get-opt-and-optarg-example.bash.snippet

...

function get_opt_and_optarg {
	local optional=false

	if [[ $1 == @optional ]]; then
		optional=true
		shift
	fi

	OPT=$1 OPTARG= OPTSHIFT=0

	if [[ $1 == -[!-]?* ]]; then
		OPT=${1:0:2} OPTARG=${1:2}
	elif [[ $1 == --*=* ]]; then
		OPT=${1%%=*} OPTARG=${1#*=}
	elif [[ ${2+.} && (${optional} == false || $2 != -?*) ]]; then
		OPTARG=$2 OPTSHIFT=1
	elif [[ ${optional} == true ]]; then
		return 1
	else
		fail "No argument specified for '$1'."
	fi

	return 0
}

if false; then
	# No optional version

	function get_opt_and_optarg {
		OPT=$1 OPTARG= OPTSHIFT=0

		if [[ $1 == -[!-]?* ]]; then
			OPT=${1:0:2} OPTARG=${1:2}
		elif [[ $1 == --*=* ]]; then
			OPT=${1%%=*} OPTARG=${1#*=}
		elif [[ ${2+.} ]]; then
			OPTARG=$2 OPTSHIFT=1
		else
			fail "No argument specified for '$1'." # Or simply return 1
		fi

		return 0
	}
fi

function main {
	...

	while [[ $# -gt 0 ]]; do
		case $1 in
		-[eIX]*)
			get_opt_and_optarg "${@:1:2}"
			shift "${OPTSHIFT}"
			[[ ${OPTARG} ]] || fail "Argument for '${OPT}' can't be empty."
			expressions+=("${OPTARG}")
			expr_opts+=("${OPT}")

			if [[ ${2-} == @* ]]; then
				flags=${2:1} invalid_flags=${flags//[EFGPliw]}
				[[ ${invalid_flags} ]] && fail "Invalid flags specified: ${invalid_flags}"
				expr_flags+=("${flags}")
				shift
			else
				expr_flags+=('')
			fi
			;;
		-E|--extended-regexp)
			...
		-[cmnps]*|--@(bytes|max-unchanged-stats|lines|pid|sleep-interval)?(=*))
			get_opt_and_optarg "${@:1:2}"
			shift "${OPTSHIFT}"
			[[ ${OPTARG} ]] || fail "Argument for '${opt}' can't be empty."
			...
			tail_opts+=("${OPT}" "${OPTARG}")
			;;
		...
		-L*|--limit-final?(=*))
			final_limit=10 timeout=1

			if get_opt_and_optarg @optional "${@:1:2}"; then
				shift "${OPTSHIFT}"

				if [[ ${OPTARG} == *,* ]]; then
					final_limit=${OPTARG%%,*} timeout=${OPTARG#*,}
				else
					final_limit=${OPTARG}
				fi

				...
			fi

			...
			;;
      ...
		--)
			files+=("${@:2}")
			break
			;;
		-[!-][!-]*)
			set -- "${1:0:2}" "-${1:2}" "${@:2}"
			continue
			;;
		-?*)
			fail "Invalid option: $1"
			;;
		*)
			files+=("$1")
			;;
		esac

		shift
	done

	...
}

main "$@"