| /* |
| * 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; |
| } |
| } |
| } |