# ConvertingMapAccessor.java

    package org.codefilarete.stalactite.engine.configurer.map;

    import java.util.HashMap;
    import java.util.Map;

    import org.codefilarete.reflection.Accessor;
    import org.codefilarete.reflection.AccessorDefinition;
    import org.codefilarete.reflection.AccessorDefinitionDefiner;
    import org.codefilarete.reflection.ValueAccessPoint;
    import org.codefilarete.tool.function.TriConsumer;

    /**
     * {@link Accessor} that converts Map&lt;K, V&gt; to Map&lt;KID, V&gt; on {@link #get(Object)}.
     * Could have been an anonymous class but {@link MapRelationConfigurer} requires to call {@link AccessorDefinition#giveDefinition(ValueAccessPoint)}
     * at some point, which causes {@link UnsupportedOperationException} since the anonymous class is unknown from it.
     * Though it as to be a named class, moreover {@link AccessorDefinition} has been enhanced take into account classes that provides their
     * {@link AccessorDefinition} by their own through {@link AccessorDefinitionDefiner}.
     *
     * @param <SRC> entity type owning the relation
     * @param <K1> Map key entity type
     * @param <V1> Map value type
     * @param <K2> converted Map key entity type
     * @param <V2> converted Map value type
     * @param <M> relation Map type
     * @param <MM> redefined Map type to get entity key identifier
     * @author Guillaume Mary
     */
    class ConvertingMapAccessor<SRC, K1, V1, K2, V2, M extends Map<K1, V1>, MM extends Map<K2, V2>> implements Accessor<SRC, MM>, AccessorDefinitionDefiner<SRC> {

    	private final MapRelation<SRC, K1, V1, M> map;

    	private final AccessorDefinition accessorDefinition;

    	private final TriConsumer<K1, V1, MM> converter;

    	public ConvertingMapAccessor(MapRelation<SRC, K1, V1, M> map,
    								 TriConsumer<K1, V1, MM> converter) {
    		this.map = map;
    		this.accessorDefinition = AccessorDefinition.giveDefinition(this.map.getMapProvider());
    		this.converter = converter;
    	}

    	@Override
    	public MM get(SRC SRC) {
    		M m = map.getMapProvider().get(SRC);
    		if (m != null) {
    			// we can use an HashMap because K2 is expected to be an identifier :
    			// either one of the entity, or an embeddable bean being a map key, so in both cases having a dedicated implementation of equals() + hashCode()
    			MM result = (MM) new HashMap<>();
    			m.forEach((k, v) -> converter.accept(k, v, result));
    			return result;
    		} else {
    			return null;
    		}
    	}

    	@Override
    	public AccessorDefinition asAccessorDefinition() {
    		return this.accessorDefinition;
    	}
    }