HT="$(printf '\t.')";   HT="${HT%.}"
LF="$(printf '\n.')";   LF="${LF%.}"
RS="$(printf '\036.')"; RS="${RS%.}"
US="$(printf '\037.')"; US="${US%.}"

dbg()
{
	dbg=true
	dbg=false
	if ${dbg}; then
		printf 'DEBUG: %s\n' "${@}" >&2
	fi
}

. ./tokens.sh
. ./lexer.sh

complete_command()
{
	if list; then
		separator
		return 0
	fi
	return 1
}

list()
{
	if and_or; then
		while separator_op; do
			if ! and_or; then
				return 1
			fi
		done
		return 0
	fi
	return 1
}
and_or()
{
	if pipeline; then
		while accept T_AND_IF || accept T_OR_IF; do
			if ! linebreak || ! pipeline; then
				return 1
			fi
		done
		return 0
	fi
	return 1
}
pipeline()
{
	accept T_BANG
	if pipe_sequence; then
		return 0
	fi
	return 1
}

pipe_sequence()
{
	if command; then
		while accept T_PIPE; do
			if ! linebreak || ! command; then
				return 1
			fi
		done
		return 0
	fi
	return 1
}

command()
{
	# XXX: Unfinished
	accept T_WORD
}



newline_list()
{
	if accept T_NEWLINE; then
		while accept T_NEWLINE; do
			:
		done
		return 0
	fi
	return 1
}
linebreak()
{
	newline_list
	return 0
}

separator_op()
{
	if accept T_AND || accept T_SEMI; then
		return 0
	fi
	return 1
}

separator()
{
	if separator_op && linebreak; then
		return 0
	elif newline_list; then
		return 0
	fi
	return 1
}

parse()
{
	local fn="${1}"
	shift 1

	init_lexer "${fn}"

	# If this returns (does not exit), there are no errors.
	while complete_command; do :; done

	get_tokens

	return 0
}

try()
{
	local tokens=
	local t=

	printf 'Trying script:\n'
	printf '\t%s\n' "${@}"
	if tokens="$(printf '%s\n' "${@}" | parse -)"; then
		IFS="${RS}"
		for t in ${tokens}; do
			printf 'Token: %s\n' "$(tokname "${t}")"
			case "${t%${US}*}" in T_WORD)
				printf '       "%s"\n' "${t#T_WORD${US}}"
				;;
			esac
		done
		unset IFS
	else
		printf 'FAIL\n'
	fi
	printf '\n\n'
}

try '"foo bar" && $baz || qux' '${quux%uux  quuux'
try '"foo bar" && $baz || qux' '${quux%uux } quuux'
try 'foo ${bar}'
try 'foo ${#bar}'
try 'foo ${bar#baz}'
try 'foo ${#bar#}'
try 'foo ${^}'
try 'foo `bar`'