[antlr-interest] Parsing multiple messages using one parser

[Andy Tripp]

Here are my ReusableJavaParser and ReusableJavaLexer classes.
The comments refer to the relevant mailing list post.
Call resetState() and prepareNextInput() rather than creating new
parser and lexer objects.

Andy

/**
 * The <code>ReusableJavaParser</code> class allows you to create
 * one instanceofan ANTLR-generated parser that you
* can reuse over and over. see
* http://www.antlr.org/pipermail/antlr-interest/2003-April/003631.html
 *
 * @author  Andy Tripp
 */

public class ReusableJavaParser extends JavaRecognizer {

        public ReusableJavaParser(TokenStream lexer) {
                super(lexer);
        }

        public void resetState() {
                // no set method for this protected field.
                this.traceDepth = 0;
                this.getInputState().reset();
        }
}

/**
 * The <code>ReusableJavaLexer</code> class allows you to create one
 * instanceof an ANTLR-generated lexer that you
 * can reuse over and over. See
 * <a 
href="http://www.antlr.org/pipermail/antlr-interest/2003-April/003631.html">here</a>.
  *
 * @author  Andy Tripp
 */
public class ReusableJavaLexer extends JavaLexer {
        private boolean savedCaseSensitive;
        private boolean savedCaseSensitiveLiterals;

        public ReusableJavaLexer(Reader in) {
                super(in);
                savedCaseSensitive = getCaseSensitive();
                savedCaseSensitiveLiterals = getCaseSensitiveLiterals();
        }

        public void prepareNextInput(Reader in) {

                LexerSharedInputState state = new LexerSharedInputState(in);
                this.setInputState(state);

                this.setCaseSensitive(savedCaseSensitive);

                // no set method for this protected field.
                this.caseSensitiveLiterals = savedCaseSensitiveLiterals;
        }
}