Add bindings for Apache Arrow interface (Giorgi#26)

DuckDB.NET.Bindings/DuckDBNativeObjects.cs

@@ -108,6 +108,57 @@ public void Dispose()
     }
 }
 
+[StructLayout(LayoutKind.Sequential)]
+public unsafe struct DuckDBArrowSchema : IDisposable
+{
+    private byte* format;
+    private byte* name;
+    private byte* metadata;
+    private long flags;
+    private long n_children;
+    private DuckDBArrowSchema** children;
+    private DuckDBArrowSchema* dictionary;
+    private delegate* unmanaged[Cdecl]<DuckDBArrowSchema*, void> release;
+    private void* private_data;
+
+    public void Dispose()
+    {
+        if (release != null)
+        {
+            fixed (DuckDBArrowSchema* ptr = &this)
+            {
+                release(ptr);
+            }
+        }
+    }
+}
+
+[StructLayout(LayoutKind.Sequential)]
+public unsafe struct DuckDBArrowArray : IDisposable
+{
+    private long length;
+    private long null_count;
+    private long offset;
+    private long n_buffers;
+    private long n_children;
+    private byte** buffers;
+    private DuckDBArrowArray** children;
+    private DuckDBArrowArray* dictionary;
+    private delegate* unmanaged[Cdecl]<DuckDBArrowArray*, void> release;
+    private void* private_data;
+
+    public void Dispose()
+    {
+        if (release != null)
+        {
+            fixed (DuckDBArrowArray* ptr = &this)
+            {
+                release(ptr);
+            }
+        }
+    }
+}
+
 [StructLayout(LayoutKind.Sequential)]
 public struct DuckDBDate
 {

DuckDB.NET.Bindings/DuckDBWrapperObjects.cs

@@ -105,4 +105,30 @@ protected override bool ReleaseHandle()
         NativeMethods.DataChunks.DuckDBDestroyDataChunk(out handle);
         return true;
     }
+}
+
+public class DuckDBArrow : SafeHandleZeroOrMinusOneIsInvalid
+{
+    public DuckDBArrow() : base(true)
+    {
+    }
+
+    protected override bool ReleaseHandle()
+    {
+        NativeMethods.Arrow.DuckDBDestroyArrow(out handle);
+        return true;
+    }
+}
+
+public class DuckDBArrowStream : SafeHandleZeroOrMinusOneIsInvalid
+{
+    public DuckDBArrowStream() : base(true)
+    {
+    }
+
+    protected override bool ReleaseHandle()
+    {
+        NativeMethods.Arrow.DuckDBDestroyArrowStream(out handle);
+        return true;
+    }
 }

DuckDB.NET.Bindings/NativeMethods/NativeMethods.Arrow.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace DuckDB.NET.Native;
+
+public partial class NativeMethods
+{
+    public static class Arrow
+    {
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_query_arrow")]
+        public static extern DuckDBState DuckDBQueryArrow(DuckDBNativeConnection connection, SafeUnmanagedMemoryHandle query, out DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_query_arrow_schema")]
+        public static extern DuckDBState DuckDBQueryArrowSchema(DuckDBNativeConnection connection, out DuckDBArrowSchema schema);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_prepared_arrow_schema")]
+        public static extern DuckDBState DuckDBPreparedArrowSchema(DuckDBPreparedStatement preparedStatement, out DuckDBArrowSchema schema);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_result_arrow_array")]
+        public static extern DuckDBState DuckDBResultArrowArray(DuckDBResult result, DuckDBDataChunk chunk, out DuckDBArrowArray array);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_query_arrow_array")]
+        public static extern DuckDBState DuckDBQueryArrowArray(DuckDBArrow result, out DuckDBArrowArray array);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_arrow_column_count")]
+        public static extern long DuckDBArrowColumnCount(DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_arrow_row_count")]
+        public static extern long DuckDBArrowRowCount(DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_arrow_rows_changed")]
+        public static extern long DuckDBArrowRowsChanged(DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_query_arrow_error")]
+        public static extern IntPtr DuckDBQueryArrowError(DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_destroy_arrow")]
+        public static extern DuckDBState DuckDBDestroyArrow(out IntPtr result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_destroy_arrow_stream")]
+        public static extern DuckDBState DuckDBDestroyArrowStream(out IntPtr stream_p);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_execute_prepared_arrow")]
+        public static extern DuckDBState DuckDBExecutePreparedArrow(DuckDBPreparedStatement preparedStatement, out DuckDBArrow result);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_arrow_scan")]
+        public static extern DuckDBState DuckDBArrowScan(DuckDBNativeConnection connection, SafeUnmanagedMemoryHandle tableName, DuckDBArrowStream arrow);
+
+        [DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_arrow_array_scan")]
+        public static extern DuckDBState DuckDBArrowArrayScan(
+            DuckDBNativeConnection connection,
+            SafeUnmanagedMemoryHandle tableName,
+            DuckDBArrowSchema arrowSchema,
+            DuckDBArrowArray arrowArray,
+            out DuckDBArrowStream stream
+        );
+    }
+}