CustomAttributeTableReader.cs

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using System.Reflection.Internal;
 
namespace System.Reflection.Metadata.Ecma335;
 
internal readonly struct CustomAttributeTableReader
{
    internal readonly int NumberOfRows;
 
    private readonly bool _IsHasCustomAttributeRefSizeSmall;
 
    private readonly bool _IsCustomAttributeTypeRefSizeSmall;
 
    private readonly bool _IsBlobHeapRefSizeSmall;
 
    private readonly int _ParentOffset;
 
    private readonly int _TypeOffset;
 
    private readonly int _ValueOffset;
 
    internal readonly int RowSize;
 
    internal readonly MemoryBlock Block;
 
    internal readonly int[]? PtrTable;
 
    internal CustomAttributeTableReader(int numberOfRows, bool declaredSorted, int hasCustomAttributeRefSize, int customAttributeTypeRefSize, int blobHeapRefSize, MemoryBlock containingBlock, int containingBlockOffset)
    {
        NumberOfRows = numberOfRows;
        _IsHasCustomAttributeRefSizeSmall = hasCustomAttributeRefSize == 2;
        _IsCustomAttributeTypeRefSizeSmall = customAttributeTypeRefSize == 2;
        _IsBlobHeapRefSizeSmall = blobHeapRefSize == 2;
        _ParentOffset = 0;
        _TypeOffset = _ParentOffset + hasCustomAttributeRefSize;
        _ValueOffset = _TypeOffset + customAttributeTypeRefSize;
        RowSize = _ValueOffset + blobHeapRefSize;
        Block = containingBlock.GetMemoryBlockAt(containingBlockOffset, RowSize * numberOfRows);
        PtrTable = null;
        if (!declaredSorted && !CheckSorted())
        {
            PtrTable = Block.BuildPtrTable(numberOfRows, RowSize, _ParentOffset, _IsHasCustomAttributeRefSizeSmall);
        }
    }
 
    internal EntityHandle GetParent(CustomAttributeHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return HasCustomAttributeTag.ConvertToHandle(Block.PeekTaggedReference(num + _ParentOffset, _IsHasCustomAttributeRefSizeSmall));
    }
 
    internal EntityHandle GetConstructor(CustomAttributeHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return CustomAttributeTypeTag.ConvertToHandle(Block.PeekTaggedReference(num + _TypeOffset, _IsCustomAttributeTypeRefSizeSmall));
    }
 
    internal BlobHandle GetValue(CustomAttributeHandle handle)
    {
        int num = (handle.RowId - 1) * RowSize;
        return BlobHandle.FromOffset(Block.PeekHeapReference(num + _ValueOffset, _IsBlobHeapRefSizeSmall));
    }
 
    internal void GetAttributeRange(EntityHandle parentHandle, out int firstImplRowId, out int lastImplRowId)
    {
        int startRowNumber;
        int endRowNumber;
        if (PtrTable != null)
        {
            Block.BinarySearchReferenceRange(PtrTable, RowSize, _ParentOffset, HasCustomAttributeTag.ConvertToTag(parentHandle), _IsHasCustomAttributeRefSizeSmall, out startRowNumber, out endRowNumber);
        }
        else
        {
            Block.BinarySearchReferenceRange(NumberOfRows, RowSize, _ParentOffset, HasCustomAttributeTag.ConvertToTag(parentHandle), _IsHasCustomAttributeRefSizeSmall, out startRowNumber, out endRowNumber);
        }
        if (startRowNumber == -1)
        {
            firstImplRowId = 1;
            lastImplRowId = 0;
        }
        else
        {
            firstImplRowId = startRowNumber + 1;
            lastImplRowId = endRowNumber + 1;
        }
    }
 
    private bool CheckSorted()
    {
        return Block.IsOrderedByReferenceAscending(RowSize, _ParentOffset, _IsHasCustomAttributeRefSizeSmall);
    }
}