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Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang. The code is tested using the latest revision of the JDK for supported LTS releases: 8, 11, 17 and 21 currently. See https://github.com/apache/commons-lang/blob/master/.github/workflows/maven.yml Please ensure your build environment is up-to-date and kindly report any build issues.

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/*
 * 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 org.apache.commons.lang3.builder;

import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.StringUtils;

/**
 * Works with {@link ToStringBuilder} to create a "deep" {@code toString}.
 * But instead a single line like the {@link RecursiveToStringStyle} this creates a multiline String
 * similar to the {@link ToStringStyle#MULTI_LINE_STYLE}.
 *
 * To use this class write code as follows:
 *
 *  * public class Job {
 *   String title;
 *   ...
 * }
 *
 * public class Person {
 *   String name;
 *   int age;
 *   boolean smoker;
 *   Job job;
 *
 *   ...
 *
 *   public String toString() {
 *     return new ReflectionToStringBuilder(this, new MultilineRecursiveToStringStyle()).toString();
 *   }
 * }
 * 
 *
 * 
 * This will produce a toString of the format:

 * Person@7f54[ 

 *   name=Stephen, 

 *   age=29, 

 *   smokealse, 

 *   job=Job@43cd2[ 

 *     title=Manager 

 *    ] 

 * ]
 * 
 * 
 *
 * @since 3.4
 */
public class MultilineRecursiveToStringStyle extends RecursiveToStringStyle {

    /**
     * Required for serialization support.
     * @see java.io.Serializable
     */
    private static final long serialVersionUID = 1L;

    /** Indenting of inner lines. */
    private static final int INDENT = 2;

    /** Current indenting. */
    private int spaces = 2;

    /**
     * Constructs a new instance.
     */
    public MultilineRecursiveToStringStyle() {
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final boolean[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final byte[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final char[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final double[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final float[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final int[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final long[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    public void appendDetail(final StringBuffer buffer, final String fieldName, final Object value) {
        if (!ClassUtils.isPrimitiveWrapper(value.getClass()) && !String.class.equals(value.getClass())
                && accept(value.getClass())) {
            spaces += INDENT;
            resetIndent();
            buffer.append(ReflectionToStringBuilder.toString(value, this));
            spaces -= INDENT;
            resetIndent();
        } else {
            super.appendDetail(buffer, fieldName, value);
        }
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final Object[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void appendDetail(final StringBuffer buffer, final String fieldName, final short[] array) {
        spaces += INDENT;
        resetIndent();
        super.appendDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    @Override
    protected void reflectionAppendArrayDetail(final StringBuffer buffer, final String fieldName, final Object array) {
        spaces += INDENT;
        resetIndent();
        super.reflectionAppendArrayDetail(buffer, fieldName, array);
        spaces -= INDENT;
        resetIndent();
    }

    /**
     * Resets the fields responsible for the line breaks and indenting.
     * Must be invoked after changing the {@link #spaces} value.
     */
    private void resetIndent() {
        setArrayStart("{" + System.lineSeparator() + spacer(spaces));
        setArraySeparator("," + System.lineSeparator() + spacer(spaces));
        setArrayEnd(System.lineSeparator() + spacer(spaces - INDENT) + "}");

        setContentStart("[" + System.lineSeparator() + spacer(spaces));
        setFieldSeparator("," + System.lineSeparator() + spacer(spaces));
        setContentEnd(System.lineSeparator() + spacer(spaces - INDENT) + "]");
    }

    /**
     * Creates a StringBuilder responsible for the indenting.
     *
     * @param spaces how far to indent
     * @return a StringBuilder with {spaces} leading space characters.
     */
    private String spacer(final int spaces) {
        return StringUtils.repeat(' ', spaces);
    }

}