--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.collections/src/org/graalvm/collections/EconomicMapImpl.java Mon Apr 23 12:53:43 2018 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,857 +0,0 @@
-/*
- * Copyright (c) 2017, 2017, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation. Oracle designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-package org.graalvm.collections;
-
-import java.util.Iterator;
-import java.util.Objects;
-import java.util.function.BiFunction;
-
-/**
- * Implementation of a map with a memory-efficient structure that always preserves insertion order
- * when iterating over keys. Particularly efficient when number of entries is 0 or smaller equal
- * {@link #INITIAL_CAPACITY} or smaller 256.
- *
- * The key/value pairs are kept in an expanding flat object array with keys at even indices and
- * values at odd indices. If the map has smaller or equal to {@link #HASH_THRESHOLD} entries, there
- * is no additional hash data structure and comparisons are done via linear checking of the
- * key/value pairs. For the case where the equality check is particularly cheap (e.g., just an
- * object identity comparison), this limit below which the map is without an actual hash table is
- * higher and configured at {@link #HASH_THRESHOLD_IDENTITY_COMPARE}.
- *
- * When the hash table needs to be constructed, the field {@link #hashArray} becomes a new hash
- * array where an entry of 0 means no hit and otherwise denotes the entry number in the
- * {@link #entries} array. The hash array is interpreted as an actual byte array if the indices fit
- * within 8 bit, or as an array of short values if the indices fit within 16 bit, or as an array of
- * integer values in other cases.
- *
- * Hash collisions are handled by chaining a linked list of {@link CollisionLink} objects that take
- * the place of the values in the {@link #entries} array.
- *
- * Removing entries will put {@code null} into the {@link #entries} array. If the occupation of the
- * map falls below a specific threshold, the map will be compressed via the
- * {@link #maybeCompress(int)} method.
- */
-final class EconomicMapImpl<K, V> implements EconomicMap<K, V>, EconomicSet<K> {
-
- /**
- * Initial number of key/value pair entries that is allocated in the first entries array.
- */
- private static final int INITIAL_CAPACITY = 4;
-
- /**
- * Maximum number of entries that are moved linearly forward if a key is removed.
- */
- private static final int COMPRESS_IMMEDIATE_CAPACITY = 8;
-
- /**
- * Minimum number of key/value pair entries added when the entries array is increased in size.
- */
- private static final int MIN_CAPACITY_INCREASE = 8;
-
- /**
- * Number of entries above which a hash table is created.
- */
- private static final int HASH_THRESHOLD = 4;
-
- /**
- * Number of entries above which a hash table is created when equality can be checked with
- * object identity.
- */
- private static final int HASH_THRESHOLD_IDENTITY_COMPARE = 8;
-
- /**
- * Maximum number of entries allowed in the map.
- */
- private static final int MAX_ELEMENT_COUNT = Integer.MAX_VALUE >> 1;
-
- /**
- * Number of entries above which more than 1 byte is necessary for the hash index.
- */
- private static final int LARGE_HASH_THRESHOLD = ((1 << Byte.SIZE) << 1);
-
- /**
- * Number of entries above which more than 2 bytes are are necessary for the hash index.
- */
- private static final int VERY_LARGE_HASH_THRESHOLD = (LARGE_HASH_THRESHOLD << Byte.SIZE);
-
- /**
- * Total number of entries (actual entries plus deleted entries).
- */
- private int totalEntries;
-
- /**
- * Number of deleted entries.
- */
- private int deletedEntries;
-
- /**
- * Entries array with even indices storing keys and odd indices storing values.
- */
- private Object[] entries;
-
- /**
- * Hash array that is interpreted either as byte or short or int array depending on number of
- * map entries.
- */
- private byte[] hashArray;
-
- /**
- * The strategy used for comparing keys or {@code null} for denoting special strategy
- * {@link Equivalence#IDENTITY}.
- */
- private final Equivalence strategy;
-
- /**
- * Intercept method for debugging purposes.
- */
- private static <K, V> EconomicMapImpl<K, V> intercept(EconomicMapImpl<K, V> map) {
- return map;
- }
-
- public static <K, V> EconomicMapImpl<K, V> create(Equivalence strategy, boolean isSet) {
- return intercept(new EconomicMapImpl<>(strategy, isSet));
- }
-
- public static <K, V> EconomicMapImpl<K, V> create(Equivalence strategy, int initialCapacity, boolean isSet) {
- return intercept(new EconomicMapImpl<>(strategy, initialCapacity, isSet));
- }
-
- public static <K, V> EconomicMapImpl<K, V> create(Equivalence strategy, UnmodifiableEconomicMap<K, V> other, boolean isSet) {
- return intercept(new EconomicMapImpl<>(strategy, other, isSet));
- }
-
- public static <K, V> EconomicMapImpl<K, V> create(Equivalence strategy, UnmodifiableEconomicSet<K> other, boolean isSet) {
- return intercept(new EconomicMapImpl<>(strategy, other, isSet));
- }
-
- private EconomicMapImpl(Equivalence strategy, boolean isSet) {
- if (strategy == Equivalence.IDENTITY) {
- this.strategy = null;
- } else {
- this.strategy = strategy;
- }
- this.isSet = isSet;
- }
-
- private EconomicMapImpl(Equivalence strategy, int initialCapacity, boolean isSet) {
- this(strategy, isSet);
- init(initialCapacity);
- }
-
- private EconomicMapImpl(Equivalence strategy, UnmodifiableEconomicMap<K, V> other, boolean isSet) {
- this(strategy, isSet);
- if (!initFrom(other)) {
- init(other.size());
- putAll(other);
- }
- }
-
- private EconomicMapImpl(Equivalence strategy, UnmodifiableEconomicSet<K> other, boolean isSet) {
- this(strategy, isSet);
- if (!initFrom(other)) {
- init(other.size());
- addAll(other);
- }
- }
-
- @SuppressWarnings("unchecked")
- private boolean initFrom(Object o) {
- if (o instanceof EconomicMapImpl) {
- EconomicMapImpl<K, V> otherMap = (EconomicMapImpl<K, V>) o;
- // We are only allowed to directly copy if the strategies of the two maps are the same.
- if (strategy == otherMap.strategy) {
- totalEntries = otherMap.totalEntries;
- deletedEntries = otherMap.deletedEntries;
- if (otherMap.entries != null) {
- entries = otherMap.entries.clone();
- }
- if (otherMap.hashArray != null) {
- hashArray = otherMap.hashArray.clone();
- }
- return true;
- }
- }
- return false;
- }
-
- private void init(int size) {
- if (size > INITIAL_CAPACITY) {
- entries = new Object[size << 1];
- }
- }
-
- /**
- * Links the collisions. Needs to be immutable class for allowing efficient shallow copy from
- * other map on construction.
- */
- private static final class CollisionLink {
-
- CollisionLink(Object value, int next) {
- this.value = value;
- this.next = next;
- }
-
- final Object value;
-
- /**
- * Index plus one of the next entry in the collision link chain.
- */
- final int next;
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public V get(K key) {
- Objects.requireNonNull(key);
-
- int index = find(key);
- if (index != -1) {
- return (V) getValue(index);
- }
- return null;
- }
-
- private int find(K key) {
- if (hasHashArray()) {
- return findHash(key);
- } else {
- return findLinear(key);
- }
- }
-
- private int findLinear(K key) {
- for (int i = 0; i < totalEntries; i++) {
- Object entryKey = entries[i << 1];
- if (entryKey != null && compareKeys(key, entryKey)) {
- return i;
- }
- }
- return -1;
- }
-
- private boolean compareKeys(Object key, Object entryKey) {
- if (key == entryKey) {
- return true;
- }
- if (strategy != null && strategy != Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE) {
- if (strategy == Equivalence.DEFAULT) {
- return key.equals(entryKey);
- } else {
- return strategy.equals(key, entryKey);
- }
- }
- return false;
- }
-
- private int findHash(K key) {
- int index = getHashArray(getHashIndex(key)) - 1;
- if (index != -1) {
- Object entryKey = getKey(index);
- if (compareKeys(key, entryKey)) {
- return index;
- } else {
- Object entryValue = getRawValue(index);
- if (entryValue instanceof CollisionLink) {
- return findWithCollision(key, (CollisionLink) entryValue);
- }
- }
- }
-
- return -1;
- }
-
- private int findWithCollision(K key, CollisionLink initialEntryValue) {
- int index;
- Object entryKey;
- CollisionLink entryValue = initialEntryValue;
- while (true) {
- CollisionLink collisionLink = entryValue;
- index = collisionLink.next;
- entryKey = getKey(index);
- if (compareKeys(key, entryKey)) {
- return index;
- } else {
- Object value = getRawValue(index);
- if (value instanceof CollisionLink) {
- entryValue = (CollisionLink) getRawValue(index);
- } else {
- return -1;
- }
- }
- }
- }
-
- private int getHashArray(int index) {
- if (entries.length < LARGE_HASH_THRESHOLD) {
- return (hashArray[index] & 0xFF);
- } else if (entries.length < VERY_LARGE_HASH_THRESHOLD) {
- int adjustedIndex = index << 1;
- return (hashArray[adjustedIndex] & 0xFF) | ((hashArray[adjustedIndex + 1] & 0xFF) << 8);
- } else {
- int adjustedIndex = index << 2;
- return (hashArray[adjustedIndex] & 0xFF) | ((hashArray[adjustedIndex + 1] & 0xFF) << 8) | ((hashArray[adjustedIndex + 2] & 0xFF) << 16) | ((hashArray[adjustedIndex + 3] & 0xFF) << 24);
- }
- }
-
- private void setHashArray(int index, int value) {
- if (entries.length < LARGE_HASH_THRESHOLD) {
- hashArray[index] = (byte) value;
- } else if (entries.length < VERY_LARGE_HASH_THRESHOLD) {
- int adjustedIndex = index << 1;
- hashArray[adjustedIndex] = (byte) value;
- hashArray[adjustedIndex + 1] = (byte) (value >> 8);
- } else {
- int adjustedIndex = index << 2;
- hashArray[adjustedIndex] = (byte) value;
- hashArray[adjustedIndex + 1] = (byte) (value >> 8);
- hashArray[adjustedIndex + 2] = (byte) (value >> 16);
- hashArray[adjustedIndex + 3] = (byte) (value >> 24);
- }
- }
-
- private int findAndRemoveHash(Object key) {
- int hashIndex = getHashIndex(key);
- int index = getHashArray(hashIndex) - 1;
- if (index != -1) {
- Object entryKey = getKey(index);
- if (compareKeys(key, entryKey)) {
- Object value = getRawValue(index);
- int nextIndex = -1;
- if (value instanceof CollisionLink) {
- CollisionLink collisionLink = (CollisionLink) value;
- nextIndex = collisionLink.next;
- }
- setHashArray(hashIndex, nextIndex + 1);
- return index;
- } else {
- Object entryValue = getRawValue(index);
- if (entryValue instanceof CollisionLink) {
- return findAndRemoveWithCollision(key, (CollisionLink) entryValue, index);
- }
- }
- }
-
- return -1;
- }
-
- private int findAndRemoveWithCollision(Object key, CollisionLink initialEntryValue, int initialIndexValue) {
- int index;
- Object entryKey;
- CollisionLink entryValue = initialEntryValue;
- int lastIndex = initialIndexValue;
- while (true) {
- CollisionLink collisionLink = entryValue;
- index = collisionLink.next;
- entryKey = getKey(index);
- if (compareKeys(key, entryKey)) {
- Object value = getRawValue(index);
- if (value instanceof CollisionLink) {
- CollisionLink thisCollisionLink = (CollisionLink) value;
- setRawValue(lastIndex, new CollisionLink(collisionLink.value, thisCollisionLink.next));
- } else {
- setRawValue(lastIndex, collisionLink.value);
- }
- return index;
- } else {
- Object value = getRawValue(index);
- if (value instanceof CollisionLink) {
- entryValue = (CollisionLink) getRawValue(index);
- lastIndex = index;
- } else {
- return -1;
- }
- }
- }
- }
-
- private int getHashIndex(Object key) {
- int hash;
- if (strategy != null && strategy != Equivalence.DEFAULT) {
- if (strategy == Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE) {
- hash = System.identityHashCode(key);
- } else {
- hash = strategy.hashCode(key);
- }
- } else {
- hash = key.hashCode();
- }
- hash = hash ^ (hash >>> 16);
- return hash & (getHashTableSize() - 1);
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public V put(K key, V value) {
- if (key == null) {
- throw new UnsupportedOperationException("null not supported as key!");
- }
- int index = find(key);
- if (index != -1) {
- Object oldValue = getValue(index);
- setValue(index, value);
- return (V) oldValue;
- }
-
- int nextEntryIndex = totalEntries;
- if (entries == null) {
- entries = new Object[INITIAL_CAPACITY << 1];
- } else if (entries.length == nextEntryIndex << 1) {
- grow();
-
- assert entries.length > totalEntries << 1;
- // Can change if grow is actually compressing.
- nextEntryIndex = totalEntries;
- }
-
- setKey(nextEntryIndex, key);
- setValue(nextEntryIndex, value);
- totalEntries++;
-
- if (hasHashArray()) {
- // Rehash on collision if hash table is more than three quarters full.
- boolean rehashOnCollision = (getHashTableSize() < (size() + (size() >> 1)));
- putHashEntry(key, nextEntryIndex, rehashOnCollision);
- } else if (totalEntries > getHashThreshold()) {
- createHash();
- }
-
- return null;
- }
-
- /**
- * Number of entries above which a hash table should be constructed.
- */
- private int getHashThreshold() {
- if (strategy == null || strategy == Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE) {
- return HASH_THRESHOLD_IDENTITY_COMPARE;
- } else {
- return HASH_THRESHOLD;
- }
- }
-
- private void grow() {
- int entriesLength = entries.length;
- int newSize = (entriesLength >> 1) + Math.max(MIN_CAPACITY_INCREASE, entriesLength >> 2);
- if (newSize > MAX_ELEMENT_COUNT) {
- throw new UnsupportedOperationException("map grown too large!");
- }
- Object[] newEntries = new Object[newSize << 1];
- System.arraycopy(entries, 0, newEntries, 0, entriesLength);
- entries = newEntries;
- if ((entriesLength < LARGE_HASH_THRESHOLD && newEntries.length >= LARGE_HASH_THRESHOLD) ||
- (entriesLength < VERY_LARGE_HASH_THRESHOLD && newEntries.length > VERY_LARGE_HASH_THRESHOLD)) {
- // Rehash in order to change number of bits reserved for hash indices.
- createHash();
- }
- }
-
- /**
- * Compresses the graph if there is a large number of deleted entries and returns the translated
- * new next index.
- */
- private int maybeCompress(int nextIndex) {
- if (entries.length != INITIAL_CAPACITY << 1 && deletedEntries >= (totalEntries >> 1) + (totalEntries >> 2)) {
- return compressLarge(nextIndex);
- }
- return nextIndex;
- }
-
- /**
- * Compresses the graph and returns the translated new next index.
- */
- private int compressLarge(int nextIndex) {
- int size = INITIAL_CAPACITY;
- int remaining = totalEntries - deletedEntries;
-
- while (size <= remaining) {
- size += Math.max(MIN_CAPACITY_INCREASE, size >> 1);
- }
-
- Object[] newEntries = new Object[size << 1];
- int z = 0;
- int newNextIndex = remaining;
- for (int i = 0; i < totalEntries; ++i) {
- Object key = getKey(i);
- if (i == nextIndex) {
- newNextIndex = z;
- }
- if (key != null) {
- newEntries[z << 1] = key;
- newEntries[(z << 1) + 1] = getValue(i);
- z++;
- }
- }
-
- this.entries = newEntries;
- totalEntries = z;
- deletedEntries = 0;
- if (z <= getHashThreshold()) {
- this.hashArray = null;
- } else {
- createHash();
- }
- return newNextIndex;
- }
-
- private int getHashTableSize() {
- if (entries.length < LARGE_HASH_THRESHOLD) {
- return hashArray.length;
- } else if (entries.length < VERY_LARGE_HASH_THRESHOLD) {
- return hashArray.length >> 1;
- } else {
- return hashArray.length >> 2;
- }
- }
-
- private void createHash() {
- int entryCount = size();
-
- // Calculate smallest 2^n that is greater number of entries.
- int size = getHashThreshold();
- while (size <= entryCount) {
- size <<= 1;
- }
-
- // Give extra size to avoid collisions.
- size <<= 1;
-
- if (this.entries.length >= VERY_LARGE_HASH_THRESHOLD) {
- // Every entry has 4 bytes.
- size <<= 2;
- } else if (this.entries.length >= LARGE_HASH_THRESHOLD) {
- // Every entry has 2 bytes.
- size <<= 1;
- } else {
- // Entries are very small => give extra size to further reduce collisions.
- size <<= 1;
- }
-
- hashArray = new byte[size];
- for (int i = 0; i < totalEntries; i++) {
- Object entryKey = getKey(i);
- if (entryKey != null) {
- putHashEntry(entryKey, i, false);
- }
- }
- }
-
- private void putHashEntry(Object key, int entryIndex, boolean rehashOnCollision) {
- int hashIndex = getHashIndex(key);
- int oldIndex = getHashArray(hashIndex) - 1;
- if (oldIndex != -1 && rehashOnCollision) {
- this.createHash();
- return;
- }
- setHashArray(hashIndex, entryIndex + 1);
- Object value = getRawValue(entryIndex);
- if (oldIndex != -1) {
- assert entryIndex != oldIndex : "this cannot happend and would create an endless collision link cycle";
- if (value instanceof CollisionLink) {
- CollisionLink collisionLink = (CollisionLink) value;
- setRawValue(entryIndex, new CollisionLink(collisionLink.value, oldIndex));
- } else {
- setRawValue(entryIndex, new CollisionLink(getRawValue(entryIndex), oldIndex));
- }
- } else {
- if (value instanceof CollisionLink) {
- CollisionLink collisionLink = (CollisionLink) value;
- setRawValue(entryIndex, collisionLink.value);
- }
- }
- }
-
- @Override
- public int size() {
- return totalEntries - deletedEntries;
- }
-
- @Override
- public boolean containsKey(K key) {
- return find(key) != -1;
- }
-
- @Override
- public void clear() {
- entries = null;
- hashArray = null;
- totalEntries = deletedEntries = 0;
- }
-
- private boolean hasHashArray() {
- return hashArray != null;
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public V removeKey(K key) {
- if (key == null) {
- throw new UnsupportedOperationException("null not supported as key!");
- }
- int index;
- if (hasHashArray()) {
- index = this.findAndRemoveHash(key);
- } else {
- index = this.findLinear(key);
- }
-
- if (index != -1) {
- Object value = getValue(index);
- remove(index);
- return (V) value;
- }
- return null;
- }
-
- /**
- * Removes the element at the specific index and returns the index of the next element. This can
- * be a different value if graph compression was triggered.
- */
- private int remove(int indexToRemove) {
- int index = indexToRemove;
- int entriesAfterIndex = totalEntries - index - 1;
- int result = index + 1;
-
- // Without hash array, compress immediately.
- if (entriesAfterIndex <= COMPRESS_IMMEDIATE_CAPACITY && !hasHashArray()) {
- while (index < totalEntries - 1) {
- setKey(index, getKey(index + 1));
- setRawValue(index, getRawValue(index + 1));
- index++;
- }
- result--;
- }
-
- setKey(index, null);
- setRawValue(index, null);
- if (index == totalEntries - 1) {
- // Make sure last element is always non-null.
- totalEntries--;
- while (index > 0 && getKey(index - 1) == null) {
- totalEntries--;
- deletedEntries--;
- index--;
- }
- } else {
- deletedEntries++;
- result = maybeCompress(result);
- }
-
- return result;
- }
-
- private abstract class SparseMapIterator<E> implements Iterator<E> {
-
- protected int current;
-
- @Override
- public boolean hasNext() {
- return current < totalEntries;
- }
-
- @Override
- public void remove() {
- if (hasHashArray()) {
- EconomicMapImpl.this.findAndRemoveHash(getKey(current - 1));
- }
- current = EconomicMapImpl.this.remove(current - 1);
- }
- }
-
- @Override
- public Iterable<V> getValues() {
- return new Iterable<V>() {
- @Override
- public Iterator<V> iterator() {
- return new SparseMapIterator<V>() {
- @SuppressWarnings("unchecked")
- @Override
- public V next() {
- Object result;
- while (true) {
- result = getValue(current);
- if (result == null && getKey(current) == null) {
- // values can be null, double-check if key is also null
- current++;
- } else {
- current++;
- break;
- }
- }
- return (V) result;
- }
- };
- }
- };
- }
-
- @Override
- public Iterable<K> getKeys() {
- return this;
- }
-
- @Override
- public boolean isEmpty() {
- return this.size() == 0;
- }
-
- @Override
- public MapCursor<K, V> getEntries() {
- return new MapCursor<K, V>() {
- int current = -1;
-
- @Override
- public boolean advance() {
- current++;
- if (current >= totalEntries) {
- return false;
- } else {
- while (EconomicMapImpl.this.getKey(current) == null) {
- // Skip over null entries
- current++;
- }
- return true;
- }
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public K getKey() {
- return (K) EconomicMapImpl.this.getKey(current);
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public V getValue() {
- return (V) EconomicMapImpl.this.getValue(current);
- }
-
- @Override
- public void remove() {
- if (hasHashArray()) {
- EconomicMapImpl.this.findAndRemoveHash(EconomicMapImpl.this.getKey(current));
- }
- current = EconomicMapImpl.this.remove(current) - 1;
- }
- };
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
- for (int i = 0; i < totalEntries; i++) {
- Object entryKey = getKey(i);
- if (entryKey != null) {
- Object newValue = function.apply((K) entryKey, (V) getValue(i));
- setValue(i, newValue);
- }
- }
- }
-
- private Object getKey(int index) {
- return entries[index << 1];
- }
-
- private void setKey(int index, Object newValue) {
- entries[index << 1] = newValue;
- }
-
- private void setValue(int index, Object newValue) {
- Object oldValue = getRawValue(index);
- if (oldValue instanceof CollisionLink) {
- CollisionLink collisionLink = (CollisionLink) oldValue;
- setRawValue(index, new CollisionLink(newValue, collisionLink.next));
- } else {
- setRawValue(index, newValue);
- }
- }
-
- private void setRawValue(int index, Object newValue) {
- entries[(index << 1) + 1] = newValue;
- }
-
- private Object getRawValue(int index) {
- return entries[(index << 1) + 1];
- }
-
- private Object getValue(int index) {
- Object object = getRawValue(index);
- if (object instanceof CollisionLink) {
- return ((CollisionLink) object).value;
- }
- return object;
- }
-
- private final boolean isSet;
-
- @Override
- public String toString() {
- StringBuilder builder = new StringBuilder();
- builder.append(isSet ? "set(size=" : "map(size=").append(size()).append(", {");
- String sep = "";
- MapCursor<K, V> cursor = getEntries();
- while (cursor.advance()) {
- builder.append(sep);
- if (isSet) {
- builder.append(cursor.getKey());
- } else {
- builder.append("(").append(cursor.getKey()).append(",").append(cursor.getValue()).append(")");
- }
- sep = ",";
- }
- builder.append("})");
- return builder.toString();
- }
-
- @Override
- public Iterator<K> iterator() {
- return new SparseMapIterator<K>() {
- @SuppressWarnings("unchecked")
- @Override
- public K next() {
- Object result;
- while ((result = getKey(current++)) == null) {
- // skip null entries
- }
- return (K) result;
- }
- };
- }
-
- @Override
- public boolean contains(K element) {
- return containsKey(element);
- }
-
- @SuppressWarnings("unchecked")
- @Override
- public boolean add(K element) {
- return put(element, (V) element) == null;
- }
-
- @Override
- public void remove(K element) {
- removeKey(element);
- }
-}