inthashtable.java

iText是一个能够快速产生PDF文件的java类库。iText的java类对于那些要产生包含文本

/*
 * This class is based on org.apache.IntHashMap.commons.lang
 * http://jakarta.apache.org/commons/lang/xref/org/apache/commons/lang/IntHashMap.html
 * It was adapted by Bruno Lowagie for use in iText,
 * reusing methods that were written by Paulo Soares.
 * Instead of being a hashtable that stores objects with an int as key,
 * it stores int values with an int as key.
 * 
 * This is the original license of the original class IntHashMap:
 * 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 * 
 * Note: originally released under the GNU LGPL v2.1, 
 * but rereleased by the original author under the ASF license (above).
 */

package com.lowagie.text.pdf;

import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;

/***
 * <p>A hash map that uses primitive ints for the key rather than objects.</p>
 *
 * <p>Note that this class is for internal optimization purposes only, and may
 * not be supported in future releases of Jakarta Commons Lang.  Utilities of
 * this sort may be included in future releases of Jakarta Commons Collections.</p>
 *
 * @author Justin Couch
 * @author Alex Chaffee ([e-mail])
 * @author Stephen Colebourne
 * @author Bruno Lowagie (change Objects as keys into int values)
 * @author Paulo Soares (added extra methods)
 */
public class IntHashtable implements Cloneable {

    /***
     * The hash table data.
     */
    private transient Entry table[];

    /***
     * The total number of entries in the hash table.
     */
    private transient int count;

    /***
     * The table is rehashed when its size exceeds this threshold.  (The
     * value of this field is (int)(capacity * loadFactor).)
     *
     * @serial
     */
    private int threshold;

    /***
     * The load factor for the hashtable.
     *
     * @serial
     */
    private float loadFactor;

    /***
     * <p>Constructs a new, empty hashtable with a default capacity and load
     * factor, which is <code>20</code> and <code>0.75</code> respectively.</p>
     */
    public IntHashtable() {
        this(150, 0.75f);
    }

    /***
     * <p>Constructs a new, empty hashtable with the specified initial capacity
     * and default load factor, which is <code>0.75</code>.</p>
     *
     * @param  initialCapacity the initial capacity of the hashtable.
     * @throws IllegalArgumentException if the initial capacity is less
     *   than zero.
     */
    public IntHashtable(int initialCapacity) {
        this(initialCapacity, 0.75f);
    }

    /***
     * <p>Constructs a new, empty hashtable with the specified initial
     * capacity and the specified load factor.</p>
     *
     * @param initialCapacity the initial capacity of the hashtable.
     * @param loadFactor the load factor of the hashtable.
     * @throws IllegalArgumentException  if the initial capacity is less
     *             than zero, or if the load factor is nonpositive.
     */
    public IntHashtable(int initialCapacity, float loadFactor) {
        super();
        if (initialCapacity < 0) {
            throw new IllegalArgumentException("Illegal Capacity: " + initialCapacity);
        }
        if (loadFactor <= 0) {
            throw new IllegalArgumentException("Illegal Load: " + loadFactor);
        }
        if (initialCapacity == 0) {
            initialCapacity = 1;
        }
        this.loadFactor = loadFactor;
        table = new Entry[initialCapacity];
        threshold = (int) (initialCapacity * loadFactor);
    }

    /***
     * <p>Returns the number of keys in this hashtable.</p>
     *
     * @return  the number of keys in this hashtable.
     */
    public int size() {
        return count;
    }

    /***
     * <p>Tests if this hashtable maps no keys to values.</p>
     *
     * @return  <code>true</code> if this hashtable maps no keys to values;
     *          <code>false</code> otherwise.
     */
    public boolean isEmpty() {
        return count == 0;
    }

    /***
     * <p>Tests if some key maps into the specified value in this hashtable.
     * This operation is more expensive than the <code>containsKey</code>
     * method.</p>
     *
     * <p>Note that this method is identical in functionality to containsValue,
     * (which is part of the Map interface in the collections framework).</p>
     *
     * @param      value   a value to search for.
     * @return     <code>true</code> if and only if some key maps to the
     *             <code>value</code> argument in this hashtable as
     *             determined by the <tt>equals</tt> method;
     *             <code>false</code> otherwise.
     * @throws  NullPointerException  if the value is <code>null</code>.
     * @see        #containsKey(int)
     * @see        #containsValue(int)
     * @see        java.util.Map
     */
    public boolean contains(int value) {

        Entry tab[] = table;
        for (int i = tab.length; i-- > 0;) {
            for (Entry e = tab[i]; e != null; e = e.next) {
                if (e.value == value) {
                    return true;
                }
            }
        }
        return false;
     }

    /***
     * <p>Returns <code>true</code> if this HashMap maps one or more keys
     * to this value.</p>
     *
     * <p>Note that this method is identical in functionality to contains
     * (which predates the Map interface).</p>
     *
     * @param value value whose presence in this HashMap is to be tested.
     * @return boolean <code>true</code> if the value is contained
     * @see    java.util.Map
     * @since JDK1.2
     */
    public boolean containsValue(int value) {
        return contains(value);
    }

    /***
     * <p>Tests if the specified int is a key in this hashtable.</p>
     *
     * @param  key  possible key.
     * @return <code>true</code> if and only if the specified int is a
     *    key in this hashtable, as determined by the <tt>equals</tt>
     *    method; <code>false</code> otherwise.
     * @see #contains(int)
     */
    public boolean containsKey(int key) {
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index]; e != null; e = e.next) {
            if (e.hash == hash && e.key == key) {
                return true;
            }
        }
        return false;
    }

    /***
     * <p>Returns the value to which the specified key is mapped in this map.</p>
     *
     * @param   key   a key in the hashtable.
     * @return  the value to which the key is mapped in this hashtable;
     *          <code>null</code> if the key is not mapped to any value in
     *          this hashtable.
     * @see     #put(int, int)
     */
    public int get(int key) {
        Entry tab[] = table;
        int hash = key;
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (Entry e = tab[index]; e != null; e = e.next) {
            if (e.hash == hash && e.key == key) {
                return e.value;
            }
        }
        return 0;
    }

    /***
     * <p>Increases the capacity of and internally reorganizes this
     * hashtable, in order to accommodate and access its entries more
     * efficiently.</p>
     *
     * <p>This method is called automatically when the number of keys
     * in the hashtable exceeds this hashtable's capacity and load
     * factor.</p>
     */
    protected void rehash() {