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Nomin is a mapping engine for the Java platform. It provides abilities to transform object trees according to declarative mapping rules. Main features of Nomin are no XML configuration, intuitively looking mapping, using arbitrary expressions and method invocations in mappings, pre and postprocessing right in a mapping listing, customizations. It's applicable for any Java compatible classes, not only JavaBeans.

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package org.nomin.core;

import org.nomin.util.*;
import static java.text.MessageFormat.format;
import static org.nomin.core.preprocessing.Preprocessing.preprocess;

/**
 * Provides access to a property.
 * @author Dmitry Dobrynin
 *         Created: 27.04.2010 20:57:15
 */
public class PropRuleElem extends RuleElem {
    protected final PropertyAccessor property;
    protected final InstanceCreator instanceCreator;

    public PropRuleElem(PropertyAccessor property, TypeInfo typeInfo, InstanceCreator instanceCreator) {
        super(typeInfo);
        this.property = property;
        this.instanceCreator = instanceCreator;
    }

    public Object get(Object instance) throws Exception {
        return instance == null ? null : next == null ? property.get(instance) : next.get(property.get(instance));
    }

    public Object set(Object instance, Object value) throws Exception {
        if (next == null) property.set(instance, preprocess(value, preprocessings, 0));
        else {
            Object ov = property.get(instance), nv =
                    next.set(ov == null ? instanceCreator.create(typeInfo.determineTypeDynamically(value)) : ov, value);
            if (ov != nv) property.set(instance, nv);
        }
        return instance;
    }

    public String toString() { return format("{0}:{1}", property.getName(), typeInfo); }
}