/**
 * Manages an editor widget
 * Widget and wrapper share the same parent
 *
 * A wrapper controls one attribute editor widget and is able to create a default
 * widget or use a pre-existent widget. It is able to set the widget to the value implied
 * by a field of a vector layer, or return the value it currently holds. Every time it is changed
 * it has to emit a valueChanged signal. If it fails to do so, there is no guarantee that the
 * changed status of the widget will be saved.
 */
class QgsSearchWidgetWrapper : QgsWidgetWrapper
{
%TypeHeaderCode
#include <qgssearchwidgetwrapper.h>
%End
  public:
    /**
     * Create a new widget wrapper
     *
     * @param vl        The layer on which the field is
     * @param fieldIdx  The field which will be controlled
     * @param parent    A parent widget for this widget wrapper and the created widget.
     */
    explicit QgsSearchWidgetWrapper( QgsVectorLayer* vl, int fieldIdx, QWidget* parent /TransferThis/ = nullptr );

    /**
     * Will be used to access the widget's value. Read the value from the widget and
     * return it properly formatted to be saved in the attribute.
     *
     * If an invalid variant is returned this will be interpreted as no change.
     * Be sure to return a NULL QVariant if it should be set to NULL.
     *
     * @return The current value the widget represents
     */
    virtual QString expression() = 0;
    /**
     * If this is true, then this search widget should take effect directly
     * when its expression changes
     */
    virtual bool applyDirectly() = 0;

  signals:

    /**
     * Emitted whenever the expression changes
     * @param exp The new search expression
     */
    void expressionChanged( const QString& exp );

  protected slots:

    virtual void setExpression( QString value ) = 0;
    void setFeature( const QgsFeature& feature );

  protected:
    //! clears the expression to search for all features
    void clearExpression();

};