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58ea1442fd
This implementation is intentionally simple. If and when the need arises, we can always implement a more performant version. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
510 lines
11 KiB
Java
510 lines
11 KiB
Java
/* Copyright (c) 2008-2013, Avian Contributors
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Permission to use, copy, modify, and/or distribute this software
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for any purpose with or without fee is hereby granted, provided
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that the above copyright notice and this permission notice appear
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in all copies.
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There is NO WARRANTY for this software. See license.txt for
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details. */
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package java.util;
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public class HashMap<K, V> implements Map<K, V> {
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private static final int MinimumCapacity = 16;
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private int size;
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private Cell[] array;
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private final Helper helper;
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public HashMap(int capacity, Helper<K, V> helper) {
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if (capacity > 0) {
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array = new Cell[nextPowerOfTwo(capacity)];
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}
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this.helper = helper;
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}
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public HashMap(int capacity) {
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this(capacity, new MyHelper());
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}
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public HashMap() {
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this(0);
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}
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public HashMap(Map<K, V> map) {
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this(map.size());
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for (Map.Entry<K, V> entry : map.entrySet()) {
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put(entry.getKey(), entry.getValue());
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}
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}
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public String toString() {
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return Collections.toString(this);
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}
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private static int nextPowerOfTwo(int n) {
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int r = 1;
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while (r < n) r <<= 1;
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return r;
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}
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public boolean isEmpty() {
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return size() == 0;
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}
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public int size() {
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return size;
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}
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private void grow() {
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if (array == null || size >= array.length * 2) {
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resize(array == null ? MinimumCapacity : array.length * 2);
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}
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}
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private void shrink() {
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if (array.length / 2 >= MinimumCapacity && size <= array.length / 3) {
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resize(array.length / 2);
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}
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}
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private void resize(int capacity) {
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Cell<K, V>[] newArray = null;
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if (capacity != 0) {
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capacity = nextPowerOfTwo(capacity);
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if (array != null && array.length == capacity) {
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return;
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}
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newArray = new Cell[capacity];
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if (array != null) {
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for (int i = 0; i < array.length; ++i) {
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Cell<K, V> next;
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for (Cell<K, V> c = array[i]; c != null; c = next) {
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next = c.next();
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int index = c.hashCode() & (capacity - 1);
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c.setNext(newArray[index]);
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newArray[index] = c;
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}
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}
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}
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}
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array = newArray;
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}
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protected Cell<K, V> find(Object key) {
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if (array != null) {
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int index = helper.hash(key) & (array.length - 1);
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for (Cell<K, V> c = array[index]; c != null; c = c.next()) {
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if (helper.equal(key, c.getKey())) {
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return c;
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}
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}
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}
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return null;
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}
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private void insert(Cell<K, V> cell) {
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++ size;
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grow();
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int index = cell.hashCode() & (array.length - 1);
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cell.setNext(array[index]);
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array[index] = cell;
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}
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public void remove(Cell<K, V> cell) {
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int index = cell.hashCode() & (array.length - 1);
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Cell<K, V> p = null;
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for (Cell<K, V> c = array[index]; c != null; c = c.next()) {
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if (c == cell) {
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if (p == null) {
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array[index] = c.next();
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} else {
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p.setNext(c.next());
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}
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-- size;
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break;
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}
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}
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shrink();
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}
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private Cell<K, V> putCell(K key, V value) {
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Cell<K, V> c = find(key);
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if (c == null) {
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insert(helper.make(key, value, null));
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} else {
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c.setValue(value);
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}
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return c;
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}
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public boolean containsKey(Object key) {
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return find(key) != null;
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}
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public boolean containsValue(Object value) {
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if (array != null) {
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for (int i = 0; i < array.length; ++i) {
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for (Cell<K, V> c = array[i]; c != null; c = c.next()) {
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if (helper.equal(value, c.getValue())) {
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return true;
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}
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}
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}
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}
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return false;
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}
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public V get(Object key) {
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Cell<K, V> c = find(key);
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return (c == null ? null : c.getValue());
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}
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public Cell<K, V> removeCell(Object key) {
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Cell<K, V> old = null;
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if (array != null) {
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int index = helper.hash(key) & (array.length - 1);
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Cell<K, V> p = null;
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for (Cell<K, V> c = array[index]; c != null; c = c.next()) {
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if (helper.equal(key, c.getKey())) {
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old = c;
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if (p == null) {
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array[index] = c.next();
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} else {
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p.setNext(c.next());
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}
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-- size;
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break;
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}
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p = c;
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}
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shrink();
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}
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return old;
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}
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public V put(K key, V value) {
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Cell<K, V> c = find(key);
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if (c == null) {
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insert(helper.make(key, value, null));
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return null;
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} else {
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V old = c.getValue();
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c.setValue(value);
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return old;
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}
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}
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public void putAll(Map<? extends K,? extends V> elts) {
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for (Map.Entry<? extends K, ? extends V> entry : elts.entrySet()) {
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put(entry.getKey(), entry.getValue());
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}
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}
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public V remove(Object key) {
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Cell<K, V> c = removeCell((K)key);
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return (c == null ? null : c.getValue());
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}
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public void clear() {
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array = null;
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size = 0;
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}
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public Set<Entry<K, V>> entrySet() {
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return new EntrySet();
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}
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public Set<K> keySet() {
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return new KeySet();
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}
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public Collection<V> values() {
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return new Values();
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}
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Iterator<Entry<K, V>> iterator() {
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return new MyIterator();
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}
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interface Cell<K, V> extends Entry<K, V> {
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public HashMap.Cell<K, V> next();
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public void setNext(HashMap.Cell<K, V> next);
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}
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interface Helper<K, V> {
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public Cell<K, V> make(K key, V value, Cell<K, V> next);
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public int hash(K key);
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public boolean equal(K a, K b);
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}
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private static class MyCell<K, V> implements Cell<K, V> {
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public final K key;
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public V value;
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public Cell<K, V> next;
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public int hashCode;
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public MyCell(K key, V value, Cell<K, V> next, int hashCode) {
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this.key = key;
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this.value = value;
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this.next = next;
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this.hashCode = hashCode;
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}
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public K getKey() {
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return key;
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}
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public V getValue() {
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return value;
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}
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public V setValue(V value) {
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V old = this.value;
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this.value = value;
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return old;
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}
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public HashMap.Cell<K, V> next() {
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return next;
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}
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public void setNext(HashMap.Cell<K, V> next) {
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this.next = next;
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}
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public int hashCode() {
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return hashCode;
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}
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}
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static class MyHelper<K, V> implements Helper<K, V> {
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public Cell<K, V> make(K key, V value, Cell<K, V> next) {
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return new MyCell(key, value, next, hash(key));
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}
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public int hash(K a) {
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return (a == null ? 0 : a.hashCode());
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}
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public boolean equal(K a, K b) {
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return (a == null && b == null) || (a != null && a.equals(b));
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}
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}
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private class EntrySet extends AbstractSet<Entry<K, V>> {
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public int size() {
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return HashMap.this.size();
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}
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public boolean isEmpty() {
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return HashMap.this.isEmpty();
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}
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public boolean contains(Object o) {
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return (o instanceof Entry<?,?>)
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&& containsKey(((Entry<?,?>)o).getKey());
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}
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public boolean add(Entry<K, V> e) {
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return putCell(e.getKey(), e.getValue()) != null;
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}
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public boolean remove(Object o) {
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return (o instanceof Entry<?,?>) && remove((Entry<?,?>)o);
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}
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public boolean remove(Entry<K, V> e) {
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return removeCell(e.getKey()) != null;
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}
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public Object[] toArray() {
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return toArray(new Object[size()]);
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}
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public <T> T[] toArray(T[] array) {
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return Collections.toArray(this, array);
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}
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public void clear() {
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HashMap.this.clear();
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}
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public Iterator<Entry<K, V>> iterator() {
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return new MyIterator();
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}
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}
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private class KeySet extends AbstractSet<K> {
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public int size() {
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return HashMap.this.size();
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}
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public boolean isEmpty() {
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return HashMap.this.isEmpty();
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}
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public boolean contains(Object key) {
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return containsKey(key);
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}
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public boolean add(K key) {
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return putCell(key, null) != null;
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}
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public boolean remove(Object key) {
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return removeCell(key) != null;
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}
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public Object[] toArray() {
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return toArray(new Object[size()]);
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}
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public <T> T[] toArray(T[] array) {
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return Collections.toArray(this, array);
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}
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public void clear() {
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HashMap.this.clear();
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}
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public Iterator<K> iterator() {
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return new Collections.KeyIterator(new MyIterator());
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}
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}
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private class Values implements Collection<V> {
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public int size() {
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return HashMap.this.size();
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}
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public boolean isEmpty() {
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return HashMap.this.isEmpty();
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}
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public boolean contains(Object value) {
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return containsValue(value);
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}
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public boolean containsAll(Collection<?> c) {
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if (c == null) {
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throw new NullPointerException("collection is null");
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}
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Iterator<?> it = c.iterator();
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while (it.hasNext()) {
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if (! contains(it.next())) {
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return false;
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}
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}
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return true;
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}
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public boolean add(V value) {
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throw new UnsupportedOperationException();
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}
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public boolean addAll(Collection<? extends V> collection) {
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throw new UnsupportedOperationException();
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}
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public boolean remove(Object value) {
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throw new UnsupportedOperationException();
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}
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public boolean removeAll(Collection<?> c) {
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throw new UnsupportedOperationException();
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}
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public Object[] toArray() {
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return toArray(new Object[size()]);
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}
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public <T> T[] toArray(T[] array) {
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return Collections.toArray(this, array);
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}
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public void clear() {
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HashMap.this.clear();
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}
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public Iterator<V> iterator() {
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return new Collections.ValueIterator(new MyIterator());
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}
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}
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private class MyIterator implements Iterator<Entry<K, V>> {
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private int currentIndex = -1;
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private int nextIndex = -1;
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private Cell<K, V> previousCell;
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private Cell<K, V> currentCell;
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private Cell<K, V> nextCell;
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public MyIterator() {
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hasNext();
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}
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public Entry<K, V> next() {
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if (hasNext()) {
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if (currentCell != null) {
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if (currentCell.next() != null) {
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previousCell = currentCell;
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} else {
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previousCell = null;
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}
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}
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currentCell = nextCell;
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currentIndex = nextIndex;
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nextCell = nextCell.next();
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return currentCell;
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} else {
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throw new NoSuchElementException();
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}
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}
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public boolean hasNext() {
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if (array != null) {
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while (nextCell == null && ++ nextIndex < array.length) {
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if (array[nextIndex] != null) {
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nextCell = array[nextIndex];
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return true;
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}
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}
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}
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return nextCell != null;
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}
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public void remove() {
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if (currentCell != null) {
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if (previousCell == null) {
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array[currentIndex] = currentCell.next();
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} else {
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previousCell.setNext(currentCell.next());
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if (previousCell.next() == null) {
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previousCell = null;
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}
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}
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currentCell = null;
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-- size;
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} else {
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throw new IllegalStateException();
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}
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}
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}
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}
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