NarwhalDB PoC for IFC Property Database

IfcPropertyDataReader.cs

using Ara3D.Buffers;
using Ara3D.Collections;
using Ara3D.NarwhalDB;

namespace Ara3D.IfcParser;

public class IfcPropertyDataReader
{
    public IfcPropertyDataReader(IReadOnlyList<ByteSpanBuffer> buffers)
    {
        LoadTable(out PropSetToValTable, buffers);
        LoadTable(out PropSetEntityToIndexTable, buffers);
        LoadTable(out PropDescTable, buffers);
        LoadTable(out PropSetTable, buffers);
        LoadTable(out PropValTable, buffers);

        var stringsBuffer = buffers.Single(b => b.Name == "_STRINGS_");
        var unpackedStrings = stringsBuffer.Span.UnpackStrings().ToIArray();
        
        // The conversion to an actual string, happens as late as possible. 
        // However: I eventually want even more usage of "ByteSpan" throughout. 
        Strings = unpackedStrings.Select(bs => bs.ToString());
    }

    public static void LoadTable<T>(out TypedSpan<T> span, IEnumerable<ByteSpanBuffer> buffers) where T: unmanaged
    {
        var name = typeof(T).Name;
        var buffer = buffers.FirstOrDefault(b => b.Name == name);
        if (buffer == null) throw new Exception($"Table {name} could not be found");
        span = new TypedSpan<T>(buffer.Span);
    }

    public TypedSpan<PropSetToVal> PropSetToValTable;
    public TypedSpan<PropSetEntityToIndex> PropSetEntityToIndexTable;
    public TypedSpan<PropDesc> PropDescTable;
    public TypedSpan<PropSet> PropSetTable;
    public TypedSpan<PropVal> PropValTable;
    public IArray<string> Strings;

    public struct PropSetToVal
    {
        public int PropSetIndex;
        public int PropValIndex;

        public PropSet GetPropSet(IArray<PropSet> xs) => xs[PropSetIndex];
        public PropVal GetPropVal(IArray<PropVal> xs) => xs[PropValIndex];
    }

    public struct PropSetEntityToIndex
    {
        public int PropSetEntity;
        public int PropSetIndex;
        public int FilePathStringIndex;

        public PropSet GetPropSet(IArray<PropSet> xs) => xs[PropSetIndex];
        public string GetFilePath(IArray<string> strings) => strings[FilePathStringIndex];
    }

    public struct PropDesc
    {
        public int NameStringIndex;
        public int DescriptionStringIndex;
        public int UnitStringIndex;
        public int EntityStringIndex;

        public string GetName(IArray<string> strings) => strings[NameStringIndex];
        public string GetDescription(IArray<string> strings) => strings[DescriptionStringIndex];
        public string GetUnit(IArray<string> strings) => strings[UnitStringIndex];
        public string GetEntity(IArray<string> strings) => strings[EntityStringIndex];
    }

    public struct PropSet
    {
        public int NameStringIndex;
        public int DescriptionStringIndex;

        public string GetName(IArray<string> strings) => strings[NameStringIndex];
        public string GetDescriptions(IArray<string> strings) => strings[DescriptionStringIndex];
    }

    public struct PropVal 
    {
        public int ValueStringIndex;
        public int PropDescIndex;

        public string GetValue(IArray<string> strings) => strings[ValueStringIndex];
        public PropDesc GetDescriptor(IArray<PropDesc> xs) => xs[PropDescIndex];
    }
}