start new object

CMakeLists.txt

@@ -75,6 +75,7 @@ set(GEOARROW_SOURCES
     src/geoarrow/array_view.c
     src/geoarrow/util.c
     src/geoarrow/visitor.c
+    src/geoarrow/native_writer.c
     src/geoarrow/wkb_reader.c
     src/geoarrow/wkb_writer.c
     src/geoarrow/wkt_reader.c

src/geoarrow/builder.c

@@ -34,7 +34,7 @@ struct BuilderPrivate {
   int64_t size[32];
   int32_t level;
   int64_t null_count;
-};
+}; 
 
 static ArrowErrorCode GeoArrowBuilderInitArrayAndCachePointers(
     struct GeoArrowBuilder* builder) {

src/geoarrow/geoarrow.h

@@ -310,6 +310,31 @@ GeoArrowErrorCode GeoArrowArrayViewVisit(const struct GeoArrowArrayView* array_v
                                          int64_t offset, int64_t length,
                                          struct GeoArrowVisitor* v);
 
+struct GeoArrowNativeWriter {
+  void* private_data;
+};
+
+/// \brief Initialize the memory of a GeoArrowNativeWriter
+///
+/// If GEOARROW_OK is returned, the caller is responsible for calling
+/// GeoArrowNativeWriterReset().
+GeoArrowErrorCode GeoArrowNativeWriterInit(struct GeoArrowNativeWriter* writer,
+                                           enum GeoArrowType type);
+
+/// \brief Populate a GeoArrowVisitor pointing to this writer
+GeoArrowErrorCode GeoArrowNativeWriterInitVisitor(struct GeoArrowNativeWriter* writer,
+                                                  struct GeoArrowVisitor* v);
+
+/// \brief Finish an ArrowArray containing elements from the visited input
+///
+/// This function can be called more than once to support multiple batches.
+GeoArrowErrorCode GeoArrowNativeWriterFinish(struct GeoArrowNativeWriter* writer,
+                                             struct ArrowArray* array,
+                                             struct GeoArrowError* error);
+
+/// \brief Free resources held by a GeoArrowNativeWriter
+void GeoArrowNativeWriterReset(struct GeoArrowNativeWriter* writer);
+
 /// \brief Well-known text writer
 ///
 /// This struct also contains options for well-known text serialization.

src/geoarrow/native_writer.c

@@ -0,0 +1,56 @@
+
+#include <string.h>
+
+#include "nanoarrow/nanoarrow.h"
+
+#include "geoarrow.h"
+
+// Bytes for four quiet (little-endian) NANs
+// static uint8_t kEmptyPointCoords[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x7f,
+//                                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x7f,
+//                                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x7f,
+//                                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 0x7f};
+
+struct GeoArrowNativeWriterPrivate {
+  struct GeoArrowBuilder builder;
+
+  // Fields to keep track of state when using the visitor pattern
+  int visitor_initialized;
+  int feat_is_null;
+  int nesting_multipoint;
+  double empty_coord_values[4];
+  struct GeoArrowCoordView empty_coord;
+  enum GeoArrowDimensions last_dimensions;
+  int64_t size[32];
+  int32_t level;
+  int64_t null_count;
+};
+
+GeoArrowErrorCode GeoArrowNativeWriterInit(struct GeoArrowNativeWriter* writer,
+
+                                           enum GeoArrowType type) {
+  struct GeoArrowNativeWriterPrivate* private_data =
+      (struct GeoArrowNativeWriterPrivate*)ArrowMalloc(
+          sizeof(struct GeoArrowNativeWriterPrivate));
+  if (private_data == NULL) {
+    return ENOMEM;
+  }
+
+  memset(private_data, 0, sizeof(struct GeoArrowNativeWriterPrivate));
+
+  GeoArrowErrorCode code = GeoArrowBuilderInitFromType(&private_data->builder, type);
+  if (code != GEOARROW_OK) {
+    ArrowFree(private_data);
+    return code;
+  }
+
+  writer->private_data = private_data;
+  return GEOARROW_OK;
+}
+
+void GeoArrowNativeWriterReset(struct GeoArrowNativeWriter* writer) {
+  struct GeoArrowNativeWriterPrivate* private_data =
+      (struct GeoArrowNativeWriterPrivate*)writer->private_data;
+  GeoArrowBuilderReset(&private_data->builder);
+  ArrowFree(private_data);
+}