Loccur

Introduction

Loccur is an amazing tool to quickly navigate in a file. It is a minor mode for Emacs acting like occur but w/o creating a new window. It just hides all the text excepting lines containing matches.

Installation

Add to your .emacs or .emacs.d/init.el following lines:

(setq package-archives '(("gnu" . "http://elpa.gnu.org/packages/")
                         ("melpa" . "http://melpa.milkbox.net/packages/")))

Press M-x in GNU Emacs and write list-packages. Find the loccur in the list of packages and press i to select this package, x to install the package.

Screenshots

Better to see it once:

Usage

To use it, add the following to your .emacs file:

(require 'loccur)
;; defines shortcut for loccur of the current word
(define-key global-map [(control o)] 'loccur-current)
;; defines shortcut for the interactive loccur command
(define-key global-map [(control meta o)] 'loccur)
;; defines shortcut for the loccur of the previously found word
(define-key global-map [(control shift o)] 'loccur-previous-match)

Now you can point the cursor to the word and press Ctrl+o to hide all lines except those containing this word. Moving cursor to the required line and pressing Ctrl+o again will shows all the text. The good thing about this mode is what you can navigate through the buffer easily. Ctrl+Shift+o will repeat last search.

Available commands

Below is the list of interactive commands available for user:

• loccur interactively asks user for regexp to search or toggle search off (if loccur-mode is already enabled)
• loccur-current searches for the current word under the cursor
• loccur-previous-match repeat previous loccur command
• loccur-no-highlight is the same as loccur but not highlighting matches
• loccur-toggle-highlight toggles highlighting of matches
• loccur-isearch: incremental occur (more details below)

Customization

• loccur-jump-beginning-of-line variable specifies if move the cursor to the beginning of the matching line. Default nil
• loccur-highlight-matching-regexp variable whenever loccur should highlight matching words. Default t.
• loccur-face face to be used while highlighting. Default points to isearch face.

Isearch integration

The loccur-isearch command filters buffer lines incrementally as you type a search string. It can also be called when Isearch is already active to turn filtering on or off. For the latter functionality, you should bind the command in isearch-mode-map, for example as follows:

(define-key global-map (kbd "M-s C-o") 'loccur-isearch)
(define-key isearch-mode-map (kbd "C-o") 'loccur-isearch)

Contributions

You can contribute to loccur in one of the following ways.

• Submit a bug report
• Submit a feature request
• Submit a simple pull request (with changes < 15 lines)

Copyright issues

Since loccur is a part of GNU ELPA, it is copyrighted by the Free Software Foundation, Inc.. Therefore in order to submit nontrivial changes (with total amount of lines > 15), one needs to to grant the right to include your works in GNU Emacs to the FSF.

For this you need to complete this form, and send it to [email protected]. The FSF will send you the assignment contract that both you and the FSF will sign.

For more information one can read here to understand why it is needed.

As soon as the paperwork is done one can contribute to loccur with bigger pull requests. Note what pull requests without paperwork done will not be accepted, so please notify the maintainer if everything is in place.