CaseBlindHashMap.java

/*
Copyright (c) 2000-2003 Board of Trustees of Leland Stanford Jr. University,
all rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in
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*/

package edu.indiana.lib.twinpeaks.util;

import java.io.*;
import java.util.*;

/**
 * CaseBlindHashMap - a HashMap extension, using <code>String</code>s as
 * key values.
 * <p>
 * Internally, keys are case insensitive: <code>ABC</code> = <code>abc</code>.
 * <p>
 * Two methods have been added to facilitate working with Sets of key strings.
 * See <code>stringKeySet()</code> and <code>stringKeyIterator()</code>.
 */
public class CaseBlindHashMap extends HashMap {

private static org.apache.commons.logging.Log	_log = LogUtils.getLog(CaseBlindHashMap.class);

  /**
   * Constructors
   */
  public CaseBlindHashMap() {
    super();
  }

  public CaseBlindHashMap(CaseBlindHashMap map) {
    super(map);
  }

  public CaseBlindHashMap(int initCap) {
    super(initCap);
  }

  public CaseBlindHashMap(int initCap, float loadFactor) {
    super(initCap, loadFactor);
  }

  /*
   * Extensions
   */

  /**
   * Get the set of keys contained in this map.  Keys values are returned as
   * simple <code>String</code>s (not the <code>CaseBlindString</code>s used
   * internally).
   *<p>
   * This is accopmlished by making a copy of the original map - modifications
   * made to this copy are not reflected in the original.
   *
   * @return The set of keys
   */
  public Set stringKeySet() {
    Iterator iterator   = super.keySet().iterator();
    HashMap  stringKeys = new HashMap();

    while (iterator.hasNext()) {
      String key = ((CaseBlindString) iterator.next()).toString();

      stringKeys.put(key, get(key));
    }
    return stringKeys.keySet();
  }

  /**
   * Get an Iterator to the String based key set
   * @return An iterator to the key set
   */
  public Iterator stringKeyIterator() {
    return stringKeySet().iterator();
  }

  /*
   * Overridden HashMap methods
   */

  /**
   * Does the map contain this key?
   * @param key The key to look up
   * @return true If the key is present in the map
   */
  public boolean containsKey(String key) {
    return super.containsKey(new CaseBlindString(key));
  }

  /**
   * Fetch a value by name - null keys are not supported
   * @param key The key to look up
   * @return The associated value object
   */
  public Object get(String key) {
     return super.get(new CaseBlindString(key));
  }

  /**
   * Add the key/value pair to the map - null values are not supported
   * @param key The key name
   * @param value The object to store
   */
  public void put(String key, Object value) {
    super.put(new CaseBlindString(key), value);
  }

  /**
   * Remove a key/value pair from this map
   * @param key Non-null key to remove
   */
  public void remove(String key) {
    if (key == null) {
      throw new UnsupportedOperationException("null key");
    }
    super.remove(new CaseBlindString(key));
  }

  /**
   * A crude, case insensitive string - used internally to represent
   * key values.  Preserve the originl case, but compare for equality
   * in a case blind fashion.
   */
  public static class CaseBlindString {

    String string;

    /**
     * Constructors
     */
    private CaseBlindString() {
    }

    public CaseBlindString(String string) {
      this.string = string;
    }

    /**
     * Fetch the original string
     * @return The original string
     */
    public String toString() {
      return string;
    }

    /**
     * Case insensitive compare
     * @return True if the two strings match
     */
    public boolean equals(Object object) {
      if (string == null) {
        return string == null;
      }
      return string.equalsIgnoreCase(((CaseBlindString) object).toString());
    }

    /**
     * Get a hash code for this case insensitive string
     * @return Hash code value
     */
    public int hashCode() {
      if (string == null) {
        return "null".hashCode();
      }
      return string.toUpperCase().hashCode();
    }
  }
}