cctrlw 0.5

Configurable Ctrl-W algorithm, xontrib and CLI.

# cctrlw

Configurable Ctrl-W (see gifs to understand what that means).

This project addresses the pitfalls of [xonsh](https://xon.sh/) (a brilliant project) btw builtin Ctrl-W functionality.

What exactly was wrong? There was no way to configure which characters are considered equivalent (and hence, to be deleted on a Ctrl-W keystoke). Say you wanted to edit a ‘cd to/a/very/long/path’ and press a C-W. Then everything till space is removed, which often is not the desired behaviour.

Ok, so how to configure such a thing? Mathematically such configuration is equivalent to a [partition](https://en.wikipedia.org/wiki/Partition_of_a_set) of the set of all characters. In terms of implementation, [disjoint set union data structure](https://en.wikipedia.org/wiki/Disjoint-set_data_structure) can be used to maintain partitions. Using a DSU is not really a requirement; however it turns out to be the simplest and cleanest implementation.

See [docstring](https://github.com/ggdwbg/cctrlw/blob/main/cctrlw/algo.py#L166) for load_partitions in cctrlw/algo.py to understand the approach used to define partitions.

## Default configuration

Default cw_modes.json defines the following partitions:

• S: singletons

• ldu: {{a..z}, {0..9}, {A..Z}} (3 nontrivial classes)

• ldup: compared to ldu: elements of string.punctuation are now equivalent (4 nontrivial classes)

• Ldp: compared to ldup: lower and upper are merged (3 nontrivial classes)

• Ap: compared to Ldp: digits and letters are merged (2 nontrivial classes)

• W: compared to Ap: digits and punctuation are merged (1 nontrivial class, but space is not punctuation and still lives in a singleton)

Xonsh default Ctrl-W corresponds to W (approximately, because it removes trailing whitespace, which is never done in default config).

You can use your own config and add space to, for example, your custom ldu, then space will be removed automatically (furthermore, FASFfdsf dsfsfdsf ` would turn into `FASF with a single keystroke). Or do something completely different, that’s why it’s named config.

## What’s included

This module provides a CLI and a xontrib for use with xonsh:

• CLI: run python -m cctrlw.cli -h for details.

• Xontrib: add xontrib load xonsh_cctrlw to your .xonshrc

  Controlling state is done through envvars:

  • $CW_MODE: active partition; default: Ap.

  • $CW_CONFIG: active configuration json; default: <package location>/cw_modes.json

  • $CW_DEBUG: true to to see debug messages like what partition is loaded, false to disable; default: false.

## What could be improved

See TODOs.txt. Major ones could be:

• a (subjectively) better version of whole-word-jumping

• *sh plugin that uses CLI; originally cli was implemented exactly with that in mind.

  Learning bash/*sh is not really that interesting, so this may never end up done, but maybe fish is not as bad.

• configurable __repr__ for dsu.