/* * Copyright 2014 Daniel Bechler * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package de.danielbechler.diff; import de.danielbechler.diff.node.DiffNode; import de.danielbechler.diff.node.Visit; /** * Careful: This class has not yet been tested very thoroughly and serves more as an example for your own * implementations. * * @author Daniel Bechler */ @SuppressWarnings("UnusedDeclaration") public final class ObjectMerger { private final ObjectDiffer objectDiffer; public ObjectMerger() { this.objectDiffer = ObjectDifferBuilder.buildDefault(); } public ObjectMerger(final ObjectDiffer objectDiffer) { this.objectDiffer = objectDiffer; } @SuppressWarnings({"unchecked"}) public <T> T merge(final T modified, final T base, final T head) { final DiffNode.Visitor visitor = new MergingDifferenceVisitor<T>(head, modified); final DiffNode difference = objectDiffer.compare(modified, base); difference.visit(visitor); return head; } private static final class MergingDifferenceVisitor<T> implements DiffNode.Visitor { private final T head; private final T modified; public MergingDifferenceVisitor(final T head, final T modified) { this.head = head; this.modified = modified; } public void node(final DiffNode node, final Visit visit) { if (node.getState() == DiffNode.State.ADDED) { node.canonicalSet(head, node.canonicalGet(modified)); } else if (node.getState() == DiffNode.State.REMOVED) { node.canonicalUnset(head); } else if (node.getState() == DiffNode.State.CHANGED) { if (node.hasChildren()) { node.visitChildren(this); visit.dontGoDeeper(); } else { node.canonicalSet(head, node.canonicalGet(modified)); } } } } }