org.jboss.marshalling.util.IdentityIntSet Maven / Gradle / Ivy
/*
* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.marshalling.util;
import java.util.Arrays;
/**
* An efficient identity object set.
*/
public final class IdentityIntSet implements Cloneable {
private Object[] keys;
private int count;
private int resizeCount;
/**
* Construct a new instance with the given initial capacity and load factor.
*
* @param initialCapacity the initial capacity
* @param loadFactor the load factor
*/
public IdentityIntSet(int initialCapacity, final float loadFactor) {
if (initialCapacity < 1) {
throw new IllegalArgumentException("initialCapacity must be > 0");
}
if (loadFactor <= 0.0f || loadFactor >= 1.0f) {
throw new IllegalArgumentException("loadFactor must be > 0.0 and < 1.0");
}
if (initialCapacity < 16) {
initialCapacity = 16;
} else {
// round up
final int c = Integer.highestOneBit(initialCapacity) - 1;
initialCapacity = Integer.highestOneBit(initialCapacity + c);
}
keys = new Object[initialCapacity];
resizeCount = (int) ((double) initialCapacity * (double) loadFactor);
}
/**
* Clone this set.
*
* @return a cloned set
*/
@SuppressWarnings({ "unchecked" })
public IdentityIntSet clone() {
try {
final IdentityIntSet clone = (IdentityIntSet) super.clone();
clone.keys = keys.clone();
return clone;
} catch (CloneNotSupportedException e) {
throw new IllegalStateException();
}
}
/**
* Construct a new instance with the given load factor and an initial capacity of 64.
*
* @param loadFactor the load factor
*/
public IdentityIntSet(final float loadFactor) {
this(64, loadFactor);
}
/**
* Construct a new instance with the given initial capacity and a load factor of {@code 0.5}.
*
* @param initialCapacity the initial capacity
*/
public IdentityIntSet(final int initialCapacity) {
this(initialCapacity, 0.5f);
}
/**
* Construct a new instance with an initial capacity of 64 and a load factor of {@code 0.5}.
*/
public IdentityIntSet() {
this(0.5f);
}
/**
* Check to see if this set contains a value.
*
* @param key the key
* @return {@code true} if the object is present in the set
*/
public boolean contains(T key) {
final Object[] keys = this.keys;
final int mask = keys.length - 1;
int hc = System.identityHashCode(key) & mask;
Object v;
for (;;) {
v = keys[hc];
if (v == key) {
return true;
}
if (v == null) {
// not found
return false;
}
hc = (hc + 1) & mask;
}
}
/**
* Add a value into the set, if it's not already in there.
*
* @param key the key
* @return {@code true} if the object was added, or {@code false} if it was already in the set
*/
public boolean add(T key) {
final Object[] keys = this.keys;
final int mask = keys.length - 1;
Object v;
int hc = System.identityHashCode(key) & mask;
for (int idx = hc;; idx = hc++ & mask) {
v = keys[idx];
if (v == null) {
keys[idx] = key;
if (++count > resizeCount) {
resize();
}
return true;
}
if (v == key) {
return false;
}
}
}
private void resize() {
final Object[] oldKeys = keys;
final int oldsize = oldKeys.length;
if (oldsize >= 0x40000000) {
throw new IllegalStateException("Table full");
}
final int newsize = oldsize << 1;
final int mask = newsize - 1;
final Object[] newKeys = new Object[newsize];
keys = newKeys;
if ((resizeCount <<= 1) == 0) {
resizeCount = Integer.MAX_VALUE;
}
for (int oi = 0; oi < oldsize; oi ++) {
final Object key = oldKeys[oi];
if (key != null) {
int ni = System.identityHashCode(key) & mask;
for (;;) {
final Object v = newKeys[ni];
if (v == null) {
// found
newKeys[ni] = key;
break;
}
ni = (ni + 1) & mask;
}
}
}
}
public void clear() {
Arrays.fill(keys, null);
count = 0;
}
/**
* Get a string summary representation of this map.
*
* @return a string representation
*/
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Set length = ").append(keys.length).append(", count = ").append(count).append(", resize count = ").append(resizeCount).append('\n');
for (int i = 0; i < keys.length; i ++) {
builder.append('[').append(i).append("] = ");
if (keys[i] != null) {
final int hc = System.identityHashCode(keys[i]);
builder.append("{ ").append(keys[i]).append(" (hash ").append(hc).append(", modulus ").append(hc % keys.length).append(") }");
} else {
builder.append("(blank)");
}
builder.append('\n');
}
return builder.toString();
}
}