unreachable method

List<String> unreachable({ required Set<String> roots, })

Library files that no entry point can reach.

Walks edges from every file in roots and from every file outside a lib/ — tests, tools, examples are entry points by nature — and reports the library files never visited. Unlike unreferenced this sees through a dead barrel to the files it exports, and through a pair of dead files that import each other. It is only as good as roots: an entry point the caller failed to name is reported along with everything only it reaches.

Implementation

List<String> unreachable({required Set<String> roots}) {
  final queue = <String>[
    ...roots.where(edges.containsKey),
    ...edges.keys.where((f) => !isLibraryFile(f)),
  ];
  final visited = queue.toSet();
  var head = 0;
  while (head < queue.length) {
    for (final next in edges[queue[head++]] ?? const <String>{}) {
      if (visited.add(next)) queue.add(next);
    }
  }
  return edges.keys
      .where((file) => isLibraryFile(file) && !visited.contains(file))
      .toList()
    ..sort();
}