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/* Glazed Lists                                                 (c) 2003-2006 */
/* http://publicobject.com/glazedlists/                      publicobject.com,*/
/*                                                     O'Dell Engineering Ltd.*/
package ca.odell.glazedlists.impl.beans;

// to implement the ThresholdEvaluator interface
import ca.odell.glazedlists.ThresholdList;

/**
 * A ThresholdEvaluator that is powered by JavaBeans and Reflection.
 *
 * @author Kevin Maltby
 */
public final class BeanThresholdEvaluator implements ThresholdList.Evaluator {

    private String propertyName = null;

    private BeanProperty beanProperty = null;

    public BeanThresholdEvaluator(String propertyName) {
        this.propertyName = propertyName;
    }

    /**
     * Returns an integer value for an Object to be used to
     * compare that object against a threshold.  This value is
     * not relative to any other object unlike a Comparator.
     */
    @Override
    public int evaluate(E object) {
        if(beanProperty == null) loadPropertyDescriptors(object);
        Object property = beanProperty.get(object);
        return ((Integer)property).intValue();
    }

    /**
     * Loads the property descriptors which are used to invoke property
     * access methods using the property names.
     */
    private void loadPropertyDescriptors(Object beanObject) {
        Class beanClass = (Class) beanObject.getClass();
        beanProperty = new BeanProperty<>(beanClass, propertyName, true, false);
    }
}