const barewordConcat = ' '; sealed class Bareword { final String word; @override int get hashCode => word.hashCode; Bareword(String word) : word = word.replaceAll('"', '""'); @override bool operator ==(Object other) { if (other is Bareword) { return word == other.word; } return false; } JoinedBareword join(Bareword other) { return JoinedBareword(other.word, this); } } final class SimpleBareword extends Bareword { SimpleBareword(super.word); @override String toString() => word; } final class EnclosedBareword extends Bareword { EnclosedBareword(super.word); @override String toString() { return '"$word"'; } } final class JoinedBareword extends Bareword { final Bareword parent; JoinedBareword(super.bareword, this.parent); bool hasDependency(Bareword other) { if (parent is JoinedBareword) { return (parent as JoinedBareword).hasDependency(other); } else { return parent == other; } } Iterable get dependencies { final depencies = [parent]; while (depencies.last is JoinedBareword) { depencies.add((depencies.last as JoinedBareword).parent); } return depencies.reversed; } @override String toString() { final deps = dependencies .map((bareword) => bareword.toString()) .join(barewordConcat); return '"$deps$barewordConcat$word"'; } }