is-vim

#! /bin/sh
# Usage: is_vim.sh <tty>
#   tty: Specify tty to check for vim process.
set -x
tty="$1"
alias /='eval'
list_length() {
	local index=0
	local item=
	for item do
		: $((index += 1))
	done
	printf "%s" $index
}
# Construct process tree.
# children=
# busybox does not support -t
# pids="$(ps -o pid= -t "$tty")"
pids="$(ps -o pid=)"

pid_list=
for pid in $pids; do
	pid_list="${pid_list:+"${pid_list}|"}$pid"
done
children_build() {
	local children_name=
	while read -r pid ppid
	do
		[ ! -z "$pid" ] && [ "$pid" -ne "$ppid" ] &&
		{
			/ "children_name=\"children_$ppid\""
			# / "children_$ppid=\"$pid\""
			/ "children_name=\"${children_name:+\"${children_name}|\"}$pid\""
		} || continue
	done < <(ps -Ao pid=,ppid=)
}
children_build
# Get all descendant pids of processes in $tty with BFS
query_relative() {
	local pid index=0
	local ifs="$IFS"
	local children_name=
	local IFS=$'|'
	for pid in $pid_list
	# while [ "$(list_length pids)" -gt "$index" ]
	do
		[ "$(IFS=$'|' list_length $pid_list)" -gt "$index" ] || break
		# pid=${pids[index++]}
		: $((index += 1))
		printf '%s %s\n' '$pid' "$pid" > "$TTY"
		/ "children_name=\"children_$pid\""
		/ "[ ! -z \"\${children_name+x}\" ]" || continue
		# / "child_value=\"\$${children_$pid-}\""
		/ "child_value=\"\$${children_name-}\""
		printf '%s %s\n' '$child_value' "$child_value" > "$TTY"
		# / "pid_list=\"${pid_list:+\"${pid_list}|\"}\$${children_$pid-}\""
		/ "pid_list=\"${pid_list:+\"${pid_list}|\"}$child_value\""
	done
}
query_relative
# Check whether any child pid_list are vim
# state -> stat, -p -> ''
# ps -o state=,comm= -p "$pid_list" | grep -iqE '^[^TXZ ]+ +(\\S+\\/)?g?(view|n?vim?x?)(diff)?$'
ps -o pid=,stat=,comm= | egrep "^(PID| *$pid_list )" | awk '{print $(NF - 1) " " $NF}' | grep -iqE '^[^TXZ ]+ +(\\S+\\/)?g?(view|n?vim?x?)(diff)?$'
set +x
exit $?
# [ is_vim does not detect vim running in a subshell #295 ](https://github.com/christoomey/vim-tmux-navigator/issues/295)