/*
 * 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 java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.tuple.Pair;

/**
 * <p>Assists in implementing {@link Object#equals(Object)} methods.</p>
 *
 * <p> This class provides methods to build a good equals method for any
 * class. It follows rules laid out in
 * <a href="http://www.oracle.com/technetwork/java/effectivejava-136174.html">Effective Java</a>
 * , by Joshua Bloch. In particular the rule for comparing <code>doubles</code>,
 * <code>floats</code>, and arrays can be tricky. Also, making sure that
 * <code>equals()</code> and <code>hashCode()</code> are consistent can be
 * difficult.</p>
 *
 * <p>Two Objects that compare as equals must generate the same hash code,
 * but two Objects with the same hash code do not have to be equal.</p>
 *
 * <p>All relevant fields should be included in the calculation of equals.
 * Derived fields may be ignored. In particular, any field used in
 * generating a hash code must be used in the equals method, and vice
 * versa.</p>
 *
 * <p>Typical use for the code is as follows:</p>
 * <pre>
 * public boolean equals(Object obj) {
 *   if (obj == null) { return false; }
 *   if (obj == this) { return true; }
 *   if (obj.getClass() != getClass()) {
 *     return false;
 *   }
 *   MyClass rhs = (MyClass) obj;
 *   return new EqualsBuilder()
 *                 .appendSuper(super.equals(obj))
 *                 .append(field1, rhs.field1)
 *                 .append(field2, rhs.field2)
 *                 .append(field3, rhs.field3)
 *                 .isEquals();
 *  }
 * </pre>
 *
 * <p> Alternatively, there is a method that uses reflection to determine
 * the fields to test. Because these fields are usually private, the method,
 * <code>reflectionEquals</code>, uses <code>AccessibleObject.setAccessible</code> to
 * change the visibility of the fields. This will fail under a security
 * manager, unless the appropriate permissions are set up correctly. It is
 * also slower than testing explicitly.</p>
 *
 * <p> A typical invocation for this method would look like:</p>
 * <pre>
 * public boolean equals(Object obj) {
 *   return EqualsBuilder.reflectionEquals(this, obj);
 * }
 * </pre>
 *
 * @since 1.0
 * @version $Id: EqualsBuilder.java 1535757 2013-10-25 15:07:13Z mbenson $
 */
public class EqualsBuilder implements Builder<Boolean> {

    /**
     * <p>
     * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
     * </p>
     *
     * @since 3.0
     */
    private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = new ThreadLocal<Set<Pair<IDKey, IDKey>>>();

    /*
     * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
     * we are in the process of calculating.
     *
     * So we generate a one-to-one mapping from the original object to a new object.
     *
     * Now HashSet uses equals() to determine if two elements with the same hashcode really
     * are equal, so we also need to ensure that the replacement objects are only equal
     * if the original objects are identical.
     *
     * The original implementation (2.4 and before) used the System.indentityHashCode()
     * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
     *
     * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
     * to disambiguate the duplicate ids.
     */

    /**
     * <p>
     * Returns the registry of object pairs being traversed by the reflection
     * methods in the current thread.
     * </p>
     *
     * @return Set the registry of objects being traversed
     * @since 3.0
     */
    static Set<Pair<IDKey, IDKey>> getRegistry() {
        return REGISTRY.get();
    }

    /**
     * <p>
     * Converters value pair into a register pair.
     * </p>
     *
     * @param lhs <code>this</code> object
     * @param rhs the other object
     *
     * @return the pair
     */
    static Pair<IDKey, IDKey> getRegisterPair(final Object lhs, final Object rhs) {
        final IDKey left = new IDKey(lhs);
        final IDKey right = new IDKey(rhs);
        return Pair.of(left, right);
    }

    /**
     * <p>
     * Returns <code>true</code> if the registry contains the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * Objects might be swapped therefore a check is needed if the object pair
     * is registered in given or swapped order.
     * </p>
     *
     * @param lhs <code>this</code> object to lookup in registry
     * @param rhs the other object to lookup on registry
     * @return boolean <code>true</code> if the registry contains the given object.
     * @since 3.0
     */
    static boolean isRegistered(final Object lhs, final Object rhs) {
        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getLeft(), pair.getRight());

        return registry != null
                && (registry.contains(pair) || registry.contains(swappedPair));
    }

    /**
     * <p>
     * Registers the given object pair.
     * Used by the reflection methods to avoid infinite loops.
     * </p>
     *
     * @param lhs <code>this</code> object to register
     * @param rhs the other object to register
     */
    static void register(final Object lhs, final Object rhs) {
        synchronized (EqualsBuilder.class) {
            if (getRegistry() == null) {
                REGISTRY.set(new HashSet<Pair<IDKey, IDKey>>());
            }
        }

        final Set<Pair<IDKey, IDKey>> registry = getRegistry();
        final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
        registry.add(pair);
    }

    /**
     * <p>
     * Unregisters the given object pair.
     * </p>
     *
     * <p>
     * Used by the reflection methods to avoid infinite loops.
     *
     * @param lhs <code>this</code> object to unregister
     * @param rhs the other object to unregister
     * @since 3.0
     */
    static void unregister(final Object lhs, final Object rhs) {
        Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry != null) {
            final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
            registry.remove(pair);
            synchronized (EqualsBuilder.class) {
                //read again
                registry = getRegistry();
                if (registry != null && registry.isEmpty()) {
                    REGISTRY.remove();
                }
            }
        }
    }

    /**
     * If the fields tested are equals.
     * The default value is <code>true</code>.
     */
    private boolean isEquals = true;

    /**
     * <p>Constructor for EqualsBuilder.</p>
     *
     * <p>Starts off assuming that equals is <code>true</code>.</p>
     * @see Object#equals(Object)
     */
    public EqualsBuilder() {
        // do nothing for now.
    }

    //-------------------------------------------------------------------------

    /**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</p>
     *
     * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly.</p>
     *
     * <p>Transient members will be not be tested, as they are likely derived
     * fields, and not part of the value of the Object.</p>
     *
     * <p>Static fields will not be tested. Superclass fields will be included.</p>
     *
     * @param lhs  <code>this</code> object
     * @param rhs  the other object
     * @param excludeFields  Collection of String field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
        return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
    }

    /**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</p>
     *
     * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly.</p>
     *
     * <p>Transient members will be not be tested, as they are likely derived
     * fields, and not part of the value of the Object.</p>
     *
     * <p>Static fields will not be tested. Superclass fields will be included.</p>
     *
     * @param lhs  <code>this</code> object
     * @param rhs  the other object
     * @param excludeFields  array of field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
        return reflectionEquals(lhs, rhs, false, null, excludeFields);
    }

    /**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</p>
     *
     * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly.</p>
     *
     * <p>If the TestTransients parameter is set to <code>true</code>, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the <code>Object</code>.</p>
     *
     * <p>Static fields will not be tested. Superclass fields will be included.</p>
     *
     * @param lhs  <code>this</code> object
     * @param rhs  the other object
     * @param testTransients  whether to include transient fields
     * @return <code>true</code> if the two Objects have tested equals.
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
        return reflectionEquals(lhs, rhs, testTransients, null);
    }

    /**
     * <p>This method uses reflection to determine if the two <code>Object</code>s
     * are equal.</p>
     *
     * <p>It uses <code>AccessibleObject.setAccessible</code> to gain access to private
     * fields. This means that it will throw a security exception if run under
     * a security manager, if the permissions are not set up correctly. It is also
     * not as efficient as testing explicitly.</p>
     *
     * <p>If the testTransients parameter is set to <code>true</code>, transient
     * members will be tested, otherwise they are ignored, as they are likely
     * derived fields, and not part of the value of the <code>Object</code>.</p>
     *
     * <p>Static fields will not be included. Superclass fields will be appended
     * up to and including the specified superclass. A null superclass is treated
     * as java.lang.Object.</p>
     *
     * @param lhs  <code>this</code> object
     * @param rhs  the other object
     * @param testTransients  whether to include transient fields
     * @param reflectUpToClass  the superclass to reflect up to (inclusive),
     *  may be <code>null</code>
     * @param excludeFields  array of field names to exclude from testing
     * @return <code>true</code> if the two Objects have tested equals.
     * @since 2.0
     */
    public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
            final String... excludeFields) {
        if (lhs == rhs) {
            return true;
        }
        if (lhs == null || rhs == null) {
            return false;
        }
        // Find the leaf class since there may be transients in the leaf
        // class or in classes between the leaf and root.
        // If we are not testing transients or a subclass has no ivars,
        // then a subclass can test equals to a superclass.
        final Class<?> lhsClass = lhs.getClass();
        final Class<?> rhsClass = rhs.getClass();
        Class<?> testClass;
        if (lhsClass.isInstance(rhs)) {
            testClass = lhsClass;
            if (!rhsClass.isInstance(lhs)) {
                // rhsClass is a subclass of lhsClass
                testClass = rhsClass;
            }
        } else if (rhsClass.isInstance(lhs)) {
            testClass = rhsClass;
            if (!lhsClass.isInstance(rhs)) {
                // lhsClass is a subclass of rhsClass
                testClass = lhsClass;
            }
        } else {
            // The two classes are not related.
            return false;
        }
        final EqualsBuilder equalsBuilder = new EqualsBuilder();
        try {
            if (testClass.isArray()) {
                equalsBuilder.append(lhs, rhs);
            } else {
                reflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients, excludeFields);
                while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
                    testClass = testClass.getSuperclass();
                    reflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients, excludeFields);
                }
            }
        } catch (final IllegalArgumentException e) {
            // In this case, we tried to test a subclass vs. a superclass and
            // the subclass has ivars or the ivars are transient and
            // we are testing transients.
            // If a subclass has ivars that we are trying to test them, we get an
            // exception and we know that the objects are not equal.
            return false;
        }
        return equalsBuilder.isEquals();
    }

    /**
     * <p>Appends the fields and values defined by the given object of the
     * given Class.</p>
     *
     * @param lhs  the left hand object
     * @param rhs  the right hand object
     * @param clazz  the class to append details of
     * @param builder  the builder to append to
     * @param useTransients  whether to test transient fields
     * @param excludeFields  array of field names to exclude from testing
     */
    private static void reflectionAppend(
        final Object lhs,
        final Object rhs,
        final Class<?> clazz,
        final EqualsBuilder builder,
        final boolean useTransients,
        final String[] excludeFields) {

        if (isRegistered(lhs, rhs)) {
            return;
        }

        try {
            register(lhs, rhs);
            final Field[] fields = clazz.getDeclaredFields();
            AccessibleObject.setAccessible(fields, true);
            for (int i = 0; i < fields.length && builder.isEquals; i++) {
                final Field f = fields[i];
                if (!ArrayUtils.contains(excludeFields, f.getName())
                    && (f.getName().indexOf('$') == -1)
                    && (useTransients || !Modifier.isTransient(f.getModifiers()))
                    && (!Modifier.isStatic(f.getModifiers()))) {
                    try {
                        builder.append(f.get(lhs), f.get(rhs));
                    } catch (final IllegalAccessException e) {
                        //this can't happen. Would get a Security exception instead
                        //throw a runtime exception in case the impossible happens.
                        throw new InternalError("Unexpected IllegalAccessException");
                    }
                }
            }
        } finally {
            unregister(lhs, rhs);
        }
    }

    //-------------------------------------------------------------------------

    /**
     * <p>Adds the result of <code>super.equals()</code> to this builder.</p>
     *
     * @param superEquals  the result of calling <code>super.equals()</code>
     * @return EqualsBuilder - used to chain calls.
     * @since 2.0
     */
    public EqualsBuilder appendSuper(final boolean superEquals) {
        if (isEquals == false) {
            return this;
        }
        isEquals = superEquals;
        return this;
    }

    //-------------------------------------------------------------------------

    /**
     * <p>Test if two <code>Object</code>s are equal using their
     * <code>equals</code> method.</p>
     *
     * @param lhs  the left hand object
     * @param rhs  the right hand object
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final Object lhs, final Object rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        final Class<?> lhsClass = lhs.getClass();
        if (!lhsClass.isArray()) {
            // The simple case, not an array, just test the element
            isEquals = lhs.equals(rhs);
        } else if (lhs.getClass() != rhs.getClass()) {
            // Here when we compare different dimensions, for example: a boolean[][] to a boolean[]
            this.setEquals(false);
        }
        // 'Switch' on type of array, to dispatch to the correct handler
        // This handles multi dimensional arrays of the same depth
        else if (lhs instanceof long[]) {
            append((long[]) lhs, (long[]) rhs);
        } else if (lhs instanceof int[]) {
            append((int[]) lhs, (int[]) rhs);
        } else if (lhs instanceof short[]) {
            append((short[]) lhs, (short[]) rhs);
        } else if (lhs instanceof char[]) {
            append((char[]) lhs, (char[]) rhs);
        } else if (lhs instanceof byte[]) {
            append((byte[]) lhs, (byte[]) rhs);
        } else if (lhs instanceof double[]) {
            append((double[]) lhs, (double[]) rhs);
        } else if (lhs instanceof float[]) {
            append((float[]) lhs, (float[]) rhs);
        } else if (lhs instanceof boolean[]) {
            append((boolean[]) lhs, (boolean[]) rhs);
        } else {
            // Not an array of primitives
            append((Object[]) lhs, (Object[]) rhs);
        }
        return this;
    }

    /**
     * <p>
     * Test if two <code>long</code> s are equal.
     * </p>
     *
     * @param lhs
     *                  the left hand <code>long</code>
     * @param rhs
     *                  the right hand <code>long</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final long lhs, final long rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Test if two <code>int</code>s are equal.</p>
     *
     * @param lhs  the left hand <code>int</code>
     * @param rhs  the right hand <code>int</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final int lhs, final int rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Test if two <code>short</code>s are equal.</p>
     *
     * @param lhs  the left hand <code>short</code>
     * @param rhs  the right hand <code>short</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final short lhs, final short rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Test if two <code>char</code>s are equal.</p>
     *
     * @param lhs  the left hand <code>char</code>
     * @param rhs  the right hand <code>char</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final char lhs, final char rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Test if two <code>byte</code>s are equal.</p>
     *
     * @param lhs  the left hand <code>byte</code>
     * @param rhs  the right hand <code>byte</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final byte lhs, final byte rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Test if two <code>double</code>s are equal by testing that the
     * pattern of bits returned by <code>doubleToLong</code> are equal.</p>
     *
     * <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
     *
     * <p>It is compatible with the hash code generated by
     * <code>HashCodeBuilder</code>.</p>
     *
     * @param lhs  the left hand <code>double</code>
     * @param rhs  the right hand <code>double</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final double lhs, final double rhs) {
        if (isEquals == false) {
            return this;
        }
        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    }

    /**
     * <p>Test if two <code>float</code>s are equal byt testing that the
     * pattern of bits returned by doubleToLong are equal.</p>
     *
     * <p>This handles NaNs, Infinities, and <code>-0.0</code>.</p>
     *
     * <p>It is compatible with the hash code generated by
     * <code>HashCodeBuilder</code>.</p>
     *
     * @param lhs  the left hand <code>float</code>
     * @param rhs  the right hand <code>float</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final float lhs, final float rhs) {
        if (isEquals == false) {
            return this;
        }
        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    }

    /**
     * <p>Test if two <code>booleans</code>s are equal.</p>
     *
     * @param lhs  the left hand <code>boolean</code>
     * @param rhs  the right hand <code>boolean</code>
     * @return EqualsBuilder - used to chain calls.
      */
    public EqualsBuilder append(final boolean lhs, final boolean rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * <p>Performs a deep comparison of two <code>Object</code> arrays.</p>
     *
     * <p>This also will be called for the top level of
     * multi-dimensional, ragged, and multi-typed arrays.</p>
     *
     * @param lhs  the left hand <code>Object[]</code>
     * @param rhs  the right hand <code>Object[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>long</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(long, long)} is used.</p>
     *
     * @param lhs  the left hand <code>long[]</code>
     * @param rhs  the right hand <code>long[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final long[] lhs, final long[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>int</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(int, int)} is used.</p>
     *
     * @param lhs  the left hand <code>int[]</code>
     * @param rhs  the right hand <code>int[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final int[] lhs, final int[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>short</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(short, short)} is used.</p>
     *
     * @param lhs  the left hand <code>short[]</code>
     * @param rhs  the right hand <code>short[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final short[] lhs, final short[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>char</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(char, char)} is used.</p>
     *
     * @param lhs  the left hand <code>char[]</code>
     * @param rhs  the right hand <code>char[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final char[] lhs, final char[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>byte</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(byte, byte)} is used.</p>
     *
     * @param lhs  the left hand <code>byte[]</code>
     * @param rhs  the right hand <code>byte[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>double</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(double, double)} is used.</p>
     *
     * @param lhs  the left hand <code>double[]</code>
     * @param rhs  the right hand <code>double[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final double[] lhs, final double[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>float</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(float, float)} is used.</p>
     *
     * @param lhs  the left hand <code>float[]</code>
     * @param rhs  the right hand <code>float[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final float[] lhs, final float[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Deep comparison of array of <code>boolean</code>. Length and all
     * values are compared.</p>
     *
     * <p>The method {@link #append(boolean, boolean)} is used.</p>
     *
     * @param lhs  the left hand <code>boolean[]</code>
     * @param rhs  the right hand <code>boolean[]</code>
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            this.setEquals(false);
            return this;
        }
        if (lhs.length != rhs.length) {
            this.setEquals(false);
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * <p>Returns <code>true</code> if the fields that have been checked
     * are all equal.</p>
     *
     * @return boolean
     */
    public boolean isEquals() {
        return this.isEquals;
    }

    /**
     * <p>Returns <code>true</code> if the fields that have been checked
     * are all equal.</p>
     *
     * @return <code>true</code> if all of the fields that have been checked
     *         are equal, <code>false</code> otherwise.
     *
     * @since 3.0
     */
    @Override
    public Boolean build() {
        return Boolean.valueOf(isEquals());
    }

    /**
     * Sets the <code>isEquals</code> value.
     *
     * @param isEquals The value to set.
     * @since 2.1
     */
    protected void setEquals(final boolean isEquals) {
        this.isEquals = isEquals;
    }

    /**
     * Reset the EqualsBuilder so you can use the same object again
     * @since 2.5
     */
    public void reset() {
        this.isEquals = true;
    }
}
