Using Regular Expressions to Find Quoted Text

Question

I have run into a couple problems with the following code.
1) Slash-Star and Slash-Slash commented text must be ignored.
2) It does not detect backslashed quotes, or if that backslash is backslashed.
Can this be accomplished with Regular Expressions, or should I implement this using if/indexOf logic?
Thank You in advance,
Brian
    * Finds position of next quoted string in a line
    * of source code.
    * If no strings exist, then a Pointer position of
    * (0,0) is returned.
    * @param startPos position to start search from
    * @param argText  the line of text to search
    * @returns next string position
   public Pointer getQuotedStringPosition(int startPos, String aString) {
      String argText = new String( aString );
      Pattern p = Pattern.compile("[\"][^\"]+[\"]");
      Matcher m = p.matcher( argText.substring(startPos); );
      if( m.find() )
         return new Pointer( m.start() + startPos, m.end() + startPos );
      else
         return new Pointer( 0, 0 ); // indicates nothing was found
   }

Answer 1

YATArchivist was right about the regular expressions.
I think I've got it but somebody test it if you want. Let me know what you find.
I've included a barebones Position class as well...
import java.util.regex.*;
import java.io.*;
import java.util.*;
  @author Joshua A. Logan, Jr.
public class RegexTest
   private static final String SLASH_SLASH = "(//.*)";
   private static final String SLASH_STAR =
                           "(/\\*(?:[^\\*]|(?:\\*(?!/)))+(\\*/)?)";
   private static final Pattern COMMENT_PATTERN =
                     Pattern.compile( SLASH_SLASH + "|" + SLASH_STAR );
   private static final Pattern QUOTED_STRING_PATTERN =
                  Pattern.compile( "\"  ( (?:(\\\\.) | [^\\\"])*+  )     \"",
                                   Pattern.COMMENTS );
   // Breaking the above regular expression down, you'd have:
   //   "  ( (?: (\\ .)  |  [^\\ "]  ) *+ )   "
   //   ^          ^     ^     ^       ^      ^
   //   |          |     |     |       |      |
   //   1          2     3     4       5      6
   // which matches:
   // 1) The starting quote...
   // Followed by something that is either:
   // 2) some escaped sequence ( e.g. _\n_  or even _\"_ ),
   // 3)                ...or...
   // 4) a character that is neither a _\_ nor a _"_ .
   // 5) Keep searching this as much as possible, w/o giving up
   //                    any found text at the end.
   //        Note: the text found would be in group(1)
   // 6) Finally, find the ending quote!!
   public static Position [] getQuotedStringPosition( final String text )
      Matcher cm = COMMENT_PATTERN.matcher( text ),
              qm = QUOTED_STRING_PATTERN.matcher( text );
      final int len = text.length();
      int startPos = 0;
      List positions = new ArrayList();
      while ( startPos < len )
         if ( cm.find(startPos) )
            int commStart = cm.start(),
                commEnd   = cm.end();
            // are we starting @ a comment?
            if ( commStart == startPos )
               startPos = commEnd;
            else if ( qm.find(startPos) )
               // Search for unescaped strings in here.
               int stringStart = qm.start(1),
                   stringEnd   = qm.end(1);
               // Is the quote start after comment start?
               if ( stringStart > commStart )
                  startPos = commEnd; // restart search after comment end...
               else if ( (stringEnd > commEnd) ||
                         (stringEnd < commStart) )
                  // In this case, the "comment" is actually part of
                  // the quoted string. We found a match.
                  positions.add( new Position(text, qm.group(1),
                                              stringStart,
                                              stringEnd) );
                  int quoteEnd = qm.end();
                  startPos = quoteEnd;
               else
                  throw new IllegalStateException( "illegal case" );
            else
               startPos = commEnd;
         else
            // no comments were found. Search for unescaped strings.
            int quoteEnd = len;
            if ( qm.find( startPos ) ) {
               quoteEnd = qm.end();
               positions.add( new Position(text,
                                           qm.group(1),
                                           qm.start(1),
                                           qm.end(1)) );
            startPos = quoteEnd;
      return positions.isEmpty() ? Position.EMPTY_ARRAY
                                 : (Position[])positions.toArray(
                                          Position.EMPTY_ARRAY);
   public static void main( String [] args )
      try
         BufferedReader br = new BufferedReader(
                  new InputStreamReader(System.in) );
         String input = null;
         final String prompt = "\nText (q to quit): ";
         System.out.print( prompt );
         while ( (input = br.readLine()) != null )
            if ( input.equals("q") ) return;
            Position [] matches = getQuotedStringPosition( input );
            // What does it do?
            for ( int i = 0, max = matches.length; i < max; i++ )
               System.out.println( "-->" + matches[i] );
            System.out.print( prompt );
      catch ( Exception e )
         System.out.println ( "Exception caught: " + e.getMessage () );
class Position
   public Position( String target,
                    String match,
                    int start,
                    int end )
      this.target = target;
      this.match = match;
      this.start = start;
      this.end = end;
   public String toString()
      return "match==" + match + ",{" + start + "," + end + "}";
   final String target;
   final int start;
   final int end;
   final String match;
   public static final Position [] EMPTY_ARRAY = { };
}