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feather_reader.h
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// 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.
#ifndef ARROW_MATLAB_FEATHER_READER_H
#define ARROW_MATLAB_FEATHER_READER_H
#include <memory>
#include <string>
#include <arrow/ipc/feather.h>
#include <arrow/status.h>
#include <arrow/type.h>
#include <matrix.h>
namespace arrow {
namespace matlab {
class FeatherReader {
public:
~FeatherReader() = default;
/// \brief Read the table metadata as an mxArray* struct from the given
/// Feather file.
/// The returned mxArray* struct contains the following fields:
/// - "Description" :: Nx1 mxChar array, table-level description
/// - "NumRows" :: scalar mxDouble array, number of rows in the
/// table
/// - "NumVariables" :: scalar mxDouble array, number of variables in
/// the table
/// Clients are responsible for freeing the returned mxArray memory
/// when it is no longer needed, or passing it to MATLAB to be managed.
/// \return metadata mxArray* scalar struct containing table level metadata
mxArray* ReadMetadata() const;
/// \brief Read the table variable data as an mxArray* struct array from the
/// given Feather file.
/// The returned mxArray* struct array has the following fields:
/// - "Name" :: Nx1 mxChar array, name of the variable
/// - "Type" :: Nx1 mxChar array, the variable's Arrow datatype
/// - "Data" :: Nx1 mxArray, data for the variable
/// - "Valid" :: Nx1 mxLogical array, validity (null) bitmap
/// Clients are responsible for freeing the returned mxArray memory
/// when it is no longer needed, or passing it to MATLAB to be managed.
/// \return variables mxArray* struct array containing table variable data
mxArray* ReadVariables() const;
/// \brief Initialize a FeatherReader object from a given Feather file.
/// \param[in] filename path to a Feather file
/// \param[out] feather_reader uninitialized FeatherReader object
static Status Open(const std::string& filename,
std::shared_ptr<FeatherReader>* feather_reader);
private:
FeatherReader() = default;
std::unique_ptr<ipc::feather::TableReader> table_reader_;
int64_t num_rows_;
int64_t num_variables_;
std::string description_;
};
} // namespace matlab
} // namespace arrow
#endif // ARROW_MATLAB_FEATHER_READER_H