/// <summary> /// 查询前缀匹配的元素 /// </summary> /// <typeparam name="T">值泛型</typeparam> /// <param name="db">待查询db</param> /// <param name="options">读选项</param> /// <param name="prefix">待查询前缀</param> /// <param name="resultSelector">值处理回调函数</param> /// <returns>T列表</returns> public static IEnumerable <T> Find <T>(this DB db, ReadOptions options, Slice prefix, Func <Slice, Slice, T> resultSelector) { using (Iterator it = db.NewIterator(options)) { for (it.Seek(prefix); it.Valid(); it.Next()) { Slice key = it.Key(); byte[] x = key.ToArray(); byte[] y = prefix.ToArray(); if (x.Length < y.Length) { break; } if (!x.Take(y.Length).SequenceEqual(y)) { break; } yield return(resultSelector(key, it.Value())); } } }
public static IEnumerable <T> Seek <T>(this DB db, ReadOptions options, byte table, byte[] prefix, SeekDirection direction, Func <byte[], byte[], T> resultSelector) { using Iterator it = db.NewIterator(options); for (it.Seek(CreateKey(table, prefix)); it.Valid();) { var key = it.Key(); if (key.Length < 1 || key[0] != table) { break; } yield return(resultSelector(it.Key(), it.Value())); if (direction == SeekDirection.Forward) { it.Next(); } else { it.Prev(); } } }