRING is a message
to display in the echo area."
  (let ((lazy-highlight-initial-delay 0)
        (isearch-search-fun-function 'evil-isearch-function)
        (isearch-case-fold-search case-fold-search)
        (disable #'(lambda (&optional _arg) (evil-flash-hook t))))
    (when evil-flash-timer
      (cancel-timer evil-flash-timer))
    (unless (or (null string)
                (string= string ""))
      (evil-echo-area-save)
      (evil-echo "%s" string)
      (isearch-highlight (match-beginning 0) (match-end 0))
      (when all
        (setq isearch-lazy-highlight-wrapped nil
              isearch-lazy-highlight-start (point)
              isearch-lazy-highlight-end (point))
        (isearch-lazy-highlight-new-loop)
        (unless isearch-lazy-highlight-overlays
          (isearch-lazy-highlight-update)))
      (add-hook 'pre-command-hook #'evil-flash-hook nil t)
      (add-hook 'evil-operator-state-exit-hook #'evil-flash-hook nil t)
      (add-hook 'pre-command-hook #'evil-clean-isearch-overlays nil t)
      (setq evil-flash-timer
            (run-at-time evil-flash-delay nil disable)))))

(defun evil-clean-isearch-overlays ()
  "Clean isearch overlays unless `this-command' is search."
  (remove-hook 'pre-command-hook #'evil-clean-isearch-overlays t)
  (unless (memq this-command
                '(evil-search-backward
                  evil-search-forward
                  evil-search-next
                  evil-search-previous
                  evil-search-word-backward
                  evil-search-word-forward))
    (isearch-clean-overlays)))
(put 'evil-clean-isearch-overlays 'permanent-local-hook t)

(defun evil-flash-hook (&optional force)
  "Disable hightlighting if `this-command' is not search.
Disable anyway if FORCE is t."
  (when (or force
            ;; to avoid flicker, don't disable highlighting
            ;; if the next command is also a search command
            (not (memq this-command
                       '(evil-search-backward
                         evil-search-forward
                         evil-search-next
                         evil-search-previous
                         evil-search-word-backward
                         evil-search-word-forward))))
    (evil-echo-area-restore)
    (isearch-dehighlight)
    (setq isearch-lazy-highlight-last-string nil)
    (lazy-highlight-cleanup t)
    (when evil-flash-timer
      (cancel-timer evil-flash-timer)))
  (remove-hook 'pre-command-hook #'evil-flash-hook t)
  (remove-hook 'evil-operator-state-exit-hook #'evil-flash-hook t))
(put 'evil-flash-hook 'permanent-local-hook t)

(defun evil-search-with-predicate (search-fun pred string bound noerror count)
  "Execute a search with a predicate function.
SEARCH-FUN is a search function (e.g. `re-search-forward') and
PREDICATE is a two-argument function satisfying the interface of
`isearch-filter-predicate', or `nil'.  STRING, BOUND, NOERROR and
COUNT are passed unchanged to SEARCH-FUN.  The first match
satisfying the predicate (or `nil') is returned."
  (catch 'done
    (while t
      (let ((result (funcall search-fun string bound noerror count)))
        (cond
         ((not result) (throw 'done nil))
         ((not pred) (throw 'done result))
         ((funcall pred (match-beginning 0) (match-end 0)) (throw 'done result)))))))

(defun evil-search-function (&optional forward regexp-p wrap predicate)
  "Return a search function.
If FORWARD is nil, search backward, otherwise forward.
If REGEXP-P is non-nil, the input is a regular expression.
If WRAP is non-nil, the search wraps around the top or bottom
of the buffer.
If PREDICATE is non-nil, it must be a function accepting two
arguments: the bounds of a match, returning non-nil if that match is
acceptable."
  `(lambda (string &optional bound noerror count)
     (let ((start (point))
           (search-fun ',(if regexp-p
                             (if forward
                                 're-search-forward
                               're-search-backward)
                           (if forward
                               'search-forward
                             'search-backward)))
           result)
       (setq result (evil-search-with-predicate
                     search-fun ,predicate string
                     bound ,(if wrap t 'noerror) count))
       (when (and ,wrap (null result))
         (goto-char ,(if forward '(point-min) '(point-max)))
         (unwind-protect
             (setq result (evil-search-with-predicate
                           search-fun ,predicate string bound noerror count))
           (unless result
             (goto-char start))))
       result)))

(defun evil-isearch-function ()
  "Return a search function for use with isearch.
Based on `isearch-regexp' and `isearch-forward'."
  (evil-search-function isearch-forward evil-regexp-search evil-search-wrap 'isearch-filter-predicate))

(defun evil-search (string forward &optional regexp-p start)
  "Search for STRING and highlight matches.
If FORWARD is nil, search backward, otherwise forward.
If REGEXP-P is non-nil, STRING is taken to be a regular expression.
START is the position to search from; if unspecified, it is
one more than the current position."
  (when (and (stringp string)
             (not (string= string "")))
    (let* ((orig (point))
           (start (or start
                      (if forward
                          (min (point-max) (1+ orig))
                        orig)))
           (isearch-regexp regexp-p)
           (isearch-forward forward)
           (case-fold-search
            (unless (and search-upper-case
                         (not (isearch-no-upper-case-p string nil)))
              case-fold-search))
           (search-func (evil-search-function
                         forward regexp-p evil-search-wrap 'isearch-filter-predicate)))
      ;; no text properties, thank you very much
      (set-text-properties 0 (length string) nil string)
      ;; position to search from
      (goto-char start)
      (setq isearch-string string)
      (isearch-update-ring string regexp-p)
      (condition-case nil
          (funcall search-func string)
        (search-failed
         (goto-char orig)
         (user-error "\"%s\": %s not found"
                     string (if regexp-p "pattern" "string"))))
      ;; always position point at the beginning of the match
      (goto-char (match-beginning 0))
      ;; determine message for echo area
      (cond
       ((and forward (< (point) start))
        (when evil-search-wrap-ring-bell (ding))
        (setq string "Search wrapped around BOTTOM of buffer"))
       ((and (not forward) (> (point) start))
        (when evil-search-wrap-ring-bell (ding))
        (setq string "Search wrapped around TOP of buffer"))
       (t
        (setq string (evil-search-message string forward))))
      (evil-flash-search-pattern string t))))

(defun evil-search-word (forward unbounded symbol)
  "Search for word near point.
If FORWARD is nil, search backward, otherwise forward. If SYMBOL
is non-nil then the functions searches for the symbol at point,
otherwise for the word at point."
  (let ((string (car-safe regexp-search-ring)))
    (setq isearch-forward forward)
    (cond
     ((and (memq last-command
                 '(evil-search-word-forward
                   evil-search-word-backward))
           (stringp string)
           (not (string= string "")))
      (evil-search string forward t))
     (t
      (setq string (evil-find-thing forward (if symbol 'symbol 'evil-word)))
      (cond
       ((null string)
        (user-error "No word under point"))
       (unbounded
        (setq string (regexp-quote string)))
       (t
        (setq string
              (format (if symbol "\\_<%s\\_>" "\\<%s\\>")
                      (regexp-quote string)))))
      (evil-push-search-history string forward)
      (evil-search string forward t)))))

(defun evil--find-thing (forward thing)
  "Return a cons of THING near point as a string and its position.
THING should be a symbol understood by `thing-at-point',
e.g. 'symbol or 'word.  If FORWARD is nil, search backward,
otherwise forward.  Returns nil if nothing is found."
  (let ((move (if forward #'forward-char #'backward-char))
        (end (if forward #'eobp #'bobp))
        string)
    (save-excursion
      (setq string (thing-at-point thing))
      ;; if there's nothing under point, go forwards
      ;; (or backwards) to find it
      (while (and (null string) (not (funcall end)))
        (funcall move)
        (setq string (thing-at-point thing)))
      (when (stringp string)
        (set-text-properties 0 (length string) nil string))
      (when (> (length string) 0)
        (cons string (point))))))

(defun evil-find-thing (forward thing)
  "Return a THING near point as a string.
THING should be a symbol understood by `thing-at-point',
e.g. 'symbol or 'word.  If FORWARD is nil, search backward,
otherwise forward.  Returns nil if nothing is found."
  (car (evil--find-thing forward thing)))

(defun evil-find-word (forward)
  "Return word near point as a string.
If FORWARD is nil, search backward, otherwise forward.  Returns
nil if nothing is found."
  (evil-find-thing forward 'word))

(defun evil-find-symbol (forward)
  "Return word near point as a string.
If FORWARD is nil, search backward, otherwise forward.  Returns
nil if nothing is found."
  (evil-find-thing forward 'symbol))

(defun evil-search-prompt (forward)
  "Return the search prompt for the given direction."
  (if forward "/" "?"))

(defun evil-search-message (string forward)
  "Prefix STRING with the search prompt."
  (format "%s%s" (evil-search-prompt forward) string))

(defadvice isearch-message-prefix (around evil activate)
  "Use `evil-search-prompt'."
  (if evil-search-prompt
      (setq ad-return-value evil-search-prompt)
    ad-do-it))

(defadvice isearch-delete-char (around evil activate)
  "Exit search if no search string."
  (cond
   ((and evil-search-prompt (string= isearch-string ""))
    (let (search-nonincremental-instead)
      (setq isearch-success nil)
      (isearch-exit)))
   (t
    ad-do-it)))

(defadvice isearch-lazy-highlight-search (around evil activate)
  "Never wrap the search in this context."
  (let (evil-search-wrap)
    ad-do-it))

;;; Ex search

(defun evil-ex-regex-without-case (re)
  "Return the regular expression without all occurrences of \\c and \\C."
  (evil-transform-regexp re '((?c . "") (?C . ""))))

(defun evil-ex-regex-case (re default-case)
  "Return the case as implied by \\c or \\C in regular expression RE.
If \\c appears anywhere in the pattern, the pattern is case
insensitive. If \\C appears, the pattern is case sensitive.
Only the first occurrence of \\c or \\C is used, all others are
ignored. If neither \\c nor \\C appears in the pattern, the case
specified by DEFAULT-CASE is used. DEFAULT-CASE should be either
`sensitive', `insensitive' or `smart'. In the latter case, the pattern
will be case-sensitive if and only if it contains an upper-case
letter, otherwise it will be case-insensitive."
  (cond
   ((string-match "\\(?:^\\|[^\\\\]\\)\\(?:\\\\\\\\\\)*\\\\\\([cC]\\)" re)
    (if (eq (aref (match-string 1 re) 0) ?c) 'insensitive 'sensitive))
   ((eq default-case 'smart)
    (if (isearch-no-upper-case-p re t)
        'insensitive
      'sensitive))
   (t default-case)))

;; a pattern
(defun evil-ex-make-substitute-pattern (regexp flags)
  "Create a PATTERN for substitution with FLAGS.
This function respects the values of `evil-ex-substitute-case'
and `evil-ex-substitute-global'."
  (evil-ex-make-pattern regexp
                        (cond
                         ((memq ?i flags) 'insensitive)
                         ((memq ?I flags) 'sensitive)
                         ((not evil-ex-substitute-case)
                          evil-ex-search-case)
                         (t evil-ex-substitute-case))
                        (or (and evil-ex-substitute-global
                                 (not (memq ?g flags)))
                            (and (not evil-ex-substitute-global)
                                 (memq ?g flags)))))

(defun evil-ex-make-search-pattern (regexp)
  "Create a PATTERN for search.
This function respects the values of `evil-ex-search-case'."
  (evil-ex-make-pattern regexp evil-ex-search-case t))

(defun evil-ex-make-pattern (regexp case whole-line)
  "Create a new search pattern.
REGEXP is the regular expression to be searched for. CASE should
be either 'sensitive, 'insensitive for case-sensitive and
case-insensitive search, respectively, or anything else.  In the
latter case the pattern is smart-case, i.e. it is automatically
sensitive of the pattern contains one upper case letter,
otherwise it is insensitive.  The input REGEXP is considered a
Vim-style regular expression if `evil-ex-search-vim-style-regexp'
is non-nil, in which case it is transformed to an Emacs style
regular expression (i.e. certain backslash-codes are
transformed. Otherwise REGEXP must be an Emacs style regular
expression and is not transformed."
  (let ((re (evil-ex-regex-without-case regexp))
        (ignore-case (eq (evil-ex-regex-case regexp case) 'insensitive)))
    ;; possibly transform regular expression from vim-style to
    ;; Emacs-style.
    (if (and evil-ex-search-vim-style-regexp
             (not (or (string-match-p "\\`\\\\_<" regexp)
                      (string-match-p "\\\\_>\\'" regexp))))
        (setq re (evil-transform-vim-style-regexp re))
      ;; Even for Emacs regular expressions we translate certain
      ;; whitespace sequences
      (setq re (evil-transform-regexp re
                                      '((?t . "\t")
                                        (?n . "\n")
                                        (?r . "\r")))))
    (list re ignore-case whole-line)))

(defun evil-ex-pattern-regex (pattern)
  "Return the regular expression of a search PATTERN."
  (nth 0 pattern))

(defun evil-ex-pattern-ignore-case (pattern)
  "Return t if and only if PATTERN should ignore case."
  (nth 1 pattern))

(defun evil-ex-pattern-whole-line (pattern)
  "Return t if and only if PATTERN should match all occurences of a line.
Otherwise PATTERN matches only the first occurence."
  (nth 2 pattern))

;; Highlight
(defun evil-ex-make-hl (name &rest args)
  "Create a new highlight object with name NAME and properties ARGS.
The following properties are supported:
:face The face to be used for the highlighting overlays.
:win The window in which the highlighting should be shown.
     Note that the highlight will be visible in all windows showing
     the corresponding buffer, but only the matches visible in the
     specified window will actually be highlighted. If :win is nil,
     the matches in all windows will be highlighted.
:min The minimal buffer position for highlighted matches.
:max The maximal buffer position for highlighted matches.
:match-hook A hook to be called once for each highlight.
            The hook must take two arguments, the highlight and
            the overlay for that highlight.
:update-hook A hook called once after updating the highlighting
             with two arguments, the highlight and a message string
             describing the current match status."
  (unless (symbolp name)
    (user-error "Expected symbol as name of highlight"))
  (let ((face 'evil-ex-lazy-highlight)
        (win (selected-window))
        min max match-hook update-hook)
    (while args
      (let ((key (pop args))
            (val (pop args)))
        (cond
         ((eq key :face) (setq face val))
         ((eq key :win)  (setq win val))
         ((eq key :min)  (setq min val))
         ((eq key :max)  (setq max val))
         ((eq key :match-hook) (setq match-hook val))
         ((eq key :update-hook) (setq update-hook val))
         (t (user-error "Unexpected keyword: %s" key)))))
    (when (assoc name evil-ex-active-highlights-alist)
      (evil-ex-delete-hl name))
    (when (null evil-ex-active-highlights-alist)
      (add-hook 'window-scroll-functions
                #'evil-ex-hl-update-highlights-scroll nil t)
      (add-hook 'window-size-change-functions
                #'evil-ex-hl-update-highlights-resize nil))
    (push (cons name (vector name
                             nil
                             face
                             win
                             min
                             max
                             match-hook
                             update-hook
                             nil))
          evil-ex-active-highlights-alist)))

(defun evil-ex-hl-name (hl)
  "Return the name of the highlight HL."
  (aref hl 0))

(defun evil-ex-hl-pattern (hl)
  "Return the pattern of the highlight HL."
  (aref hl 1))

(defun evil-ex-hl-set-pattern (hl pattern)
  "Set the pattern of the highlight HL to PATTERN."
  (aset hl 1 pattern))

(defun evil-ex-hl-face (hl)
  "Return the face of the highlight HL."
  (aref hl 2))

(defun evil-ex-hl-window (hl)
  "Return the window of the highlight HL."
  (aref hl 3))

(defun evil-ex-hl-min (hl)
  "Return the minimal buffer position of the highlight HL."
  (aref hl 4))

(defun evil-ex-hl-set-min (hl min)
  "Set the minimal buffer position of the highlight HL to MIN."
  (aset hl 4 min))

(defun evil-ex-hl-max (hl)
  "Return the maximal buffer position of the highlight HL."
  (aref hl 5))

(defun evil-ex-hl-set-max (hl max)
  "Set the minimal buffer position of the highlight HL to MAX."
  (aset hl 5 max))

(defun evil-ex-hl-match-hook (hl)
  "Return the match-hook of the highlight HL."
  (aref hl 6))

(defun evil-ex-hl-update-hook (hl)
  "Return the update-hook of the highlight HL."
  (aref hl 7))

(defun evil-ex-hl-overlays (hl)
  "Return the list of active overlays of the highlight HL."
  (aref hl 8))

(defun evil-ex-hl-set-overlays (hl overlays)
  "Set the list of active overlays of the highlight HL to OVERLAYS."
  (aset hl 8 overlays))

(defun evil-ex-delete-hl (name)
  "Remove the highlighting object with a certain NAME."
  (let ((hl (cdr-safe (assoc name evil-ex-active-highlights-alist))))
    (when hl
      (mapc #'delete-overlay (evil-ex-hl-overlays hl))
      (setq evil-ex-active-highlights-alist
            (assq-delete-all name evil-ex-active-highlights-alist))
      (evil-ex-hl-update-highlights))
    (when (null evil-ex-active-highlights-alist)
      (remove-hook 'window-scroll-functions
                   #'evil-ex-hl-update-highlights-scroll t)
      (remove-hook 'window-size-change-functions
                   #'evil-ex-hl-update-highlights-resize))))

(defun evil-ex-hl-active-p (name)
  "Whether the highlight with a certain NAME is active."
  (and (assoc name evil-ex-active-highlights-alist) t))

(defun evil-ex-hl-change (name pattern)
  "Set the regular expression of highlight NAME to PATTERN."
  (let ((hl (cdr-safe (assoc name evil-ex-active-highlights-alist))))
    (when hl
      (evil-ex-hl-set-pattern hl
                              (if (zerop (length pattern))
                                  nil
                                pattern))
      (evil-ex-hl-idle-update))))

(defun evil-ex-hl-set-region (name beg end &optional _type)
  "Set minimal and maximal position of highlight NAME to BEG and END."
  (let ((hl (cdr-safe (assoc name evil-ex-active-highlights-alist))))
    (when hl
      (evil-ex-hl-set-min hl beg)
      (evil-ex-hl-set-max hl end)
      (evil-ex-hl-idle-update))))

(defun evil-ex-hl-get-max (name)
  "Return the maximal position of the highlight with name NAME."
  (let ((hl (cdr-safe (assoc name evil-ex-active-highlights-alist))))
    (and hl (evil-ex-hl-max hl))))

(defun evil-ex-hl-update-highlights ()
  "Update the overlays of all active highlights."
  (dolist (hl (mapcar #'cdr evil-ex-active-highlights-alist))
    (let* ((old-ovs (evil-ex-hl-overlays hl))
           new-ovs
           (pattern (evil-ex-hl-pattern hl))
           (case-fold-search (evil-ex-pattern-ignore-case pattern))
           (case-replace case-fold-search)
           (face (evil-ex-hl-face hl))
           (match-hook (evil-ex-hl-match-hook hl))
           result)
      (if pattern
          ;; collect all visible ranges
          (let (ranges sranges)
            (dolist (win (if (eq evil-ex-interactive-search-highlight
                                 'all-windows)
                             (get-buffer-window-list (current-buffer) nil t)
                           (list (evil-ex-hl-window hl))))
              (when (window-live-p win)
                (let ((beg (max (window-start win)
                                (or (evil-ex-hl-min hl) (point-min))))
                      (end (min (window-end win)
                                (or (evil-ex-hl-max hl) (point-max)))))
                  (when (< beg end)
                    (push (cons beg end) ranges)))))
            (setq ranges
                  (sort ranges #'(lambda (r1 r2) (< (car r1) (car r2)))))
            (while ranges
              (let ((r1 (pop ranges))
                    (r2 (pop ranges)))
                (cond
                 ;; last range
                 ((null r2)
                  (push r1 sranges))
                 ;; ranges overlap, union
                 ((>= (cdr r1) (car r2))
                  (push (cons (car r1)
                              (max (cdr r1) (cdr r2)))
                        ranges))
                 ;; ranges distinct
                 (t
                  (push r1 sranges)
                  (push r2 ranges)))))

            ;; run through all ranges
            (condition-case lossage
                (save-match-data
                  (dolist (r sranges)
                    (let ((beg (car r))
                          (end (cdr r)))
                      (save-excursion
                        (goto-char beg)
                        ;; set the overlays for the current highlight,
                        ;; reusing old overlays (if possible)
                        (while (and (not (eobp))
                                    (evil-ex-search-find-next-pattern pattern)
                                    (<= (match-end 0) end)
                                    (not (and (= (match-beginning 0) end)
                                              (save-excursion
                                                (goto-char (match-beginning 0))
                                                (bolp)))))
                          (let ((ov (or (pop old-ovs) (make-overlay 0 0))))
                            (move-overlay ov (match-beginning 0) (match-end 0))
                            (overlay-put ov 'face face)
                            (overlay-put ov 'evil-ex-hl (evil-ex-hl-name hl))
                            (overlay-put ov 'priority 1000)
                            (push ov new-ovs)
                            (when match-hook (funcall match-hook hl ov)))
                          (cond
                           ((and (not (evil-ex-pattern-whole-line pattern))
                                 (not (string-match-p "\n" (buffer-substring-no-properties
                                                            (match-beginning 0)
                                                            (match-end 0)))))
                            (forward-line))
                           ((= (match-beginning 0) (match-end 0))
                            (forward-char))
                           (t (goto-char (match-end 0))))))))
                  (mapc #'delete-overlay old-ovs)
                  (evil-ex-hl-set-overlays hl new-ovs)
                  (if (or (null pattern) new-ovs)
                      (setq result t)
                    ;; Maybe the match could just not be found somewhere else?
                    (save-excursion
                      (goto-char (or (evil-ex-hl-min hl) (point-min)))
                      (if (and (evil-ex-search-find-next-pattern pattern)
                               (< (match-end 0) (or (evil-ex-hl-max hl)
                                                    (point-max))))
                          (setq result (format "Match in line %d"
                                               (line-number-at-pos
                                                (match-beginning 0))))
                        (setq result "No match")))))

              (invalid-regexp
               (setq result (cadr lossage)))

              (search-failed
               (setq result (nth 2 lossage)))

              (error
               (setq result (format "%s" (cadr lossage))))

              (user-error
               (setq result (format "%s" (cadr lossage))))))
        ;; no pattern, remove all highlights
        (mapc #'delete-overlay old-ovs)
        (evil-ex-hl-set-overlays hl new-ovs))
      (when (evil-ex-hl-update-hook hl)
        (funcall (evil-ex-hl-update-hook hl) hl result)))))

(defun evil-ex-search-find-next-pattern (pattern &optional direction)
  "Look for the next occurrence of PATTERN in a certain DIRECTION.
Note that this function ignores the whole-line property of PATTERN."
  (setq direction (or direction 'forward))
  (let ((case-fold-search (evil-ex-pattern-ignore-case pattern)))
    (cond
     ((eq direction 'forward)
      (re-search-forward (evil-ex-pattern-regex pattern) nil t))
     ((eq direction 'backward)
      (let* ((pnt (point))
             (ret (re-search-backward (evil-ex-pattern-regex pattern) nil t))
             (m (and ret (match-data))))
        (if ret
            (forward-char)
          (goto-char (point-min)))
        (let ((fwdret
               (re-search-forward (evil-ex-pattern-regex pattern) nil t)))
          (cond
           ((and fwdret (< (match-beginning 0) pnt))
            (setq ret fwdret)
            (goto-char (match-beginning 0)))
           (ret
            (set-match-data m)
            (goto-char (match-beginning 0)))
           (t
            (goto-char pnt)
            ret)))))
     (t
      (user-error "Unknown search direction: %s" direction)))))

(defun evil-ex-hl-idle-update ()
  "Trigger the timer to update the highlights in the current buffer."
  (when (and evil-ex-interactive-search-highlight
             evil-ex-active-highlights-alist)
    (when evil-ex-hl-update-timer
      (cancel-timer evil-ex-hl-update-timer))
    (setq evil-ex-hl-update-timer
          (run-at-time evil-ex-hl-update-delay nil
                       #'evil-ex-hl-do-update-highlight
                       (current-buffer)))))

(defun evil-ex-hl-do-update-highlight (&optional buffer)
  "Timer function for updating the highlights."
  (when (buffer-live-p buffer)
    (with-current-buffer buffer
      (evil-ex-hl-update-highlights)))
  (setq evil-ex-hl-update-timer nil))

(defun evil-ex-hl-update-highlights-scroll (win _beg)
  "Update highlights after scrolling in some window."
  (with-current-buffer (window-buffer win)
    (evil-ex-hl-idle-update)))
(put 'evil-ex-hl-update-highlights-scroll 'permanent-local-hook t)

(defun evil-ex-hl-update-highlights-resize (frame)
  "Update highlights after resizing a window."
  (let ((buffers (delete-dups (mapcar #'window-buffer (window-list frame)))))
    (dolist (buf buffers)
      (with-current-buffer buf
        (evil-ex-hl-idle-update)))))
(put 'evil-ex-hl-update-highlights-resize 'permanent-local-hook t)

;; interactive search
(defun evil-ex-search-activate-highlight (pattern)
  "Activate highlighting of the search pattern set to PATTERN.
This function does nothing if `evil-ex-search-interactive' or
`evil-ex-search-highlight-all' is nil. "
  (when (and evil-ex-search-interactive evil-ex-search-highlight-all)
    (with-current-buffer (or evil-ex-current-buffer (current-buffer))
      (unless (evil-ex-hl-active-p 'evil-ex-search)
        (evil-ex-make-hl 'evil-ex-search
                         :win (or (minibuffer-selected-window) (selected-window))))
      (if pattern
          (evil-ex-hl-change 'evil-ex-search pattern)))))

(defun evil-ex-search (&optional count)
  "Search forward or backward COUNT times for the current ex search pattern.
The search pattern is determined by `evil-ex-search-pattern' and
the direcion is determined by `evil-ex-search-direction'."
  (setq evil-ex-search-start-point (point)
        evil-ex-last-was-search t
        count (or count 1))
  (let ((orig (point))
        wrapped)
    (dotimes (_ (or count 1))
      (when (eq evil-ex-search-direction 'forward)
        (unless (eobp) (forward-char))
        ;; maybe skip end-of-line
        (when (and (not evil-move-beyond-eol) (eolp) (not (eobp)))
          (forward-char)))
      (let ((res (evil-ex-find-next nil nil (not evil-search-wrap))))
        (cond
         ((not res)
          (goto-char orig)
          (signal 'search-failed
                  (list (evil-ex-pattern-regex evil-ex-search-pattern))))
         ((eq res 'wrapped) (setq wrapped t)))))
    (if wrapped
        (let (message-log-max)
          (message "Search wrapped")))
    (goto-char (match-beginning 0))
    (setq evil-ex-search-match-beg (match-beginning 0)
          evil-ex-search-match-end (match-end 0))
    (evil-ex-search-goto-offset evil-ex-search-offset)
    (evil-ex-search-activate-highlight evil-ex-search-pattern)))

(defun evil-ex-find-next (&optional pattern direction nowrap)
  "Search for the next occurrence of the PATTERN in DIRECTION.
PATTERN must be created using `evil-ex-make-pattern', DIRECTION
is either 'forward or 'backward. If NOWRAP is non nil, the search
does not wrap at buffer boundaries. Furthermore this function
only searches invisible text if `search-invisible' is t. If
PATTERN is not specified the current global pattern
`evil-ex-search-pattern' and if DIRECTION is not specified the
current global direction `evil-ex-search-direction' is used.
This function returns t if the search was successful, nil if it
was unsuccessful and 'wrapped if the search was successful but
has been wrapped at the buffer boundaries."
  (setq pattern (or pattern evil-ex-search-pattern)
        direction (or direction evil-ex-search-direction))
  (unless (and pattern (evil-ex-pattern-regex pattern))
    (signal 'search-failed (list "No search pattern")))
  (catch 'done
    (let (wrapped)
      (while t
        (let ((search-result (evil-ex-search-find-next-pattern pattern
                                                               direction)))
          (cond
           ((and search-result
                 (or (eq search-invisible t)
                     (not (isearch-range-invisible
                           (match-beginning 0) (match-end 0)))))
            ;; successful search and not invisible
            (throw 'done (if wrapped 'wrapped t)))
           ((not search-result)
            ;; unsuccessful search
            (if nowrap
                (throw 'done nil)
              (setq nowrap t
                    wrapped t)
              (goto-char (if (eq direction 'forward)
                             (point-min)
                           (point-max)))))))))))

(defun evil-ex-search-update (pattern offset beg end message)
  "Update the highlighting and info-message for the search pattern.
PATTERN is the search pattern and OFFSET the associated offset.
BEG and END specifiy the current match, MESSAGE is the info
message to be shown. This function does nothing if
`evil-ex-search-interactive' is nil."
  (when evil-ex-search-interactive
    (cond
     ((and beg end)
      ;; update overlay
      (if evil-ex-search-overlay
          (move-overlay evil-ex-search-overlay beg end)
        (setq evil-ex-search-overlay
              (make-overlay beg end))
        (overlay-put evil-ex-search-overlay 'priority 1001)
        (overlay-put evil-ex-search-overlay 'face 'evil-ex-search))
      ;; move point
      (goto-char beg)
      (evil-ex-search-goto-offset offset)
      ;; update highlights
      (when evil-ex-search-highlight-all
        (evil-ex-hl-change 'evil-ex-search pattern)))
     (t
      ;; no match
      (when evil-ex-search-overlay
        ;; remove overlay
        (delete-overlay evil-ex-search-overlay)
        (setq evil-ex-search-overlay nil))
      ;; no highlights
      (when evil-ex-search-highlight-all
        (evil-ex-hl-change 'evil-ex-search nil))
      ;; and go to initial position
      (goto-char evil-ex-search-start-point)))
    (when (stringp message)
      (evil-ex-echo "%s" message))))

(defun evil-ex-search-start-session ()
  "Initialize Ex for interactive search."
  (remove-hook 'minibuffer-setup-hook #'evil-ex-search-start-session)
  (when evil-ex-search-incremental
    (add-hook 'after-change-functions #'evil-ex-search-update-pattern nil t))
  (add-hook 'minibuffer-exit-hook #'evil-ex-search-stop-session)
  (add-hook 'mouse-leave-buffer-hook #'evil-ex-search-exit)
  (evil-ex-search-activate-highlight nil))
(put 'evil-ex-search-start-session 'permanent-local-hook t)

(defvar evil-ex-search-yank-point nil)

(defun evil-ex-search-stop-session ()
  "Stop interactive search."
  (with-current-buffer evil-ex-current-buffer
    ;; TODO: This is a bad fix to remove duplicates. The duplicates
    ;;       exist because `isearch-range-invisible' may add a single
    ;;       overlay multiple times if we are in an unlucky situation
    ;;       of overlapping overlays. This happens in our case because
    ;;       of the overlays that are used for (lazy) highlighting.
    ;;       Perhaps it would be better to disable those overlays
    ;;       temporarily before calling `isearch-range-invisible'.
    (setq isearch-opened-overlays (delete-dups isearch-opened-overlays))
    (isearch-clean-overlays))
  (remove-hook 'minibuffer-exit-hook #'evil-ex-search-stop-session)
  (remove-hook 'mouse-leave-buffer-hook #'evil-ex-search-exit)
  (remove-hook 'after-change-functions #'evil-ex-search-update-pattern t)
  (when evil-ex-search-overlay
    (delete-overlay evil-ex-search-overlay)
    (setq evil-ex-search-overlay nil))
  (setq evil-ex-search-yank-point nil))
(put 'evil-ex-search-stop-session 'permanent-local-hook t)

(defun evil-ex-split-search-pattern (pattern direction)
  "Split PATTERN in regexp, offset and next-pattern parts.
Return a triple (regexp offset next-search)."
  (save-match-data
    (if (or (and (eq direction 'forward)
                 (string-match "\\(?:^\\|[^\\\\]\\)\\(?:\\\\\\\\\\)*\\(/\\([^;]*\\)\\(?:;\\([/?].*\\)?\\)?\\)?$"
                               pattern))
            (and (eq direction 'backward)
                 (string-match "\\(?:^\\|[^\\\\]\\)\\(?:\\\\\\\\\\)*\\(\\?\\([^;]*\\)\\(?:;\\([/?].*\\)?\\)?\\)?$"
                               pattern)))
        (list (substring pattern 0 (match-beginning 1))
              (match-string 2 pattern)
              (match-string 3 pattern))
      (list pattern nil nil))))

(defun evil-ex-search-full-pattern (pattern-string count direction)
  "Search for a full search pattern PATTERN-STRING in DIRECTION.
This function splits PATTERN-STRING into
pattern/offset/;next-pattern parts and performs the search in
DIRECTION which must be either 'forward or 'backward. The first
search is repeated COUNT times. If the pattern part of
PATTERN-STRING is empty, the last global pattern stored in
`evil-ex-search-pattern' is used instead if in addition the
offset part is nil (i.e. no pattern/offset separator), the last
global offset stored in `evil-ex-search-offset' is used as
offset. The current match data will correspond to the last
successful match.  This function returns a triple (RESULT PATTERN
OFFSET) where RESULT is

  t              the search has been successful without wrap
  'wrap          the search has been successful with wrap
  'empty-pattern the last pattern has been empty
  nil            the search has not been successful

and PATTERN and OFFSET are the last pattern and offset this
function searched for. Note that this function does not handle
any error conditions."
  (setq count (or count 1))
  (catch 'done
    (while t
      (let* ((res (evil-ex-split-search-pattern pattern-string direction))
             (pat (pop res))
             (offset (pop res))
             (next-pat (pop res))
             (orig-pat pat))
        ;; use last pattern if no new pattern has been specified
        (if (not (zerop (length pat)))
            (setq pat (evil-ex-make-search-pattern pat))
          (setq pat evil-ex-search-pattern
                offset (or offset evil-ex-search-offset)))
        (when (zerop (length pat))
          (throw 'done (list 'empty-pattern pat offset)))
        (let (new-dir repeat-last search-result)
          (while (> count 0)
            (let ((result (evil-ex-find-next pat direction
                                             (not evil-search-wrap))))
              (if (not result) (setq search-result nil count 0)
                (setq search-result
                      (if (or (eq result 'wrap)
                              (eq search-result 'wrap))
                          'wrap t)
                      count (1- count)))))
          (cond
           ;; search failed
           ((not search-result) (throw 'done (list nil pat offset)))
           ;; no next pattern, search complete
           ((zerop (length next-pat))
            (evil-ex-search-goto-offset offset)
            (throw 'done (list search-result pat offset)))
           ;; single `?' or `/' means repeat last pattern and finish
           ((= 1 (length next-pat))
            (evil-ex-search-goto-offset offset)
            (setq new-dir (if (string= "/" next-pat) 'forward 'backward)
                  count (if (eq direction new-dir) 1 2)
                  pattern-string orig-pat
                  direction new-dir))
           ;; next non-empty pattern, next search iteration
           (t
            (evil-ex-search-goto-offset offset)
            (setq new-dir (if (= (aref next-pat 0) ?/) 'forward 'backward)
                  repeat-last (and (<= 2 (length next-pat))
                                   (member (substring next-pat 0 2) '("//" "??")))
                  count (if (or (eq direction new-dir) (not repeat-last)) 1 2)
                  pattern-string (if repeat-last
                                     (concat orig-pat (substring next-pat 1))
                                   (substring next-pat 1))
                  direction new-dir))))))))

(defun evil-ex-search-update-pattern (_beg _end _range)
  "Update the current search pattern."
  (save-match-data
    (let ((pattern-string (minibuffer-contents)))
      (with-current-buffer evil-ex-current-buffer
        (with-selected-window (minibuffer-selected-window)
          (goto-char (1+ evil-ex-search-start-point))
          (condition-case err
              (let* ((result (evil-ex-search-full-pattern pattern-string
                                                          (or evil-ex-search-count 1)
                                                          evil-ex-search-direction))
                     (success (pop result))
                     (pattern (pop result))
                     (offset (pop result)))
                (cond
                 ((eq success 'wrap)
                  (evil-ex-search-update pattern offset
                                         (match-beginning 0) (match-end 0)
                                         "Wrapped"))
                 ((eq success 'empty-pattern)
                  (evil-ex-search-update nil nil nil nil nil))
                 (success
                  (evil-ex-search-update pattern offset
                                         (match-beginning 0) (match-end 0)
                                         nil))
                 (t
                  (evil-ex-search-update nil nil
                                         nil nil
                                         "search failed"))))
            (invalid-regexp
             (evil-ex-search-update nil nil nil nil (cadr err)))
            (error
             (evil-ex-search-update nil nil nil nil (format "%s" err)))))))))
(put 'evil-ex-search-update-pattern 'permanent-local-hook t)

(defun evil-ex-search-exit ()
  "Exit interactive search, keeping lazy highlighting active."
  (interactive)
  (evil-ex-search-stop-session)
  (exit-minibuffer))

(defun evil-ex-search-abort ()
  "Abort interactive search, disabling lazy highlighting."
  (interactive)
  (evil-ex-search-stop-session)
  (evil-ex-delete-hl 'evil-ex-search)
  (abort-recursive-edit))

(defun evil-ex-search-goto-offset (offset)
  "Move point according to search OFFSET and set `evil-this-type' accordingly.
This function assumes that the current match data represents the
current search result."
  (unless (zerop (length offset))
    (let ((beg (match-beginning 0))
          (end (match-end 0)))
      (save-match-data
        (unless
            (string-match
             "^\\([esb]\\)?\\(\\([-+]\\)?\\([0-9]*\\)\\)$"
             offset)
          (user-error "Invalid search offset: %s" offset))
        (let ((count (if (= (match-beginning 4) (match-end 4))
                         (cond
                          ((not (match-beginning 3)) 0)
                          ((= (aref offset (match-beginning 3)) ?+) +1)
                          (t -1))
                       (string-to-number (match-string 2 offset)))))
          (cond
           ((not (match-beginning 1))
            (setq evil-this-type 'line)
            (forward-line count))
           ((= (aref offset (match-beginning 1)) ?e)
            (goto-char (+ end count -1))
            (setq evil-this-type 'inclusive))
           ((memq (aref offset (match-beginning 1)) '(?s ?b))
            (goto-char (+ beg count))
            (setq evil-this-type 'inclusive))))))))

(defun evil-ex-search-setup ()
  "Hook to initialize the minibuffer for ex search."
  (add-hook 'pre-command-hook #'evil-ex-remove-default nil t))

(defun evil-ex-start-search (direction count)
  "Start a new search in a certain DIRECTION."
  ;; store buffer and window where the search started
  (let ((evil-ex-current-buffer (current-buffer)))
    (setq evil-ex-search-count count
          evil-ex-search-direction direction
          evil-ex-search-start-point (point)
          evil-ex-last-was-search t)
    (progn
      ;; ensure minibuffer is initialized accordingly
      (add-hook 'minibuffer-setup-hook #'evil-ex-search-start-session)
      ;; read the search string
      (let* ((minibuffer-local-map evil-ex-search-keymap)
             (search-string
              (condition-case err
                  (minibuffer-with-setup-hook
                      #'evil-ex-search-setup
                    (read-string (if (eq evil-ex-search-direction 'forward)
                                     "/" "?")
                                 (and evil-ex-search-history
                                      (propertize
                                       (car evil-ex-search-history)
                                       'face 'shadow))
                                 'evil-ex-search-history))
                (quit
                 (evil-ex-search-stop-session)
                 (evil-ex-delete-hl 'evil-ex-search)
                 (goto-char evil-ex-search-start-point)
                 (signal (car err) (cdr err))))))
        ;; pattern entered successful
        (goto-char (if (eq evil-ex-search-direction 'forward)
                       (1+ evil-ex-search-start-point)
                     (1- evil-ex-search-start-point)))
        (let* ((result
                (evil-ex-search-full-pattern search-string
                                             evil-ex-search-count
                                             evil-ex-search-direction))
               (success (pop result))
               (pattern (pop result))
               (offset (pop result)))
          (setq evil-ex-search-pattern pattern
                evil-ex-search-offset offset)
          (cond
           ((memq success '(t wrap))
            (goto-char (match-beginning 0))
            (setq evil-ex-search-match-beg (match-beginning 0)
                  evil-ex-search-match-end (match-end 0))
            (evil-ex-search-goto-offset offset)
            (evil-push-search-history search-string (eq direction 'forward))
            (when (and (not evil-ex-search-incremental) evil-ex-search-highlight-all)
              (evil-ex-search-activate-highlight pattern))
            (when (and evil-ex-search-incremental (not evil-ex-search-persistent-highlight))
              (evil-ex-delete-hl 'evil-ex-search)))
           (t
            (goto-char evil-ex-search-start-point)
            (evil-ex-delete-hl 'evil-ex-search)
            (signal 'search-failed (list search-string)))))))))

(defun evil-ex-start-word-search (unbounded direction count &optional symbol)
  "Search for the symbol under point.
The search matches the COUNT-th occurrence of the word.  If the
UNBOUNDED argument is nil, the search matches only at symbol
boundaries, otherwise it matches anywhere.  The DIRECTION
argument should be either `forward' or `backward', determining
the search direction. If SYMBOL is non-nil then the functions
searches for the symbol at point, otherwise for the word at
point."
  (let ((string (evil-find-thing (eq direction 'forward)
                                 (if symbol 'symbol 'word))))
    (if (null string)
        (user-error "No word under point")
      (let ((regex (if unbounded
                       (regexp-quote string)
                     (format (if symbol "\\_<%s\\_>" "\\<%s\\>")
                             (regexp-quote string)))))
        (setq evil-ex-search-count count
              evil-ex-search-direction direction
              evil-ex-search-pattern
              (let (evil-ex-search-vim-style-regexp)
                (evil-ex-make-search-pattern regex))
              evil-ex-search-offset nil
              evil-ex-last-was-search t)
        ;; update search history unless this pattern equals the
        ;; previous pattern
        (unless (equal (car-safe evil-ex-search-history) regex)
          (push regex evil-ex-search-history))
        (evil-push-search-history regex (eq direction 'forward)))
      (evil-ex-delete-hl 'evil-ex-search)
      (when (fboundp 'evil-ex-search-next)
        (evil-ex-search-next count)))))

;; substitute
(evil-ex-define-argument-type substitution
  "A substitution pattern argument /pattern/replacement/flags.
This handler highlights the pattern of the current substitution."
  :runner
  (lambda (flag &optional arg)
    (with-selected-window (minibuffer-selected-window)
      (with-current-buffer evil-ex-current-buffer
        (cond
         ((eq flag 'start)
          (evil-ex-make-hl
           'evil-ex-substitute
           :face 'evil-ex-substitute-matches
           :update-hook #'evil-ex-pattern-update-ex-info
           :match-hook (and evil-ex-substitute-interactive-replace
                            #'evil-ex-pattern-update-replacement))
          (setq flag 'update))

         ((eq flag 'stop)
          (evil-ex-delete-hl 'evil-ex-substitute))))

      (when (and (eq flag 'update)
                 evil-ex-substitute-highlight-all
                 (not (zerop (length arg))))
        (condition-case lossage
            (let* ((result (evil-ex-get-substitute-info arg t))
                   (pattern (pop result))
                   (replacement (pop result))
                   (range (or (evil-copy-range evil-ex-range)
                              (evil-range (line-beginning-position)
                                          (line-end-position)
                                          'line
                                          :expanded t))))
              (setq evil-ex-substitute-current-replacement replacement)
              (evil-expand-range range)
              (evil-ex-hl-set-region 'evil-ex-substitute
                                     (evil-range-beginning range)
                                     (evil-range-end range))
              (evil-ex-hl-change 'evil-ex-substitute pattern))
          (end-of-file
           (evil-ex-pattern-update-ex-info nil
                                           "incomplete replacement"))
          (user-error
           (evil-ex-pattern-update-ex-info nil
                                           (format "%s" lossage))))))))

(defun evil-ex-pattern-update-ex-info (_hl result)
  "Update the Ex info string."
  (when (stringp result)
    (evil-ex-echo "%s" result)))

(defun evil-ex-pattern-update-replacement (_hl overlay)
  "Update the replacement display."
  (let ((repl (if evil-ex-substitute-current-replacement
                  (evil-match-substitute-replacement
                   evil-ex-substitute-current-replacement
                   (not case-replace))
                "")))
    (put-text-property 0 (length repl)
                       'face 'evil-ex-substitute-replacement
                       repl)
    (overlay-put overlay 'after-string repl)))

(defun evil-ex-parse-global (string)
  "Parse STRING as a global argument."
  (let* ((pattern (nth 0 (evil-delimited-arguments string 2)))
         (command (and pattern
                       (>= (- (length string) (length pattern)) 2)
                       (substring string (+ (length pattern) 2)))))
    ;; use last pattern if none given
    (when (zerop (length pattern))
      (setq pattern
            (cond
             ((and (eq evil-search-module 'evil-search) evil-ex-search-pattern)
              (evil-ex-pattern-regex evil-ex-search-pattern))
             ((and (eq evil-search-module 'isearch) (not (zerop (length isearch-string))))
              isearch-string)
             (t (user-error "No previous pattern")))))
    (list pattern command)))

(defun evil-ex-get-substitute-info (string &optional implicit-r)
  "Return the substitution info of command line STRING.
This function returns a three-element list \(PATTERN REPLACEMENT
FLAGS) consisting of the substitution parts of STRING. PATTERN is
a ex-pattern (see `evil-ex-make-pattern') and REPLACEMENT in a
compiled replacement expression (see `evil-compile-replacement').
The information returned is the actual substitution information
w.r.t. to special situations like empty patterns or repetition of
previous substitution commands. If IMPLICIT-R is non-nil, then
the flag 'r' is assumed, i.e. in the case of an empty pattern the
last search pattern is used. This will be used when called from
a :substitute command with arguments."
  (let (pattern replacement flags)
    (cond
     ((or (null string) (string-match "^[a-zA-Z]" string))
      ;; starts with letter so there is no pattern because the
      ;; separator must not be a letter repeat last substitute
      (setq replacement evil-ex-substitute-replacement)
      ;; flags are everything that is not a white space
      (when (and string (string-match "[^[:space:]]+" string))
        (setq flags (match-string 0 string))))
     (t
      (let ((args (evil-delimited-arguments string 3)))
        (setq pattern (pop args)
              replacement (pop args)
              flags (pop args))
        ;; if replacment equals "~" use previous replacement
        (if (equal replacement "~")
            (setq replacement evil-ex-substitute-replacement)
          (setq replacement (evil-compile-replacement replacement)))
        ;; append implicit "r" flag if required
        (when (and implicit-r (not (memq ?r (append flags nil))))
          (setq flags (concat flags "r"))))))
    ;; if flags equals "&" add previous flags
    (if (and (not (zerop (length flags)))
             (= (aref flags 0) ?&))
        (setq flags (append (substring flags 1)
                            evil-ex-substitute-flags))
      (setq flags (append flags nil)))
    ;; if no pattern, use previous pattern, either search or
    ;; substitute pattern depending on `evil-ex-last-was-search' and
    ;; the r flag
    (when (zerop (length pattern))
      (setq pattern
            (if (eq evil-search-module 'evil-search)
                (if (and evil-ex-last-was-search (memq ?r flags))
                    (and evil-ex-search-pattern
                         (evil-ex-pattern-regex evil-ex-search-pattern))
                  (and evil-ex-substitute-pattern
                       (evil-ex-pattern-regex evil-ex-substitute-pattern)))
              (if (eq case-fold-search t)
                  isearch-string
                (concat isearch-string "\\C")))
            flags (remq ?r flags)))
    ;; generate pattern
    (when pattern
      (setq pattern (evil-ex-make-substitute-pattern pattern flags)))
    (list pattern replacement flags)))

(defun evil-ex-nohighlight ()
  "Disable the active search highlightings."
  (interactive)
  (evil-ex-delete-hl 'evil-ex-substitute)
  (evil-ex-delete-hl 'evil-ex-search))

(defun evil-search-yank-word ()
  "Pull next word from buffer into search string."
  (interactive)
  (let ((fwd-fn #'forward-word)
        (minibuf-content (minibuffer-contents-no-properties))
        (word "") start)
    (with-current-buffer evil-ex-current-buffer
      ;; Start to initial point if C-w have never been hit.
      (unless evil-ex-search-yank-point
        (if (string= "" minibuf-content)
            (setq evil-ex-search-yank-point evil-ex-search-start-point)
          (setq evil-ex-search-yank-point (point))))
      (save-excursion
        (goto-char evil-ex-search-yank-point)
        (setq start (point))
        (when (looking-at-p (regexp-quote minibuf-content))
          (forward-char (length minibuf-content))
          (setq start (point))
          (funcall fwd-fn 1))
        (setq word (buffer-substring-no-properties start (point)))))
    (when (equal evil-ex-search-case 'smart)
      (let ((case-fold-search nil))
        (unless (string-match-p "[A-Z]" minibuf-content)
          (setq word (downcase word)))))
    (insert word)))


(provide 'evil-search)

;;; evil-search.el ends here