Symbol Overlay

Highlight symbols with overlays while providing a keymap for various operations about highlighted symbols. It was originally inspired by the package highlight-symbol. The fundamental difference is that in symbol-overlay every symbol is highlighted by the Emacs built-in function overlay-put rather than the font-lock mechanism used in highlight-symbol.

What's New!

20190306:

New commands symbol-overlay-jump-first (key "<") and symbol-overlay-jump-last (key ">") are now enabled.

20190305:

New customizable variable symbol-overlay-displayed-window is introduced to control the overlay behavior at symbol-overlay-mode. If it is non-nil, occurrences outside the displayed window will not be counted or highlighted.

20170826:

symbol-overlay-toggle-in-scope now affects both global and in-scope highlighting. symbol-overlay-rename now uses the original symbol name as the initial text in minibuffer. New command symbol-overlay-count for counting symbol at point. And other improvements.

20170426:

Minor-mode symbol-overlay-mode for auto-highlighting is now enabled.

20170423:

Toggling to isearch-mode is now enabled. Try symbol-overlay-isearch-literally via "s" to search the not-quoted symbol in isearch-mode.

20170420:

Toggling overlays to be showed in buffer or only in scope is now enabled. When symbol is highlighted in scope, all related operations is narrowed to the scope, too. Try symbol-overlay-toggle-in-scope via "t". This feature is applicable only for languages that support the lisp function narrow-to-defun. Otherwise you may specify beginning-of-defun-function and end-of-defun-function on your own.

20170417:

Auto-refresh is now enabled. Every time the highlighted text is changed or a new occurrence shows up, the buffer will refresh automatically.

Two new commands added: symbol-overlay-save-symbol for copying the current symbol, symbol-overlay-echo-mark for undoing a recent jump.

Advantages

Fast

When highlighting symbols in a buffer of regular size and language, overlay-put behaves as fast as the traditional Highlighting method font-lock. However, for a buffer of major-mode with complicated keywords syntax, like haskell-mode, font-lock is quite slow even the buffer is less than 100 lines. Besides, when counting the number of highlighted occurrences, highlight-symbol will call the function how-many twice, which could also result in an unpleasant delay in a large buffer. Those problems don't exist in symbol-overlay.

Convenient

When putting overlays on symbols, an auto-activated overlay-inside keymap will enable you to call various useful commands with a single keystroke.

Powerful

• Toggle all overlays of symbol at point: symbol-overlay-put
• Jump between locations of symbol at point: symbol-overlay-jump-next & symbol-overlay-jump-prev
• Switch to the closest symbol highlighted nearby: symbol-overlay-switch-forward & symbol-overlay-switch-backward
• Minor mode for auto-highlighting symbol at point: symbol-overlay-mode
• Remove all highlighted symbols in the buffer: symbol-overlay-remove-all
• Copy symbol at point: symbol-overlay-save-symbol
• Toggle overlays to be showed in buffer or only in scope: symbol-overlay-toggle-in-scope
• Jump back to the position before a recent jump: symbol-overlay-echo-mark
• Jump to the definition of symbol at point: symbol-overlay-jump-to-definition
• Isearch symbol at point literally, without regexp-quote the symbol: symbol-overlay-isearch-literally
• Query replace symbol at point: symbol-overlay-query-replace
• Rename symbol at point on all its occurrences: symbol-overlay-rename

Usage

To use symbol-overlay in your Emacs, you need only to bind these keys:

(require 'symbol-overlay)
(global-set-key (kbd "M-i") 'symbol-overlay-put)
(global-set-key (kbd "M-n") 'symbol-overlay-switch-forward)
(global-set-key (kbd "M-p") 'symbol-overlay-switch-backward)
(global-set-key (kbd "<f7>") 'symbol-overlay-mode)
(global-set-key (kbd "<f8>") 'symbol-overlay-remove-all)

Default key-bindings defined in symbol-overlay-map:

"i" -> symbol-overlay-put
"n" -> symbol-overlay-jump-next
"p" -> symbol-overlay-jump-prev
"w" -> symbol-overlay-save-symbol
"t" -> symbol-overlay-toggle-in-scope
"e" -> symbol-overlay-echo-mark
"d" -> symbol-overlay-jump-to-definition
"s" -> symbol-overlay-isearch-literally
"q" -> symbol-overlay-query-replace
"r" -> symbol-overlay-rename

You can re-bind the commands to any keys you prefer by simply writing

(define-key symbol-overlay-map (kbd "your-prefer-key") 'any-command)

Or you may prefer to overwrite the keymap

(let ((map (make-sparse-keymap)))
  (define-key map (kbd "key1") 'command-1)
  (define-key map (kbd "key2") 'command-2)
  (setq symbol-overlay-map map))

As a final example, you can define a handy set of keys using transient: see the snippet posted here.