qgsvectorlayerjoinbuffer.h

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/***************************************************************************
                          qgsvectorlayerjoinbuffer.h
                          ---------------------------
    begin                : Feb 09, 2011
    copyright            : (C) 2011 by Marco Hugentobler
    email                : marco dot hugentobler at sourcepole dot ch
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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 QGSVECTORLAYERJOINBUFFER_H
#define QGSVECTORLAYERJOINBUFFER_H

#include "qgsfeature.h"
#include "qgsvectorlayer.h"

#include <QHash>
#include <QString>


typedef QList< QgsVectorJoinInfo > QgsVectorJoinList;


class CORE_EXPORT QgsVectorLayerJoinBuffer : public QObject
{
    Q_OBJECT
  public:
    QgsVectorLayerJoinBuffer( QgsVectorLayer* layer = nullptr );
    ~QgsVectorLayerJoinBuffer();

    bool addJoin( const QgsVectorJoinInfo& joinInfo );

    bool removeJoin( const QString& joinLayerId );

    void updateFields( QgsFields& fields );

    void createJoinCaches();

    void writeXml( QDomNode& layer_node, QDomDocument& document ) const;

    void readXml( const QDomNode& layer_node );

    bool containsJoins() const { return !mVectorJoins.isEmpty(); }

    const QgsVectorJoinList& vectorJoins() const { return mVectorJoins; }

    const QgsVectorJoinInfo* joinForFieldIndex( int index, const QgsFields& fields, int& sourceFieldIndex ) const;

    int joinedFieldsOffset( const QgsVectorJoinInfo* info, const QgsFields& fields );

    static QVector<int> joinSubsetIndices( QgsVectorLayer* joinLayer, const QStringList& joinFieldsSubset );

    QgsVectorLayerJoinBuffer* clone() const;

  signals:
    void joinedFieldsChanged();

  private slots:
    void joinedLayerUpdatedFields();

  private:

    QgsVectorLayer* mLayer;

    QgsVectorJoinList mVectorJoins;

    void cacheJoinLayer( QgsVectorJoinInfo& joinInfo );
};

#endif // QGSVECTORLAYERJOINBUFFER_H