How can I emulate Vim's * search in GNU Emacs?

Question

In Vim the * key in normal mode searches for the word under the cursor. In GNU Emacs the closest native equivalent would be:

C-s C-w

But that isn't quite the same. It opens up the incremental search mini buffer and copies from the cursor in the current buffer to the end of the word. In Vim you'd search for the whole word, even if you are in the middle of the word when you press *.

I've cooked up a bit of elisp to do something similar:

(defun find-word-under-cursor (arg)
  (interactive "p")
  (if (looking-at "\\<") () (re-search-backward "\\<" (point-min)))
  (isearch-forward))

That trots backwards to the start of the word before firing up isearch. I've bound it to C-+, which is easy to type on my keyboard and similar to *, so when I type C-+ C-w it copies from the start of the word to the search mini-buffer.

However, this still isn't perfect. Ideally it would regexp search for "\<" word "\>" to not show partial matches (searching for the word "bar" shouldn't match "foobar", just "bar" on its own). I tried using search-forward-regexp and concat'ing \<> but this doesn't wrap in the file, doesn't highlight matches and is generally pretty lame. An isearch-* function seems the best bet, but these don't behave well when scripted.

Any ideas? Can anyone offer any improvements to the bit of elisp? Or is there some other way that I've overlooked?

Answer 1

scottfrazer's answer works well for me, except for words that end in '_' (or perhaps other non-word characters?). I found that the code for light-symbol mode was using a different regex for word boundary depending on the version of emacs, and that fixed it for me. Here is the modified code:

(defconst my-isearch-rx-start
  (if (< emacs-major-version 22)
      "\\<"
    "\\_<")
  "Start-of-symbol regular expression marker.")

(defconst my-isearch-rx-end
  (if (< emacs-major-version 22)
      "\\>"
    "\\_>")
  "End-of-symbol regular expression marker.")

(defun my-isearch-word-at-point ()
  (interactive)
  (call-interactively 'isearch-forward-regexp))

(defun my-isearch-yank-word-hook ()
  (when (equal this-command 'my-isearch-word-at-point)
    (let ((string (concat my-isearch-rx-start
                          (buffer-substring-no-properties
                           (progn (skip-syntax-backward "w_") (point))
                           (progn (skip-syntax-forward "w_") (point)))
                          my-isearch-rx-end)))
      (if (and isearch-case-fold-search
               (eq 'not-yanks search-upper-case))
          (setq string (downcase string)))
      (setq isearch-string string
            isearch-message
            (concat isearch-message
                    (mapconcat 'isearch-text-char-description
                               string ""))
            isearch-yank-flag t)
      (isearch-search-and-update))))

(add-hook 'isearch-mode-hook 'my-isearch-yank-word-hook)

Answer 2

;Here is my version: Emulates Visual Studio/Windows key bindings 
; C-F3 - Start searching the word at the point
; F3 searches forward and Shift F3 goes reverse

(setq my-search-wrap nil)

(defun my-search-func (dir)
  (interactive)
  (let* ((text (car search-ring)) newpoint)
        (when my-search-wrap  
             (goto-char (if (= dir 1) (point-min) (point-max)))
             (setq my-search-wrap nil))
        (setq newpoint (search-forward text nil t dir))
        (if newpoint
          (set-mark (if (= dir 1) (- newpoint (length text))
                         (+ newpoint (length text))))
          (message "Search Failed: %s" text) (ding)
          (setq my-search-wrap text))))

(defun my-search-fwd () (interactive) (my-search-func 1))
(defun my-search-bwd () (interactive) (my-search-func -1))

(defun yank-thing-into-search ()
   (interactive)
   (let ((text (if mark-active
          (buffer-substring-no-properties (region-beginning)(region-end))
                 (or (current-word) ""))))
     (when (> (length text) 0) (isearch-update-ring text) (setq my-search-wrap nil)
            (my-search-fwd))))
(global-set-key (kbd "")    'my-search-fwd)            ; Visual Studio like search keys
(global-set-key (kbd "")  'my-search-bwd)
(global-set-key (kbd "")  'yank-thing-into-search)

Answer 3

There are lots of ways to do this:

http://www.emacswiki.org/emacs/SearchAtPoint

Answer 4

The highlight symbol emacs extension provides this functionality. In particular, the recommend .emacsrc setup:

(require 'highlight-symbol)

(global-set-key [(control f3)] 'highlight-symbol-at-point)
(global-set-key [f3] 'highlight-symbol-next)
(global-set-key [(shift f3)] 'highlight-symbol-prev)

Allows jumping to the next symbol at the current point (F3), jumping to the previous symbol (Shift+F3) or highlighting symbols matching the one under the cursor (Ctrl+F3). The commands continue to do the right thing if your cursor is mid-word.

Unlike vim's super star, highlighting symbols and jumping between symbols are bound to two different commands. I personally don't mind the separation, but you could bind the two commands under the same keystroke if you wanted to precisely match vim's behaviour.

Answer 5

I have not tried it but there is some code here called Grep-O-Matic.

Answer 6

How about built in commands M-b C-s C-w (start of word,search,word search)