LongMap.java
- /*
- * Copyright (C) 2009, Google Inc. and others
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0 which is available at
- * https://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
- package org.eclipse.jgit.util;
- /**
- * Simple Map<long, Object>.
- *
- * @param <V>
- * type of the value instance.
- * @since 4.9
- */
- public class LongMap<V> {
- private static final float LOAD_FACTOR = 0.75f;
- private Node<V>[] table;
- /** Number of entries currently in the map. */
- private int size;
- /** Next {@link #size} to trigger a {@link #grow()}. */
- private int growAt;
- /**
- * Initialize an empty LongMap.
- */
- public LongMap() {
- table = createArray(64);
- growAt = (int) (table.length * LOAD_FACTOR);
- }
- /**
- * Whether {@code key} is present in the map.
- *
- * @param key
- * the key to find.
- * @return {@code true} if {@code key} is present in the map.
- */
- public boolean containsKey(long key) {
- return get(key) != null;
- }
- /**
- * Get value for this {@code key}
- *
- * @param key
- * the key to find.
- * @return stored value for this key, or {@code null}.
- */
- public V get(long key) {
- for (Node<V> n = table[index(key)]; n != null; n = n.next) {
- if (n.key == key)
- return n.value;
- }
- return null;
- }
- /**
- * Remove an entry from the map
- *
- * @param key
- * key to remove from the map.
- * @return old value of the key, or {@code null}.
- */
- public V remove(long key) {
- Node<V> n = table[index(key)];
- Node<V> prior = null;
- while (n != null) {
- if (n.key == key) {
- if (prior == null)
- table[index(key)] = n.next;
- else
- prior.next = n.next;
- size--;
- return n.value;
- }
- prior = n;
- n = n.next;
- }
- return null;
- }
- /**
- * Put a new entry into the map
- *
- * @param key
- * key to store {@code value} under.
- * @param value
- * new value.
- * @return prior value, or null.
- */
- public V put(long key, V value) {
- for (Node<V> n = table[index(key)]; n != null; n = n.next) {
- if (n.key == key) {
- final V o = n.value;
- n.value = value;
- return o;
- }
- }
- if (++size == growAt)
- grow();
- insert(new Node<>(key, value));
- return null;
- }
- private void insert(Node<V> n) {
- final int idx = index(n.key);
- n.next = table[idx];
- table[idx] = n;
- }
- private void grow() {
- final Node<V>[] oldTable = table;
- final int oldSize = table.length;
- table = createArray(oldSize << 1);
- growAt = (int) (table.length * LOAD_FACTOR);
- for (int i = 0; i < oldSize; i++) {
- Node<V> e = oldTable[i];
- while (e != null) {
- final Node<V> n = e.next;
- insert(e);
- e = n;
- }
- }
- }
- private final int index(long key) {
- int h = ((int) key) >>> 1;
- h ^= (h >>> 20) ^ (h >>> 12);
- return h & (table.length - 1);
- }
- @SuppressWarnings("unchecked")
- private static final <V> Node<V>[] createArray(int sz) {
- return new Node[sz];
- }
- private static class Node<V> {
- final long key;
- V value;
- Node<V> next;
- Node(long k, V v) {
- key = k;
- value = v;
- }
- }
- }