create jsonvar.bash

scraps/jsonvar.bash

@@ -0,0 +1,257 @@
+#!/usr/bin/env bash
+#
+# Serialize bash variables to JSON output
+#
+# # Created
+# Author: Dave Eddy <ysap@daveeddy.com>
+# Date: July 09, 2026
+# License: MIT
+#
+# # Contributors
+# - Dave Eddy <ysap@daveeddy.com>
+
+_jv-usage() {
+	local usage
+	read -r -d '' usage <<-EOF
+	Usage: jsonvar [-aev] [[name], ...]
+
+	Serialize bash variables to JSON output
+
+	Options
+	    -a    show all variables
+	    -e    show only exported variables
+	    -v    show only the values of the variables
+	    -h    show this message and exit
+	EOF
+	echo "$usage"
+}
+
+_jv-json-encode-string() {
+	local s=$1
+
+	local LC_ALL=C
+	local -A table=()
+
+	# we can start at 1 because bash variables can't have nul bytes in them
+	local hex byte esc i
+	for ((i = 1; i < 0x20; i++)); do
+		printf -v hex '%02x' "$i"
+
+		printf -v byte '%b' "\\x$hex"
+		printf -v esc '\\u%04x' "$i"
+		table[$byte]=$esc
+	done
+
+	table[$'\b']='\b'
+	table[$'\t']='\t'
+	table[$'\n']='\n'
+	table[$'\f']='\f'
+	table[$'\r']='\r'
+
+	table['\']='\\'
+	table['"']='\"'
+
+	# serialize the string
+	local out=''
+	local len=${#s}
+	local c
+	for ((i = 0; i < len; i++)); do
+		c=${s:i:1}
+		esc=${table[$c]}
+
+		if [[ -n $esc ]]; then
+			# lookup table matched for this byte
+			out+=$esc
+		else
+			# no lookup table match, byte falls through
+			out+=$c
+		fi
+	done
+
+
+	printf '"%s"' "$out"
+}
+
+_jv-encode-variable() {
+	local _jv_name=$1
+	local -n _jv_ref=$_jv_name
+	local _jv_attrs=${_jv_ref@a}
+
+	case "$_jv_attrs" in
+		*a*) # process indexed array
+			echo -n '['
+			local _jv_value _jv_i=0
+			for _jv_value in "${_jv_ref[@]}"; do
+				((_jv_i++))
+
+				# check member type
+				if [[ $_jv_attrs == *i* ]]; then
+					printf '%d' "$_jv_value"
+				else
+					_jv-json-encode-string "$_jv_value"
+				fi
+
+				if ((_jv_i < ${#_jv_ref[@]})); then
+					echo -n ', '
+				fi
+			done
+			echo -n ']'
+			;;
+		*A*) # process associative array
+			echo -n '{'
+			local _jv_key _jv_value _jv_i=0
+			for _jv_key in "${!_jv_ref[@]}"; do
+				((_jv_i++))
+
+				_jv_value=${_jv_ref[$_jv_key]}
+
+				_jv-json-encode-string "$_jv_key"
+				echo -n ': '
+
+				if [[ $_jv_attrs == *i* ]]; then
+					printf '%d' "$_jv_value"
+				else
+					_jv-json-encode-string "$_jv_value"
+				fi
+
+				if ((_jv_i < ${#_jv_ref[@]})); then
+					echo -n ', '
+				fi
+			done
+			echo -n '}'
+			;;
+		*i*) # process integer
+			echo -n "$_jv_ref"
+			;;
+		*) # anything else, it's probably a string lol
+			_jv-json-encode-string "$_jv_ref"
+			;;
+	esac
+
+}
+
+jsonvar() {
+	local _jv_all='false'
+	local _jv_exported='false'
+	local _jv_value='false'
+
+	# get arguments from user
+	local OPTIND OPTARG _jv_opt
+	while getopts 'aevh' _jv_opt; do
+		case "$_jv_opt" in
+			a) _jv_all='true';;
+			e) _jv_exported='true';;
+			v) _jv_value='true';;
+			h) _jv-usage; return 0;;
+			*) _jv-usage >&2; return 2;;
+		esac
+	done
+	shift "$((OPTIND - 1))"
+
+	local _jv_key
+
+	# figure out what variables to look at
+	local -a _jv_variables
+	if $_jv_all; then
+		readarray -t _jv_variables < <(compgen -v)
+	elif $_jv_exported; then
+		readarray -t _jv_variables < <(compgen -e)
+	else
+		_jv_variables=("$@")
+
+		# ensure the user gave us *something*
+		if (( ${#_jv_variables[@]} == 0 )); then
+			echo 'variable name or flag required' >&2
+			_jv-usage >&2
+			return 2
+		fi
+
+		# check variables given
+		local _jv_error='false'
+		for _jv_key in "${_jv_variables[@]}"; do
+			# warn the user if they gave us an internal name
+			if [[ $_jv_key == _jv_* ]]; then
+				echo "[error] invalid internal variable '$_jv_key'" >&2
+				_jv_error='true'
+			fi
+
+			# check to make sure the variable is defined
+			if ! declare -p "$_jv_key" &>/dev/null; then
+				echo "[error] variable '$_jv_key' not defined" >&2
+				_jv_error='true'
+			fi
+		done
+
+		if $_jv_error; then
+			return 1
+		fi
+	fi
+
+	# loop the variables first to filter out hidden / internal var names
+	local _jv_i
+	local _jv_len=${#_jv_variables[@]}
+	for ((_jv_i = 0; _jv_i < _jv_len; _jv_i++)); do
+		_jv_key=${_jv_variables[_jv_i]}
+
+		# filter out internal variables by name
+		if [[ $_jv_key == _jv_* ]]; then
+			unset '_jv_variables[_jv_i]'
+			continue
+		fi
+
+		# variable name was good, do nothing
+	done
+
+	# loop the remaining variables and format them
+	$_jv_value || echo '{'
+	_jv_i=0
+	for _jv_key in "${_jv_variables[@]}"; do
+		((_jv_i++))
+
+		if ! $_jv_value; then
+			# indent
+			echo -n '    '
+
+			# print the key
+			_jv-json-encode-string "$_jv_key"
+			echo -n ': '
+		fi
+
+		# print the value
+		_jv-encode-variable "$_jv_key"
+
+		# optionally print the comma
+		if ! $_jv_value && ((_jv_i < ${#_jv_variables[@]})); then
+			echo -n ','
+		fi
+		echo
+	done
+	$_jv_value || echo '}'
+}
+
+_jv-complete() {
+	COMPREPLY=(
+		# add all variables
+		$(compgen -v -- "${COMP_WORDS[COMP_CWORD]}")
+
+		# add the individual flags
+		$(compgen -W '-a -e -v -h' -- "${COMP_WORDS[COMP_CWORD]}")
+	)
+}
+
+if ( return 0 &>/dev/null ); then
+	# we are being sourced
+	complete -F _jv-complete jsonvar
+else
+	# we are being executed directly
+	declare -a test_indexed=(a b c)
+	declare -a test_sparse=(a b c [67]=d)
+	declare -A test_assoc=([a]=1 [b]=2 [c]=3)
+	declare -i test_int=67
+	declare -- test_string='hello world'
+
+	declare -ai test_indexed_ints=(0 1 2 0xff foo bar baz)
+	declare -Ai test_assoc_ints=([foo]=0 [bar]=1 [baz]=0xff [bat]=foo)
+
+	jsonvar "$@"
+fi