/// <summary> Creates instance of <see cref="ElementSource" /> from persistent storage. </summary>
/// <param name="directory">Already resolved directory which contains all indecies.</param>
/// <param name="fileService">File system service.</param>
/// <param name="objectPool">ObjectPool.</param>
internal ElementSource(string directory, IFileSystemService fileService, IObjectPool objectPool)
{
// load map data from streams
BoundingBox = PersistentIndexBuilder.ReadBoundingBox(fileService.ReadStream(string.Format(MapConsts.HeaderPathFormat, directory)));
KvUsage = new KeyValueUsage(fileService.ReadStream(string.Format(MapConsts.KeyValueUsagePathFormat, directory)));
KvIndex = KeyValueIndex.Load(fileService.ReadStream(string.Format(MapConsts.KeyValueIndexPathFormat, directory)));
KvStore = new KeyValueStore(KvIndex, KvUsage, fileService.ReadStream(string.Format(MapConsts.KeyValueStorePathFormat, directory)));
ElementStore = new ElementStore(KvStore, fileService.ReadStream(string.Format(MapConsts.ElementStorePathFormat, directory)), objectPool);
SpatialIndexTree = SpatialIndex.Load(fileService.ReadStream(string.Format(MapConsts.SpatialIndexPathFormat, directory)));
IsReadOnly = true;
}