CycleAvoidingMappingContext.java

/*
 * Copyright 2005-2025 the original author or authors.
 *
 * 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 org.openwms.wms;

import org.mapstruct.BeforeMapping;
import org.mapstruct.MappingTarget;
import org.mapstruct.TargetType;

import java.util.IdentityHashMap;
import java.util.Map;

/**
 * A CycleAvoidingMappingContext.
 *
 * @author Heiko Scherrer
 */
public class CycleAvoidingMappingContext {

    private Map<Object, Map<Class<?>, Object>> knownInstances = new IdentityHashMap<>();

    @BeforeMapping
    public <T> T getMappedInstance(Object source, @TargetType Class<T> targetType) {
        return (T) knownInstances.getOrDefault( source , new IdentityHashMap<>()).get( targetType );
    }

    @BeforeMapping
    public void storeMappedInstance(Object source, @MappingTarget Object target) {
        knownInstances.computeIfAbsent( source, k -> new IdentityHashMap<>()).put(target.getClass(), target );
    }
}