Re: Keeping the split token in a Java regular expression

ram@zedat.fu-berlin.de (Stefan Ram) writes:


  Thanks for the comments! I believe Jim's answer was most
  close to what the OP asked for, and Robert is right with
  most of his criticism.

  As someone said regular expressions were too much overhead,
  I tried a solution without regular expressions (with custom
  pattern matching); it was not thoroughly tested, though:

final class Tracer
{ private int pos = 0;
  private boolean matched = false;
  private final boolean advance(){ ++this.pos; return false; }
  public final boolean reset()
  { this.pos = 0; this.matched = false; return false; }
  public final boolean matched(){ return this.matched; }
  public final boolean accept( final char c )
  { final char ch = java.lang.Character.toLowerCase( c );
    switch( pos )
    { case 0: /* the pattern is hardcoded below */
      return ch == 'a' || ch == 'p' ? this.advance(): this.reset();
      case 1:
      if( ch == 'm' ){ this.matched = true; return true; }
      else { --pos; return this.accept( c ); }
      default: this.reset(); return false; }}}

final class Splitter
{
  private final java.util.List<java.lang.CharSequence> target
  = new java.util.ArrayList<java.lang.CharSequence>();

  private final int comma
  ( final java.lang.CharSequence text, final int i, final int length )
  { final int j = i + 1;
    return j < length ? text.charAt( j ) == ',' ? j : i : j; }

  public final java.util.List<java.lang.CharSequence> split
  ( final java.lang.CharSequence text )
  { final Tracer tracer = new Tracer();
    final int length = text.length();
    int l = 0;
    for( int i = 0; i < length; ++i )
    { tracer.accept( text.charAt( i ));
      if( tracer.matched() )
      { i = comma( text, i, length );
        this.target.add( text.subSequence( l, i ));
        tracer.reset();
        l = i + 1; }}
    return target; }}

public final class Main
{
  public static void main( final java.lang.String[] args )
  {
    java.lang.System.out.println
    ( new Splitter().split
      ( "Fri 7:30 PM, Sat 2 PM, Sun 2:30 PM" )); }}

[Fri 7:30 PM, Sat 2 PM, Sun 2:30 PM]