# SingleKeyLinkageSupport.java

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

    import javax.annotation.Nullable;

    import org.codefilarete.reflection.ReversibleAccessor;
    import org.codefilarete.reflection.SerializableAccessor;
    import org.codefilarete.reflection.SerializableMutator;
    import org.codefilarete.stalactite.dsl.entity.EntityMappingConfiguration.SingleKeyMapping;
    import org.codefilarete.stalactite.dsl.idpolicy.IdentifierPolicy;
    import org.codefilarete.stalactite.engine.configurer.ValueAccessPointVariantSupport;
    import org.codefilarete.stalactite.engine.configurer.property.ColumnLinkageOptionsSupport;
    import org.codefilarete.stalactite.engine.configurer.property.LocalColumnLinkageOptions;

    /**
     * Storage for single key mapping definition. See {@link org.codefilarete.stalactite.dsl.entity.FluentEntityMappingBuilder#mapKey(SerializableAccessor, IdentifierPolicy)} methods.
     */
    class SingleKeyLinkageSupport<C, I> implements SingleKeyMapping<C, I> {

    	private final IdentifierPolicy<I> identifierPolicy;

    	private LocalColumnLinkageOptions columnOptions = new ColumnLinkageOptionsSupport();

    	private boolean setByConstructor;

    	private final ValueAccessPointVariantSupport<C, I> accessor;

    	@Nullable
    	private String fieldName;

    	public SingleKeyLinkageSupport(SerializableAccessor<C, I> getter, IdentifierPolicy<I> identifierPolicy) {
    		this.accessor = new ValueAccessPointVariantSupport<>(getter);
    		this.identifierPolicy = identifierPolicy;
    	}

    	public SingleKeyLinkageSupport(SerializableMutator<C, I> setter, IdentifierPolicy<I> identifierPolicy) {
    		this.accessor = new ValueAccessPointVariantSupport<>(setter);
    		this.identifierPolicy = identifierPolicy;
    	}

    	public SingleKeyLinkageSupport(Class<C> classToPersist, String fieldName, IdentifierPolicy<I> identifierPolicy) {
    		this.accessor = new ValueAccessPointVariantSupport<>(classToPersist, fieldName);
    		this.identifierPolicy = identifierPolicy;
    	}

    	@Override
    	public IdentifierPolicy<I> getIdentifierPolicy() {
    		return identifierPolicy;
    	}

    	@Override
    	public ReversibleAccessor<C, I> getAccessor() {
    		return accessor.getAccessor();
    	}

    	@Override
    	public LocalColumnLinkageOptions getColumnOptions() {
    		return columnOptions;
    	}

    	public void setColumnOptions(LocalColumnLinkageOptions columnOptions) {
    		this.columnOptions = columnOptions;
    	}

    	public void setByConstructor() {
    		this.setByConstructor = true;
    	}

    	@Override
    	@Nullable
    	public String getFieldName() {
    		return fieldName;
    	}

    	public void setField(Class<C> classToPersist, String fieldName) {
    		this.fieldName = fieldName;
    		this.accessor.setField(classToPersist, fieldName);
    	}

    	@Override
    	public boolean isSetByConstructor() {
    		return setByConstructor;
    	}
    }