[C++] Support iterable types for RowEncoder

src/fury/encoder/row_encode_trait.h

@@ -95,7 +95,7 @@ template <typename C> struct DefaultWriteVisitor {
 
   DefaultWriteVisitor(C &cont) : cont(cont) {}
 
-  template <typename> void Visit(std::unique_ptr<RowWriter> writer) {
+  template <typename, typename T> void Visit(std::unique_ptr<T> writer) {
     cont.push_back(std::move(writer));
   }
 };

src/fury/encoder/row_encoder.h

@@ -17,37 +17,93 @@
 #pragma once
 
 #include "fury/encoder/row_encode_trait.h"
+#include "src/fury/row/writer.h"
 #include <memory>
 #include <type_traits>
 
 namespace fury {
 
 namespace encoder {
 
+namespace details {
+
+template <typename T, typename Enabled = void> struct GetWriterTypeImpl;
+
+template <typename T>
+struct GetWriterTypeImpl<T,
+                         std::enable_if_t<details::IsClassButNotBuiltin<T>>> {
+  using type = RowWriter;
+};
+
+template <typename T>
+struct GetWriterTypeImpl<T, std::enable_if_t<details::IsArray<T>>> {
+  using type = ArrayWriter;
+};
+
+template <typename T> using GetWriterType = typename GetWriterTypeImpl<T>::type;
+
+template <typename T, std::enable_if_t<
+                          std::is_same_v<GetWriterType<T>, RowWriter>, int> = 0>
+auto GetSchemaOrType() {
+  return RowEncodeTrait<T>::Schema();
+}
+
+template <
+    typename T,
+    std::enable_if_t<std::is_same_v<GetWriterType<T>, ArrayWriter>, int> = 0>
+auto GetSchemaOrType() {
+  return std::dynamic_pointer_cast<arrow::ListType>(RowEncodeTrait<T>::Type());
+}
+
+} // namespace details
+
 template <typename T> struct RowEncoder {
-  static_assert(std::is_class_v<T>, "currently only class types are supported");
+  static_assert(details::IsClassButNotBuiltin<T> || details::IsArray<T>,
+                "only class types and iterable types are supported");
+
+  using WriterType = details::GetWriterType<T>;
 
   RowEncoder()
-      : writer_(std::make_unique<RowWriter>(RowEncodeTrait<T>::Schema())) {
+      : writer_(std::make_unique<WriterType>(details::GetSchemaOrType<T>())) {}
+
+  template <typename U = WriterType,
+            std::enable_if_t<std::is_same_v<U, RowWriter>, int> = 0>
+  void Encode(const T &value) {
     writer_->Reset();
+    RowEncodeTrait<T>::Write(DefaultWriteVisitor{children_}, value,
+                             GetWriter());
   }
 
+  template <typename U = WriterType,
+            std::enable_if_t<std::is_same_v<U, ArrayWriter>, int> = 0>
   void Encode(const T &value) {
+    writer_->Reset(value.size());
     RowEncodeTrait<T>::Write(DefaultWriteVisitor{children_}, value,
                              GetWriter());
   }
 
-  RowWriter &GetWriter() const { return *writer_.get(); }
-  const std::vector<std::unique_ptr<RowWriter>> &GetChildren() const {
+  WriterType &GetWriter() const { return *writer_.get(); }
+  const std::vector<std::unique_ptr<Writer>> &GetChildren() const {
     return children_;
   }
-  const arrow::Schema &GetSchema() const { return *writer_->schema().get(); }
+
+  template <typename U = WriterType,
+            std::enable_if_t<std::is_same_v<U, RowWriter>, int> = 0>
+  const arrow::Schema &GetSchema() const {
+    return *writer_->schema().get();
+  }
+
+  template <typename U = WriterType,
+            std::enable_if_t<std::is_same_v<U, ArrayWriter>, int> = 0>
+  const arrow::ListType &GetType() const {
+    return *writer_->type().get();
+  }
 
   void ResetChildren() { children_.clear(); }
 
 private:
-  std::unique_ptr<RowWriter> writer_;
-  std::vector<std::unique_ptr<RowWriter>> children_;
+  std::unique_ptr<WriterType> writer_;
+  std::vector<std::unique_ptr<Writer>> children_;
 };
 
 } // namespace encoder

src/fury/encoder/row_encoder_test.cc

@@ -62,5 +62,68 @@ TEST(RowEncoder, Simple) {
   ASSERT_FLOAT_EQ(y_row->GetFloat(0), 1.23);
 }
 
+struct C {
+  std::vector<A> x;
+  bool y;
+};
+
+FURY_FIELD_INFO(C, x, y);
+
+TEST(RowEncoder, SimpleArray) {
+  std::vector<C> v{C{{{1, "a"}, {2, "b"}}, false},
+                   C{{{1.1, "x"}, {2.2, "y"}, {3.3, "z"}}, true}};
+
+  encoder::RowEncoder<decltype(v)> enc;
+
+  auto &type = enc.GetType();
+  ASSERT_EQ(type.name(), "list");
+  ASSERT_EQ(type.field(0)->type()->name(), "struct");
+  ASSERT_EQ(type.field(0)->type()->field(0)->name(), "x");
+  ASSERT_EQ(type.field(0)->type()->field(1)->name(), "y");
+  ASSERT_EQ(type.field(0)->type()->field(0)->type()->name(), "list");
+  ASSERT_EQ(type.field(0)->type()->field(0)->type()->field(0)->type()->name(),
+            "struct");
+  ASSERT_EQ(type.field(0)
+                ->type()
+                ->field(0)
+                ->type()
+                ->field(0)
+                ->type()
+                ->field(0)
+                ->type()
+                ->name(),
+            "float");
+  ASSERT_EQ(type.field(0)
+                ->type()
+                ->field(0)
+                ->type()
+                ->field(0)
+                ->type()
+                ->field(1)
+                ->type()
+                ->name(),
+            "utf8");
+  ASSERT_EQ(type.field(0)->type()->field(1)->type()->name(), "bool");
+
+  enc.Encode(v);
+
+  auto data = enc.GetWriter().CopyToArrayData();
+  ASSERT_EQ(data->GetStruct(0)->GetArray(0)->GetStruct(0)->GetFloat(0), 1);
+  ASSERT_EQ(data->GetStruct(0)->GetArray(0)->GetStruct(1)->GetFloat(0), 2);
+  ASSERT_FLOAT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(0)->GetFloat(0),
+                  1.1);
+  ASSERT_FLOAT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(1)->GetFloat(0),
+                  2.2);
+  ASSERT_FLOAT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(2)->GetFloat(0),
+                  3.3);
+  ASSERT_EQ(data->GetStruct(0)->GetArray(0)->GetStruct(0)->GetString(1), "a");
+  ASSERT_EQ(data->GetStruct(0)->GetArray(0)->GetStruct(1)->GetString(1), "b");
+  ASSERT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(0)->GetString(1), "x");
+  ASSERT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(1)->GetString(1), "y");
+  ASSERT_EQ(data->GetStruct(1)->GetArray(0)->GetStruct(2)->GetString(1), "z");
+  ASSERT_EQ(data->GetStruct(0)->GetBoolean(1), false);
+  ASSERT_EQ(data->GetStruct(1)->GetBoolean(1), true);
+}
+
 } // namespace test2
 } // namespace fury

src/fury/row/writer.h

@@ -118,13 +118,13 @@ class Writer {
     }
   }
 
+  virtual ~Writer() = default;
+
 protected:
   explicit Writer(int bytes_before_bitmap);
 
   explicit Writer(Writer *parent_writer, int bytes_before_bitmap);
 
-  virtual ~Writer() = default;
-
   std::shared_ptr<Buffer> buffer_;
 
   // The offset of the global buffer where we start to WriteString this