[GitHub] [arrow] sgilmore10 commented on a diff in pull request #37620: GH-37571: [MATLAB] Add `arrow.tabular.Table` MATLAB class

["sgilmore10 (via GitHub)" <gi...@apache.org>]

sgilmore10 commented on code in PR #37620:
URL: https://github.com/apache/arrow/pull/37620#discussion_r1319062395


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matlab/src/cpp/arrow/matlab/tabular/proxy/table.cc:
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@@ -0,0 +1,211 @@
+// 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 "libmexclass/proxy/ProxyManager.h"
+
+#include "arrow/matlab/array/proxy/array.h"
+#include "arrow/matlab/array/proxy/chunked_array.h"
+#include "arrow/matlab/array/proxy/wrap.h"
+
+#include "arrow/matlab/error/error.h"
+#include "arrow/matlab/tabular/proxy/table.h"
+#include "arrow/matlab/tabular/proxy/schema.h"
+#include "arrow/type.h"
+#include "arrow/util/utf8.h"
+
+#include "libmexclass/proxy/ProxyManager.h"
+#include "libmexclass/error/Error.h"
+
+namespace arrow::matlab::tabular::proxy {
+
+    namespace {
+        libmexclass::error::Error makeEmptyTableError() {
+            const std::string error_msg =  "Numeric indexing using the column method is not supported for tables with no columns.";
+            return libmexclass::error::Error{error::TABLE_NUMERIC_INDEX_WITH_EMPTY_TABLE, error_msg};
+        }
+
+        libmexclass::error::Error makeInvalidNumericIndexError(const int32_t matlab_index, const int32_t num_columns) {
+            std::stringstream error_message_stream;
+            error_message_stream << "Invalid column index: ";
+            error_message_stream << matlab_index;
+            error_message_stream << ". Column index must be between 1 and the number of columns (";
+            error_message_stream << num_columns;
+            error_message_stream << ").";
+            return libmexclass::error::Error{error::TABLE_INVALID_NUMERIC_COLUMN_INDEX, error_message_stream.str()};
+        }
+    }
+
+    Table::Table(std::shared_ptr<arrow::Table> table) : table{table} {
+        REGISTER_METHOD(Table, toString);
+        REGISTER_METHOD(Table, getNumRows);
+        REGISTER_METHOD(Table, getNumColumns);
+        REGISTER_METHOD(Table, getColumnNames);
+        REGISTER_METHOD(Table, getSchema);
+        REGISTER_METHOD(Table, getColumnByIndex);
+        REGISTER_METHOD(Table, getColumnByName);
+    }
+
+    std::shared_ptr<arrow::Table> Table::unwrap() {
+        return table;
+    }
+
+    void Table::toString(libmexclass::proxy::method::Context& context) {
+        namespace mda = ::matlab::data;
+        MATLAB_ASSIGN_OR_ERROR_WITH_CONTEXT(const auto utf16_string, arrow::util::UTF8StringToUTF16(table->ToString()), context, error::UNICODE_CONVERSION_ERROR_ID);
+        mda::ArrayFactory factory;
+        auto str_mda = factory.createScalar(utf16_string);
+        context.outputs[0] = str_mda;
+    }
+
+    libmexclass::proxy::MakeResult Table::make(const libmexclass::proxy::FunctionArguments& constructor_arguments) {
+        namespace mda = ::matlab::data;
+        mda::StructArray opts = constructor_arguments[0];
+        const mda::TypedArray<uint64_t> arrow_array_proxy_ids = opts[0]["ArrayProxyIDs"];
+        const mda::StringArray column_names = opts[0]["ColumnNames"];
+
+        std::vector<std::shared_ptr<arrow::Array>> arrow_arrays;
+        // Retrieve all of the Arrow Array Proxy instances from the libmexclass ProxyManager.
+        for (const auto& arrow_array_proxy_id : arrow_array_proxy_ids) {
+            auto proxy = libmexclass::proxy::ProxyManager::getProxy(arrow_array_proxy_id);
+            auto arrow_array_proxy = std::static_pointer_cast<arrow::matlab::array::proxy::Array>(proxy);

Review Comment:
   You can just use `proxy::Array` here instead of `arrow::matlab::array::proxy::Array`. Just an fyi.



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