TUI select fn

Those of you familiar with bash's select builtin know that the automated layout of choices is a nice feature. Last week while prototyping some SQL I became frustrated with select, mostly because you must type in a number and then press the Enter key. Remembering the TUI interfaces of the 1980's, I set about writing hkselect, a hotkey driven replacement for select. Here are the main features:

• Automated layout of choices.
• Assign item hotkey with &.
• Automatic hotkey assignment if & is missing.
• Bind escaped keys to callback functions.
• Transparently caches layout information and composed labels.

Full project is here

Below is an example bash program with a functioning hotkey TUI that includes callbacks for F1, F2, and F3:

	# Comments from hkselect() implementation in bash++
	function hkselect
	################################################
	# Approximate replacement for bash's builtin `select'.
	# hkselect() does not require the user to press enter key
	# to finalize choice.
	# Usage: hkselect [command_flags] arg1 ...
	#
	# User choices are supplied as args to the function, and
	# the hotkey may be indicated by placing an `&' in
	# the preceding character, e.g.
	# press&kplease
	# where `k' is the hotkey. If a hotkey is not indicated,
	# then one will be assigned automatically.
	#
	# Command flags:
	# -b 'keystr|funcname|arg1 arg2 ...' Bind escape-based key (F1-F12, Arrows, ...) to a function
	# -B global_arr_name Array of -b arguments
	# -p left_pad Left margin padding count
	# -r 'rebuke string' String to print when user pressed invalid key
	# -s 'subtitle string' Subtitle to print below choices
	# -w max_width Limit the width of choices layout
	#
	# Global variables:
	# HKSELKEY - key the user pressed when making a successful choice
	# REPLY - zero based index of the arg whose hotkey was pressed
	#
	# RETURN: upon return the value of HKSELKEY will contain the key which
	# the user pressed, and REPLY will contain the 0-based index of the
	# matching argument passed when hkselect() was called

view raw bash++ hosted with ❤ by GitHub

	#!/bin/bash
	##############################################################
	# Script to demonstrate use of hkselect() function in bash++
	#
	# John Robertson <[e-mail]>
	# Initial release: Tue Mar 30 11:02:44 EDT 2021
	#
	# Halt on error, no globbing, no unbound variables
	set -efu
	# import bash++ facilities
	source ../bash++
	# Flag so we know when a bound key was pressed
	is_boundKey=0
	function FnKey_cb
	###############################################################
	# This function is bound to function keys
	{
	1>&2 echo -en "\nI can see you've pressed $1\nPress return to continue "
	read
	# Note that a bound key callback cause hkselect() to return.
	is_boundKey=1
	}
	function cleanup
	################################################
	# Cleanup on exit
	{
	# Restore cursor
	tput cvvis
	# Reset any text attributes
	tput sgr0
	}
	###################################
	### Execution starts here #########
	###################################
	# cleanup on exit
	trap cleanup 0
	# Data might come from a dynamic source, like a file or pipe or ...
	declare -a DATA_CHOICES=([0]=one [1]=two [2]=three)
	# Strings we'll use repeatedly
	PAD=" "
	REBUKE="${PAD}$(tput bold)Please make a selection, or press a function key.$(tput sgr0)"
	SUBTITLE="${PAD}You will write awesome programs with $(tput bold)bash++$(tput sgr0)"
	# Loop processing user keystrokes
	while true; do
	# Clear the terminal
	tput clear
	# Print banner
	1>&2 echo -e "\n${PAD}$(tput rev)Welcome to the hkselect example program$(tput sgr0)"
	1>&2 echo -e "${PAD}$(tput bold)Press a function key!$(tput sgr0)"
	# Wait for user to press a valid key
	hkselect \
	-r "$REBUKE"\
	-s "$SUBTITLE"\
	-p 4 \
	-b $(tput kf1)'|FnKey_cb|F1' \
	-b $(tput kf2)'|FnKey_cb|F2' \
	-b $(tput kf3)'|FnKey_cb|F3' \
	"${DATA_CHOICES[@]}"\
	'&Shout hurray!' 'E&xit'
	# Handle known hotkeys first
	case $HKSELKEY in
	s|S)
	1>&2 echo -en 'Hurray!\nPress return to continue '
	read discard
	;;
	x|X) break;;
	$'\e') # User pressed escape
	echo
	break
	;;
	*) # Could be an automatically assigned hotkey
	if (( !is_boundKey )); then
	# If we get to here, then REPLY contains the zero based index of the item chosen by the user
	1>&2 echo -en "Thank you for selecting '${DATA_CHOICES[$REPLY]}'.\nPress return to continue "
	read
	fi
	;;
	esac
	is_boundKey=0
	done

view raw hkselect.sh hosted with ❤ by GitHub