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IdentityHashMap类源码解析

来源:互联网 作者:佚名 时间:2016-07-17 21:11
IdentityHashMap 1.内部通过数组存储键值对,相邻元素存在键值对 比如:i 位置是key,i+1位置是value 2.当hashcode相等,出现冲突的时候,通过线性探索发解决冲突问题 3.比较的是引用相等 IdentityHashMap与常用的HashMap的区别是: 前者比较key时是“引用相

IdentityHashMap
1.内部通过数组存储键值对,相邻元素存在键值对
比如:i 位置是key,i+1位置是value
2.当hashcode相等,出现冲突的时候,通过线性探索发解决冲突问题
3.比较的是引用相等
IdentityHashMap与常用的HashMap的区别是:
前者比较key时是“引用相等”而后者是“对象相等”,即对于k1和k2,当k1==k2时,IdentityHashMap认为两个key相等,而HashMap只有在k1.equals(k2) == true 时才会认为两个key相等。
默认的加载因子为2/3,在重新哈希后,加载因子变为1/3.当哈希表中的条目数超出了加载因子与当前容量的乘积时,通过调用 reszie 方法将容量翻倍,重新进行哈希。增加桶数,重新哈希,可能相当昂贵。

继承AbstractMap
实现Map、java.io.Serializable、Cloneable



package java.util;
import java.io.*;


public class IdentityHashMap<K,V>
    extends AbstractMap<K,V>
    implements Map<K,V>, java.io.Serializable, Cloneable
{
    /**
     * 默认容量
     */
    private static final int DEFAULT_CAPACITY = 32;

    /**
     * 最小容量
     */
    private static final int MINIMUM_CAPACITY = 4;

    /**
     * 最大容量
     */
    private static final int MAXIMUM_CAPACITY = 1 << 29;

    /**
     * 输出存储结构
     */
    private transient Object[] table;

    /**
     * 键值对个数
     * @serial
     */
    private int size;

    /**
     * 修改次数
     */
    private transient int modCount;

    /**
     * 更新容器时候的阈值= (capacity * load factor).
     */
    private transient int threshold;

    /**
     * Value representing null keys inside tables.
     */
    private static final Object NULL_KEY = new Object();

    /**
     * Use NULL_KEY for key if it is null.
     */
    private static Object maskNull(Object key) {
        return (key == null ? NULL_KEY : key);
    }

    /**
     * Returns internal representation of null key back to caller as null.
     */
    private static Object unmaskNull(Object key) {
        return (key == NULL_KEY ? null : key);
    }

    /**
     * 构造函数
     */
    public IdentityHashMap() {
        init(DEFAULT_CAPACITY);
    }

    /**
     * 构造函数
     *
     * @param expectedMaxSize the expected maximum size of the map
     * @throws IllegalArgumentException if <tt>expectedMaxSize</tt> is negative
     */
    public IdentityHashMap(int expectedMaxSize) {
        if (expectedMaxSize < 0)
            throw new IllegalArgumentException("expectedMaxSize is negative: "
                                               + expectedMaxSize);
        init(capacity(expectedMaxSize));
    }

    /**
     * Returns the appropriate capacity for the specified expected maximum
     * size.  Returns the smallest power of two between MINIMUM_CAPACITY
     * and MAXIMUM_CAPACITY, inclusive, that is greater than
     * (3 * expectedMaxSize)/2, if such a number exists.  Otherwise
     * returns MAXIMUM_CAPACITY.  If (3 * expectedMaxSize)/2 is negative, it
     * is assumed that overflow has occurred, and MAXIMUM_CAPACITY is returned.
     */
    private int capacity(int expectedMaxSize) {
        // Compute min capacity for expectedMaxSize given a load factor of 2/3
        int minCapacity = (3 * expectedMaxSize)/2;

        // Compute the appropriate capacity
        int result;
        if (minCapacity > MAXIMUM_CAPACITY || minCapacity < 0) {
            result = MAXIMUM_CAPACITY;
        } else {
            result = MINIMUM_CAPACITY;
            while (result < minCapacity)
                result <<= 1;
        }
        return result;
    }

    /**
     * init
     */
    private void init(int initCapacity) {
        // assert (initCapacity & -initCapacity) == initCapacity; // power of 2
        // assert initCapacity >= MINIMUM_CAPACITY;
        // assert initCapacity <= MAXIMUM_CAPACITY;

        threshold = (initCapacity * 2)/3; // 进行扩容时候的阈值
        table = new Object[2 * initCapacity]; // 2倍,表示key value相邻存储
    }

    /**
     * 构造函数,m集合元素加入到当前集合中
     */
    public IdentityHashMap(Map<? extends K, ? extends V> m) {
        // Allow for a bit of growth
        this((int) ((1 + m.size()) * 1.1));
        putAll(m);
    }

    /**
     * size
     */
    public int size() {
        return size;
    }

    /**
     * isEmpty
     */
    public boolean isEmpty() {
        return size == 0;
    }

    /**
     * Returns index for Object x.
     */
    private static int hash(Object x, int length) {
        int h = System.identityHashCode(x);
        // Multiply by -127, and left-shift to use least bit as part of hash
        return ((h << 1) - (h << 8)) & (length - 1);
    }

    /**
     *循环的方式,找到下一个key的id 
     */
    private static int nextKeyIndex(int i, int len) {
        return (i + 2 < len ? i + 2 : 0);
    }

    /**
     * V get(Object key)
     */
    public V get(Object key) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len); // 根据hash计算应该在数组中的id 
        while (true) {
            Object item = tab[i]; // 当前key 
            if (item == k) // 比较是否相等,相等下一个位置就是value 
                return (V) tab[i + 1];
            if (item == null)
                return null;
            i = nextKeyIndex(i, len); // 上面不满足,根据上一个i 更新 i 
        }
    }

    /**
     * containsKey 和  get 很类似 
     */
    public boolean containsKey(Object key) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);
        while (true) {
            Object item = tab[i];
            if (item == k)
                return true;
            if (item == null)
                return false;
            i = nextKeyIndex(i, len);
        }
    }

    /**
     * containsValue
     */
    public boolean containsValue(Object value) {
        Object[] tab = table;
        for (int i = 1; i < tab.length; i += 2) // 顺序遍历,1 3 5 7 9 位置是value 
            if (tab[i] == value && tab[i - 1] != null)
                return true;

        return false;
    }

    /**
     * containsMapping 和containsKey 很类似 
     */
    private boolean containsMapping(Object key, Object value) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);
        while (true) {
            Object item = tab[i];
            if (item == k)
                return tab[i + 1] == value; // i 位置相等时 key相等,i+1 相等时value相等,比较的是引用相等
            if (item == null)
                return false;
            i = nextKeyIndex(i, len);
        }
    }

    /**
     *put(K key, V value)
     */
    public V put(K key, V value) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);

        Object item;
        while ( (item = tab[i]) != null) {
            if (item == k) { 
                V oldValue = (V) tab[i + 1];
                tab[i + 1] = value; // key 存在更新value 
                return oldValue;
            }
            i = nextKeyIndex(i, len);
        }

        modCount++;
        tab[i] = k;  // key 不存在加入 
        tab[i + 1] = value;
        if (++size >= threshold)
            resize(len); // len == 2 * current capacity.
        return null;
    }

    /**
     * resize 需要移动大量元素,效率很低 
     *
     * @param newCapacity the new capacity, must be a power of two.
     */
    private void resize(int newCapacity) {
        // assert (newCapacity & -newCapacity) == newCapacity; // power of 2
        int newLength = newCapacity * 2;

        Object[] oldTable = table;
        int oldLength = oldTable.length;
        if (oldLength == 2*MAXIMUM_CAPACITY) { // can't expand any further
            if (threshold == MAXIMUM_CAPACITY-1)
                throw new IllegalStateException("Capacity exhausted.");
            threshold = MAXIMUM_CAPACITY-1;  // Gigantic map!
            return;
        }
        if (oldLength >= newLength)
            return;

        Object[] newTable = new Object[newLength];
        threshold = newLength / 3;

        for (int j = 0; j < oldLength; j += 2) {
            Object key = oldTable[j];
            if (key != null) {
                Object value = oldTable[j+1];
                oldTable[j] = null;
                oldTable[j+1] = null;
                int i = hash(key, newLength);
                while (newTable[i] != null) // 找到可以插入的位置 
                    i = nextKeyIndex(i, newLength);
                newTable[i] = key;
                newTable[i + 1] = value;
            }
        }
        table = newTable;
    }

    /**
     * putAll 
     * @param m mappings to be stored in this map
     * @throws NullPointerException if the specified map is null
     */
    public void putAll(Map<? extends K, ? extends V> m) {
        int n = m.size();
        if (n == 0)
            return;
        if (n > threshold) // conservatively pre-expand
            resize(capacity(n));

        for (Entry<? extends K, ? extends V> e : m.entrySet())
            put(e.getKey(), e.getValue());
    }

    /**
     * remove
     */
    public V remove(Object key) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);

        while (true) {
            Object item = tab[i];
            if (item == k) {
                modCount++;
                size--;
                V oldValue = (V) tab[i + 1];
                tab[i + 1] = null;
                tab[i] = null;
                closeDeletion(i);
                return oldValue;
            }
            if (item == null)
                return null;
            i = nextKeyIndex(i, len);
        }

    }

    /**
     * removeMapping
     */
    private boolean removeMapping(Object key, Object value) {
        Object k = maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);

        while (true) {
            Object item = tab[i];
            if (item == k) {
                if (tab[i + 1] != value)
                    return false;
                modCount++;
                size--;
                tab[i] = null;
                tab[i + 1] = null;
                closeDeletion(i);
                return true;
            }
            if (item == null)
                return false;
            i = nextKeyIndex(i, len);
        }
    }

    /**
     * closeDeletion 作用:i位置元素删除了,更新后面元素的 位置,这里一个原因就是减少地址冲突
     */
    private void closeDeletion(int d) {
        // Adapted from Knuth Section 6.4 Algorithm R
        Object[] tab = table;
        int len = tab.length;

        // Look for items to swap into newly vacated slot
        // starting at index immediately following deletion,
        // and continuing until a null slot is seen, indicating
        // the end of a run of possibly-colliding keys.
        Object item;
        for (int i = nextKeyIndex(d, len); (item = tab[i]) != null;
             i = nextKeyIndex(i, len) ) {
            // The following test triggers if the item at slot i (which
            // hashes to be at slot r) should take the spot vacated by d.
            // If so, we swap it in, and then continue with d now at the
            // newly vacated i.  This process will terminate when we hit
            // the null slot at the end of this run.
            // The test is messy because we are using a circular table.
            int r = hash(item, len);
            if ((i < r && (r <= d || d <= i)) || (r <= d && d <= i)) {
                tab[d] = item;
                tab[d + 1] = tab[i + 1];
                tab[i] = null;
                tab[i + 1] = null;
                d = i;
            }
        }
    }

    /**
     * clear
     */
    public void clear() {
        modCount++;
        Object[] tab = table;
        for (int i = 0; i < tab.length; i++)
            tab[i] = null;
        size = 0;
    }

    /**
     * equals
     */
    public boolean equals(Object o) {
        if (o == this) {
            return true;
        } else if (o instanceof IdentityHashMap) {
            IdentityHashMap m = (IdentityHashMap) o;
            if (m.size() != size)
                return false;

            Object[] tab = m.table;
            for (int i = 0; i < tab.length; i+=2) {
                Object k = tab[i];
                if (k != null && !containsMapping(k, tab[i + 1]))
                    return false;
            }
            return true;
        } else if (o instanceof Map) {
            Map m = (Map)o;
            return entrySet().equals(m.entrySet());
        } else {
            return false;  // o is not a Map
        }
    }

    /**
     * hashCode
     */
    public int hashCode() {
        int result = 0;
        Object[] tab = table;
        for (int i = 0; i < tab.length; i +=2) {
            Object key = tab[i];
            if (key != null) {
                Object k = unmaskNull(key);
                result += System.identityHashCode(k) ^
                          System.identityHashCode(tab[i + 1]);
            }
        }
        return result;
    }

    /**
     * clone
     */
    public Object clone() {
        try {
            IdentityHashMap<K,V> m = (IdentityHashMap<K,V>) super.clone();
            m.entrySet = null;
            m.table = table.clone();
            return m;
        } catch (CloneNotSupportedException e) {
            throw new InternalError();
        }
    }
    // 迭代器 
    private abstract class IdentityHashMapIterator<T> implements Iterator<T> {
        int index = (size != 0 ? 0 : table.length); // current slot.
        int expectedModCount = modCount; // to support fast-fail
        int lastReturnedIndex = -1;      // to allow remove()
        boolean indexValid; // To avoid unnecessary next computation
        Object[] traversalTable = table; // reference to main table or copy

        public boolean hasNext() {
            Object[] tab = traversalTable;
            for (int i = index; i < tab.length; i+=2) {
                Object key = tab[i];
                if (key != null) {
                    index = i;
                    return indexValid = true;
                }
            }
            index = tab.length;
            return false;
        }

        protected int nextIndex() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
            if (!indexValid && !hasNext())
                throw new NoSuchElementException();

            indexValid = false;
            lastReturnedIndex = index;
            index += 2;
            return lastReturnedIndex;
        }

        public void remove() {
            if (lastReturnedIndex == -1)
                throw new IllegalStateException();
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();

            expectedModCount = ++modCount;
            int deletedSlot = lastReturnedIndex;
            lastReturnedIndex = -1;
            // back up index to revisit new contents after deletion
            index = deletedSlot;
            indexValid = false;

            // Removal code proceeds as in closeDeletion except that
            // it must catch the rare case where an element already
            // seen is swapped into a vacant slot that will be later
            // traversed by this iterator. We cannot allow future
            // next() calls to return it again.  The likelihood of
            // this occurring under 2/3 load factor is very slim, but
            // when it does happen, we must make a copy of the rest of
            // the table to use for the rest of the traversal. Since
            // this can only happen when we are near the end of the table,
            // even in these rare cases, this is not very expensive in
            // time or space.

            Object[] tab = traversalTable;
            int len = tab.length;

            int d = deletedSlot;
            K key = (K) tab[d];
            tab[d] = null;        // vacate the slot
            tab[d + 1] = null;

            // If traversing a copy, remove in real table.
            // We can skip gap-closure on copy.
            if (tab != IdentityHashMap.this.table) {
                IdentityHashMap.this.remove(key);
                expectedModCount = modCount;
                return;
            }

            size--;

            Object item;
            for (int i = nextKeyIndex(d, len); (item = tab[i]) != null;
                 i = nextKeyIndex(i, len)) {
                int r = hash(item, len);
                // See closeDeletion for explanation of this conditional
                if ((i < r && (r <= d || d <= i)) ||
                    (r <= d && d <= i)) {

                    // If we are about to swap an already-seen element
                    // into a slot that may later be returned by next(),
                    // then clone the rest of table for use in future
                    // next() calls. It is OK that our copy will have
                    // a gap in the "wrong" place, since it will never
                    // be used for searching anyway.

                    if (i < deletedSlot && d >= deletedSlot &&
                        traversalTable == IdentityHashMap.this.table) {
                        int remaining = len - deletedSlot;
                        Object[] newTable = new Object[remaining];
                        System.arraycopy(tab, deletedSlot,
                                         newTable, 0, remaining);
                        traversalTable = newTable;
                        index = 0;
                    }

                    tab[d] = item;
                    tab[d + 1] = tab[i + 1];
                    tab[i] = null;
                    tab[i + 1] = null;
                    d = i;
                }
            }
        }
    }

    private class KeyIterator extends IdentityHashMapIterator<K> {
        public K next() {
            return (K) unmaskNull(traversalTable[nextIndex()]);
        }
    }

    private class ValueIterator extends IdentityHashMapIterator<V> {
        public V next() {
            return (V) traversalTable[nextIndex() + 1];
        }
    }

    private class EntryIterator
        extends IdentityHashMapIterator<Map.Entry<K,V>>
    {
        private Entry lastReturnedEntry = null;

        public Map.Entry<K,V> next() {
            lastReturnedEntry = new Entry(nextIndex());
            return lastReturnedEntry;
        }

        public void remove() {
            lastReturnedIndex =
                ((null == lastReturnedEntry) ? -1 : lastReturnedEntry.index);
            super.remove();
            lastReturnedEntry.index = lastReturnedIndex;
            lastReturnedEntry = null;
        }

        private class Entry implements Map.Entry<K,V> {
            private int index;

            private Entry(int index) {
                this.index = index;
            }

            public K getKey() {
                checkIndexForEntryUse();
                return (K) unmaskNull(traversalTable[index]);
            }

            public V getValue() {
                checkIndexForEntryUse();
                return (V) traversalTable[index+1];
            }

            public V setValue(V value) {
                checkIndexForEntryUse();
                V oldValue = (V) traversalTable[index+1];
                traversalTable[index+1] = value;
                // if shadowing, force into main table
                if (traversalTable != IdentityHashMap.this.table)
                    put((K) traversalTable[index], value);
                return oldValue;
            }

            public boolean equals(Object o) {
                if (index < 0)
                    return super.equals(o);

                if (!(o instanceof Map.Entry))
                    return false;
                Map.Entry e = (Map.Entry)o;
                return (e.getKey() == unmaskNull(traversalTable[index]) &&
                       e.getValue() == traversalTable[index+1]);
            }

            public int hashCode() {
                if (lastReturnedIndex < 0)
                    return super.hashCode();

                return (System.identityHashCode(unmaskNull(traversalTable[index])) ^
                       System.identityHashCode(traversalTable[index+1]));
            }

            public String toString() {
                if (index < 0)
                    return super.toString();

                return (unmaskNull(traversalTable[index]) + "="
                        + traversalTable[index+1]);
            }

            private void checkIndexForEntryUse() {
                if (index < 0)
                    throw new IllegalStateException("Entry was removed");
            }
        }
    }

    // Views

    /**
     * This field is initialized to contain an instance of the entry set
     * view the first time this view is requested.  The view is stateless,
     * so there's no reason to create more than one.
     */
    private transient Set<Map.Entry<K,V>> entrySet = null;

    /**
     * keySet
     */
    public Set<K> keySet() {
        Set<K> ks = keySet;
        if (ks != null)
            return ks;
        else
            return keySet = new KeySet();
    }

    private class KeySet extends AbstractSet<K> {
        public Iterator<K> iterator() {
            return new KeyIterator();
        }
        public int size() {
            return size;
        }
        public boolean contains(Object o) {
            return containsKey(o);
        }
        public boolean remove(Object o) {
            int oldSize = size;
            IdentityHashMap.this.remove(o);
            return size != oldSize;
        }
        /*
         * Must revert from AbstractSet's impl to AbstractCollection's, as
         * the former contains an optimization that results in incorrect
         * behavior when c is a smaller "normal" (non-identity-based) Set.
         */
        public boolean removeAll(Collection<?> c) {
            boolean modified = false;
            for (Iterator<K> i = iterator(); i.hasNext(); ) {
                if (c.contains(i.next())) {
                    i.remove();
                    modified = true;
                }
            }
            return modified;
        }
        public void clear() {
            IdentityHashMap.this.clear();
        }
        public int hashCode() {
            int result = 0;
            for (K key : this)
                result += System.identityHashCode(key);
            return result;
        }
    }

    /**
     * values
     */
    public Collection<V> values() {
        Collection<V> vs = values;
        if (vs != null)
            return vs;
        else
            return values = new Values();
    }

    private class Values extends AbstractCollection<V> {
        public Iterator<V> iterator() {
            return new ValueIterator();
        }
        public int size() {
            return size;
        }
        public boolean contains(Object o) {
            return containsValue(o);
        }
        public boolean remove(Object o) {
            for (Iterator<V> i = iterator(); i.hasNext(); ) {
                if (i.next() == o) {
                    i.remove();
                    return true;
                }
            }
            return false;
        }
        public void clear() {
            IdentityHashMap.this.clear();
        }
    }

    /**
     *entrySet
     */
    public Set<Map.Entry<K,V>> entrySet() {
        Set<Map.Entry<K,V>> es = entrySet;
        if (es != null)
            return es;
        else
            return entrySet = new EntrySet();
    }

    private class EntrySet extends AbstractSet<Map.Entry<K,V>> {
        public Iterator<Map.Entry<K,V>> iterator() {
            return new EntryIterator();
        }
        public boolean contains(Object o) {
            if (!(o instanceof Map.Entry))
                return false;
            Map.Entry entry = (Map.Entry)o;
            return containsMapping(entry.getKey(), entry.getValue());
        }
        public boolean remove(Object o) {
            if (!(o instanceof Map.Entry))
                return false;
            Map.Entry entry = (Map.Entry)o;
            return removeMapping(entry.getKey(), entry.getValue());
        }
        public int size() {
            return size;
        }
        public void clear() {
            IdentityHashMap.this.clear();
        }
        /*
         * Must revert from AbstractSet's impl to AbstractCollection's, as
         * the former contains an optimization that results in incorrect
         * behavior when c is a smaller "normal" (non-identity-based) Set.
         */
        public boolean removeAll(Collection<?> c) {
            boolean modified = false;
            for (Iterator<Map.Entry<K,V>> i = iterator(); i.hasNext(); ) {
                if (c.contains(i.next())) {
                    i.remove();
                    modified = true;
                }
            }
            return modified;
        }

        public Object[] toArray() {
            int size = size();
            Object[] result = new Object[size];
            Iterator<Map.Entry<K,V>> it = iterator();
            for (int i = 0; i < size; i++)
                result[i] = new AbstractMap.SimpleEntry<>(it.next());
            return result;
        }

        @SuppressWarnings("unchecked")
        public <T> T[] toArray(T[] a) {
            int size = size();
            if (a.length < size)
                a = (T[])java.lang.reflect.Array
                    .newInstance(a.getClass().getComponentType(), size);
            Iterator<Map.Entry<K,V>> it = iterator();
            for (int i = 0; i < size; i++)
                a[i] = (T) new AbstractMap.SimpleEntry<>(it.next());
            if (a.length > size)
                a[size] = null;
            return a;
        }
    }


    private static final long serialVersionUID = 8188218128353913216L;

    /**
     * Save the state of the <tt>IdentityHashMap</tt> instance to a stream
     * (i.e., serialize it).
     *
     * @serialData The <i>size</i> of the HashMap (the number of key-value
     *          mappings) (<tt>int</tt>), followed by the key (Object) and
     *          value (Object) for each key-value mapping represented by the
     *          IdentityHashMap.  The key-value mappings are emitted in no
     *          particular order.
     */
    private void writeObject(java.io.ObjectOutputStream s)
        throws java.io.IOException  {
        // Write out and any hidden stuff
        s.defaultWriteObject();

        // Write out size (number of Mappings)
        s.writeInt(size);

        // Write out keys and values (alternating)
        Object[] tab = table;
        for (int i = 0; i < tab.length; i += 2) {
            Object key = tab[i];
            if (key != null) {
                s.writeObject(unmaskNull(key));
                s.writeObject(tab[i + 1]);
            }
        }
    }

    /**
     * Reconstitute the <tt>IdentityHashMap</tt> instance from a stream (i.e.,
     * deserialize it).
     */
    private void readObject(java.io.ObjectInputStream s)
        throws java.io.IOException, ClassNotFoundException  {
        // Read in any hidden stuff
        s.defaultReadObject();

        // Read in size (number of Mappings)
        int size = s.readInt();

        // Allow for 33% growth (i.e., capacity is >= 2* size()).
        init(capacity((size*4)/3));

        // Read the keys and values, and put the mappings in the table
        for (int i=0; i<size; i++) {
            K key = (K) s.readObject();
            V value = (V) s.readObject();
            putForCreate(key, value);
        }
    }

    /**
     * The put method for readObject.  It does not resize the table,
     * update modCount, etc.
     */
    private void putForCreate(K key, V value)
        throws IOException
    {
        K k = (K)maskNull(key);
        Object[] tab = table;
        int len = tab.length;
        int i = hash(k, len);

        Object item;
        while ( (item = tab[i]) != null) {
            if (item == k)
                throw new java.io.StreamCorruptedException();
            i = nextKeyIndex(i, len);
        }
        tab[i] = k;
        tab[i + 1] = value;
    }
}
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