1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util;
27
28 import java.io.IOException;
29 import java.io.InvalidObjectException;
30 import java.io.Serializable;
31 import java.lang.reflect.ParameterizedType;
32 import java.lang.reflect.Type;
33 import java.util.function.BiConsumer;
34 import java.util.function.BiFunction;
35 import java.util.function.Consumer;
36 import java.util.function.Function;
37 import jdk.internal.access.SharedSecrets;
38
39 /**
40 * Hash table based implementation of the {@code Map} interface. This
41 * implementation provides all of the optional map operations, and permits
42 * {@code null} values and the {@code null} key. (The {@code HashMap}
43 * class is roughly equivalent to {@code Hashtable}, except that it is
44 * unsynchronized and permits nulls.) This class makes no guarantees as to
45 * the order of the map; in particular, it does not guarantee that the order
46 * will remain constant over time.
47 *
48 * <p>This implementation provides constant-time performance for the basic
49 * operations ({@code get} and {@code put}), assuming the hash function
50 * disperses the elements properly among the buckets. Iteration over
51 * collection views requires time proportional to the "capacity" of the
52 * {@code HashMap} instance (the number of buckets) plus its size (the number
53 * of key-value mappings). Thus, it's very important not to set the initial
54 * capacity too high (or the load factor too low) if iteration performance is
55 * important.
56 *
57 * <p>An instance of {@code HashMap} has two parameters that affect its
58 * performance: <i>initial capacity</i> and <i>load factor</i>. The
59 * <i>capacity</i> is the number of buckets in the hash table, and the initial
60 * capacity is simply the capacity at the time the hash table is created. The
61 * <i>load factor</i> is a measure of how full the hash table is allowed to
62 * get before its capacity is automatically increased. When the number of
63 * entries in the hash table exceeds the product of the load factor and the
64 * current capacity, the hash table is <i>rehashed</i> (that is, internal data
65 * structures are rebuilt) so that the hash table has approximately twice the
66 * number of buckets.
67 *
68 * <p>As a general rule, the default load factor (.75) offers a good
69 * tradeoff between time and space costs. Higher values decrease the
70 * space overhead but increase the lookup cost (reflected in most of
71 * the operations of the {@code HashMap} class, including
72 * {@code get} and {@code put}). The expected number of entries in
73 * the map and its load factor should be taken into account when
74 * setting its initial capacity, so as to minimize the number of
75 * rehash operations. If the initial capacity is greater than the
76 * maximum number of entries divided by the load factor, no rehash
77 * operations will ever occur.
78 *
79 * <p>If many mappings are to be stored in a {@code HashMap}
80 * instance, creating it with a sufficiently large capacity will allow
81 * the mappings to be stored more efficiently than letting it perform
82 * automatic rehashing as needed to grow the table. Note that using
83 * many keys with the same {@code hashCode()} is a sure way to slow
84 * down performance of any hash table. To ameliorate impact, when keys
85 * are {@link Comparable}, this class may use comparison order among
86 * keys to help break ties.
87 *
88 * <p><strong>Note that this implementation is not synchronized.</strong>
89 * If multiple threads access a hash map concurrently, and at least one of
90 * the threads modifies the map structurally, it <i>must</i> be
91 * synchronized externally. (A structural modification is any operation
92 * that adds or deletes one or more mappings; merely changing the value
93 * associated with a key that an instance already contains is not a
94 * structural modification.) This is typically accomplished by
95 * synchronizing on some object that naturally encapsulates the map.
96 *
97 * If no such object exists, the map should be "wrapped" using the
98 * {@link Collections#synchronizedMap Collections.synchronizedMap}
99 * method. This is best done at creation time, to prevent accidental
100 * unsynchronized access to the map:<pre>
101 * Map m = Collections.synchronizedMap(new HashMap(...));</pre>
102 *
103 * <p>The iterators returned by all of this class's "collection view methods"
104 * are <i>fail-fast</i>: if the map is structurally modified at any time after
105 * the iterator is created, in any way except through the iterator's own
106 * {@code remove} method, the iterator will throw a
107 * {@link ConcurrentModificationException}. Thus, in the face of concurrent
108 * modification, the iterator fails quickly and cleanly, rather than risking
109 * arbitrary, non-deterministic behavior at an undetermined time in the
110 * future.
111 *
112 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
113 * as it is, generally speaking, impossible to make any hard guarantees in the
114 * presence of unsynchronized concurrent modification. Fail-fast iterators
115 * throw {@code ConcurrentModificationException} on a best-effort basis.
116 * Therefore, it would be wrong to write a program that depended on this
117 * exception for its correctness: <i>the fail-fast behavior of iterators
118 * should be used only to detect bugs.</i>
119 *
120 * <p>This class is a member of the
121 * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
122 * Java Collections Framework</a>.
123 *
124 * @param <K> the type of keys maintained by this map
125 * @param <V> the type of mapped values
126 *
127 * @author Doug Lea
128 * @author Josh Bloch
129 * @author Arthur van Hoff
130 * @author Neal Gafter
131 * @see Object#hashCode()
132 * @see Collection
133 * @see Map
134 * @see TreeMap
135 * @see Hashtable
136 * @since 1.2
137 */
138 public class HashMap<K,V> extends AbstractMap<K,V>
139 implements Map<K,V>, Cloneable, Serializable {
140
141 private static final long serialVersionUID = 362498820763181265L;
142
143 /*
144 * Implementation notes.
145 *
146 * This map usually acts as a binned (bucketed) hash table, but
147 * when bins get too large, they are transformed into bins of
148 * TreeNodes, each structured similarly to those in
149 * java.util.TreeMap. Most methods try to use normal bins, but
150 * relay to TreeNode methods when applicable (simply by checking
151 * instanceof a node). Bins of TreeNodes may be traversed and
152 * used like any others, but additionally support faster lookup
153 * when overpopulated. However, since the vast majority of bins in
154 * normal use are not overpopulated, checking for existence of
155 * tree bins may be delayed in the course of table methods.
156 *
157 * Tree bins (i.e., bins whose elements are all TreeNodes) are
158 * ordered primarily by hashCode, but in the case of ties, if two
159 * elements are of the same "class C implements Comparable<C>",
160 * type then their compareTo method is used for ordering. (We
161 * conservatively check generic types via reflection to validate
162 * this -- see method comparableClassFor). The added complexity
163 * of tree bins is worthwhile in providing worst-case O(log n)
164 * operations when keys either have distinct hashes or are
165 * orderable, Thus, performance degrades gracefully under
166 * accidental or malicious usages in which hashCode() methods
167 * return values that are poorly distributed, as well as those in
168 * which many keys share a hashCode, so long as they are also
169 * Comparable. (If neither of these apply, we may waste about a
170 * factor of two in time and space compared to taking no
171 * precautions. But the only known cases stem from poor user
172 * programming practices that are already so slow that this makes
173 * little difference.)
174 *
175 * Because TreeNodes are about twice the size of regular nodes, we
176 * use them only when bins contain enough nodes to warrant use
177 * (see TREEIFY_THRESHOLD). And when they become too small (due to
178 * removal or resizing) they are converted back to plain bins. In
179 * usages with well-distributed user hashCodes, tree bins are
180 * rarely used. Ideally, under random hashCodes, the frequency of
181 * nodes in bins follows a Poisson distribution
182 * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
183 * parameter of about 0.5 on average for the default resizing
184 * threshold of 0.75, although with a large variance because of
185 * resizing granularity. Ignoring variance, the expected
186 * occurrences of list size k are (exp(-0.5) * pow(0.5, k) /
187 * factorial(k)). The first values are:
188 *
189 * 0: 0.60653066
190 * 1: 0.30326533
191 * 2: 0.07581633
192 * 3: 0.01263606
193 * 4: 0.00157952
194 * 5: 0.00015795
195 * 6: 0.00001316
196 * 7: 0.00000094
197 * 8: 0.00000006
198 * more: less than 1 in ten million
199 *
200 * The root of a tree bin is normally its first node. However,
201 * sometimes (currently only upon Iterator.remove), the root might
202 * be elsewhere, but can be recovered following parent links
203 * (method TreeNode.root()).
204 *
205 * All applicable internal methods accept a hash code as an
206 * argument (as normally supplied from a public method), allowing
207 * them to call each other without recomputing user hashCodes.
208 * Most internal methods also accept a "tab" argument, that is
209 * normally the current table, but may be a new or old one when
210 * resizing or converting.
211 *
212 * When bin lists are treeified, split, or untreeified, we keep
213 * them in the same relative access/traversal order (i.e., field
214 * Node.next) to better preserve locality, and to slightly
215 * simplify handling of splits and traversals that invoke
216 * iterator.remove. When using comparators on insertion, to keep a
217 * total ordering (or as close as is required here) across
218 * rebalancings, we compare classes and identityHashCodes as
219 * tie-breakers.
220 *
221 * The use and transitions among plain vs tree modes is
222 * complicated by the existence of subclass LinkedHashMap. See
223 * below for hook methods defined to be invoked upon insertion,
224 * removal and access that allow LinkedHashMap internals to
225 * otherwise remain independent of these mechanics. (This also
226 * requires that a map instance be passed to some utility methods
227 * that may create new nodes.)
228 *
229 * The concurrent-programming-like SSA-based coding style helps
230 * avoid aliasing errors amid all of the twisty pointer operations.
231 */
232
233 /**
234 * The default initial capacity - MUST be a power of two.
235 */
236 static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
237
238 /**
239 * The maximum capacity, used if a higher value is implicitly specified
240 * by either of the constructors with arguments.
241 * MUST be a power of two <= 1<<30.
242 */
243 static final int MAXIMUM_CAPACITY = 1 << 30;
244
245 /**
246 * The load factor used when none specified in constructor.
247 */
248 static final float DEFAULT_LOAD_FACTOR = 0.75f;
249
250 /**
251 * The bin count threshold for using a tree rather than list for a
252 * bin. Bins are converted to trees when adding an element to a
253 * bin with at least this many nodes. The value must be greater
254 * than 2 and should be at least 8 to mesh with assumptions in
255 * tree removal about conversion back to plain bins upon
256 * shrinkage.
257 */
258 static final int TREEIFY_THRESHOLD = 8;
259
260 /**
261 * The bin count threshold for untreeifying a (split) bin during a
262 * resize operation. Should be less than TREEIFY_THRESHOLD, and at
263 * most 6 to mesh with shrinkage detection under removal.
264 */
265 static final int UNTREEIFY_THRESHOLD = 6;
266
267 /**
268 * The smallest table capacity for which bins may be treeified.
269 * (Otherwise the table is resized if too many nodes in a bin.)
270 * Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
271 * between resizing and treeification thresholds.
272 */
273 static final int MIN_TREEIFY_CAPACITY = 64;
274
275 /**
276 * Basic hash bin node, used for most entries. (See below for
277 * TreeNode subclass, and in LinkedHashMap for its Entry subclass.)
278 */
279 static class Node<K,V> implements Map.Entry<K,V> {
280 final int hash;
281 final K key;
282 V value;
283 Node<K,V> next;
284
285 Node(int hash, K key, V value, Node<K,V> next) {
286 this.hash = hash;
287 this.key = key;
288 this.value = value;
289 this.next = next;
290 }
291
292 public final K getKey() { return key; }
293 public final V getValue() { return value; }
294 public final String toString() { return key + "=" + value; }
295
296 public final int hashCode() {
297 return Objects.hashCode(key) ^ Objects.hashCode(value);
298 }
299
300 public final V setValue(V newValue) {
301 V oldValue = value;
302 value = newValue;
303 return oldValue;
304 }
305
306 public final boolean equals(Object o) {
307 if (o == this)
308 return true;
309 if (o instanceof Map.Entry) {
310 Map.Entry<?,?> e = (Map.Entry<?,?>)o;
311 if (Objects.equals(key, e.getKey()) &&
312 Objects.equals(value, e.getValue()))
313 return true;
314 }
315 return false;
316 }
317 }
318
319 /* ---------------- Static utilities -------------- */
320
321 /**
322 * Computes key.hashCode() and spreads (XORs) higher bits of hash
323 * to lower. Because the table uses power-of-two masking, sets of
324 * hashes that vary only in bits above the current mask will
325 * always collide. (Among known examples are sets of Float keys
326 * holding consecutive whole numbers in small tables.) So we
327 * apply a transform that spreads the impact of higher bits
328 * downward. There is a tradeoff between speed, utility, and
329 * quality of bit-spreading. Because many common sets of hashes
330 * are already reasonably distributed (so don't benefit from
331 * spreading), and because we use trees to handle large sets of
332 * collisions in bins, we just XOR some shifted bits in the
333 * cheapest possible way to reduce systematic lossage, as well as
334 * to incorporate impact of the highest bits that would otherwise
335 * never be used in index calculations because of table bounds.
336 */
337 static final int hash(Object key) {
338 int h;
339 return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
340 }
341
342 /**
343 * Returns x's Class if it is of the form "class C implements
344 * Comparable<C>", else null.
345 */
346 static Class<?> comparableClassFor(Object x) {
347 if (x instanceof Comparable) {
348 Class<?> c; Type[] ts, as; ParameterizedType p;
349 if ((c = x.getClass()) == String.class) // bypass checks
350 return c;
351 if ((ts = c.getGenericInterfaces()) != null) {
352 for (Type t : ts) {
353 if ((t instanceof ParameterizedType) &&
354 ((p = (ParameterizedType) t).getRawType() ==
355 Comparable.class) &&
356 (as = p.getActualTypeArguments()) != null &&
357 as.length == 1 && as[0] == c) // type arg is c
358 return c;
359 }
360 }
361 }
362 return null;
363 }
364
365 /**
366 * Returns k.compareTo(x) if x matches kc (k's screened comparable
367 * class), else 0.
368 */
369 @SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
370 static int compareComparables(Class<?> kc, Object k, Object x) {
371 return (x == null || x.getClass() != kc ? 0 :
372 ((Comparable)k).compareTo(x));
373 }
374
375 /**
376 * Returns a power of two size for the given target capacity.
377 */
378 static final int tableSizeFor(int cap) {
379 int n = -1 >>> Integer.numberOfLeadingZeros(cap - 1);
380 return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
381 }
382
383 /* ---------------- Fields -------------- */
384
385 /**
386 * The table, initialized on first use, and resized as
387 * necessary. When allocated, length is always a power of two.
388 * (We also tolerate length zero in some operations to allow
389 * bootstrapping mechanics that are currently not needed.)
390 */
391 transient Node<K,V>[] table;
392
393 /**
394 * Holds cached entrySet(). Note that AbstractMap fields are used
395 * for keySet() and values().
396 */
397 transient Set<Map.Entry<K,V>> entrySet;
398
399 /**
400 * The number of key-value mappings contained in this map.
401 */
402 transient int size;
403
404 /**
405 * The number of times this HashMap has been structurally modified
406 * Structural modifications are those that change the number of mappings in
407 * the HashMap or otherwise modify its internal structure (e.g.,
408 * rehash). This field is used to make iterators on Collection-views of
409 * the HashMap fail-fast. (See ConcurrentModificationException).
410 */
411 transient int modCount;
412
413 /**
414 * The next size value at which to resize (capacity * load factor).
415 *
416 * @serial
417 */
418 // (The javadoc description is true upon serialization.
419 // Additionally, if the table array has not been allocated, this
420 // field holds the initial array capacity, or zero signifying
421 // DEFAULT_INITIAL_CAPACITY.)
422 int threshold;
423
424 /**
425 * The load factor for the hash table.
426 *
427 * @serial
428 */
429 final float loadFactor;
430
431 /* ---------------- Public operations -------------- */
432
433 /**
434 * Constructs an empty {@code HashMap} with the specified initial
435 * capacity and load factor.
436 *
437 * @param initialCapacity the initial capacity
438 * @param loadFactor the load factor
439 * @throws IllegalArgumentException if the initial capacity is negative
440 * or the load factor is nonpositive
441 */
442 public HashMap(int initialCapacity, float loadFactor) {
443 if (initialCapacity < 0)
444 throw new IllegalArgumentException("Illegal initial capacity: " +
445 initialCapacity);
446 if (initialCapacity > MAXIMUM_CAPACITY)
447 initialCapacity = MAXIMUM_CAPACITY;
448 if (loadFactor <= 0 || Float.isNaN(loadFactor))
449 throw new IllegalArgumentException("Illegal load factor: " +
450 loadFactor);
451 this.loadFactor = loadFactor;
452 this.threshold = tableSizeFor(initialCapacity);
453 }
454
455 /**
456 * Constructs an empty {@code HashMap} with the specified initial
457 * capacity and the default load factor (0.75).
458 *
459 * @param initialCapacity the initial capacity.
460 * @throws IllegalArgumentException if the initial capacity is negative.
461 */
462 public HashMap(int initialCapacity) {
463 this(initialCapacity, DEFAULT_LOAD_FACTOR);
464 }
465
466 /**
467 * Constructs an empty {@code HashMap} with the default initial capacity
468 * (16) and the default load factor (0.75).
469 */
470 public HashMap() {
471 this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
472 }
473
474 /**
475 * Constructs a new {@code HashMap} with the same mappings as the
476 * specified {@code Map}. The {@code HashMap} is created with
477 * default load factor (0.75) and an initial capacity sufficient to
478 * hold the mappings in the specified {@code Map}.
479 *
480 * @param m the map whose mappings are to be placed in this map
481 * @throws NullPointerException if the specified map is null
482 */
483 public HashMap(Map<? extends K, ? extends V> m) {
484 this.loadFactor = DEFAULT_LOAD_FACTOR;
485 putMapEntries(m, false);
486 }
487
488 /**
489 * Implements Map.putAll and Map constructor.
490 *
491 * @param m the map
492 * @param evict false when initially constructing this map, else
493 * true (relayed to method afterNodeInsertion).
494 */
495 final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
496 int s = m.size();
497 if (s > 0) {
498 if (table == null) { // pre-size
499 float ft = ((float)s / loadFactor) + 1.0F;
500 int t = ((ft < (float)MAXIMUM_CAPACITY) ?
501 (int)ft : MAXIMUM_CAPACITY);
502 if (t > threshold)
503 threshold = tableSizeFor(t);
504 } else {
505 // Because of linked-list bucket constraints, we cannot
506 // expand all at once, but can reduce total resize
507 // effort by repeated doubling now vs later
508 while (s > threshold && table.length < MAXIMUM_CAPACITY)
509 resize();
510 }
511
512 for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
513 K key = e.getKey();
514 V value = e.getValue();
515 putVal(hash(key), key, value, false, evict);
516 }
517 }
518 }
519
520 /**
521 * Returns the number of key-value mappings in this map.
522 *
523 * @return the number of key-value mappings in this map
524 */
525 public int size() {
526 return size;
527 }
528
529 /**
530 * Returns {@code true} if this map contains no key-value mappings.
531 *
532 * @return {@code true} if this map contains no key-value mappings
533 */
534 public boolean isEmpty() {
535 return size == 0;
536 }
537
538 /**
539 * Returns the value to which the specified key is mapped,
540 * or {@code null} if this map contains no mapping for the key.
541 *
542 * <p>More formally, if this map contains a mapping from a key
543 * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
544 * key.equals(k))}, then this method returns {@code v}; otherwise
545 * it returns {@code null}. (There can be at most one such mapping.)
546 *
547 * <p>A return value of {@code null} does not <i>necessarily</i>
548 * indicate that the map contains no mapping for the key; it's also
549 * possible that the map explicitly maps the key to {@code null}.
550 * The {@link #containsKey containsKey} operation may be used to
551 * distinguish these two cases.
552 *
553 * @see #put(Object, Object)
554 */
555 public V get(Object key) {
556 Node<K,V> e;
557 return (e = getNode(hash(key), key)) == null ? null : e.value;
558 }
559
560 /**
561 * Implements Map.get and related methods.
562 *
563 * @param hash hash for key
564 * @param key the key
565 * @return the node, or null if none
566 */
567 final Node<K,V> getNode(int hash, Object key) {
568 Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
569 if ((tab = table) != null && (n = tab.length) > 0 &&
570 (first = tab[(n - 1) & hash]) != null) {
571 if (first.hash == hash && // always check first node
572 ((k = first.key) == key || (key != null && key.equals(k))))
573 return first;
574 if ((e = first.next) != null) {
575 if (first instanceof TreeNode)
576 return ((TreeNode<K,V>)first).getTreeNode(hash, key);
577 do {
578 if (e.hash == hash &&
579 ((k = e.key) == key || (key != null && key.equals(k))))
580 return e;
581 } while ((e = e.next) != null);
582 }
583 }
584 return null;
585 }
586
587 /**
588 * Returns {@code true} if this map contains a mapping for the
589 * specified key.
590 *
591 * @param key The key whose presence in this map is to be tested
592 * @return {@code true} if this map contains a mapping for the specified
593 * key.
594 */
595 public boolean containsKey(Object key) {
596 return getNode(hash(key), key) != null;
597 }
598
599 /**
600 * Associates the specified value with the specified key in this map.
601 * If the map previously contained a mapping for the key, the old
602 * value is replaced.
603 *
604 * @param key key with which the specified value is to be associated
605 * @param value value to be associated with the specified key
606 * @return the previous value associated with {@code key}, or
607 * {@code null} if there was no mapping for {@code key}.
608 * (A {@code null} return can also indicate that the map
609 * previously associated {@code null} with {@code key}.)
610 */
611 public V put(K key, V value) {
612 return putVal(hash(key), key, value, false, true);
613 }
614
615 /**
616 * Implements Map.put and related methods.
617 *
618 * @param hash hash for key
619 * @param key the key
620 * @param value the value to put
621 * @param onlyIfAbsent if true, don't change existing value
622 * @param evict if false, the table is in creation mode.
623 * @return previous value, or null if none
624 */
625 final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
626 boolean evict) {
627 Node<K,V>[] tab; Node<K,V> p; int n, i;
628 if ((tab = table) == null || (n = tab.length) == 0)
629 n = (tab = resize()).length;
630 if ((p = tab[i = (n - 1) & hash]) == null)
631 tab[i] = newNode(hash, key, value, null);
632 else {
633 Node<K,V> e; K k;
634 if (p.hash == hash &&
635 ((k = p.key) == key || (key != null && key.equals(k))))
636 e = p;
637 else if (p instanceof TreeNode)
638 e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
639 else {
640 for (int binCount = 0; ; ++binCount) {
641 if ((e = p.next) == null) {
642 p.next = newNode(hash, key, value, null);
643 if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
644 treeifyBin(tab, hash);
645 break;
646 }
647 if (e.hash == hash &&
648 ((k = e.key) == key || (key != null && key.equals(k))))
649 break;
650 p = e;
651 }
652 }
653 if (e != null) { // existing mapping for key
654 V oldValue = e.value;
655 if (!onlyIfAbsent || oldValue == null)
656 e.value = value;
657 afterNodeAccess(e);
658 return oldValue;
659 }
660 }
661 ++modCount;
662 if (++size > threshold)
663 resize();
664 afterNodeInsertion(evict);
665 return null;
666 }
667
668 /**
669 * Initializes or doubles table size. If null, allocates in
670 * accord with initial capacity target held in field threshold.
671 * Otherwise, because we are using power-of-two expansion, the
672 * elements from each bin must either stay at same index, or move
673 * with a power of two offset in the new table.
674 *
675 * @return the table
676 */
677 final Node<K,V>[] resize() {
678 Node<K,V>[] oldTab = table;
679 int oldCap = (oldTab == null) ? 0 : oldTab.length;
680 int oldThr = threshold;
681 int newCap, newThr = 0;
682 if (oldCap > 0) {
683 if (oldCap >= MAXIMUM_CAPACITY) {
684 threshold = Integer.MAX_VALUE;
685 return oldTab;
686 }
687 else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
688 oldCap >= DEFAULT_INITIAL_CAPACITY)
689 newThr = oldThr << 1; // double threshold
690 }
691 else if (oldThr > 0) // initial capacity was placed in threshold
692 newCap = oldThr;
693 else { // zero initial threshold signifies using defaults
694 newCap = DEFAULT_INITIAL_CAPACITY;
695 newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
696 }
697 if (newThr == 0) {
698 float ft = (float)newCap * loadFactor;
699 newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
700 (int)ft : Integer.MAX_VALUE);
701 }
702 threshold = newThr;
703 @SuppressWarnings({"rawtypes","unchecked"})
704 Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
705 table = newTab;
706 if (oldTab != null) {
707 for (int j = 0; j < oldCap; ++j) {
708 Node<K,V> e;
709 if ((e = oldTab[j]) != null) {
710 oldTab[j] = null;
711 if (e.next == null)
712 newTab[e.hash & (newCap - 1)] = e;
713 else if (e instanceof TreeNode)
714 ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
715 else { // preserve order
716 Node<K,V> loHead = null, loTail = null;
717 Node<K,V> hiHead = null, hiTail = null;
718 Node<K,V> next;
719 do {
720 next = e.next;
721 if ((e.hash & oldCap) == 0) {
722 if (loTail == null)
723 loHead = e;
724 else
725 loTail.next = e;
726 loTail = e;
727 }
728 else {
729 if (hiTail == null)
730 hiHead = e;
731 else
732 hiTail.next = e;
733 hiTail = e;
734 }
735 } while ((e = next) != null);
736 if (loTail != null) {
737 loTail.next = null;
738 newTab[j] = loHead;
739 }
740 if (hiTail != null) {
741 hiTail.next = null;
742 newTab[j + oldCap] = hiHead;
743 }
744 }
745 }
746 }
747 }
748 return newTab;
749 }
750
751 /**
752 * Replaces all linked nodes in bin at index for given hash unless
753 * table is too small, in which case resizes instead.
754 */
755 final void treeifyBin(Node<K,V>[] tab, int hash) {
756 int n, index; Node<K,V> e;
757 if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)
758 resize();
759 else if ((e = tab[index = (n - 1) & hash]) != null) {
760 TreeNode<K,V> hd = null, tl = null;
761 do {
762 TreeNode<K,V> p = replacementTreeNode(e, null);
763 if (tl == null)
764 hd = p;
765 else {
766 p.prev = tl;
767 tl.next = p;
768 }
769 tl = p;
770 } while ((e = e.next) != null);
771 if ((tab[index] = hd) != null)
772 hd.treeify(tab);
773 }
774 }
775
776 /**
777 * Copies all of the mappings from the specified map to this map.
778 * These mappings will replace any mappings that this map had for
779 * any of the keys currently in the specified map.
780 *
781 * @param m mappings to be stored in this map
782 * @throws NullPointerException if the specified map is null
783 */
784 public void putAll(Map<? extends K, ? extends V> m) {
785 putMapEntries(m, true);
786 }
787
788 /**
789 * Removes the mapping for the specified key from this map if present.
790 *
791 * @param key key whose mapping is to be removed from the map
792 * @return the previous value associated with {@code key}, or
793 * {@code null} if there was no mapping for {@code key}.
794 * (A {@code null} return can also indicate that the map
795 * previously associated {@code null} with {@code key}.)
796 */
797 public V remove(Object key) {
798 Node<K,V> e;
799 return (e = removeNode(hash(key), key, null, false, true)) == null ?
800 null : e.value;
801 }
802
803 /**
804 * Implements Map.remove and related methods.
805 *
806 * @param hash hash for key
807 * @param key the key
808 * @param value the value to match if matchValue, else ignored
809 * @param matchValue if true only remove if value is equal
810 * @param movable if false do not move other nodes while removing
811 * @return the node, or null if none
812 */
813 final Node<K,V> removeNode(int hash, Object key, Object value,
814 boolean matchValue, boolean movable) {
815 Node<K,V>[] tab; Node<K,V> p; int n, index;
816 if ((tab = table) != null && (n = tab.length) > 0 &&
817 (p = tab[index = (n - 1) & hash]) != null) {
818 Node<K,V> node = null, e; K k; V v;
819 if (p.hash == hash &&
820 ((k = p.key) == key || (key != null && key.equals(k))))
821 node = p;
822 else if ((e = p.next) != null) {
823 if (p instanceof TreeNode)
824 node = ((TreeNode<K,V>)p).getTreeNode(hash, key);
825 else {
826 do {
827 if (e.hash == hash &&
828 ((k = e.key) == key ||
829 (key != null && key.equals(k)))) {
830 node = e;
831 break;
832 }
833 p = e;
834 } while ((e = e.next) != null);
835 }
836 }
837 if (node != null && (!matchValue || (v = node.value) == value ||
838 (value != null && value.equals(v)))) {
839 if (node instanceof TreeNode)
840 ((TreeNode<K,V>)node).removeTreeNode(this, tab, movable);
841 else if (node == p)
842 tab[index] = node.next;
843 else
844 p.next = node.next;
845 ++modCount;
846 --size;
847 afterNodeRemoval(node);
848 return node;
849 }
850 }
851 return null;
852 }
853
854 /**
855 * Removes all of the mappings from this map.
856 * The map will be empty after this call returns.
857 */
858 public void clear() {
859 Node<K,V>[] tab;
860 modCount++;
861 if ((tab = table) != null && size > 0) {
862 size = 0;
863 for (int i = 0; i < tab.length; ++i)
864 tab[i] = null;
865 }
866 }
867
868 /**
869 * Returns {@code true} if this map maps one or more keys to the
870 * specified value.
871 *
872 * @param value value whose presence in this map is to be tested
873 * @return {@code true} if this map maps one or more keys to the
874 * specified value
875 */
876 public boolean containsValue(Object value) {
877 Node<K,V>[] tab; V v;
878 if ((tab = table) != null && size > 0) {
879 for (Node<K,V> e : tab) {
880 for (; e != null; e = e.next) {
881 if ((v = e.value) == value ||
882 (value != null && value.equals(v)))
883 return true;
884 }
885 }
886 }
887 return false;
888 }
889
890 /**
891 * Returns a {@link Set} view of the keys contained in this map.
892 * The set is backed by the map, so changes to the map are
893 * reflected in the set, and vice-versa. If the map is modified
894 * while an iteration over the set is in progress (except through
895 * the iterator's own {@code remove} operation), the results of
896 * the iteration are undefined. The set supports element removal,
897 * which removes the corresponding mapping from the map, via the
898 * {@code Iterator.remove}, {@code Set.remove},
899 * {@code removeAll}, {@code retainAll}, and {@code clear}
900 * operations. It does not support the {@code add} or {@code addAll}
901 * operations.
902 *
903 * @return a set view of the keys contained in this map
904 */
905 public Set<K> keySet() {
906 Set<K> ks = keySet;
907 if (ks == null) {
908 ks = new KeySet();
909 keySet = ks;
910 }
911 return ks;
912 }
913
914 /**
915 * Prepares the array for {@link Collection#toArray(Object[])} implementation.
916 * If supplied array is smaller than this map size, a new array is allocated.
917 * If supplied array is bigger than this map size, a null is written at size index.
918 *
919 * @param a an original array passed to {@code toArray()} method
920 * @param <T> type of array elements
921 * @return an array ready to be filled and returned from {@code toArray()} method.
922 */
923 @SuppressWarnings("unchecked")
924 final <T> T[] prepareArray(T[] a) {
925 int size = this.size;
926 if (a.length < size) {
927 return (T[]) java.lang.reflect.Array
928 .newInstance(a.getClass().getComponentType(), size);
929 }
930 if (a.length > size) {
931 a[size] = null;
932 }
933 return a;
934 }
935
936 /**
937 * Fills an array with this map keys and returns it. This method assumes
938 * that input array is big enough to fit all the keys. Use
939 * {@link #prepareArray(Object[])} to ensure this.
940 *
941 * @param a an array to fill
942 * @param <T> type of array elements
943 * @return supplied array
944 */
945 <T> T[] keysToArray(T[] a) {
946 Object[] r = a;
947 Node<K,V>[] tab;
948 int idx = 0;
949 if (size > 0 && (tab = table) != null) {
950 for (Node<K,V> e : tab) {
951 for (; e != null; e = e.next) {
952 r[idx++] = e.key;
953 }
954 }
955 }
956 return a;
957 }
958
959 /**
960 * Fills an array with this map values and returns it. This method assumes
961 * that input array is big enough to fit all the values. Use
962 * {@link #prepareArray(Object[])} to ensure this.
963 *
964 * @param a an array to fill
965 * @param <T> type of array elements
966 * @return supplied array
967 */
968 <T> T[] valuesToArray(T[] a) {
969 Object[] r = a;
970 Node<K,V>[] tab;
971 int idx = 0;
972 if (size > 0 && (tab = table) != null) {
973 for (Node<K,V> e : tab) {
974 for (; e != null; e = e.next) {
975 r[idx++] = e.value;
976 }
977 }
978 }
979 return a;
980 }
981
982 final class KeySet extends AbstractSet<K> {
983 public final int size() { return size; }
984 public final void clear() { HashMap.this.clear(); }
985 public final Iterator<K> iterator() { return new KeyIterator(); }
986 public final boolean contains(Object o) { return containsKey(o); }
987 public final boolean remove(Object key) {
988 return removeNode(hash(key), key, null, false, true) != null;
989 }
990 public final Spliterator<K> spliterator() {
991 return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
992 }
993
994 public Object[] toArray() {
995 return keysToArray(new Object[size]);
996 }
997
998 public <T> T[] toArray(T[] a) {
999 return keysToArray(prepareArray(a));
1000 }
1001
1002 public final void forEach(Consumer<? super K> action) {
1003 Node<K,V>[] tab;
1004 if (action == null)
1005 throw new NullPointerException();
1006 if (size > 0 && (tab = table) != null) {
1007 int mc = modCount;
1008 for (Node<K,V> e : tab) {
1009 for (; e != null; e = e.next)
1010 action.accept(e.key);
1011 }
1012 if (modCount != mc)
1013 throw new ConcurrentModificationException();
1014 }
1015 }
1016 }
1017
1018 /**
1019 * Returns a {@link Collection} view of the values contained in this map.
1020 * The collection is backed by the map, so changes to the map are
1021 * reflected in the collection, and vice-versa. If the map is
1022 * modified while an iteration over the collection is in progress
1023 * (except through the iterator's own {@code remove} operation),
1024 * the results of the iteration are undefined. The collection
1025 * supports element removal, which removes the corresponding
1026 * mapping from the map, via the {@code Iterator.remove},
1027 * {@code Collection.remove}, {@code removeAll},
1028 * {@code retainAll} and {@code clear} operations. It does not
1029 * support the {@code add} or {@code addAll} operations.
1030 *
1031 * @return a view of the values contained in this map
1032 */
1033 public Collection<V> values() {
1034 Collection<V> vs = values;
1035 if (vs == null) {
1036 vs = new Values();
1037 values = vs;
1038 }
1039 return vs;
1040 }
1041
1042 final class Values extends AbstractCollection<V> {
1043 public final int size() { return size; }
1044 public final void clear() { HashMap.this.clear(); }
1045 public final Iterator<V> iterator() { return new ValueIterator(); }
1046 public final boolean contains(Object o) { return containsValue(o); }
1047 public final Spliterator<V> spliterator() {
1048 return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
1049 }
1050
1051 public Object[] toArray() {
1052 return valuesToArray(new Object[size]);
1053 }
1054
1055 public <T> T[] toArray(T[] a) {
1056 return valuesToArray(prepareArray(a));
1057 }
1058
1059 public final void forEach(Consumer<? super V> action) {
1060 Node<K,V>[] tab;
1061 if (action == null)
1062 throw new NullPointerException();
1063 if (size > 0 && (tab = table) != null) {
1064 int mc = modCount;
1065 for (Node<K,V> e : tab) {
1066 for (; e != null; e = e.next)
1067 action.accept(e.value);
1068 }
1069 if (modCount != mc)
1070 throw new ConcurrentModificationException();
1071 }
1072 }
1073 }
1074
1075 /**
1076 * Returns a {@link Set} view of the mappings contained in this map.
1077 * The set is backed by the map, so changes to the map are
1078 * reflected in the set, and vice-versa. If the map is modified
1079 * while an iteration over the set is in progress (except through
1080 * the iterator's own {@code remove} operation, or through the
1081 * {@code setValue} operation on a map entry returned by the
1082 * iterator) the results of the iteration are undefined. The set
1083 * supports element removal, which removes the corresponding
1084 * mapping from the map, via the {@code Iterator.remove},
1085 * {@code Set.remove}, {@code removeAll}, {@code retainAll} and
1086 * {@code clear} operations. It does not support the
1087 * {@code add} or {@code addAll} operations.
1088 *
1089 * @return a set view of the mappings contained in this map
1090 */
1091 public Set<Map.Entry<K,V>> entrySet() {
1092 Set<Map.Entry<K,V>> es;
1093 return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
1094 }
1095
1096 final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
1097 public final int size() { return size; }
1098 public final void clear() { HashMap.this.clear(); }
1099 public final Iterator<Map.Entry<K,V>> iterator() {
1100 return new EntryIterator();
1101 }
1102 public final boolean contains(Object o) {
1103 if (!(o instanceof Map.Entry))
1104 return false;
1105 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1106 Object key = e.getKey();
1107 Node<K,V> candidate = getNode(hash(key), key);
1108 return candidate != null && candidate.equals(e);
1109 }
1110 public final boolean remove(Object o) {
1111 if (o instanceof Map.Entry) {
1112 Map.Entry<?,?> e = (Map.Entry<?,?>) o;
1113 Object key = e.getKey();
1114 Object value = e.getValue();
1115 return removeNode(hash(key), key, value, true, true) != null;
1116 }
1117 return false;
1118 }
1119 public final Spliterator<Map.Entry<K,V>> spliterator() {
1120 return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
1121 }
1122 public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
1123 Node<K,V>[] tab;
1124 if (action == null)
1125 throw new NullPointerException();
1126 if (size > 0 && (tab = table) != null) {
1127 int mc = modCount;
1128 for (Node<K,V> e : tab) {
1129 for (; e != null; e = e.next)
1130 action.accept(e);
1131 }
1132 if (modCount != mc)
1133 throw new ConcurrentModificationException();
1134 }
1135 }
1136 }
1137
1138 // Overrides of JDK8 Map extension methods
1139
1140 @Override
1141 public V getOrDefault(Object key, V defaultValue) {
1142 Node<K,V> e;
1143 return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
1144 }
1145
1146 @Override
1147 public V putIfAbsent(K key, V value) {
1148 return putVal(hash(key), key, value, true, true);
1149 }
1150
1151 @Override
1152 public boolean remove(Object key, Object value) {
1153 return removeNode(hash(key), key, value, true, true) != null;
1154 }
1155
1156 @Override
1157 public boolean replace(K key, V oldValue, V newValue) {
1158 Node<K,V> e; V v;
1159 if ((e = getNode(hash(key), key)) != null &&
1160 ((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
1161 e.value = newValue;
1162 afterNodeAccess(e);
1163 return true;
1164 }
1165 return false;
1166 }
1167
1168 @Override
1169 public V replace(K key, V value) {
1170 Node<K,V> e;
1171 if ((e = getNode(hash(key), key)) != null) {
1172 V oldValue = e.value;
1173 e.value = value;
1174 afterNodeAccess(e);
1175 return oldValue;
1176 }
1177 return null;
1178 }
1179
1180 /**
1181 * {@inheritDoc}
1182 *
1183 * <p>This method will, on a best-effort basis, throw a
1184 * {@link ConcurrentModificationException} if it is detected that the
1185 * mapping function modifies this map during computation.
1186 *
1187 * @throws ConcurrentModificationException if it is detected that the
1188 * mapping function modified this map
1189 */
1190 @Override
1191 public V computeIfAbsent(K key,
1192 Function<? super K, ? extends V> mappingFunction) {
1193 if (mappingFunction == null)
1194 throw new NullPointerException();
1195 int hash = hash(key);
1196 Node<K,V>[] tab; Node<K,V> first; int n, i;
1197 int binCount = 0;
1198 TreeNode<K,V> t = null;
1199 Node<K,V> old = null;
1200 if (size > threshold || (tab = table) == null ||
1201 (n = tab.length) == 0)
1202 n = (tab = resize()).length;
1203 if ((first = tab[i = (n - 1) & hash]) != null) {
1204 if (first instanceof TreeNode)
1205 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1206 else {
1207 Node<K,V> e = first; K k;
1208 do {
1209 if (e.hash == hash &&
1210 ((k = e.key) == key || (key != null && key.equals(k)))) {
1211 old = e;
1212 break;
1213 }
1214 ++binCount;
1215 } while ((e = e.next) != null);
1216 }
1217 V oldValue;
1218 if (old != null && (oldValue = old.value) != null) {
1219 afterNodeAccess(old);
1220 return oldValue;
1221 }
1222 }
1223 int mc = modCount;
1224 V v = mappingFunction.apply(key);
1225 if (mc != modCount) { throw new ConcurrentModificationException(); }
1226 if (v == null) {
1227 return null;
1228 } else if (old != null) {
1229 old.value = v;
1230 afterNodeAccess(old);
1231 return v;
1232 }
1233 else if (t != null)
1234 t.putTreeVal(this, tab, hash, key, v);
1235 else {
1236 tab[i] = newNode(hash, key, v, first);
1237 if (binCount >= TREEIFY_THRESHOLD - 1)
1238 treeifyBin(tab, hash);
1239 }
1240 modCount = mc + 1;
1241 ++size;
1242 afterNodeInsertion(true);
1243 return v;
1244 }
1245
1246 /**
1247 * {@inheritDoc}
1248 *
1249 * <p>This method will, on a best-effort basis, throw a
1250 * {@link ConcurrentModificationException} if it is detected that the
1251 * remapping function modifies this map during computation.
1252 *
1253 * @throws ConcurrentModificationException if it is detected that the
1254 * remapping function modified this map
1255 */
1256 @Override
1257 public V computeIfPresent(K key,
1258 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1259 if (remappingFunction == null)
1260 throw new NullPointerException();
1261 Node<K,V> e; V oldValue;
1262 int hash = hash(key);
1263 if ((e = getNode(hash, key)) != null &&
1264 (oldValue = e.value) != null) {
1265 int mc = modCount;
1266 V v = remappingFunction.apply(key, oldValue);
1267 if (mc != modCount) { throw new ConcurrentModificationException(); }
1268 if (v != null) {
1269 e.value = v;
1270 afterNodeAccess(e);
1271 return v;
1272 }
1273 else
1274 removeNode(hash, key, null, false, true);
1275 }
1276 return null;
1277 }
1278
1279 /**
1280 * {@inheritDoc}
1281 *
1282 * <p>This method will, on a best-effort basis, throw a
1283 * {@link ConcurrentModificationException} if it is detected that the
1284 * remapping function modifies this map during computation.
1285 *
1286 * @throws ConcurrentModificationException if it is detected that the
1287 * remapping function modified this map
1288 */
1289 @Override
1290 public V compute(K key,
1291 BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
1292 if (remappingFunction == null)
1293 throw new NullPointerException();
1294 int hash = hash(key);
1295 Node<K,V>[] tab; Node<K,V> first; int n, i;
1296 int binCount = 0;
1297 TreeNode<K,V> t = null;
1298 Node<K,V> old = null;
1299 if (size > threshold || (tab = table) == null ||
1300 (n = tab.length) == 0)
1301 n = (tab = resize()).length;
1302 if ((first = tab[i = (n - 1) & hash]) != null) {
1303 if (first instanceof TreeNode)
1304 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1305 else {
1306 Node<K,V> e = first; K k;
1307 do {
1308 if (e.hash == hash &&
1309 ((k = e.key) == key || (key != null && key.equals(k)))) {
1310 old = e;
1311 break;
1312 }
1313 ++binCount;
1314 } while ((e = e.next) != null);
1315 }
1316 }
1317 V oldValue = (old == null) ? null : old.value;
1318 int mc = modCount;
1319 V v = remappingFunction.apply(key, oldValue);
1320 if (mc != modCount) { throw new ConcurrentModificationException(); }
1321 if (old != null) {
1322 if (v != null) {
1323 old.value = v;
1324 afterNodeAccess(old);
1325 }
1326 else
1327 removeNode(hash, key, null, false, true);
1328 }
1329 else if (v != null) {
1330 if (t != null)
1331 t.putTreeVal(this, tab, hash, key, v);
1332 else {
1333 tab[i] = newNode(hash, key, v, first);
1334 if (binCount >= TREEIFY_THRESHOLD - 1)
1335 treeifyBin(tab, hash);
1336 }
1337 modCount = mc + 1;
1338 ++size;
1339 afterNodeInsertion(true);
1340 }
1341 return v;
1342 }
1343
1344 /**
1345 * {@inheritDoc}
1346 *
1347 * <p>This method will, on a best-effort basis, throw a
1348 * {@link ConcurrentModificationException} if it is detected that the
1349 * remapping function modifies this map during computation.
1350 *
1351 * @throws ConcurrentModificationException if it is detected that the
1352 * remapping function modified this map
1353 */
1354 @Override
1355 public V merge(K key, V value,
1356 BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
1357 if (value == null || remappingFunction == null)
1358 throw new NullPointerException();
1359 int hash = hash(key);
1360 Node<K,V>[] tab; Node<K,V> first; int n, i;
1361 int binCount = 0;
1362 TreeNode<K,V> t = null;
1363 Node<K,V> old = null;
1364 if (size > threshold || (tab = table) == null ||
1365 (n = tab.length) == 0)
1366 n = (tab = resize()).length;
1367 if ((first = tab[i = (n - 1) & hash]) != null) {
1368 if (first instanceof TreeNode)
1369 old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key);
1370 else {
1371 Node<K,V> e = first; K k;
1372 do {
1373 if (e.hash == hash &&
1374 ((k = e.key) == key || (key != null && key.equals(k)))) {
1375 old = e;
1376 break;
1377 }
1378 ++binCount;
1379 } while ((e = e.next) != null);
1380 }
1381 }
1382 if (old != null) {
1383 V v;
1384 if (old.value != null) {
1385 int mc = modCount;
1386 v = remappingFunction.apply(old.value, value);
1387 if (mc != modCount) {
1388 throw new ConcurrentModificationException();
1389 }
1390 } else {
1391 v = value;
1392 }
1393 if (v != null) {
1394 old.value = v;
1395 afterNodeAccess(old);
1396 }
1397 else
1398 removeNode(hash, key, null, false, true);
1399 return v;
1400 } else {
1401 if (t != null)
1402 t.putTreeVal(this, tab, hash, key, value);
1403 else {
1404 tab[i] = newNode(hash, key, value, first);
1405 if (binCount >= TREEIFY_THRESHOLD - 1)
1406 treeifyBin(tab, hash);
1407 }
1408 ++modCount;
1409 ++size;
1410 afterNodeInsertion(true);
1411 return value;
1412 }
1413 }
1414
1415 @Override
1416 public void forEach(BiConsumer<? super K, ? super V> action) {
1417 Node<K,V>[] tab;
1418 if (action == null)
1419 throw new NullPointerException();
1420 if (size > 0 && (tab = table) != null) {
1421 int mc = modCount;
1422 for (Node<K,V> e : tab) {
1423 for (; e != null; e = e.next)
1424 action.accept(e.key, e.value);
1425 }
1426 if (modCount != mc)
1427 throw new ConcurrentModificationException();
1428 }
1429 }
1430
1431 @Override
1432 public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
1433 Node<K,V>[] tab;
1434 if (function == null)
1435 throw new NullPointerException();
1436 if (size > 0 && (tab = table) != null) {
1437 int mc = modCount;
1438 for (Node<K,V> e : tab) {
1439 for (; e != null; e = e.next) {
1440 e.value = function.apply(e.key, e.value);
1441 }
1442 }
1443 if (modCount != mc)
1444 throw new ConcurrentModificationException();
1445 }
1446 }
1447
1448 /* ------------------------------------------------------------ */
1449 // Cloning and serialization
1450
1451 /**
1452 * Returns a shallow copy of this {@code HashMap} instance: the keys and
1453 * values themselves are not cloned.
1454 *
1455 * @return a shallow copy of this map
1456 */
1457 @SuppressWarnings("unchecked")
1458 @Override
1459 public Object clone() {
1460 HashMap<K,V> result;
1461 try {
1462 result = (HashMap<K,V>)super.clone();
1463 } catch (CloneNotSupportedException e) {
1464 // this shouldn't happen, since we are Cloneable
1465 throw new InternalError(e);
1466 }
1467 result.reinitialize();
1468 result.putMapEntries(this, false);
1469 return result;
1470 }
1471
1472 // These methods are also used when serializing HashSets
1473 final float loadFactor() { return loadFactor; }
1474 final int capacity() {
1475 return (table != null) ? table.length :
1476 (threshold > 0) ? threshold :
1477 DEFAULT_INITIAL_CAPACITY;
1478 }
1479
1480 /**
1481 * Saves this map to a stream (that is, serializes it).
1482 *
1483 * @param s the stream
1484 * @throws IOException if an I/O error occurs
1485 * @serialData The <i>capacity</i> of the HashMap (the length of the
1486 * bucket array) is emitted (int), followed by the
1487 * <i>size</i> (an int, the number of key-value
1488 * mappings), followed by the key (Object) and value (Object)
1489 * for each key-value mapping. The key-value mappings are
1490 * emitted in no particular order.
1491 */
1492 private void writeObject(java.io.ObjectOutputStream s)
1493 throws IOException {
1494 int buckets = capacity();
1495 // Write out the threshold, loadfactor, and any hidden stuff
1496 s.defaultWriteObject();
1497 s.writeInt(buckets);
1498 s.writeInt(size);
1499 internalWriteEntries(s);
1500 }
1501
1502 /**
1503 * Reconstitutes this map from a stream (that is, deserializes it).
1504 * @param s the stream
1505 * @throws ClassNotFoundException if the class of a serialized object
1506 * could not be found
1507 * @throws IOException if an I/O error occurs
1508 */
1509 private void readObject(java.io.ObjectInputStream s)
1510 throws IOException, ClassNotFoundException {
1511 // Read in the threshold (ignored), loadfactor, and any hidden stuff
1512 s.defaultReadObject();
1513 reinitialize();
1514 if (loadFactor <= 0 || Float.isNaN(loadFactor))
1515 throw new InvalidObjectException("Illegal load factor: " +
1516 loadFactor);
1517 s.readInt(); // Read and ignore number of buckets
1518 int mappings = s.readInt(); // Read number of mappings (size)
1519 if (mappings < 0)
1520 throw new InvalidObjectException("Illegal mappings count: " +
1521 mappings);
1522 else if (mappings > 0) { // (if zero, use defaults)
1523 // Size the table using given load factor only if within
1524 // range of 0.25...4.0
1525 float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
1526 float fc = (float)mappings / lf + 1.0f;
1527 int cap = ((fc < DEFAULT_INITIAL_CAPACITY) ?
1528 DEFAULT_INITIAL_CAPACITY :
1529 (fc >= MAXIMUM_CAPACITY) ?
1530 MAXIMUM_CAPACITY :
1531 tableSizeFor((int)fc));
1532 float ft = (float)cap * lf;
1533 threshold = ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY) ?
1534 (int)ft : Integer.MAX_VALUE);
1535
1536 // Check Map.Entry[].class since it's the nearest public type to
1537 // what we're actually creating.
1538 SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Map.Entry[].class, cap);
1539 @SuppressWarnings({"rawtypes","unchecked"})
1540 Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
1541 table = tab;
1542
1543 // Read the keys and values, and put the mappings in the HashMap
1544 for (int i = 0; i < mappings; i++) {
1545 @SuppressWarnings("unchecked")
1546 K key = (K) s.readObject();
1547 @SuppressWarnings("unchecked")
1548 V value = (V) s.readObject();
1549 putVal(hash(key), key, value, false, false);
1550 }
1551 }
1552 }
1553
1554 /* ------------------------------------------------------------ */
1555 // iterators
1556
1557 abstract class HashIterator {
1558 Node<K,V> next; // next entry to return
1559 Node<K,V> current; // current entry
1560 int expectedModCount; // for fast-fail
1561 int index; // current slot
1562
1563 HashIterator() {
1564 expectedModCount = modCount;
1565 Node<K,V>[] t = table;
1566 current = next = null;
1567 index = 0;
1568 if (t != null && size > 0) { // advance to first entry
1569 do {} while (index < t.length && (next = t[index++]) == null);
1570 }
1571 }
1572
1573 public final boolean hasNext() {
1574 return next != null;
1575 }
1576
1577 final Node<K,V> nextNode() {
1578 Node<K,V>[] t;
1579 Node<K,V> e = next;
1580 if (modCount != expectedModCount)
1581 throw new ConcurrentModificationException();
1582 if (e == null)
1583 throw new NoSuchElementException();
1584 if ((next = (current = e).next) == null && (t = table) != null) {
1585 do {} while (index < t.length && (next = t[index++]) == null);
1586 }
1587 return e;
1588 }
1589
1590 public final void remove() {
1591 Node<K,V> p = current;
1592 if (p == null)
1593 throw new IllegalStateException();
1594 if (modCount != expectedModCount)
1595 throw new ConcurrentModificationException();
1596 current = null;
1597 removeNode(p.hash, p.key, null, false, false);
1598 expectedModCount = modCount;
1599 }
1600 }
1601
1602 final class KeyIterator extends HashIterator
1603 implements Iterator<K> {
1604 public final K next() { return nextNode().key; }
1605 }
1606
1607 final class ValueIterator extends HashIterator
1608 implements Iterator<V> {
1609 public final V next() { return nextNode().value; }
1610 }
1611
1612 final class EntryIterator extends HashIterator
1613 implements Iterator<Map.Entry<K,V>> {
1614 public final Map.Entry<K,V> next() { return nextNode(); }
1615 }
1616
1617 /* ------------------------------------------------------------ */
1618 // spliterators
1619
1620 static class HashMapSpliterator<K,V> {
1621 final HashMap<K,V> map;
1622 Node<K,V> current; // current node
1623 int index; // current index, modified on advance/split
1624 int fence; // one past last index
1625 int est; // size estimate
1626 int expectedModCount; // for comodification checks
1627
1628 HashMapSpliterator(HashMap<K,V> m, int origin,
1629 int fence, int est,
1630 int expectedModCount) {
1631 this.map = m;
1632 this.index = origin;
1633 this.fence = fence;
1634 this.est = est;
1635 this.expectedModCount = expectedModCount;
1636 }
1637
1638 final int getFence() { // initialize fence and size on first use
1639 int hi;
1640 if ((hi = fence) < 0) {
1641 HashMap<K,V> m = map;
1642 est = m.size;
1643 expectedModCount = m.modCount;
1644 Node<K,V>[] tab = m.table;
1645 hi = fence = (tab == null) ? 0 : tab.length;
1646 }
1647 return hi;
1648 }
1649
1650 public final long estimateSize() {
1651 getFence(); // force init
1652 return (long) est;
1653 }
1654 }
1655
1656 static final class KeySpliterator<K,V>
1657 extends HashMapSpliterator<K,V>
1658 implements Spliterator<K> {
1659 KeySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1660 int expectedModCount) {
1661 super(m, origin, fence, est, expectedModCount);
1662 }
1663
1664 public KeySpliterator<K,V> trySplit() {
1665 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1666 return (lo >= mid || current != null) ? null :
1667 new KeySpliterator<>(map, lo, index = mid, est >>>= 1,
1668 expectedModCount);
1669 }
1670
1671 public void forEachRemaining(Consumer<? super K> action) {
1672 int i, hi, mc;
1673 if (action == null)
1674 throw new NullPointerException();
1675 HashMap<K,V> m = map;
1676 Node<K,V>[] tab = m.table;
1677 if ((hi = fence) < 0) {
1678 mc = expectedModCount = m.modCount;
1679 hi = fence = (tab == null) ? 0 : tab.length;
1680 }
1681 else
1682 mc = expectedModCount;
1683 if (tab != null && tab.length >= hi &&
1684 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1685 Node<K,V> p = current;
1686 current = null;
1687 do {
1688 if (p == null)
1689 p = tab[i++];
1690 else {
1691 action.accept(p.key);
1692 p = p.next;
1693 }
1694 } while (p != null || i < hi);
1695 if (m.modCount != mc)
1696 throw new ConcurrentModificationException();
1697 }
1698 }
1699
1700 public boolean tryAdvance(Consumer<? super K> action) {
1701 int hi;
1702 if (action == null)
1703 throw new NullPointerException();
1704 Node<K,V>[] tab = map.table;
1705 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1706 while (current != null || index < hi) {
1707 if (current == null)
1708 current = tab[index++];
1709 else {
1710 K k = current.key;
1711 current = current.next;
1712 action.accept(k);
1713 if (map.modCount != expectedModCount)
1714 throw new ConcurrentModificationException();
1715 return true;
1716 }
1717 }
1718 }
1719 return false;
1720 }
1721
1722 public int characteristics() {
1723 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1724 Spliterator.DISTINCT;
1725 }
1726 }
1727
1728 static final class ValueSpliterator<K,V>
1729 extends HashMapSpliterator<K,V>
1730 implements Spliterator<V> {
1731 ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
1732 int expectedModCount) {
1733 super(m, origin, fence, est, expectedModCount);
1734 }
1735
1736 public ValueSpliterator<K,V> trySplit() {
1737 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1738 return (lo >= mid || current != null) ? null :
1739 new ValueSpliterator<>(map, lo, index = mid, est >>>= 1,
1740 expectedModCount);
1741 }
1742
1743 public void forEachRemaining(Consumer<? super V> action) {
1744 int i, hi, mc;
1745 if (action == null)
1746 throw new NullPointerException();
1747 HashMap<K,V> m = map;
1748 Node<K,V>[] tab = m.table;
1749 if ((hi = fence) < 0) {
1750 mc = expectedModCount = m.modCount;
1751 hi = fence = (tab == null) ? 0 : tab.length;
1752 }
1753 else
1754 mc = expectedModCount;
1755 if (tab != null && tab.length >= hi &&
1756 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1757 Node<K,V> p = current;
1758 current = null;
1759 do {
1760 if (p == null)
1761 p = tab[i++];
1762 else {
1763 action.accept(p.value);
1764 p = p.next;
1765 }
1766 } while (p != null || i < hi);
1767 if (m.modCount != mc)
1768 throw new ConcurrentModificationException();
1769 }
1770 }
1771
1772 public boolean tryAdvance(Consumer<? super V> action) {
1773 int hi;
1774 if (action == null)
1775 throw new NullPointerException();
1776 Node<K,V>[] tab = map.table;
1777 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1778 while (current != null || index < hi) {
1779 if (current == null)
1780 current = tab[index++];
1781 else {
1782 V v = current.value;
1783 current = current.next;
1784 action.accept(v);
1785 if (map.modCount != expectedModCount)
1786 throw new ConcurrentModificationException();
1787 return true;
1788 }
1789 }
1790 }
1791 return false;
1792 }
1793
1794 public int characteristics() {
1795 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
1796 }
1797 }
1798
1799 static final class EntrySpliterator<K,V>
1800 extends HashMapSpliterator<K,V>
1801 implements Spliterator<Map.Entry<K,V>> {
1802 EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
1803 int expectedModCount) {
1804 super(m, origin, fence, est, expectedModCount);
1805 }
1806
1807 public EntrySpliterator<K,V> trySplit() {
1808 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1809 return (lo >= mid || current != null) ? null :
1810 new EntrySpliterator<>(map, lo, index = mid, est >>>= 1,
1811 expectedModCount);
1812 }
1813
1814 public void forEachRemaining(Consumer<? super Map.Entry<K,V>> action) {
1815 int i, hi, mc;
1816 if (action == null)
1817 throw new NullPointerException();
1818 HashMap<K,V> m = map;
1819 Node<K,V>[] tab = m.table;
1820 if ((hi = fence) < 0) {
1821 mc = expectedModCount = m.modCount;
1822 hi = fence = (tab == null) ? 0 : tab.length;
1823 }
1824 else
1825 mc = expectedModCount;
1826 if (tab != null && tab.length >= hi &&
1827 (i = index) >= 0 && (i < (index = hi) || current != null)) {
1828 Node<K,V> p = current;
1829 current = null;
1830 do {
1831 if (p == null)
1832 p = tab[i++];
1833 else {
1834 action.accept(p);
1835 p = p.next;
1836 }
1837 } while (p != null || i < hi);
1838 if (m.modCount != mc)
1839 throw new ConcurrentModificationException();
1840 }
1841 }
1842
1843 public boolean tryAdvance(Consumer<? super Map.Entry<K,V>> action) {
1844 int hi;
1845 if (action == null)
1846 throw new NullPointerException();
1847 Node<K,V>[] tab = map.table;
1848 if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
1849 while (current != null || index < hi) {
1850 if (current == null)
1851 current = tab[index++];
1852 else {
1853 Node<K,V> e = current;
1854 current = current.next;
1855 action.accept(e);
1856 if (map.modCount != expectedModCount)
1857 throw new ConcurrentModificationException();
1858 return true;
1859 }
1860 }
1861 }
1862 return false;
1863 }
1864
1865 public int characteristics() {
1866 return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) |
1867 Spliterator.DISTINCT;
1868 }
1869 }
1870
1871 /* ------------------------------------------------------------ */
1872 // LinkedHashMap support
1873
1874
1875 /*
1876 * The following package-protected methods are designed to be
1877 * overridden by LinkedHashMap, but not by any other subclass.
1878 * Nearly all other internal methods are also package-protected
1879 * but are declared final, so can be used by LinkedHashMap, view
1880 * classes, and HashSet.
1881 */
1882
1883 // Create a regular (non-tree) node
1884 Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
1885 return new Node<>(hash, key, value, next);
1886 }
1887
1888 // For conversion from TreeNodes to plain nodes
1889 Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) {
1890 return new Node<>(p.hash, p.key, p.value, next);
1891 }
1892
1893 // Create a tree bin node
1894 TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
1895 return new TreeNode<>(hash, key, value, next);
1896 }
1897
1898 // For treeifyBin
1899 TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
1900 return new TreeNode<>(p.hash, p.key, p.value, next);
1901 }
1902
1903 /**
1904 * Reset to initial default state. Called by clone and readObject.
1905 */
1906 void reinitialize() {
1907 table = null;
1908 entrySet = null;
1909 keySet = null;
1910 values = null;
1911 modCount = 0;
1912 threshold = 0;
1913 size = 0;
1914 }
1915
1916 // Callbacks to allow LinkedHashMap post-actions
1917 void afterNodeAccess(Node<K,V> p) { }
1918 void afterNodeInsertion(boolean evict) { }
1919 void afterNodeRemoval(Node<K,V> p) { }
1920
1921 // Called only from writeObject, to ensure compatible ordering.
1922 void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
1923 Node<K,V>[] tab;
1924 if (size > 0 && (tab = table) != null) {
1925 for (Node<K,V> e : tab) {
1926 for (; e != null; e = e.next) {
1927 s.writeObject(e.key);
1928 s.writeObject(e.value);
1929 }
1930 }
1931 }
1932 }
1933
1934 /* ------------------------------------------------------------ */
1935 // Tree bins
1936
1937 /**
1938 * Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
1939 * extends Node) so can be used as extension of either regular or
1940 * linked node.
1941 */
1942 static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
1943 TreeNode<K,V> parent; // red-black tree links
1944 TreeNode<K,V> left;
1945 TreeNode<K,V> right;
1946 TreeNode<K,V> prev; // needed to unlink next upon deletion
1947 boolean red;
1948 TreeNode(int hash, K key, V val, Node<K,V> next) {
1949 super(hash, key, val, next);
1950 }
1951
1952 /**
1953 * Returns root of tree containing this node.
1954 */
1955 final TreeNode<K,V> root() {
1956 for (TreeNode<K,V> r = this, p;;) {
1957 if ((p = r.parent) == null)
1958 return r;
1959 r = p;
1960 }
1961 }
1962
1963 /**
1964 * Ensures that the given root is the first node of its bin.
1965 */
1966 static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
1967 int n;
1968 if (root != null && tab != null && (n = tab.length) > 0) {
1969 int index = (n - 1) & root.hash;
1970 TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
1971 if (root != first) {
1972 Node<K,V> rn;
1973 tab[index] = root;
1974 TreeNode<K,V> rp = root.prev;
1975 if ((rn = root.next) != null)
1976 ((TreeNode<K,V>)rn).prev = rp;
1977 if (rp != null)
1978 rp.next = rn;
1979 if (first != null)
1980 first.prev = root;
1981 root.next = first;
1982 root.prev = null;
1983 }
1984 assert checkInvariants(root);
1985 }
1986 }
1987
1988 /**
1989 * Finds the node starting at root p with the given hash and key.
1990 * The kc argument caches comparableClassFor(key) upon first use
1991 * comparing keys.
1992 */
1993 final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
1994 TreeNode<K,V> p = this;
1995 do {
1996 int ph, dir; K pk;
1997 TreeNode<K,V> pl = p.left, pr = p.right, q;
1998 if ((ph = p.hash) > h)
1999 p = pl;
2000 else if (ph < h)
2001 p = pr;
2002 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
2003 return p;
2004 else if (pl == null)
2005 p = pr;
2006 else if (pr == null)
2007 p = pl;
2008 else if ((kc != null ||
2009 (kc = comparableClassFor(k)) != null) &&
2010 (dir = compareComparables(kc, k, pk)) != 0)
2011 p = (dir < 0) ? pl : pr;
2012 else if ((q = pr.find(h, k, kc)) != null)
2013 return q;
2014 else
2015 p = pl;
2016 } while (p != null);
2017 return null;
2018 }
2019
2020 /**
2021 * Calls find for root node.
2022 */
2023 final TreeNode<K,V> getTreeNode(int h, Object k) {
2024 return ((parent != null) ? root() : this).find(h, k, null);
2025 }
2026
2027 /**
2028 * Tie-breaking utility for ordering insertions when equal
2029 * hashCodes and non-comparable. We don't require a total
2030 * order, just a consistent insertion rule to maintain
2031 * equivalence across rebalancings. Tie-breaking further than
2032 * necessary simplifies testing a bit.
2033 */
2034 static int tieBreakOrder(Object a, Object b) {
2035 int d;
2036 if (a == null || b == null ||
2037 (d = a.getClass().getName().
2038 compareTo(b.getClass().getName())) == 0)
2039 d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
2040 -1 : 1);
2041 return d;
2042 }
2043
2044 /**
2045 * Forms tree of the nodes linked from this node.
2046 */
2047 final void treeify(Node<K,V>[] tab) {
2048 TreeNode<K,V> root = null;
2049 for (TreeNode<K,V> x = this, next; x != null; x = next) {
2050 next = (TreeNode<K,V>)x.next;
2051 x.left = x.right = null;
2052 if (root == null) {
2053 x.parent = null;
2054 x.red = false;
2055 root = x;
2056 }
2057 else {
2058 K k = x.key;
2059 int h = x.hash;
2060 Class<?> kc = null;
2061 for (TreeNode<K,V> p = root;;) {
2062 int dir, ph;
2063 K pk = p.key;
2064 if ((ph = p.hash) > h)
2065 dir = -1;
2066 else if (ph < h)
2067 dir = 1;
2068 else if ((kc == null &&
2069 (kc = comparableClassFor(k)) == null) ||
2070 (dir = compareComparables(kc, k, pk)) == 0)
2071 dir = tieBreakOrder(k, pk);
2072
2073 TreeNode<K,V> xp = p;
2074 if ((p = (dir <= 0) ? p.left : p.right) == null) {
2075 x.parent = xp;
2076 if (dir <= 0)
2077 xp.left = x;
2078 else
2079 xp.right = x;
2080 root = balanceInsertion(root, x);
2081 break;
2082 }
2083 }
2084 }
2085 }
2086 moveRootToFront(tab, root);
2087 }
2088
2089 /**
2090 * Returns a list of non-TreeNodes replacing those linked from
2091 * this node.
2092 */
2093 final Node<K,V> untreeify(HashMap<K,V> map) {
2094 Node<K,V> hd = null, tl = null;
2095 for (Node<K,V> q = this; q != null; q = q.next) {
2096 Node<K,V> p = map.replacementNode(q, null);
2097 if (tl == null)
2098 hd = p;
2099 else
2100 tl.next = p;
2101 tl = p;
2102 }
2103 return hd;
2104 }
2105
2106 /**
2107 * Tree version of putVal.
2108 */
2109 final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
2110 int h, K k, V v) {
2111 Class<?> kc = null;
2112 boolean searched = false;
2113 TreeNode<K,V> root = (parent != null) ? root() : this;
2114 for (TreeNode<K,V> p = root;;) {
2115 int dir, ph; K pk;
2116 if ((ph = p.hash) > h)
2117 dir = -1;
2118 else if (ph < h)
2119 dir = 1;
2120 else if ((pk = p.key) == k || (k != null && k.equals(pk)))
2121 return p;
2122 else if ((kc == null &&
2123 (kc = comparableClassFor(k)) == null) ||
2124 (dir = compareComparables(kc, k, pk)) == 0) {
2125 if (!searched) {
2126 TreeNode<K,V> q, ch;
2127 searched = true;
2128 if (((ch = p.left) != null &&
2129 (q = ch.find(h, k, kc)) != null) ||
2130 ((ch = p.right) != null &&
2131 (q = ch.find(h, k, kc)) != null))
2132 return q;
2133 }
2134 dir = tieBreakOrder(k, pk);
2135 }
2136
2137 TreeNode<K,V> xp = p;
2138 if ((p = (dir <= 0) ? p.left : p.right) == null) {
2139 Node<K,V> xpn = xp.next;
2140 TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
2141 if (dir <= 0)
2142 xp.left = x;
2143 else
2144 xp.right = x;
2145 xp.next = x;
2146 x.parent = x.prev = xp;
2147 if (xpn != null)
2148 ((TreeNode<K,V>)xpn).prev = x;
2149 moveRootToFront(tab, balanceInsertion(root, x));
2150 return null;
2151 }
2152 }
2153 }
2154
2155 /**
2156 * Removes the given node, that must be present before this call.
2157 * This is messier than typical red-black deletion code because we
2158 * cannot swap the contents of an interior node with a leaf
2159 * successor that is pinned by "next" pointers that are accessible
2160 * independently during traversal. So instead we swap the tree
2161 * linkages. If the current tree appears to have too few nodes,
2162 * the bin is converted back to a plain bin. (The test triggers
2163 * somewhere between 2 and 6 nodes, depending on tree structure).
2164 */
2165 final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
2166 boolean movable) {
2167 int n;
2168 if (tab == null || (n = tab.length) == 0)
2169 return;
2170 int index = (n - 1) & hash;
2171 TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
2172 TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
2173 if (pred == null)
2174 tab[index] = first = succ;
2175 else
2176 pred.next = succ;
2177 if (succ != null)
2178 succ.prev = pred;
2179 if (first == null)
2180 return;
2181 if (root.parent != null)
2182 root = root.root();
2183 if (root == null
2184 || (movable
2185 && (root.right == null
2186 || (rl = root.left) == null
2187 || rl.left == null))) {
2188 tab[index] = first.untreeify(map); // too small
2189 return;
2190 }
2191 TreeNode<K,V> p = this, pl = left, pr = right, replacement;
2192 if (pl != null && pr != null) {
2193 TreeNode<K,V> s = pr, sl;
2194 while ((sl = s.left) != null) // find successor
2195 s = sl;
2196 boolean c = s.red; s.red = p.red; p.red = c; // swap colors
2197 TreeNode<K,V> sr = s.right;
2198 TreeNode<K,V> pp = p.parent;
2199 if (s == pr) { // p was s's direct parent
2200 p.parent = s;
2201 s.right = p;
2202 }
2203 else {
2204 TreeNode<K,V> sp = s.parent;
2205 if ((p.parent = sp) != null) {
2206 if (s == sp.left)
2207 sp.left = p;
2208 else
2209 sp.right = p;
2210 }
2211 if ((s.right = pr) != null)
2212 pr.parent = s;
2213 }
2214 p.left = null;
2215 if ((p.right = sr) != null)
2216 sr.parent = p;
2217 if ((s.left = pl) != null)
2218 pl.parent = s;
2219 if ((s.parent = pp) == null)
2220 root = s;
2221 else if (p == pp.left)
2222 pp.left = s;
2223 else
2224 pp.right = s;
2225 if (sr != null)
2226 replacement = sr;
2227 else
2228 replacement = p;
2229 }
2230 else if (pl != null)
2231 replacement = pl;
2232 else if (pr != null)
2233 replacement = pr;
2234 else
2235 replacement = p;
2236 if (replacement != p) {
2237 TreeNode<K,V> pp = replacement.parent = p.parent;
2238 if (pp == null)
2239 (root = replacement).red = false;
2240 else if (p == pp.left)
2241 pp.left = replacement;
2242 else
2243 pp.right = replacement;
2244 p.left = p.right = p.parent = null;
2245 }
2246
2247 TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
2248
2249 if (replacement == p) { // detach
2250 TreeNode<K,V> pp = p.parent;
2251 p.parent = null;
2252 if (pp != null) {
2253 if (p == pp.left)
2254 pp.left = null;
2255 else if (p == pp.right)
2256 pp.right = null;
2257 }
2258 }
2259 if (movable)
2260 moveRootToFront(tab, r);
2261 }
2262
2263 /**
2264 * Splits nodes in a tree bin into lower and upper tree bins,
2265 * or untreeifies if now too small. Called only from resize;
2266 * see above discussion about split bits and indices.
2267 *
2268 * @param map the map
2269 * @param tab the table for recording bin heads
2270 * @param index the index of the table being split
2271 * @param bit the bit of hash to split on
2272 */
2273 final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
2274 TreeNode<K,V> b = this;
2275 // Relink into lo and hi lists, preserving order
2276 TreeNode<K,V> loHead = null, loTail = null;
2277 TreeNode<K,V> hiHead = null, hiTail = null;
2278 int lc = 0, hc = 0;
2279 for (TreeNode<K,V> e = b, next; e != null; e = next) {
2280 next = (TreeNode<K,V>)e.next;
2281 e.next = null;
2282 if ((e.hash & bit) == 0) {
2283 if ((e.prev = loTail) == null)
2284 loHead = e;
2285 else
2286 loTail.next = e;
2287 loTail = e;
2288 ++lc;
2289 }
2290 else {
2291 if ((e.prev = hiTail) == null)
2292 hiHead = e;
2293 else
2294 hiTail.next = e;
2295 hiTail = e;
2296 ++hc;
2297 }
2298 }
2299
2300 if (loHead != null) {
2301 if (lc <= UNTREEIFY_THRESHOLD)
2302 tab[index] = loHead.untreeify(map);
2303 else {
2304 tab[index] = loHead;
2305 if (hiHead != null) // (else is already treeified)
2306 loHead.treeify(tab);
2307 }
2308 }
2309 if (hiHead != null) {
2310 if (hc <= UNTREEIFY_THRESHOLD)
2311 tab[index + bit] = hiHead.untreeify(map);
2312 else {
2313 tab[index + bit] = hiHead;
2314 if (loHead != null)
2315 hiHead.treeify(tab);
2316 }
2317 }
2318 }
2319
2320 /* ------------------------------------------------------------ */
2321 // Red-black tree methods, all adapted from CLR
2322
2323 static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
2324 TreeNode<K,V> p) {
2325 TreeNode<K,V> r, pp, rl;
2326 if (p != null && (r = p.right) != null) {
2327 if ((rl = p.right = r.left) != null)
2328 rl.parent = p;
2329 if ((pp = r.parent = p.parent) == null)
2330 (root = r).red = false;
2331 else if (pp.left == p)
2332 pp.left = r;
2333 else
2334 pp.right = r;
2335 r.left = p;
2336 p.parent = r;
2337 }
2338 return root;
2339 }
2340
2341 static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
2342 TreeNode<K,V> p) {
2343 TreeNode<K,V> l, pp, lr;
2344 if (p != null && (l = p.left) != null) {
2345 if ((lr = p.left = l.right) != null)
2346 lr.parent = p;
2347 if ((pp = l.parent = p.parent) == null)
2348 (root = l).red = false;
2349 else if (pp.right == p)
2350 pp.right = l;
2351 else
2352 pp.left = l;
2353 l.right = p;
2354 p.parent = l;
2355 }
2356 return root;
2357 }
2358
2359 static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
2360 TreeNode<K,V> x) {
2361 x.red = true;
2362 for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
2363 if ((xp = x.parent) == null) {
2364 x.red = false;
2365 return x;
2366 }
2367 else if (!xp.red || (xpp = xp.parent) == null)
2368 return root;
2369 if (xp == (xppl = xpp.left)) {
2370 if ((xppr = xpp.right) != null && xppr.red) {
2371 xppr.red = false;
2372 xp.red = false;
2373 xpp.red = true;
2374 x = xpp;
2375 }
2376 else {
2377 if (x == xp.right) {
2378 root = rotateLeft(root, x = xp);
2379 xpp = (xp = x.parent) == null ? null : xp.parent;
2380 }
2381 if (xp != null) {
2382 xp.red = false;
2383 if (xpp != null) {
2384 xpp.red = true;
2385 root = rotateRight(root, xpp);
2386 }
2387 }
2388 }
2389 }
2390 else {
2391 if (xppl != null && xppl.red) {
2392 xppl.red = false;
2393 xp.red = false;
2394 xpp.red = true;
2395 x = xpp;
2396 }
2397 else {
2398 if (x == xp.left) {
2399 root = rotateRight(root, x = xp);
2400 xpp = (xp = x.parent) == null ? null : xp.parent;
2401 }
2402 if (xp != null) {
2403 xp.red = false;
2404 if (xpp != null) {
2405 xpp.red = true;
2406 root = rotateLeft(root, xpp);
2407 }
2408 }
2409 }
2410 }
2411 }
2412 }
2413
2414 static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
2415 TreeNode<K,V> x) {
2416 for (TreeNode<K,V> xp, xpl, xpr;;) {
2417 if (x == null || x == root)
2418 return root;
2419 else if ((xp = x.parent) == null) {
2420 x.red = false;
2421 return x;
2422 }
2423 else if (x.red) {
2424 x.red = false;
2425 return root;
2426 }
2427 else if ((xpl = xp.left) == x) {
2428 if ((xpr = xp.right) != null && xpr.red) {
2429 xpr.red = false;
2430 xp.red = true;
2431 root = rotateLeft(root, xp);
2432 xpr = (xp = x.parent) == null ? null : xp.right;
2433 }
2434 if (xpr == null)
2435 x = xp;
2436 else {
2437 TreeNode<K,V> sl = xpr.left, sr = xpr.right;
2438 if ((sr == null || !sr.red) &&
2439 (sl == null || !sl.red)) {
2440 xpr.red = true;
2441 x = xp;
2442 }
2443 else {
2444 if (sr == null || !sr.red) {
2445 if (sl != null)
2446 sl.red = false;
2447 xpr.red = true;
2448 root = rotateRight(root, xpr);
2449 xpr = (xp = x.parent) == null ?
2450 null : xp.right;
2451 }
2452 if (xpr != null) {
2453 xpr.red = (xp == null) ? false : xp.red;
2454 if ((sr = xpr.right) != null)
2455 sr.red = false;
2456 }
2457 if (xp != null) {
2458 xp.red = false;
2459 root = rotateLeft(root, xp);
2460 }
2461 x = root;
2462 }
2463 }
2464 }
2465 else { // symmetric
2466 if (xpl != null && xpl.red) {
2467 xpl.red = false;
2468 xp.red = true;
2469 root = rotateRight(root, xp);
2470 xpl = (xp = x.parent) == null ? null : xp.left;
2471 }
2472 if (xpl == null)
2473 x = xp;
2474 else {
2475 TreeNode<K,V> sl = xpl.left, sr = xpl.right;
2476 if ((sl == null || !sl.red) &&
2477 (sr == null || !sr.red)) {
2478 xpl.red = true;
2479 x = xp;
2480 }
2481 else {
2482 if (sl == null || !sl.red) {
2483 if (sr != null)
2484 sr.red = false;
2485 xpl.red = true;
2486 root = rotateLeft(root, xpl);
2487 xpl = (xp = x.parent) == null ?
2488 null : xp.left;
2489 }
2490 if (xpl != null) {
2491 xpl.red = (xp == null) ? false : xp.red;
2492 if ((sl = xpl.left) != null)
2493 sl.red = false;
2494 }
2495 if (xp != null) {
2496 xp.red = false;
2497 root = rotateRight(root, xp);
2498 }
2499 x = root;
2500 }
2501 }
2502 }
2503 }
2504 }
2505
2506 /**
2507 * Recursive invariant check
2508 */
2509 static <K,V> boolean checkInvariants(TreeNode<K,V> t) {
2510 TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
2511 tb = t.prev, tn = (TreeNode<K,V>)t.next;
2512 if (tb != null && tb.next != t)
2513 return false;
2514 if (tn != null && tn.prev != t)
2515 return false;
2516 if (tp != null && t != tp.left && t != tp.right)
2517 return false;
2518 if (tl != null && (tl.parent != t || tl.hash > t.hash))
2519 return false;
2520 if (tr != null && (tr.parent != t || tr.hash < t.hash))
2521 return false;
2522 if (t.red && tl != null && tl.red && tr != null && tr.red)
2523 return false;
2524 if (tl != null && !checkInvariants(tl))
2525 return false;
2526 if (tr != null && !checkInvariants(tr))
2527 return false;
2528 return true;
2529 }
2530 }
2531
2532 }