read method

@override Future<Ledger?> read(String blueprint)

The ledger for blueprint, or null if it has never been applied here.

Implementation

@override
Future<Ledger?> read(String blueprint) async {
  final file = _fileFor(blueprint);
  if (!file.existsSync()) return null;
  try {
    final decoded = jsonDecode(await file.readAsString());
    if (decoded is! Map) return null;
    return Ledger.fromJson(decoded.cast<String, dynamic>());
  } on Object {
    // A truncated or hand-edited ledger reads as "we own nothing", which is
    // the safe direction: the node will adopt what it finds rather than delete
    // things on the strength of a file it could not parse.
    return null;
  }
}