org.jboss.marshalling.util.IdentityIntMap Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source
* Copyright 2008, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.marshalling.util;
import java.util.Arrays;
/**
* An efficient identity object map whose keys are objects and whose values are {@code int}s.
*/
public final class IdentityIntMap implements Cloneable {
private int[] values;
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 IdentityIntMap(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];
values = new int[initialCapacity];
resizeCount = (int) ((double) initialCapacity * (double) loadFactor);
}
/**
* Clone this map.
*
* @return a cloned map
*/
@SuppressWarnings({ "unchecked" })
public IdentityIntMap clone() {
try {
final IdentityIntMap clone = (IdentityIntMap) super.clone();
clone.values = values.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 IdentityIntMap(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 IdentityIntMap(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 IdentityIntMap() {
this(0.5f);
}
/**
* Get a value from the map.
*
* @param key the key
* @param defVal the value to return if the key is not found
* @return the map value at the given key, or the value of {@code defVal} if it's not found
*/
public int get(T key, int defVal) {
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 values[hc];
}
if (v == null) {
// not found
return defVal;
}
hc = (hc + 1) & mask;
}
}
/**
* Put a value into the map. Any previous mapping is discarded silently.
*
* @param key the key
* @param value the value to store
*/
public void put(T key, int value) {
final Object[] keys = this.keys;
final int mask = keys.length - 1;
final int[] values = this.values;
Object v;
int hc = System.identityHashCode(key) & mask;
for (int idx = hc;; idx = hc++ & mask) {
v = keys[idx];
if (v == null) {
keys[idx] = key;
values[idx] = value;
if (++count > resizeCount) {
resize();
}
return;
}
if (v == key) {
values[idx] = value;
return;
}
}
}
private void resize() {
final Object[] oldKeys = keys;
final int oldsize = oldKeys.length;
final int[] oldValues = values;
if (oldsize >= 0x40000000) {
throw new IllegalStateException("Table full");
}
final int newsize = oldsize << 1;
final int mask = newsize - 1;
final Object[] newKeys = new Object[newsize];
final int[] newValues = new int[newsize];
keys = newKeys;
values = newValues;
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;
newValues[ni] = oldValues[oi];
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("Map 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(") => ").append(values[i]).append(" }");
} else {
builder.append("(blank)");
}
builder.append('\n');
}
return builder.toString();
}
}