Start high level writer scaffold

Change-Id: I325f3c3a33c1ded53b083d19d72234794338b28b

Author: wesm

cpp/src/arrow/ipc/ipc-json-test.cc

@@ -15,7 +15,6 @@
 // specific language governing permissions and limitations
 // under the License.
 
-#include "arrow/ipc/json-internal.h"
 
 #include <cstdint>
 #include <cstdio>
@@ -25,12 +24,11 @@
 #include <string>
 #include <vector>
 
-#include "rapidjson/document.h"
-#include "rapidjson/filewritestream.h"
-#include "rapidjson/prettywriter.h"
 #include "gtest/gtest.h"
 
 #include "arrow/array.h"
+#include "arrow/ipc/json.h"
+#include "arrow/ipc/json-internal.h"
 #include "arrow/test-util.h"
 #include "arrow/type.h"
 #include "arrow/type_traits.h"

cpp/src/arrow/ipc/json-internal.h

@@ -15,10 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
-// Implement Arrow JSON serialization format
-
-#ifndef ARROW_IPC_JSON_H
-#define ARROW_IPC_JSON_H
+#ifndef ARROW_IPC_JSON_INTERNAL_H
+#define ARROW_IPC_JSON_INTERNAL_H
 
 #define RAPIDJSON_HAS_STDSTRING 1
 #define RAPIDJSON_HAS_CXX11_RVALUE_REFS 1
@@ -57,4 +55,4 @@ Status ARROW_EXPORT ReadJsonArray(MemoryPool* pool, const rj::Value& json_obj,
 }  // namespace ipc
 }  // namespace arrow
 
-#endif  // ARROW_IPC_FILE_H
+#endif  // ARROW_IPC_JSON_INTERNAL_H

cpp/src/arrow/ipc/json.cc

@@ -22,5 +22,62 @@
 #include "arrow/util/status.h"
 
 namespace arrow {
-namespace ipc {}  // namespace ipc
+namespace ipc {
+
+class JsonWriter::JsonWriterImpl {
+ public:
+  JsonWriterImpl(const std::shared_ptr<Schema>& schema)
+      : schema_(schema) {
+    writer_.reset(new RjWriter(string_buffer_));
+  }
+
+  Status Start() {
+    writer_->StartObject();
+
+    writer_->Key("schema");
+    RETURN_NOT_OK(WriteJsonSchema(schema_, writer_.get()));
+
+    // Record batches
+    writer_->Key("batches");
+    writer_->StartArray();
+    return Status::OK();
+  }
+
+  Status Finish() {
+    writer_->EndArray();  // Record batches
+    writer_->EndObject();
+    return Status::OK();
+  }
+
+  Status WriteRecordBatch(const std::vector<std::shared_ptr<Array>>& columns, int32_t num_rows) {
+    return Status::OK();
+  }
+
+ private:
+  std::shared_ptr<Schema> schema_;
+
+  rj::StringBuffer string_buffer_;
+  std::unique_ptr<RjWriter> writer_;
+};
+
+JsonWriter::JsonWriter(const std::shared_ptr<Schema>& schema) {
+  impl_.reset(new JsonWriteImpl(schema));
+}
+
+Status JsonWriter::Open(
+    const std::shared_ptr<Schema>& schema, std::unique_ptr<JsonWriter>* writer) {
+  *writer = std::unique_ptr<JsonWriter>(new JsonWriter(schema));
+  return (*writer)->impl_->Start();
+}
+
+Status JsonWriter::Close() {
+  return impl_->Close();
+}
+
+Status JsonWriter::WriteRecordBatch(
+    const std::vector<std::shared_ptr<Array>>& columns, int32_t num_rows) {
+
+}
+
+}  // namespace ipc
 }  // namespace arrow

cpp/src/arrow/ipc/json.h

@@ -43,8 +43,7 @@ namespace ipc {
 
 class ARROW_EXPORT JsonWriter {
  public:
-  static Status Open(io::OutputStream* sink, const std::shared_ptr<Schema>& schema,
-      std::shared_ptr<JsonWriter>* out);
+  static Status Open(const std::shared_ptr<Schema>& schema, std::unique_ptr<JsonWriter>* out);
 
   // TODO(wesm): Write dictionaries
 
@@ -54,25 +53,21 @@ class ARROW_EXPORT JsonWriter {
   Status Close();
 
  private:
-  JsonWriter(io::OutputStream* sink, const std::shared_ptr<Schema>& schema);
-
-  io::OutputStream* sink_;
-  std::shared_ptr<Schema> schema_;
+  explicit JsonWriter(const std::shared_ptr<Schema>& schema);
 
   // Hide RapidJSON details from public API
   class JsonWriterImpl;
   std::unique_ptr<JsonWriterImpl> impl_;
 };
 
+// TODO(wesm): Read from a file stream rather than an in-memory buffer
 class ARROW_EXPORT JsonReader {
  public:
-  static Status Open(MemoryPool* pool,
-      const std::shared_ptr<io::ReadableFileInterface>& file,
-      std::shared_ptr<JsonReader>* reader);
+  static Status Open(MemoryPool* pool, const std::shared_ptr<Buffer>& data,
+      std::unique_ptr<JsonReader>* reader);
 
   // Use the default memory pool
-  static Status Open(const std::shared_ptr<io::ReadableFileInterface>& file,
-      std::shared_ptr<JsonReader>* reader);
+  static Status Open(const std::shared_ptr<Buffer>& data, std::unique_ptr<JsonReader>* reader);
 
   std::shared_ptr<Schema> schema() const;
 
@@ -82,10 +77,7 @@ class ARROW_EXPORT JsonReader {
   Status GetRecordBatch(int i, std::shared_ptr<RecordBatch>* batch);
 
  private:
-  explicit JsonReader(const std::shared_ptr<io::ReadableFileInterface>& file);
-
-  std::shared_ptr<io::ReadableFileInterface> file_;
-  std::shared_ptr<Schema> schema_;
+  explicit JsonReader(const std::shared_ptr<Buffer>& data);
 
   // Hide RapidJSON details from public API
   class JsonReaderImpl;
@@ -95,4 +87,4 @@ class ARROW_EXPORT JsonReader {
 }  // namespace ipc
 }  // namespace arrow
 
-#endif  // ARROW_IPC_FILE_H
+#endif  // ARROW_IPC_JSON_H