Partial implementation for C++ RecordBatchStreamReader class.

matlab/src/cpp/arrow/matlab/io/ipc/proxy/record_batch_stream_reader.cc

@@ -0,0 +1,119 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "arrow/matlab/io/ipc/proxy/record_batch_stream_reader.h"
+#include "arrow/io/file.h"
+#include "arrow/matlab/error/error.h"
+#include "arrow/matlab/tabular/proxy/record_batch.h"
+#include "arrow/matlab/tabular/proxy/schema.h"
+#include "arrow/util/utf8.h"
+
+#include "libmexclass/proxy/ProxyManager.h"
+
+namespace arrow::matlab::io::ipc::proxy {
+
+RecordBatchStreamReader::RecordBatchStreamReader(
+    const std::shared_ptr<arrow::ipc::RecordBatchStreamReader> reader)
+    : reader{std::move(reader)} {
+  REGISTER_METHOD(RecordBatchStreamReader, getSchema);
+  REGISTER_METHOD(RecordBatchStreamReader, readRecordBatch);
+  REGISTER_METHOD(RecordBatchStreamReader, hasNextRecordBatch);
+  REGISTER_METHOD(RecordBatchStreamReader, readTable);
+}
+
+libmexclass::proxy::MakeResult RecordBatchStreamReader::make(
+    const libmexclass::proxy::FunctionArguments& constructor_arguments) {
+  namespace mda = ::matlab::data;
+  using RecordBatchStreamReaderProxy = arrow::matlab::io::ipc::proxy::RecordBatchStreamReader;
+
+  const mda::StructArray opts = constructor_arguments[0];
+
+  const mda::StringArray filename_mda = opts[0]["Filename"];
+  const auto filename_utf16 = std::u16string(filename_mda[0]);
+  MATLAB_ASSIGN_OR_ERROR(const auto filename_utf8,
+                         arrow::util::UTF16StringToUTF8(filename_utf16),
+                         error::UNICODE_CONVERSION_ERROR_ID);
+
+  MATLAB_ASSIGN_OR_ERROR(auto input_stream, arrow::io::ReadableFile::Open(filename_utf8),
+                         error::FAILED_TO_OPEN_FILE_FOR_WRITE);
+
+  MATLAB_ASSIGN_OR_ERROR(auto reader,
+                         arrow::ipc::RecordBatchStreamReader::Open(input_stream),
+                         error::IPC_RECORD_BATCH_READER_OPEN_FAILED);
+
+  return std::make_shared<RecordBatchStreamReaderProxy>(std::move(reader));
+}
+
+void RecordBatchStreamReader::getSchema(libmexclass::proxy::method::Context& context) {
+  namespace mda = ::matlab::data;
+  using SchemaProxy = arrow::matlab::tabular::proxy::Schema;
+
+  auto schema = reader->schema();
+
+  auto schema_proxy = std::make_shared<SchemaProxy>(std::move(schema));
+  const auto schema_proxy_id =
+      libmexclass::proxy::ProxyManager::manageProxy(schema_proxy);
+
+  mda::ArrayFactory factory;
+  const auto schema_proxy_id_mda = factory.createScalar(schema_proxy_id);
+  context.outputs[0] = schema_proxy_id_mda;
+}
+
+void RecordBatchStreamReader::readRecordBatch(
+    libmexclass::proxy::method::Context& context) {
+  namespace mda = ::matlab::data;
+  using RecordBatchProxy = arrow::matlab::tabular::proxy::RecordBatch;
+  // If we don't have a "pre-cached" record batch to return, then try reading another record batch
+  // from the IPC Stream. If there are no more record batches in the stream, then error.
+  if (!nextRecordBatch) {
+     MATLAB_ASSIGN_OR_ERROR_WITH_CONTEXT(nextRecordBatch, reader->Next(), context, error::IPC_RECORD_BATCH_READ_FAILED);
+  }
+  auto record_batch_proxy = std::make_shared<RecordBatchProxy>(std::move(nextRecordBatch));
+  const auto record_batch_proxy_id = libmexclass::proxy::ProxyManager::manageProxy(record_batch_proxy);
+  // Once we have "consumed" the next RecordBatch, set nextRecordBatch to nullptr
+  // so that the next call to hasNextRecordBatch correctly checks whether there are more record batches remaining in the IPC Stream.
+  nextRecordBatch = nullptr;
+  mda::ArrayFactory factory;
+  const auto record_batch_proxy_id_mda = factory.createScalar(record_batch_proxy_id);
+  context.outputs[0] = record_batch_proxy_id_mda;
+  }
+}
+
+void RecordBatchStreamReader::hasNextRecordBatch(
+    libmexclass::proxy::method::Context& context) {
+  namespace mda = ::matlab::data;
+  bool has_next_record_batch = true;
+  if (!nextRecordBatch) {
+	  // Try to read another RecordBatch from the
+	  // IPC Stream.
+	  const auto maybe_record_batch = reader->Next();
+	  if (!maybe_record_batch) {
+		has_next_record_batch = false;
+	  } else {
+		// If we read a RecordBatch successfully,
+		// then "cache" the RecordBatch
+		// so that we can return it on the next
+		// call to readRecordBatch.
+	  	nextRecordBatch = *maybe_record_batch;
+	  }
+  }
+
+  mda::ArrayFactory factory;
+  context.outputs[0] = factory.createScalar(has_next_record_batch);
+}
+
+}  // namespace arrow::matlab::io::ipc::proxy

matlab/src/cpp/arrow/matlab/io/ipc/proxy/record_batch_stream_reader.h

@@ -0,0 +1,44 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#pragma once
+
+#include "arrow/ipc/reader.h"
+#include "libmexclass/proxy/Proxy.h"
+
+namespace arrow::matlab::io::ipc::proxy {
+
+class RecordBatchStreamReader : public libmexclass::proxy::Proxy {
+ public:
+  RecordBatchStreamReader(std::shared_ptr<arrow::ipc::RecordBatchStreamReader> reader);
+
+  ~RecordBatchStreamReader() = default;
+
+  static libmexclass::proxy::MakeResult make(
+      const libmexclass::proxy::FunctionArguments& constructor_arguments);
+
+ protected:
+  std::shared_ptr<arrow::ipc::RecordBatchStreamReader> reader;
+  std::shared_ptr<arrow::ipc::RecordBatchStreamReader> nextRecordBatch;
+
+  void getSchema(libmexclass::proxy::method::Context& context);
+  void readRecordBatch(libmexclass::proxy::method::Context& context);
+  void hasNextRecordBatch(libmexclass::proxy::method::Context& context);
+  void readTable(libmexclass::proxy::method::Context& context);
+};
+
+}  // namespace arrow::matlab::io::ipc::proxy