hashfinder.java

linux下建立JAVA虚拟机的源码KAFFE

package gnu.classpath.tools.giop.grmic;

import java.util.HashSet;

/**
 * This class finds the hash character (the most different character in
 * the passed array of strings). This character is used to accelerate the
 * method invocation by name.
 *
 * @author Audrius Meskauskas ([e-mail]) 
 */
public class HashFinder
{
   /**
   * Find the hash char position in the given collection of strings.
   * 
   * @param strings the string collection
   * 
   * @return the optimal hash character position, always less then the
   * length of the shortest string.
   */
  public int findHashCharPosition(String[] strings)
  {
    // Find the length of the shortest string:

    int l = strings[0].length();
    for (int i = 1; i < strings.length; i++)
      {
        if (strings[i].length() < l)
          l = strings[i].length();
      }

    // Find the position with the smallest number of the matching characters:
    HashSet[] charLists = new HashSet[l];

    for (int i = 0; i < charLists.length; i++)
      {
        charLists[i] = new HashSet(strings.length);
      }

    for (int i = 0; i < strings.length; i++)
      for (int p = 0; p < l; p++)
        {
          charLists[p].add(new Integer(strings[i].charAt(p)));
        }
    
    int m = 0;
    int v = charLists[0].size();
    
    for (int i = 1; i < charLists.length; i++)
      {
        // Replace on equality also, seeking the hash char closer to the end
        // of line.
        if (charLists[i].size()>=v)
          {
            m = i;
            v = charLists[i].size();
          }
      }
    return m;
  }
}