StringBuilder AsSpan

cs

#if NET8_0_OR_GREATER
    [UnsafeAccessor(UnsafeAccessorKind.Field, Name = "m_ChunkPrevious")]
    private static extern ref StringBuilder? ChunkPrevious(StringBuilder builder);

    static bool HasSingleChunk(this StringBuilder builder) =>
        ChunkPrevious(builder) == null;
#endif

    public static CharSpan AsSpan(this StringBuilder builder)
    {
#if NET8_0_OR_GREATER
        if (builder.HasSingleChunk())
        {
            foreach (var chunk in builder.GetChunks())
            {
                return chunk.Span;
            }
        }
#endif
        return builder
            .ToString()
            .AsSpan();
    }