Header.h

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/*
 * (C) Copyright 1996-2012 ECMWF.
 * 
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0. 
 * In applying this licence, ECMWF does not waive the privileges and immunities 
 * granted to it by virtue of its status as an intergovernmental organisation nor
 * does it submit to any jurisdiction.
 */
 
/// @author Piotr Kuchta
/// @date April 2009
/// @author Simon Smart
/// @date January 2019
 
#ifndef odc_core_Header_H
#define odc_core_Header_H
 
#include <cstddef>
#include <cstdint>
#include <map>
#include <string>
#include <vector>
 
#include "eckit/memory/NonCopyable.h"
#include "eckit/io/Buffer.h"
 
namespace eckit { class DataHandle; }
 
 
namespace odc {
namespace core {
 
class MetaData;
using Properties = std::map<std::string, std::string>;
using Flags = std::vector<double>;
 
//----------------------------------------------------------------------------------------------------------------------
 
const int32_t BYTE_ORDER_INDICATOR = 1;
const uint16_t ODA_MAGIC_NUMBER = 0xffff;
 
const int32_t FORMAT_VERSION_NUMBER_MAJOR = 0;
const int32_t FORMAT_VERSION_NUMBER_MINOR = 5;
 
//----------------------------------------------------------------------------------------------------------------------
 
class Header : private eckit::NonCopyable {
 
public: // methods
 
    Header (MetaData& md, Properties& props);
    ~Header ();
 
    size_t dataSize() const { return dataSize_; }
 
    size_t rowsNumber() const { return rowsNumber_; }
 
    int32_t byteOrder() { return byteOrder_; }
 
    /// read Magic loads the MAGIC from the data handle. Returns 0 for end of stream,
    /// and throws an exception if the magic is incorrect.
    static bool readMagic(eckit::DataHandle& dh);
 
    void loadAfterMagic(eckit::DataHandle& dh);
 
    static std::pair<eckit::Buffer, size_t>
    serializeHeader(size_t dataSize, size_t rowsNumber, const Properties& properties, const MetaData& columns);
 
    static std::pair<eckit::Buffer, size_t>
    serializeHeaderOtherByteOrder(size_t dataSize, size_t rowsNumber, const Properties& properties, const MetaData& columns);
 
private: // members
 
    template <typename ByteOrder> void load(eckit::DataHandle& dh);
 
    MetaData& md_;
    Properties& props_;
    size_t dataSize_;
    size_t rowsNumber_;
 
    int32_t byteOrder_;
};
 
//----------------------------------------------------------------------------------------------------------------------
 
} // namespace core
} // namespace odc 
 
 
#endif // odc_core_Header_H