emotional.hx

Motion commands for the Helix⁠ editor, written in Steel Scheme.

(Partial) implementation of motion features from 4 old, unmerged PRs, implemented as a plug-in: moving lines, motions that respect line boundaries, word motions where a count selects everything it passes over, and matching the next or previous character pair.

Upstream

Feature	PR	Open since
Move lines or selections up and down	#4545⁠	Oct 2022
same_line and anchored motions	#10576⁠	Apr 2024
Count selects everything swept over	#1570⁠	Jan 2022
Match next/previous character pair	#11695⁠	Sep 2024

Install

Requires a plugin-enabled Helix build. With forge⁠, Steel’s package manager:

forge pkg install --git https://github.com/waddie/emotional.hx

Then in ~/.config/helix/init.scm:

(require "emotional.hx/emotional.scm")

It’s unlikely you want all the commands provided by the plug-in.

You can import only the ones you want like this:

(require (only-in "emotional.hx/emotional.scm"
          move_lines_up
          move_lines_down))

Commands

Line movement

Command	Action
move_lines_up	Swap the lines the selection touches with the line above
move_lines_down	Swap them with the line below

The selection travels with the text, so the cursor stays on what it was on.

Same-line motions

Horizontal motions that stop at the line boundary instead of wrapping onto the neighbouring line.

Command	Action
move_same_line_char_left	Left one character, stopping at the line start
move_same_line_char_right	Right one character, stopping at the line end
extend_same_line_char_left	As above, extending the selection
extend_same_line_char_right	As above, extending the selection
append_mode_same_line	Append, without crossing onto the next line

Anchored motions

Vertical motions that keep the cursor off newline characters. A cursor on an ordinary character takes the same column on the target line, or the last real character if that column holds the newline. A cursor already sitting on newlines carries on doing so.

Command	Action
move_anchored_line_up	Up one line, avoiding newlines
move_anchored_line_down	Down one line, avoiding newlines
extend_anchored_line_up	As above, extending the selection
extend_anchored_line_down	As above, extending the selection

Word motions

3w in stock Helix selects the third word. These select all three so, if sweep_next_word_start is bound to w, 3wd deletes three words without needing v3wd.

To be useful, you must invoke these via a keybinding, as you can’t pass a count to a typed command.

Command	Action
sweep_next_word_start	Next word start, keeping everything crossed
sweep_prev_word_start	Previous word start
sweep_next_word_end	Next word end
sweep_next_long_word_start	Next WORD start
sweep_prev_long_word_start	Previous WORD start
sweep_next_long_word_end	Next WORD end

Pair matching

Select inside or around the nearest character pair, without the cursor having to be inside it already. Each prompts for the pair character. Brackets nest properly; quote-like characters match the next occurrence.

These must be invoked via a keybinding to work properly, they won’t work as typed commands.

Command	Action
match_inside_next	Contents of the next pair
match_around_next	Next pair including delimiters
match_inside_prev	Contents of the previous pair
match_around_prev	Previous pair including delimiters

Keymap

Counts only reach a command through a keybinding, and the pair-matching commands only work through one, so bind the ones you want:

(require "helix/keymaps.scm")
(require "emotional.hx/emotional.scm")

(keymap (global)
  (normal
    (w ":sweep_next_word_start")
    (b ":sweep_prev_word_start")
    (e ":sweep_next_word_end")
    (A-up ":move_lines_up")
    (A-down ":move_lines_down")))

Known limitations

• The pair-matching commands must be bound to keys. Running :match_inside_next from the command line leaves on-key-callback unregistered, so the pair character falls through to Helix, starts a register selection, and the keystrokes after it run as normal-mode commands. This will chew up your buffer. Bind them or leave them alone.
• Counts need a keybinding too. A typable command invoked with : has no count to read, so sweep_* behaves as though the count were 1.
• The *_visual_line_* commands from #10576 are not implemented. They need the soft-wrap and annotation layout to resolve visual rows, which Steel cannot compute. If you use soft wrap, the anchored motions work on real lines only.
• move_lines_* discards extra cursors. The edit goes through replace-selection-with, which rewrites every non-empty range with the same string, so the selection is reduced to one range first.
• Pair matching converts the whole document to a string per invocation. Fine on ordinary source files, wasteful on very large ones.
• The anchored motions keep their own goal column, because Helix’s lives in the view and is not exposed. It is trusted only while the cursor stays where the last vertical move left it, so mixing in other motions re-derives it rather than jumping somewhere stale.

Tests

The pure logic (line rotation, column arithmetic, pair scanning, range merging) is unit tested and runs headless. Requires steel-test⁠ in ~/.steel/cogs:

sh tests/run-all.sh

The command modules require Helix modules, which cannot load under the bare steel CLI, so they are verified in the editor rather than in the suite.

Licence

AGPL-3.0. See LICENSE⁠.