/*
    * Copyright (c) 2002-2026 Gargoyle Software Inc.
    *
    * 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
    * https://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.htmlunit.util;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.NoSuchElementException;
  import java.util.Objects;
  import java.util.Set;
  
  /**
   * Simple and efficient linked map or better ordered map implementation to
   * replace the default linked list which is heavy.
   * <p>
   * This map does not support null and it is not thread-safe. It implements the
   * map interface but only for compatibility reason in the sense of replacing a
   * regular map. Iterator and streaming methods are either not implemented or
   * less efficient.
   * </p>
   * <p>
   * It goes the extra mile to avoid the overhead of wrapper objects.
   * </p>
   * <p>
   * Because you typically know what you do, we run minimal index checks only and
   * rely on the default exceptions by Java. Why should we do things twice?
   * </p>
   * <p>
   * Important Note: This is meant for small maps because to save on memory
   * allocation and churn, we are not keeping a wrapper for a reference from the
   * map to the list, only from the list to the map. Hence when you remove a key,
   * we have to iterate the entire list. Mostly, half of it most likely, but still
   * expensive enough. When you have something small like 10 to 20 entries, this
   * won't matter that much especially when a remove might be a rare event.
   * </p>
   * <p>
   * This is based on FashHashMap from XLT which is based on a version from:
   * https://github.com/mikvor/hashmapTest/blob/master/src/main/java/map/objobj/ObjObjMap.java
   * No concrete license specified at the source. The project is public domain.
   * </p>
   *
   * @param <K> the type of the key
   * @param <V> the type of the value
   *
   * @author Ren&eacute; Schwietzke
   */
  public class OrderedFastHashMap<K, V> implements Map<K, V>, Serializable {
      // our placeholders in the map
      private static final Object FREE_KEY_ = null;
      private static final Object REMOVED_KEY_ = new Object();
  
      // Fill factor, must be between (0 and 1)
      private static final double FILLFACTOR_ = 0.7d;
  
      // The map with the key value pairs */
      private Object[] mapData_;
  
      // We will resize a map once it reaches this size
      private int mapThreshold_;
  
      // Current map size
      private int mapSize_;
  
      // the list to impose order, the list refers to the key and value
      // position in the map, hence needs an update every time the
      // map sees an update (in regards to positions).
      private int[] orderedList_;
  
      // the size of the orderedList, in case we proactivly sized
      // it larger
      private int orderedListSize_;
  
      /**
       * Default constructor which create an ordered map with default size.
       */
      public OrderedFastHashMap() {
          this(8);
      }
  
      /**
      * Custom constructor to get a map with a custom size and fill factor. We are
      * not spending time on range checks, rather use a default if things are wrong.
      *
      * @param size the size to use, must 0 or positive, negative values default to 0
      */
     public OrderedFastHashMap(final int size) {
         if (size > 0) {
             final int capacity = arraySize(size, FILLFACTOR_);
 
             this.mapData_ = new Object[capacity << 1];
             this.mapThreshold_ = (int) (capacity * FILLFACTOR_);
 
             this.orderedList_ = new int[capacity];
         }
         else {
             this.mapData_ = new Object[0];
             this.mapThreshold_ = 0;
 
             this.orderedList_ = new int[0];
         }
     }
 
     /**
      * Get a value for a key, any key type is permitted due to
      * the nature of the Map interface.
      *
      * @param key the key
      * @return the value or null, if the key does not exist
      */
     @Override
     public V get(final Object key) {
         final int length = this.mapData_.length;
 
         // nothing in it
         if (length == 0) {
             return null;
         }
 
         int ptr = (key.hashCode() & ((length >> 1) - 1)) << 1;
         Object k = mapData_[ptr];
 
         if (k == FREE_KEY_) {
             return null; // end of chain already
         }
 
         // we checked FREE
         if (k.hashCode() == key.hashCode() && k.equals(key)) {
             return (V) this.mapData_[ptr + 1];
         }
 
         // we have not found it, search longer
         final int originalPtr = ptr;
         while (true) {
             ptr = (ptr + 2) & (length - 1); // that's next index
 
             // if we searched the entire array, we can stop
             if (originalPtr == ptr) {
                 return null;
             }
 
             k = this.mapData_[ptr];
 
             if (k == FREE_KEY_) {
                 return null;
             }
 
             if (k != REMOVED_KEY_) {
                 if (k.hashCode() == key.hashCode() && k.equals(key)) {
                     return (V) this.mapData_[ptr + 1];
                 }
             }
         }
     }
 
     /**
      * Adds a key and value to the internal position structure.
      *
      * @param key the key
      * @param value the value to store
      * @param listPosition defines where to add the new key/value pair
      *
      * @return the old value or null if they key was not known before
      */
     private V put(final K key, final V value, final Position listPosition) {
         if (mapSize_ >= mapThreshold_) {
             rehash(this.mapData_.length == 0 ? 4 : this.mapData_.length << 1);
         }
 
         int ptr = getStartIndex(key) << 1;
         Object k = mapData_[ptr];
 
         if (k == FREE_KEY_) {
             // end of chain already
             mapData_[ptr] = key;
             mapData_[ptr + 1] = value;
 
             // ok, remember position, it is a new entry
             orderedListAdd(listPosition, ptr);
 
             mapSize_++;
 
             return null;
         }
         else if (k.equals(key)) {
             // we check FREE and REMOVED prior to this call
             final Object ret = mapData_[ptr + 1];
             mapData_[ptr + 1] = value;
 
             // existing entry, no need to update the position
 
             return (V) ret;
         }
 
         int firstRemoved = -1;
         if (k == REMOVED_KEY_) {
             firstRemoved = ptr; // we may find a key later
         }
 
         while (true) {
             ptr = (ptr + 2) & (this.mapData_.length - 1); // that's next index calculation
             k = mapData_[ptr];
 
             if (k == FREE_KEY_) {
                 if (firstRemoved != -1) {
                     ptr = firstRemoved;
                 }
                 mapData_[ptr] = key;
                 mapData_[ptr + 1] = value;
 
                 // ok, remember position, it is a new entry
                 orderedListAdd(listPosition, ptr);
 
                 mapSize_++;
 
                 return null;
             }
             else if (k.equals(key)) {
                 final Object ret = mapData_[ptr + 1];
                 mapData_[ptr + 1] = value;
 
                 // same key, different value, this does not change the order
 
                 return (V) ret;
             }
             else if (k == REMOVED_KEY_) {
                 if (firstRemoved == -1) {
                     firstRemoved = ptr;
                 }
             }
         }
     }
 
     /**
      * Remove a key from the map. Returns the stored value or
      * null of the key is not known.
      *
      * @param key the key to remove
      * @return the stored value or null if the key does not exist
      */
     @Override
     public V remove(final Object key) {
         final int length = this.mapData_.length;
         // it is empty
         if (length == 0) {
             return null;
         }
 
         int ptr = getStartIndex(key) << 1;
         Object k = this.mapData_[ptr];
 
         if (k == FREE_KEY_) {
             return null; // end of chain already
         }
         else if (k.equals(key)) {
             // we check FREE and REMOVED prior to this call
             this.mapSize_--;
 
             if (this.mapData_[(ptr + 2) & (length - 1)] == FREE_KEY_) {
                 this.mapData_[ptr] = FREE_KEY_;
             }
             else {
                 this.mapData_[ptr] = REMOVED_KEY_;
             }
 
             final V ret = (V) this.mapData_[ptr + 1];
             this.mapData_[ptr + 1] = null;
 
             // take this out of the list
             orderedListRemove(ptr);
 
             return ret;
         }
 
         while (true) {
             ptr = (ptr + 2) & (length - 1); // that's next index calculation
             k = this.mapData_[ptr];
 
             if (k == FREE_KEY_) {
                 return null;
             }
             else if (k.equals(key)) {
                 this.mapSize_--;
                 if (this.mapData_[(ptr + 2) & (length - 1)] == FREE_KEY_) {
                     this.mapData_[ptr] = FREE_KEY_;
                 }
                 else {
                     this.mapData_[ptr] = REMOVED_KEY_;
                 }
 
                 final V ret = (V) this.mapData_[ptr + 1];
                 this.mapData_[ptr + 1] = null;
 
                 // take this out of the list
                 orderedListRemove(ptr);
 
                 return ret;
             }
         }
     }
 
     /**
      * Returns the size of the map, effectively the number of entries.
      *
      * @return the size of the map
      */
     @Override
     public int size() {
         return mapSize_;
     }
 
     /**
      * Rehash the map.
      *
      * @param newCapacity the new size of the map
      */
     private void rehash(final int newCapacity) {
         this.mapThreshold_ = (int) (newCapacity / 2 * FILLFACTOR_);
 
         final Object[] oldData = this.mapData_;
 
         this.mapData_ = new Object[newCapacity];
 
         // we just have to grow it and not touch it at all after that,
         // just use it as source for the new map via the old
         final int[] oldOrderedList = this.orderedList_;
         final int oldOrderedListSize = this.orderedListSize_;
         this.orderedList_ = new int[newCapacity];
 
         this.mapSize_ = 0;
         this.orderedListSize_ = 0;
 
         // we use our ordered list as source and the old
         // array as reference
         // we basically rebuild the map and the ordering
         // from scratch
         for (int i = 0; i < oldOrderedListSize; i++) {
             final int pos = oldOrderedList[i];
 
             // get us the old data
             final K key = (K) oldData[pos];
             final V value = (V) oldData[pos + 1];
 
             // write the old to the new map without updating
             // the positioning
             put(key, value, Position.LAST);
         }
     }
 
     /**
      * Returns a list of all keys in order of addition.
      * This is an expensive operation, because we get a static
      * list back that is not backed by the implementation. Changes
      * to the returned list are not reflected in the map.
      *
      * @return a list of keys as inserted into the map
      */
     public List<K> keys() {
         final List<K> result = new ArrayList<>(this.orderedListSize_);
 
         for (int i = 0; i < this.orderedListSize_; i++) {
             final int pos = this.orderedList_[i];
             final Object o = this.mapData_[pos];
             result.add((K) o);
         }
 
         return result;
     }
 
     /**
      * Returns a list of all values ordered by when the key was
      * added. This is an expensive operation, because we get a static
      * list back that is not backed by the implementation. Changes
      * to the returned list are not reflected in the map.
      *
      * @return a list of values
      */
     @Override
     public List<V> values() {
         final List<V> result = new ArrayList<>(this.orderedListSize_);
 
         for (int i = 0; i < this.orderedListSize_; i++) {
             final int pos = this.orderedList_[i];
             final Object o = this.mapData_[pos + 1];
             result.add((V) o);
         }
 
         return result;
     }
 
     /**
      * Clears the map, reuses the data structure by clearing it out. It won't shrink
      * the underlying arrays!
      */
     @Override
     public void clear() {
         this.mapSize_ = 0;
         this.orderedListSize_ = 0;
         Arrays.fill(this.mapData_, FREE_KEY_);
         // Arrays.fill(this.orderedList, 0);
     }
 
     /**
      * Get us the start index from where we search or insert into the map.
      *
      * @param key the key to calculate the position for
      * @return the start position
      */
     private int getStartIndex(final Object key) {
         // key is not null here
         return key.hashCode() & ((this.mapData_.length >> 1) - 1);
     }
 
     /**
      * Return the least power of two greater than or equal to the specified value.
      *
      * <p>
      * Note that this function will return 1 when the argument is 0.
      * </p>
      *
      * @param x a long integer smaller than or equal to 2<sup>62</sup>.
      * @return the least power of two greater than or equal to the specified value.
      */
     private static long nextPowerOfTwo(final long x) {
         if (x == 0) {
             return 1;
         }
 
         long r = x - 1;
         r |= r >> 1;
         r |= r >> 2;
         r |= r >> 4;
         r |= r >> 8;
         r |= r >> 16;
 
         return (r | r >> 32) + 1;
     }
 
     /**
      * Returns the least power of two smaller than or equal to 2<sup>30</sup> and
      * larger than or equal to <code>Math.ceil( expected / f )</code>.
      *
      * @param expected the expected number of elements in a hash table.
      * @param f        the load factor.
      * @return the minimum possible size for a backing array.
      * @throws IllegalArgumentException if the necessary size is larger than
      *                                  2<sup>30</sup>.
      */
     private static int arraySize(final int expected, final double f) {
         final long s = Math.max(2, nextPowerOfTwo((long) Math.ceil(expected / f)));
 
         if (s > (1 << 30)) {
             throw new IllegalArgumentException(
                     "Too large (" + expected + " expected elements with load factor " + f + ")");
         }
         return (int) s;
     }
 
     /**
      * Returns an entry consisting of key and value at a given position.
      * This position relates to the ordered key list that maintain the
      * addition order for this map.
      *
      * @param index the position to fetch
      * @return an entry of key and value
      * @throws IndexOutOfBoundsException when the ask for the position is invalid
      */
     public Entry<K, V> getEntry(final int index) {
         if (index < 0 || index >= this.orderedListSize_) {
             throw new IndexOutOfBoundsException("Index: %s, Size: %s".formatted(index, this.orderedListSize_));
         }
 
         final int pos = this.orderedList_[index];
         return new Entry(this.mapData_[pos], this.mapData_[pos + 1]);
     }
 
     /**
      * Returns the key at a certain position of the ordered list that
      * keeps the addition order of this map.
      *
      * @param index the position to fetch
      * @return the key at this position
      * @throws IndexOutOfBoundsException when the ask for the position is invalid
      */
     public K getKey(final int index) {
         if (index < 0 || index >= this.orderedListSize_) {
             throw new IndexOutOfBoundsException("Index: %s, Size: %s".formatted(index, this.orderedListSize_));
         }
 
         final int pos = this.orderedList_[index];
         return (K) this.mapData_[pos];
     }
 
     /**
      * Returns the value at a certain position of the ordered list that
      * keeps the addition order of this map.
      *
      * @param index the position to fetch
      * @return the value at this position
      * @throws IndexOutOfBoundsException when the ask for the position is invalid
      */
     public V getValue(final int index) {
         if (index < 0 || index >= this.orderedListSize_) {
             throw new IndexOutOfBoundsException("Index: %s, Size: %s".formatted(index, this.orderedListSize_));
         }
 
         final int pos = this.orderedList_[index];
         return (V) this.mapData_[pos + 1];
     }
 
     /**
      * Removes a key and value from this map based on the position
      * in the backing list, rather by key as usual.
      *
      * @param index the position to remove the data from
      * @return the value stored
      * @throws IndexOutOfBoundsException when the ask for the position is invalid
      */
     public V remove(final int index) {
         if (index < 0 || index >= this.orderedListSize_) {
             throw new IndexOutOfBoundsException("Index: %s, Size: %s".formatted(index, this.orderedListSize_));
         }
 
         final int pos = this.orderedList_[index];
         final K key = (K) this.mapData_[pos];
 
         return remove(key);
     }
 
     @Override
     public V put(final K key, final V value) {
         return this.put(key, value, Position.LAST);
     }
 
     /**
      * Insert at the beginning.
      * @param key the key
      * @param value the value
      * @return the inserted value
      */
     public V addFirst(final K key, final V value) {
         return this.put(key, value, Position.FIRST);
     }
 
     /**
      * Append at the end.
      * @param key the key
      * @param value the value
      * @return the appended value
      */
     public V add(final K key, final V value) {
         return this.put(key, value, Position.LAST);
     }
 
     /**
      * Append at the end.
      * @param key the key
      * @param value the value
      * @return the appended value
      */
     public V addLast(final K key, final V value) {
         return this.put(key, value, Position.LAST);
     }
 
     /**
      * Returns the first value.
      *
      * @return the first value.
      */
     public V getFirst() {
         return getValue(0);
     }
 
     /**
      * Returns the last value.
      *
      * @return the last value.
      */
     public V getLast() {
         return getValue(this.orderedListSize_ - 1);
     }
 
     /**
      * Removes the first entry.
      * @return the removed value or null if the map was empty.
      */
     public V removeFirst() {
         if (this.orderedListSize_ > 0) {
             final int pos = this.orderedList_[0];
             final K key = (K) this.mapData_[pos];
             return remove(key);
         }
         return null;
     }
 
     /**
      * Removes the last entry.
      * @return the removed value or null if the map was empty.
      */
     public V removeLast() {
         if (this.orderedListSize_ > 0) {
             final int pos = this.orderedList_[this.orderedListSize_ - 1];
             final K key = (K) this.mapData_[pos];
             return remove(key);
         }
         return null;
     }
 
     /**
      * Checks of a key is in the map.
      *
      * @param key the key to check
      * @return true of the key is in the map, false otherwise
      */
     @Override
     public boolean containsKey(final Object key) {
         return get(key) != null;
     }
 
     @Override
     public boolean containsValue(final Object value) {
         // that is expensive, we have to iterate everything
         for (int i = 0; i < this.orderedListSize_; i++) {
             final int pos = this.orderedList_[i] + 1;
             final Object v = this.mapData_[pos];
 
             // do we match?
             if (v == value || v.equals(value)) {
                 return true;
             }
         }
 
         return false;
     }
 
     @Override
     public boolean isEmpty() {
         return this.mapSize_ == 0;
     }
 
     @Override
     public Set<Map.Entry<K, V>> entrySet() {
         return new OrderedEntrySet<>(this);
     }
 
     @Override
     public Set<K> keySet() {
         return new OrderedKeySet<>(this);
     }
 
     /**
      * Just reverses the ordering of the map as created so far.
      */
     public void reverse() {
         // In-place reversal
         final int to = this.orderedListSize_ / 2;
 
         for (int i = 0; i < to; i++) {
             // Swapping the elements
             final int j = this.orderedList_[i];
             this.orderedList_[i] = this.orderedList_[this.orderedListSize_ - i - 1];
             this.orderedList_[this.orderedListSize_ - i - 1] = j;
         }
     }
 
     /**
      * We have to overwrite the export due to the use of static object as marker.
      *
      * @param aInputStream the inputstream to read from
      * @throws IOException when the reading from the source fails
      * @throws ClassNotFoundException in case we cannot restore a class
      */
     private void readObject(final ObjectInputStream aInputStream) throws ClassNotFoundException, IOException {
         // perform the default de-serialization first
         aInputStream.defaultReadObject();
 
         // we have to restore order, keep relevant data
         final Object[] srcData = Arrays.copyOf(this.mapData_, this.mapData_.length);
         final int[] srcIndex = Arrays.copyOf(this.orderedList_, this.orderedList_.length);
         final int orderedListSize = this.orderedListSize_;
 
         // now, empty the original map
         clear();
 
         // sort things in, so we get a nice clean new map, this will
         // also cleanup what was previously a removed entry, we have not
         // kept that information anyway
         for (int i = 0; i < orderedListSize; i++) {
             final int pos = srcIndex[i];
 
             final K key = (K) srcData[pos];
             final V value = (V) srcData[pos + 1];
             put(key, value);
         }
     }
 
     /**
      * We have to overwrite the export due to the use of static object as marker.
      *
      * @param aOutputStream the stream to write to
      * @throws IOException in case we have issue writing our data to the stream
      */
     private void writeObject(final ObjectOutputStream aOutputStream) throws IOException {
         // we will remove all placeholder object references,
         // when putting it back together, we rebuild the map from scratch
         for (int i = 0; i < this.mapData_.length; i++) {
             final Object entry = this.mapData_[i];
             if (entry == FREE_KEY_ || entry == REMOVED_KEY_) {
                 this.mapData_[i] = null;
             }
         }
 
         // perform the default serialization for all non-transient, non-static fields
         aOutputStream.defaultWriteObject();
     }
 
     /**
      * This set does not support any modifications through its interface. All such
      * methods will throw {@link UnsupportedOperationException}.
      */
     static class OrderedEntrySet<K, V> implements Set<Map.Entry<K, V>> {
         private final OrderedFastHashMap<K, V> backingMap_;
 
         OrderedEntrySet(final OrderedFastHashMap<K, V> backingMap) {
             this.backingMap_ = backingMap;
         }
 
         @Override
         public int size() {
             return this.backingMap_.size();
         }
 
         @Override
         public boolean isEmpty() {
             return this.backingMap_.isEmpty();
         }
 
         @Override
         public boolean contains(final Object o) {
             if (o instanceof Map.Entry ose) {
                 final Object k = ose.getKey();
                 final Object v = ose.getValue();
 
                 final Object value = this.backingMap_.get(k);
                 if (value != null) {
                     return v.equals(value);
                 }
             }
 
             return false;
         }
 
         @Override
         public Object[] toArray() {
             final Object[] array = new Object[this.backingMap_.orderedListSize_];
             return toArray(array);
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public <T> T[] toArray(final T[] a) {
             final T[] array;
             if (a.length >= this.backingMap_.orderedListSize_) {
                 array = a;
             }
             else {
                 array = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(),
                         this.backingMap_.orderedListSize_);
             }
 
             for (int i = 0; i < this.backingMap_.orderedListSize_; i++) {
                 array[i] = (T) this.backingMap_.getEntry(i);
             }
 
             return array;
         }
 
         @Override
         public Iterator<Map.Entry<K, V>> iterator() {
             return new OrderedEntryIterator();
         }
 
         @Override
         public boolean add(final Map.Entry<K, V> e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean remove(final Object o) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean containsAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(final Collection<? extends Map.Entry<K, V>> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean retainAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean removeAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void clear() {
             throw new UnsupportedOperationException();
         }
 
         class OrderedEntryIterator implements Iterator<Map.Entry<K, V>> {
             private int pos_ = 0;
 
             @Override
             public boolean hasNext() {
                 return pos_ < backingMap_.orderedListSize_;
             }
 
             @Override
             public Map.Entry<K, V> next() {
                 if (pos_ < backingMap_.orderedListSize_) {
                     return backingMap_.getEntry(pos_++);
                 }
                 throw new NoSuchElementException();
             }
         }
     }
 
     static class OrderedKeySet<K, V> implements Set<K> {
         private final OrderedFastHashMap<K, V> backingMap_;
 
         OrderedKeySet(final OrderedFastHashMap<K, V> backingMap) {
             this.backingMap_ = backingMap;
         }
 
         @Override
         public int size() {
             return this.backingMap_.size();
         }
 
         @Override
         public boolean isEmpty() {
             return this.backingMap_.isEmpty();
         }
 
         @Override
         public boolean contains(final Object o) {
             return this.backingMap_.containsKey(o);
         }
 
         @Override
         public Object[] toArray() {
             final Object[] array = new Object[this.backingMap_.orderedListSize_];
             return toArray(array);
         }
 
         @Override
         @SuppressWarnings("unchecked")
         public <T> T[] toArray(final T[] a) {
             final T[] array;
 
             if (a.length >= this.backingMap_.orderedListSize_) {
                 array = a;
             }
             else {
                 array = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(),
                         this.backingMap_.orderedListSize_);
             }
 
             for (int i = 0; i < this.backingMap_.orderedListSize_; i++) {
                 array[i] = (T) this.backingMap_.getKey(i);
             }
 
             return array;
         }
 
         @Override
         public Iterator<K> iterator() {
             return new OrderedKeyIterator();
         }
 
         class OrderedKeyIterator implements Iterator<K> {
             private int pos_ = 0;
 
             @Override
             public boolean hasNext() {
                 return this.pos_ < backingMap_.orderedListSize_;
             }
 
             @Override
             public K next() {
                 if (this.pos_ < backingMap_.orderedListSize_) {
                     return backingMap_.getKey(this.pos_++);
                 }
                 throw new NoSuchElementException();
             }
         }
 
         @Override
         public boolean add(final K e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean remove(final Object o) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean containsAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean addAll(final Collection<? extends K> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean retainAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public boolean removeAll(final Collection<?> c) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void clear() {
             throw new UnsupportedOperationException();
         }
     }
 
     @Override
     public void putAll(final Map<? extends K, ? extends V> src) {
         if (src == this) {
             throw new IllegalArgumentException("Cannot add myself");
         }
 
         for (final Map.Entry<? extends K, ? extends V> entry : src.entrySet()) {
             put(entry.getKey(), entry.getValue(), Position.LAST);
         }
     }
 
     private void orderedListAdd(final Position listPosition, final int position) {
         // the list should still have room, otherwise the map was
         // grown already and the ordering list with it
         if (listPosition == Position.FIRST) {
             System.arraycopy(this.orderedList_, 0, this.orderedList_, 1, this.orderedList_.length - 1);
             this.orderedList_[0] = position;
             this.orderedListSize_++;
         }
         else if (listPosition == Position.LAST) {
             this.orderedList_[this.orderedListSize_] = position;
             this.orderedListSize_++;
         }
         else {
             // if none, we are rebuilding the map and don't have to do a thing
         }
     }
 
     private void orderedListRemove(final int position) {
         // find the positional information
         int i = 0;
         for ( ; i < this.orderedListSize_; i++) {
             if (this.orderedList_[i] == position) {
                 this.orderedList_[i] = -1;
                 if (i < this.orderedListSize_) {
                     // not the last element, compact
                     System.arraycopy(this.orderedList_, i + 1, this.orderedList_, i, this.orderedListSize_ - i);
                 }
                 this.orderedListSize_--;
 
                 return;
             }
         }
 
         if (i == this.orderedListSize_) {
             throw new IllegalArgumentException("Position %s was not in order list".formatted(position));
         }
     }
 
     @Override
     public String toString() {
         final int maxLen = 10;
 
         return "mapData=%s, mapFillFactor=%s, mapThreshold=%s, mapSize=%s,%norderedList=%s, orderedListSize=%s"
                 .formatted(
                     mapData_ != null
                         ? Arrays.asList(mapData_).subList(0, Math.min(mapData_.length, maxLen))
                         : null,
                     FILLFACTOR_, mapThreshold_, mapSize_,
                     orderedList_ != null
                         ? Arrays.toString(Arrays.copyOf(orderedList_, Math.min(orderedList_.length, maxLen)))
                         : null,
                     orderedListSize_);
     }
 
     /**
      * Helper for identifying if we need to position our new entry differently.
      */
     private enum Position {
         NONE, FIRST, LAST
     }
 
     /**
      * Well, we need that to satisfy the map implementation concept.
      *
      * @param <K> the key
      * @param <V> the value
      */
     static class Entry<K, V> implements Map.Entry<K, V> {
         private final K key_;
         private final V value_;
 
         Entry(final K key, final V value) {
             this.key_ = key;
             this.value_ = value;
         }
 
         @Override
         public K getKey() {
             return key_;
         }
 
         @Override
         public V getValue() {
             return value_;
         }
 
         @Override
         public V setValue(final V value) {
             throw new UnsupportedOperationException("This map does not support write-through via an entry");
         }
 
         @Override
         public int hashCode() {
             return Objects.hashCode(key_) ^ Objects.hashCode(value_);
         }
 
         @Override
         public String toString() {
             return key_ + "=" + value_;
         }
 
         @Override
         public boolean equals(final Object o) {
             if (o == this) {
                 return true;
             }
 
             if (o instanceof Map.Entry<?, ?> e) {
 
                 if (Objects.equals(key_, e.getKey()) && Objects.equals(value_, e.getValue())) {
                     return true;
                 }
             }
 
             return false;
         }
     }
 }