Perl list emulation in Java...

I don't know where to put this code, because it's a Java emulation of some of the perl list's common functions. Even though it's Java, I thought folks might be interested and/or amused to see where my whimsy takes me.

//package gen.eaglestone.util;

import java.util.*;

/*****************************************************************
*
*  PerlList roughly imitates the perl list type, providing
*  the following methods:
*
*            push( Object  scalar )
*            push( Object[] array )
*            push( PerlList list  )
*
*   Object   pop()
*
*            unshift( Object  scalar )
*            unshift( Object[] array )
*            unshift( PerlList list  )
*
*   Object   shift()
*
* # PerlList split( String delims, String scalar )
*
*   String   join( String joiner )
* # String   join( String joiner, PerlList[] lists )
*
*   Object   $( int index )
*****************************************************************/
[download]

public class PerlList extends Vector
{
   /*************************************************************
   * 
   *    constructors
   * 
   *************************************************************/
   public PerlList()
   {
      super();
   }
   
   public PerlList( int cap )
   {
      super( cap );
   }
   
   /*************************************************************
   * 
   *    push() and pop()
   * 
   *************************************************************/
   public void push( PerlList list )
   {
      Enumeration elems = list.elements();
      
      while( elems.hasMoreElements() )
         addElement( elems.nextElement() );
   }
   
   public void push( Object[] elems )
   {
      for( int i=0; i<elems.length; i++ )
         addElement( elems[i] );
   }

   public void push( Object scalar )
   {
      addElement( scalar );
   }
   
   public Object pop()
   {
      Object scalar = lastElement();
      removeElement( scalar );
      
      return scalar;
   }
   
   /*************************************************************
   * 
   *    shift() and unshift()
   * 
   *************************************************************/
   public Object shift()
   {
      Object scalar = firstElement();
      removeElement( scalar );
      
      return scalar;
   }
   
   public void unshift( Object scalar )
   {
      insertElementAt( scalar, 0 );
   }
     
   public void unshift( Object[] elems )
   {
      for( int i=0; i<elems.length; i++ )
         insertElementAt( elems[i], 0 );
   }
    
   public void unshift( PerlList list )
   {
      Enumeration elems = list.elements();
      
      while( elems.hasMoreElements() )
         insertElementAt( elems.nextElement(), 0 );
   }
   
   /*************************************************************
   * 
   *    split() and join()
   * 
   *************************************************************/
   
   public static PerlList split( String delims, String scalar )
   {
      PerlList l = new PerlList();
      
      StringTokenizer tok = new StringTokenizer( scalar, delims );
      
      while( tok.hasMoreTokens() )
      {
         l.push( tok.nextToken() );
      }
      
      return l;
   }
   
   public String join( String joiner )
   {
      StringBuffer buf   = new StringBuffer();
      Enumeration  elems = elements();
      
      if( elems.hasMoreElements() )
      {
         buf.append( (String) elems.nextElement() );
      }
      
      while( elems.hasMoreElements() )
      {
         buf.append( joiner );
         buf.append( (String) elems.nextElement() );
      }
      
      return buf.toString();      
   }
   
   
   public static String join( String joiner, PerlList[] list )
   {
      PerlList nu = new PerlList();
      
      for( int i=0; i<list.length; i++ )
         nu.push( list[i] );
         
      return nu.join( joiner );
   }
   
   
   /*************************************************************
   * 
   *    default access
   * 
   *************************************************************/
   public Object $( int index )
   {
      return (String) elementAt( index );
   }
   
   
   /*************************************************************
   * 
   *    test
   * 
   *************************************************************/
   public static void main( String args[] )
   {
      String a = "abcd 123-4 b  ag ag ag   x 567";
      
      PerlList pl = PerlList.split( " ", a );
      
      System.out.println( pl.join( "\n" ) );
      System.out.println( pl.$(0) );
   }

}
[download]

Comment on Perl list emulation in Java... Select or Download Code

Replies are listed 'Best First'.
(Ovid) Re: Perl list emulation in Java... by Ovid (Cardinal) on Jan 09, 2002 at 03:02 UTC
Interestingly, this is not terribly uncommon. While living in Amsterdam and being forced to endure the hell that is VBScript, I wrote many of the same routines for that language. Like you, though, I failed to emulate them properly. For example, push actually returns the number of elements added to the array: `public int push( PerlList list ) { Enumeration elems = list.elements(); while( elems.hasMoreElements() ) addElement( elems.nextElement() ); return list.size(); }` [download] Of course, I can't help but wonder if that's a waste of time. I don't recall ever seeing any code that actually checks that return value, but then, if you're going to emulate... :) Cheers, Ovid Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l]
(RhetTbull) Re: Perl list emulation in Java... by RhetTbull (Curate) on Jan 09, 2002 at 06:51 UTC
Cool. I suggest posting this over on the Java Junkies site.	[reply]
Re: Perl list emulation in Java... by mdog (Pilgrim) on Jan 09, 2002 at 23:23 UTC
Very Cool! Whenever I dabble in Java, I always wish that I could just use the functions I am used to... If you have any more Perl-esque Java, I'd be interested in seeing it. Lazy Mdog	[reply]


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