content: /*
   * 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.
   */
  
  package mf.org.apache.xerces.util;
  
  
  /**
   * This class is an unsynchronized hash table primary used for String
   * to Object mapping.
   * <p/>
   * The hash code uses the same algorithm as SymbolTable class.
   *
   * @author Elena Litani
   * @version $Id: SymbolHash.java 819653 2009-09-28 17:29:56Z knoaman $
   */
  public class SymbolHash {
  
      //
      // Constants
      //
  
      /**
       * Default table size.
       */
      protected int fTableSize = 101;
  
      //
      // Data
      //
  
      /**
       * Buckets.
       */
      protected Entry[] fBuckets;
  
      /**
       * Number of elements.
       */
      protected int fNum = 0;
  
      //
      // Constructors
      //
  
      /**
       * Constructs a key table with the default size.
       */
      public SymbolHash() {
          fBuckets = new Entry[fTableSize];
      }
  
      /**
       * Constructs a key table with a given size.
       *
       * @param size the size of the key table.
       */
      public SymbolHash(int size) {
          fTableSize = size;
          fBuckets = new Entry[fTableSize];
      }
  
      //
      // Public methods
      //
  
      /**
       * Adds the key/value mapping to the key table. If the key already exists,
       * the previous value associated with this key is overwritten by the new
       * value.
       *
       * @param key
       * @param value
       */
      public void put(Object key, Object value) {
          int bucket = (key.hashCode() & 0x7FFFFFFF) % fTableSize;
          Entry entry = search(key, bucket);
  
          // replace old value
          if (entry != null) {
              entry.value = value;
          }
          // create new entry
          else {
              entry = new Entry(key, value, fBuckets[bucket]);
              fBuckets[bucket] = entry;
              fNum++;
          }
      }
  
      /**
       * Get the value associated with the given key.
       *
       * @param key
       * @return the value associated with the given key.
       */
      public Object get(Object key) {
          int bucket = (key.hashCode() & 0x7FFFFFFF) % fTableSize;
          Entry entry = search(key, bucket);
          if (entry != null) {
              return entry.value;
          }
          return null;
      }
  
      /**
       * Get the number of key/value pairs stored in this table.
       *
       * @return the number of key/value pairs stored in this table.
       */
      public int getLength() {
          return fNum;
      }
  
      /**
       * Add all values to the given array. The array must have enough entry.
       *
       * @param elements the array to store the elements
       * @param from     where to start store element in the array
       * @return number of elements copied to the array
       */
      public int getValues(Object[] elements, int from) {
          for (int i = 0, j = 0; i < fTableSize && j < fNum; i++) {
              for (Entry entry = fBuckets[i]; entry != null; entry = entry.next) {
                  elements[from + j] = entry.value;
                  j++;
              }
          }
          return fNum;
      }
  
      /**
       * Return key/value pairs of all entries in the map
       */
      public Object[] getEntries() {
          Object[] entries = new Object[fNum << 1];
          for (int i = 0, j = 0; i < fTableSize && j < fNum << 1; i++) {
              for (Entry entry = fBuckets[i]; entry != null; entry = entry.next) {
                  entries[j] = entry.key;
                  entries[++j] = entry.value;
                  j++;
              }
          }
          return entries;
      }
  
      /**
       * Make a clone of this object.
       */
      public SymbolHash makeClone() {
          SymbolHash newTable = new SymbolHash(fTableSize);
          newTable.fNum = fNum;
          for (int i = 0; i < fTableSize; i++) {
              if (fBuckets[i] != null)
                  newTable.fBuckets[i] = fBuckets[i].makeClone();
          }
          return newTable;
      }
  
      /**
       * Remove all key/value assocaition. This tries to save a bit of GC'ing
       * by at least keeping the fBuckets array around.
       */
      public void clear() {
          for (int i = 0; i < fTableSize; i++) {
              fBuckets[i] = null;
          }
          fNum = 0;
      } // clear():  void
  
      protected Entry search(Object key, int bucket) {
          // search for identical key
          for (Entry entry = fBuckets[bucket]; entry != null; entry = entry.next) {
              if (key.equals(entry.key))
                  return entry;
          }
          return null;
      }
  
      //
      // Classes
      //
  
      /**
       * This class is a key table entry. Each entry acts as a node
       * in a linked list.
       */
      protected static final class Entry {
          // key/value
          public Object key;
          public Object value;
          /**
           * The next entry.
           */
          public Entry next;
  
          public Entry() {
              key = null;
              value = null;
              next = null;
          }
  
          public Entry(Object key, Object value, Entry next) {
              this.key = key;
              this.value = value;
              this.next = next;
          }
  
          public Entry makeClone() {
              Entry entry = new Entry();
              entry.key = key;
              entry.value = value;
              if (next != null)
                  entry.next = next.makeClone();
              return entry;
          }
      } // entry
  
  } // class SymbolHash
  
  