# ksh93 brainfuck compiler
typeset -T countcache_t=(
	typeset op=""
	integer count=0

	typeset tabe="" # tab engine
	
	function flush
	{
		nameref t=${_.tabe}
		if [[ "${_.op}" != "" ]] ; then
			t.w ; printf "${_.op}\n" _.count
		fi
		
		# reset
		(( _.count=0 ))
		_.op=""
		return 0
	}
	function write_op
	{
		typeset wop="$1"

		[[ "${wop}" != "${_.op}" ]] && _.flush

		(( _.count++ ))
		_.op="${wop}"
		return 0
	}
)

# manage tab intents
typeset -T tab_t=(
	typeset indent=""

	function inc
	{
		_.indent+=$'\t'
		return 0
	}
	function dec
	{
		_.indent="${_.indent:0:${#_.indent}-1}"
		return 0
	}
	function w # write
	{
		printf "%s" "${_.indent}"
		return 0
	}
)


function write_bf_head
{
cat <<EOF
#!/usr/bin/ksh93

# I/O functions
function pc # putchar
{
	nameref x=\$1
	typeset c
	c=\${ printf "%x\n" "\$x" ; }
	printf "\u[\${c}]"
	return 0
}

function gc # getchar
{
	nameref x="\$1"
	typeset c

	# we only write into "x" if we could read a character
	if read -N1 c ; then
		(( x='\${c} ))
	fi
	return 0
}

# main
set -o noglob
IFS=''

integer -a t
integer p
(( p=2**18 )) # tape start position

# bf program start

EOF
	return 0
}

function write_bf_tail
{
cat <<EOF
# bf program end

exit 0
EOF
	return 0
}

function brainfuck2shell
{
	typeset c

	while read -N1 c ; do
		case "$c" in
			'>') cc.write_op '(( p+=%d ))' ;;
			'<') cc.write_op '(( p-=%d ))' ;;
			'+') cc.write_op '(( t[p]+=%d ))' ;;
			'-') cc.write_op '(( t[p]-=%d ))' ;;
			'.') cc.flush ; tb.w ; print 'pc t[p]' ;;
			',') cc.flush ; tb.w ; print 'gc t[p]' ;;
			'[') cc.flush ; tb.w ; print 'while (( t[p] != 0 )) ; do' ; tb.inc ;;
			']') cc.flush ; tb.dec ; tb.w ; print 'done' ;;
		esac
	done
	return 0
}


# main
set -o noglob
set -o nounset
IFS=''

tab_t tb
countcache_t cc=( tabe=tb )

write_bf_head
brainfuck2shell
write_bf_tail

exit 0