DataView Proposal

DataView.cs

namespace Microsoft.Data.DataView {
    public sealed class BooleanDataViewType : PrimitiveDataViewType {
        public static BooleanDataViewType Instance { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public abstract class DataViewRow : IDisposable {
        protected DataViewRow();
        public abstract long Batch { get; }
        public abstract long Position { get; }
        public abstract DataViewSchema Schema { get; }
        public void Dispose();
        protected virtual void Dispose(bool disposing);
        public abstract ValueGetter<TValue> GetGetter<TValue>(int col);
        public abstract ValueGetter<DataViewRowId> GetIdGetter();
        public abstract bool IsColumnActive(int col);
    }
    public abstract class DataViewRowCursor : DataViewRow {
        protected DataViewRowCursor();
        public abstract bool MoveNext();
    }
    public readonly struct DataViewRowId : IComparable<DataViewRowId>, IEquatable<DataViewRowId> {
        public readonly ulong High;
        public readonly ulong Low;
        public DataViewRowId(ulong low, ulong high);
        public DataViewRowId Combine(DataViewRowId other);
        public int CompareTo(DataViewRowId other);
        public bool Equals(DataViewRowId other);
        public override bool Equals(object obj);
        public DataViewRowId Fork();
        public override int GetHashCode();
        public DataViewRowId Next();
        public static DataViewRowId operator +(DataViewRowId first, ulong second);
        public static bool operator ==(DataViewRowId first, ulong second);
        public static explicit operator double (DataViewRowId x);
        public static bool operator >(DataViewRowId first, ulong second);
        public static bool operator >=(DataViewRowId first, ulong second);
        public static bool operator !=(DataViewRowId first, ulong second);
        public static bool operator <(DataViewRowId first, ulong second);
        public static bool operator <=(DataViewRowId first, ulong second);
        public static DataViewRowId operator -(DataViewRowId first, ulong second);
        public override string ToString();
    }
    public sealed class DataViewSchema : IEnumerable, IEnumerable<DataViewSchema.Column>, IReadOnlyCollection<DataViewSchema.Column>, IReadOnlyList<DataViewSchema.Column> {
        public int Count { get; }
        public DataViewSchema.Column this[int columnIndex] { get; }
        public DataViewSchema.Column this[string name] { get; }
        public Nullable<DataViewSchema.Column> GetColumnOrNull(string name);
        public IEnumerator<DataViewSchema.Column> GetEnumerator();
        IEnumerator System.Collections.IEnumerable.GetEnumerator();
        public override string ToString();
        public sealed class Annotations {
            public static DataViewSchema.Annotations Empty { get; }
            public DataViewSchema Schema { get; }
            public ValueGetter<TValue> GetGetter<TValue>(int col);
            public void GetValue<TValue>(string kind, ref TValue value);
            public override string ToString();
            public sealed class Builder {
                public Builder();
                public void Add(DataViewSchema.Annotations annotations, Func<string, bool> selector);
                public void Add(string name, DataViewType type, Delegate getter, DataViewSchema.Annotations annotations = null);
                public void Add<TValue>(string name, DataViewType type, ValueGetter<TValue> getter, DataViewSchema.Annotations annotations = null);
                public void AddPrimitiveValue<TValue>(string name, PrimitiveDataViewType type, TValue value, DataViewSchema.Annotations annotations = null);
                public DataViewSchema.Annotations GetAnnotations();
            }
        }
        public sealed class Builder {
            public Builder();
            public void AddColumn(string name, DataViewType type, DataViewSchema.Annotations annotations = null);
            public void AddColumns(IEnumerable<DataViewSchema.Column> source);
            public void AddColumns(IEnumerable<DataViewSchema.DetachedColumn> source);
            public DataViewSchema GetSchema();
        }
        public struct Column {
            public DataViewSchema.Annotations Annotations { get; }
            public int Index { get; }
            public bool IsHidden { get; }
            public string Name { get; }
            public DataViewType Type { get; }
            public override string ToString();
        }
        public struct DetachedColumn {
            public DetachedColumn(DataViewSchema.Column column);
            public DetachedColumn(string name, DataViewType type, DataViewSchema.Annotations annotations = null);
            public DataViewSchema.Annotations Annotations { get; }
            public string Name { get; }
            public DataViewType Type { get; }
        }
    }
    public abstract class DataViewType : IEquatable<DataViewType> {
        public Type RawType { get; }
        public abstract bool Equals(DataViewType other);
    }
    public sealed class DateTimeDataViewType : PrimitiveDataViewType {
        public static DateTimeDataViewType Instance { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public sealed class DateTimeOffsetDataViewType : PrimitiveDataViewType {
        public static DateTimeOffsetDataViewType Instance { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public interface IDataView {
        bool CanShuffle { get; }
        DataViewSchema Schema { get; }
        Nullable<long> GetRowCount();
        DataViewRowCursor GetRowCursor(IEnumerable<DataViewSchema.Column> columnsNeeded, Random rand = null);
        DataViewRowCursor[] GetRowCursorSet(IEnumerable<DataViewSchema.Column> columnsNeeded, int n, Random rand = null);
    }
    public sealed class NumberDataViewType : PrimitiveDataViewType {
        public static NumberDataViewType Byte { get; }
        public static NumberDataViewType DataViewRowId { get; }
        public static NumberDataViewType Double { get; }
        public static NumberDataViewType Int16 { get; }
        public static NumberDataViewType Int32 { get; }
        public static NumberDataViewType Int64 { get; }
        public static NumberDataViewType SByte { get; }
        public static NumberDataViewType Single { get; }
        public static NumberDataViewType UInt16 { get; }
        public static NumberDataViewType UInt32 { get; }
        public static NumberDataViewType UInt64 { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public abstract class PrimitiveDataViewType : DataViewType {
        protected PrimitiveDataViewType(Type rawType);
    }
    public abstract class StructuredDataViewType : DataViewType {
        protected StructuredDataViewType(Type rawType);
    }
    public sealed class TextDataViewType : PrimitiveDataViewType {
        public static TextDataViewType Instance { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public sealed class TimeSpanDataViewType : PrimitiveDataViewType {
        public static TimeSpanDataViewType Instance { get; }
        public override bool Equals(DataViewType other);
        public override string ToString();
    }
    public delegate void ValueGetter<TValue>(ref TValue value);
}