Dynamically Filter By Column (like Helix)?

[pbnj-dragon]

Helix introduced a new feature to their fuzzy finder/picker, called tabular pickers. Basically, the feature adds support for columnar/tabular data with individually filterable columns.

For example, say you want to fuzzy search through ps aux to find process bar by user foo:

USER               PID  %CPU %MEM      VSZ    RSS   TT  STAT STARTED      TIME COMMAND
_windowserver      380  11.1  0.6 413026976  93328   ??  Rs   Wed10AM 216:09.73 /System/Library/PrivateFrameworks/SkyLight.framework/Resources/WindowServer -daemon
root               373   1.1  0.2 426996736  29248   ??  Ss   Wed10AM  18:30.80 /usr/sbin/bluetoothd
root               374   0.9  0.0 426912016   3424   ??  Ss   Wed10AM   7:04.58 /usr/sbin/notifyd
root                 1   0.4  0.1 426852528  15856   ??  Ss   Wed10AM  20:14.09 /sbin/launchd
foo                731   0.4  0.1 426961120  11424   ??  Ss   Wed10AM   2:50.66 /usr/libexec/bar
baz                731   0.4  0.1 426961120  11424   ??  Ss   Wed10AM   2:50.66 /usr/libexec/bar

In Helix, users would filter by specific columns with a query syntax like %COMMAND bar %USER foo (short-hand: %C ba %U fo, or fuzzily %CMD br %USR fo), which would match on /usr/libexec/bar command by user foo:

foo                731   0.4  0.1 426961120  11424   ??  Ss   Wed10AM   2:50.66 /usr/libexec/bar

This is an extremely useful & productive feature because many CLI programs output tabular data (e.g. kubectl, docker, ps, top) and users would be able to filter by arbitrary columns without having to "massage" the data before piping it to fzf (e.g. ps aux | fzf --query '%U foo %C bar' vs ps aux | awk '{print $1"\t"$2"\t"$11}' | fzf --header-lines=1).

The closest I was able to get was using --nth, like ps aux | fzf --nth 1,11 --header-lines 1 --query 'foo bar', but this approach is limited to pre-determined columns. Users cannot filter by arbitrary columns.

Unless I am missing a way that users can dynamically change --nth, it would be nice for this feature to be supported by fzf, either via a search syntax (e.g. %<column> <term>) or a bind + action (e.g. --bind "tab:increment-nth()" / --bind "shift-tab:decrement-nth()".

[junegunn]

There is an open issue for adding change-nth action. #2743

Changing --with-nth dynamically probably is not going to be supported because it will have a huge impact on loading performance, but I think it's feasible to add an action to change nth though it would require careful cache management.

[junegunn]

Also see #4183

[gennaro-tedesco]

Woow, this is a fantastic feature! I have browsed the newest docs here: is there a specific grammar to indicate "cycle all columns" instead of change-nth(2|3|4|..) (which would require the user to write a different command for each different case instead of specifying it in the general configuration)?

[junegunn]

Because fzf is a text filter that runs asynchronously, it cannot know the exact number of columns in the list in advance (it can dynamically grow as the new data comes in), so there's no nice and overhead-free way to implement the suggested feature.

Instead, you might want to check out d658454 that I just pushed to master. It allows you to implement a clickable header.

click-header-transform-nth.mov

[junegunn]

A more sophisticated implementation which allows selecting multiple columns (with ctrl-click, alt-click, or shift-click).

fzf/shell/completion.bash

Lines 411 to 442 in 4b74f88

	_fzf_proc_completion() {
	local transformer
	transformer='
	if [[ $FZF_KEY =~ ctrl|alt|shift ]] && [[ -n $FZF_NTH ]]; then
	nths=( $(tr , " " <<< "$FZF_NTH") )
	new_nths=()
	found=0
	for nth in ${nths[@]}; do
	if [[ $nth = $FZF_CLICK_HEADER_NTH ]]; then
	found=1
	else
	new_nths+=($nth)
	fi
	done
	[[ $found = 0 ]] && new_nths+=($FZF_CLICK_HEADER_NTH)
	new_nths=$(echo ${new_nths[@]} | tr " " ,)
	echo "change-nth($new_nths)+change-prompt($new_nths> )"
	else
	if [[ $FZF_NTH = $FZF_CLICK_HEADER_NTH ]]; then
	echo "change-nth()+change-prompt(> )"
	else
	echo "change-nth($FZF_CLICK_HEADER_NTH)+change-prompt($FZF_CLICK_HEADER_WORD> )"
	fi
	fi
	'
	_fzf_complete -m --header-lines=1 --no-preview --wrap --color fg:dim,nth:regular \
	--bind "click-header:transform:$transformer" -- "$@" < <(
	command ps -eo user,pid,ppid,start,time,command 2> /dev/null ||
	command ps -eo user,pid,ppid,time,args 2> /dev/null || # For BusyBox
	command ps --everyone --full --windows # For cygwin
	)
	}

[gennaro-tedesco]

This is fantastic work, thank you for all the effort you're putting in! 🚀