Imenu is a built-in emacs package for navigating around source files. It is a feature that allows you to jump around by scanning on predefined regex’s - mostly to variable of function declarations. Imenu is very useful for quickly navigating around a source file - I recommend you start using it whenever you need to navigate to a different function in the same file. The default for imenu is to use emac’s built in completion for variables; however, I much prefer using ido’s completion, and for that you need the following commands and function in your initialization file:
This just allows you to use the imenu commands.
(defun ido-goto-symbol () "Will update the imenu index and then use ido to select a symbol to navigate to" (interactive) (imenu--make-index-alist) (let ((name-and-pos '()) (symbol-names '())) (flet ((addsymbols (symbol-list) (when (listp symbol-list) (dolist (symbol symbol-list) (let ((name nil) (position nil)) (cond ((and (listp symbol) (imenu--subalist-p symbol)) (addsymbols symbol)) ((listp symbol) (setq name (car symbol)) (setq position (cdr symbol))) ((stringp symbol) (setq name symbol) (setq position (get-text-property 1 'org-imenu-marker symbol)))) (unless (or (null position) (null name)) (add-to-list 'symbol-names name) (add-to-list 'name-and-pos (cons name position)))))))) (addsymbols imenu--index-alist)) (let* ((selected-symbol (ido-completing-read "Symbol? " symbol-names)) (position (cdr (assoc selected-symbol name-and-pos)))) (if (markerp position) (goto-char position) (goto-char (overlay-start position))))))
This is the function that uses ido for imenu. Since imenu occasionally has multiple levels - you select whether you want functions or variables, etc - this loops through all those sublists and adds all possibilities to a list. Once the list is compiled, it prompts you using ido for which definition you want to go to.
(setq imenu-auto-rescan t)
This just ensures that whenever you call imenu or the new function ido-goto-symbol you get the latest information, and not only functions which may have been cached.
(global-set-key (kbd "M-s") 'ido-goto-symbol)
I use this function quite frequently, so I rebound it to M-s. M-s is usually a prefix key for a few commands, but the only one I use that this interferes with is occur, but I use that rarely enough that I’m fine with just having to M-x occur. I use ido-goto-symbol enough that I really want it to be as few key presses as possible, so using something like M-s M-s would be pretty irritating.