com.envimate.mapmate.serialization.CircularReferenceDetector Maven / Gradle / Ivy

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/*
 * Copyright (c) 2019 envimate GmbH - https://envimate.com/.
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 com.envimate.mapmate.serialization;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

/**
 * CircularReferenceDetector provides ways to scan and detect circular references in a given object.
 */
@SuppressWarnings({"rawtypes", "unchecked"})
public final class CircularReferenceDetector {

    private static final int WRAPPER_COUNT = 10;
    private static final Set> WRAPPER_TYPES = getWrapperTypes();

    private static boolean isWrapperType(final Class clazz) {
        return WRAPPER_TYPES.contains(clazz);
    }

    private static Set> getWrapperTypes() {
        final Set> ret = new HashSet<>(WRAPPER_COUNT);
        ret.add(Boolean.class);
        ret.add(Character.class);
        ret.add(Byte.class);
        ret.add(Short.class);
        ret.add(Integer.class);
        ret.add(Long.class);
        ret.add(Float.class);
        ret.add(Double.class);
        ret.add(Void.class);
        ret.add(String.class);
        return ret;
    }

    /**
     * Detect scans a given object for circular references in its publicly accessible fields recursively.
     *
     * @param subject to be scanned
     * @throws CircularReferenceException if a circular reference is found.
     */
    void detect(final Object subject) {
        if (Objects.isNull(subject)) {
            return;
        }
        this.detect(subject, new ArrayList<>());
    }

    private void detect(final Object subject, final ArrayList