Narrow or widen dwim

The name says it all: This package wraps convenience functions for narrowing or widening the entity at point. I moved it from my .init.el to a separate package, and so why not make it public.

Installation

I use quelpa to download and install github packages; you might as well use straight or just copy the .el file. Here’s my personal setup:

;; * Narrow or widen dwim
(use-package narrow-or-widen-dwim
  :quelpa (narrow-or-widen-dwim
	     :fetcher github
	     :repo "publicimageltd/narrow-or-widen-dwim")
  :bind*
  (("C-x n" . narrow-or-widen-dwim)
   ("C-x i" . narrow-or-widwn-dwim-clone)))

Usage

narrow-or-widen-dwim

If narrowing is on, widen the buffer. Else narrow on the entity at point. That means:

If a region is active, narrow on the region.
If you are on a defun or anything conceptually similar which is recognized in your programming language mode, narrow on that function.
If you are on an org subtree, narrow buffer to this tree.
If you are on an org source code block, open it in the editor (that’s a kind of narrowing).
If you are in a Latex environment, narrow on that environment.

If called with prefix (C-u), narrow with a wider scope. E.g. if you press two time C-u before calling the function, in org mode, go up two levels before narrowing. If you are on a defun, widening the scope means to include the comments before the function definition.

narrow-or-widen-dwim-clone

Call narrow-or-widen-dwim in a newly created indirect buffer. This new buffer is displayed in the window returned by narrow-or-widen-dwim-window-split-function, which defaults to window-split-horizontally.

So effectively, the narrowed part is displayed in a newly created side window. Alternatives to splitting horizontally are to set narrow-or-widen-dwim-window-split-function to the function symbol split-window-vertically or to a more sophisticated wrapper around split-window.

If you prefer to switch to the cloned buffer without interfering with the window layout, set narrow-or-widen-dwim-window-split-function to selected-window. Maybe it is even possible to write a rule for display-buffer-alist which positions indirect buffers in the right way.

Credits

I saw the original narrowing function once somewhere on the blog of endless parentheses. I copied it and changed it to my need. Here we are.

publicimageltd / narrow-or-widen-dwim