feat: Move BaseEntityMapper to persistence package to eliminate duplication across projects

• feat: Move BaseEntityMapper to persistence package to eliminate duplication across projects

Relates to #32 (closed)

persistence/runtime/src/main/java/org/eclipsefoundation/persistence/mapper/BaseEntityMapper.java

+/*********************************************************************
+* Copyright (c) 2022, 2024 Eclipse Foundation.
+*
+* This program and the accompanying materials are made
+* available under the terms of the Eclipse Public License 2.0
+* which is available at https://www.eclipse.org/legal/epl-2.0/
+*
+* Author: Martin Lowe <martin.lowe@eclipse-foundation.org>
+*
+* SPDX-License-Identifier: EPL-2.0
+**********************************************************************/
+package org.eclipsefoundation.persistence.mapper;
+
+import org.eclipsefoundation.persistence.dao.PersistenceDao;
+import org.eclipsefoundation.persistence.dto.BareNode;
+import org.mapstruct.Context;
+import org.mapstruct.InheritInverseConfiguration;
+import org.mapstruct.ObjectFactory;
+import org.mapstruct.TargetType;
+
+/**
+ * Indicates an entity mapping between DTOs and models. Is used to help simplify
+ * the lookups where possible.
+ * 
+ * @author Martin Lowe
+ *
+ * @param <T> the DTO object in the mapping pair
+ * @param <U> the model object in the mapping pair
+ */
+public interface BaseEntityMapper<T extends BareNode, U> {
+
+    U toModel(T dtoEntity);
+
+    @InheritInverseConfiguration
+    T toDTO(U model, @Context PersistenceDao repo);
+
+    /**
+     * Used for generic BareNode lookups. This assumes that the string in the
+     * inverse is the key of the field. This will
+     * be used in a lookup of a reference of the object to be used in the DTO mapped
+     * object.
+     * 
+     * @param <E>        the BareNode actual type
+     * @param id         the string ID of the object to lookup
+     * @param repo       the passed repo context to be used for reference lookups
+     * @param targetType the injected class type reference
+     * @return a reference to the target entity if it exists, or a new object to be
+     *         persisted.
+     */
+    @ObjectFactory
+    default <E extends BareNode> E lookup(String id, @Context PersistenceDao repo, @TargetType Class<E> targetType) {
+        E entity = repo.getReference(id, targetType);
+        if (entity == null) {
+            try {
+                entity = targetType.getConstructor().newInstance();
+            } catch (Exception e) {
+                throw new IllegalStateException("Could not access no-param constructor of entity type", e);
+            }
+        }
+        return entity;
+    }
+}