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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.
// Public API for the "Feather" file format, originally created at
// http://github.com/wesm/feather
#pragma once
#include <cstdint>
#include <memory>
#include <string>
#include <vector>
#include "arrow/ipc/options.h"
#include "arrow/type_fwd.h"
#include "arrow/util/compression.h"
#include "arrow/util/visibility.h"
namespace arrow {
class Schema;
class Status;
class Table;
namespace io {
class OutputStream;
class RandomAccessFile;
} // namespace io
namespace ipc {
namespace feather {
static constexpr const int kFeatherV1Version = 2;
static constexpr const int kFeatherV2Version = 3;
// ----------------------------------------------------------------------
// Metadata accessor classes
/// \class Reader
/// \brief An interface for reading columns from Feather files
class ARROW_EXPORT Reader {
public:
virtual ~Reader() = default;
/// \brief Open a Feather file from a RandomAccessFile interface
///
/// \param[in] source a RandomAccessFile instance
/// \return the table reader
static Result<std::shared_ptr<Reader>> Open(
const std::shared_ptr<io::RandomAccessFile>& source);
/// \brief Open a Feather file from a RandomAccessFile interface
/// with IPC Read options
///
/// \param[in] source a RandomAccessFile instance
/// \param[in] options IPC Read options
/// \return the table reader
static Result<std::shared_ptr<Reader>> Open(
const std::shared_ptr<io::RandomAccessFile>& source, const IpcReadOptions& options);
/// \brief Return the version number of the Feather file
virtual int version() const = 0;
virtual std::shared_ptr<Schema> schema() const = 0;
/// \brief Read all columns from the file as an arrow::Table.
///
/// \param[out] out the returned table
/// \return Status
///
/// This function is zero-copy if the file source supports zero-copy reads
virtual Status Read(std::shared_ptr<Table>* out) = 0;
/// \brief Read only the specified columns from the file as an arrow::Table.
///
/// \param[in] indices the column indices to read
/// \param[out] out the returned table
/// \return Status
///
/// This function is zero-copy if the file source supports zero-copy reads
virtual Status Read(const std::vector<int>& indices, std::shared_ptr<Table>* out) = 0;
/// \brief Read only the specified columns from the file as an arrow::Table.
///
/// \param[in] names the column names to read
/// \param[out] out the returned table
/// \return Status
///
/// This function is zero-copy if the file source supports zero-copy reads
virtual Status Read(const std::vector<std::string>& names,
std::shared_ptr<Table>* out) = 0;
};
struct ARROW_EXPORT WriteProperties {
static WriteProperties Defaults();
static WriteProperties DefaultsV1() {
WriteProperties props = Defaults();
props.version = kFeatherV1Version;
return props;
}
/// Feather file version number
///
/// version 2: "Feather V1" Apache Arrow <= 0.16.0
/// version 3: "Feather V2" Apache Arrow > 0.16.0
int version = kFeatherV2Version;
// Parameters for Feather V2 only
/// Number of rows per intra-file chunk. Use smaller chunksize when you need
/// faster random row access
int64_t chunksize = 1LL << 16;
/// Compression type to use. Only UNCOMPRESSED, LZ4_FRAME, and ZSTD are
/// supported. The default compression returned by Defaults() is LZ4 if the
/// project is built with support for it, otherwise
/// UNCOMPRESSED. UNCOMPRESSED is set as the object default here so that if
/// WriteProperties::Defaults() is not used, the default constructor for
/// WriteProperties will work regardless of the options used to build the C++
/// project.
Compression::type compression = Compression::UNCOMPRESSED;
/// Compressor-specific compression level
int compression_level = ::arrow::util::kUseDefaultCompressionLevel;
};
ARROW_EXPORT
Status WriteTable(const Table& table, io::OutputStream* dst,
const WriteProperties& properties = WriteProperties::Defaults());
} // namespace feather
} // namespace ipc
} // namespace arrow
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