[GitHub] [arrow] Platob commented on pull request #35299: GH-35285: [C#] Need refacto IArrowArrayBuilder for nested types

["Platob (via GitHub)" <gi...@apache.org>]

Platob commented on PR #35299:
URL: https://github.com/apache/arrow/pull/35299#issuecomment-1537094036

   > Also, it seems there is already ArrowBuffer.BitmapBuilder which is a buffer builder that is optimized for bits (and #35342 adds an efficient `AppendRange`). Perhaps you could use that and leave your buffer builder focused on non-bit types? Either way, it might be good to align on one approach to maintain.
   > 
   > CC @asmirnov82
   
   Indeed, but for nested structures it needs specify the builders to check how to merge correctly 2 arrow buffers knowing if they are bit based or byte based
   
   the main reason would be merge 2 array data by just checking their datatypes since their structures should be the same
   
   ```csharp
   public virtual IArrayBuilder AppendValues(ArrayData data)
   {
       // TODO: Make better / recursive fields data type check
       if (data.DataType.TypeId != DataType.TypeId)
           throw new ArgumentException($"Cannot append data type {data.DataType} in builder with data type {DataType}");
   
       NullCount += data.NullCount;
       Length += data.Length;
   
       Reserve(data.Length);
   
       for (int i = 0; i < Buffers.Length; i++)
       {
           IValueBufferBuilder current = Buffers[i];
           ArrowBuffer other = data.Buffers[i];
   
           if (current.ValueBitSize % 8 == 0)
           {
               // Full byte encoded
               current.AppendBytes(other.Span);
           }
           else
           {
               // Safe copy Bytes and remaining bits
               int end = (data.Length * current.ValueBitSize) / 8;
   
               current.AppendBytes(other.Span.Slice(0, end));
   
               Span<bool> bits = BitUtility.BytesToBits(other.Span.Slice(end)).Slice(0, data.Length - end * 8);
               current.AppendBits(bits);
           }
       }
   
       if (Children != null && data.Children != null)
       {
           for (int i = 0; i < Children.Length; i++)
           {
               Children[i].AppendValues(data.Children[i]);
           }
       }
   
       if (Dictionary != null && data.Dictionary != null)
       {
           Dictionary.AppendValues(data.Dictionary);
       }
   
       return this;
   }
   ```


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