gleber / expand-region.el

Emacs extension to increase selected region by semantic units.

expand-region.el

Expand region increases the selected region by semantic units. Just keep pressing the key until it selects what you want.

An example:

(setq alphabet-start "abc def")

With the cursor at the c, it starts by marking the entire word abc, then expand to the contents of the quotes abc def, then to the entire quote "abc def", then to the contents of the sexp setq alphabet-start "abc def" and finally to the entire sexp.

You can set it up like this:

(require 'expand-region)
(global-set-key (kbd "C-@") 'er/expand-region)

There's also er/contract-region if you expand too far.

Video

You can watch an intro to expand-region at Emacs Rocks.

Language support

Expand region works fairly well with most languages, due to the general nature of the basic expansions:

er/mark-word
er/mark-symbol
er/mark-method-call
er/mark-comment
er/mark-comment-block
er/mark-inside-quotes
er/mark-outside-quotes
er/mark-inside-pairs
er/mark-outside-pairs

However, most languages also will benefit from some specially crafted expansions. For instance, expand-region comes with these extra expansions for html-mode:

er/mark-html-attribute
er/mark-inner-tag
er/mark-outer-tag

You can add your own expansions to the languages of your choice simply by creating a function that looks around point to see if it's inside or looking at the construct you want to mark, and if so - mark it.

There's plenty of examples to look at in these files.

After you make your function, add it to a buffer-local version of the er/try-expand-list.

Example:

Let's say you want expand-region to also mark paragraphs and pages in text-mode. Incidentally Emacs already comes with mark-paragraph and mark-page. To add it to the try-list, do this:

(defun er/add-text-mode-expansions ()
  (make-variable-buffer-local 'er/try-expand-list)
  (setq er/try-expand-list (append
                            er/try-expand-list
                            '(mark-paragraph
                              mark-page))))

(add-hook 'text-mode-hook 'er/add-text-mode-expansions)

Add that to its own file, and require it at the bottom of this one, where it says "Mode-specific expansions"

Warning: Badly written expansions might slow down expand-region dramatically. Remember to exit quickly before you start traversing the entire document looking for constructs to mark.

Contribute

If you make some nice expansions for your favorite mode, it would be great if you opened a pull-request. The repo is at:

https://github.com/magnars/expand-region.el

Changes to the er/expand-region functions itself must be accompanied by feature tests. They are written in Ecukes, a Cucumber for Emacs.

To fetch the test dependencies:

$ cd /path/to/expand-region
$ git submodule init
$ git submodule update

Run the tests with:

$ ./util/ecukes/ecukes features

If you want to add feature-tests for your mode-specific expansions as well, that is utterly excellent.

Contributors

• Josh Johnston contributed er/contract-region
• Le Wang contributed consistent handling of the mark ring, expanding into pairs/quotes just left of the cursor, and general code clean-up.
• Matt Briggs contributed expansions for ruby-mode.
• Ivan Andrus contributed expansions for python-mode, text-mode and LaTeX-mode.
• Raimon Grau added support for when transient-mark-mode is off.
• Gleb Peregud contributed expansions for erlang-mode.

Thanks!

License

Copyright (C) 2011 Magnar Sveen

Author: Magnar Sveen [email protected] Keywords: marking region

This program 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.

This program 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 this program. If not, see http://www.gnu.org/licenses/.