qgsarrowiterator.h

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/***************************************************************************
    qgsarrowiterator.h
    ---------------------
    begin                : November 2025
    copyright            : (C) 2025 by Dewey Dunnington
    email                : dewey at dunnington dot ca
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#ifndef QGSARROWITERATOR_H
#define QGSARROWITERATOR_H
 
#include "qgis_core.h"
#include "qgsfeatureiterator.h"
#include "qgsvectorlayer.h"
 
#ifndef ARROW_C_DATA_INTERFACE
#define ARROW_C_DATA_INTERFACE
 
#define ARROW_FLAG_DICTIONARY_ORDERED 1
#define ARROW_FLAG_NULLABLE 2
#define ARROW_FLAG_MAP_KEYS_SORTED 4
 
#ifndef SIP_RUN
struct ArrowSchema
{
  // Array type description
  const char *format;
  const char *name;
  const char *metadata;
  int64_t flags;
  int64_t n_children;
  struct ArrowSchema **children;
  struct ArrowSchema *dictionary;
 
  // Release callback
  void ( *release )( struct ArrowSchema * );
  // Opaque producer-specific data
  void *private_data;
};
#endif
 
#ifndef SIP_RUN
struct ArrowArray
{
  // Array data description
  int64_t length;
  int64_t null_count;
  int64_t offset;
  int64_t n_buffers;
  int64_t n_children;
  const void **buffers;
  struct ArrowArray **children;
  struct ArrowArray *dictionary;
 
  // Release callback
  void ( *release )( struct ArrowArray * );
  // Opaque producer-specific data
  void *private_data;
};
#endif
 
#endif // ARROW_C_DATA_INTERFACE
 
#ifndef ARROW_C_STREAM_INTERFACE
#define ARROW_C_STREAM_INTERFACE
 
#ifndef SIP_RUN
struct ArrowArrayStream
{
  // Callbacks providing stream functionality
  int ( *get_schema )( struct ArrowArrayStream *, struct ArrowSchema *out );
  int ( *get_next )( struct ArrowArrayStream *, struct ArrowArray *out );
  const char *( *get_last_error )( struct ArrowArrayStream * );
 
  // Release callback
  void ( *release )( struct ArrowArrayStream * );
 
  // Opaque producer-specific data
  void *private_data;
};
#endif
 
#endif // ARROW_C_STREAM_INTERFACE

class CORE_EXPORT QgsArrowInferSchemaOptions
{
  public:
    QgsArrowInferSchemaOptions();

    void setGeometryColumnName( const QString &geometryColumnName );

    QString geometryColumnName() const;
 
  private:
    QString mGeometryColumnName;
};

class CORE_EXPORT QgsArrowSchema
{
  public:
    QgsArrowSchema();

    QgsArrowSchema( const QgsArrowSchema &other );

    QgsArrowSchema &operator=( const QgsArrowSchema &other );
 
    ~QgsArrowSchema();
 
#ifndef SIP_RUN
    struct ArrowSchema *schema();

    const struct ArrowSchema *schema() const;
#endif

    unsigned long long cSchemaAddress() const;

    void exportToAddress( unsigned long long otherAddress );

    bool isValid() const;

    int geometryColumnIndex() const;

    void setGeometryColumnIndex( int geometryColumnIndex );
 
  private:
    struct ArrowSchema mSchema {};
    int mGeometryColumnIndex = -1;
};

class CORE_EXPORT QgsArrowArray
{
  public:
    QgsArrowArray() = default;
 
    QgsArrowArray &operator=( QgsArrowArray &other ) = delete;
    QgsArrowArray( const QgsArrowArray &other ) = delete;
 
#ifndef SIP_RUN
    QgsArrowArray( QgsArrowArray &&other );

    QgsArrowArray &operator=( QgsArrowArray &&other );
#endif
 
    ~QgsArrowArray();
 
#ifndef SIP_RUN
    struct ArrowArray *array();

    const struct ArrowArray *array() const;
#endif

    unsigned long long cArrayAddress() const;

    void exportToAddress( unsigned long long otherAddress );

    bool isValid() const;
 
  private:
    struct ArrowArray mArray {};
 
#ifdef SIP_RUN
    QgsArrowArray( const QgsArrowArray &other );
#endif
};

class CORE_EXPORT QgsArrowIterator
{
  public:
    QgsArrowIterator() = default;

    explicit QgsArrowIterator( QgsFeatureIterator featureIterator );

    void setSchema( const QgsArrowSchema &schema );

    QgsArrowArray nextFeatures( int n ) SIP_THROW( QgsException );

    static QgsArrowSchema inferSchema( const QgsVectorLayer &layer, const QgsArrowInferSchemaOptions &options = QgsArrowInferSchemaOptions() ) SIP_THROW( QgsException );

    static QgsArrowSchema inferSchema( const QgsFields &fields, bool hasGeometry = false, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem(), const QgsArrowInferSchemaOptions &options = QgsArrowInferSchemaOptions() ) SIP_THROW( QgsException );
 
  private:
    QgsFeatureIterator mFeatureIterator;
    QgsArrowSchema mSchema;
};
 
#endif // QGSARROWITERATOR_H