Antlr

ANTLR is a parser generator tool.

BITPlan has been using ANTLR in projects for a few years now and Wolfgang Fahl has been active in improving ANTLR see e.g. #Motivation

Library with helpers for ANTLR Language development com.bitplan.antlr

To simplify Parser development with ANTLR BITPlan has created a library with some helper code for ANTLR Language Development and published it as Open Source at:

• https://github.com/BITPlan/com.bitplan.antlr

Base Class Language Parser

The abstract base class LanguageParser has some help code that makes language development and debugging easier.

Example

/**
 * example parser
 * @author wf
 *
 */
public class ExpLanguageParser extends LanguageParser {
  private ExpParser parser;
  ExpLexer lexer;
  
  public ExpParser getParser() {
    return parser;
  }
  
  @Override
  protected ParseTree getRootContext(Parser parser) {
    if (!(parser instanceof ExpParser)) {
      throw new RuntimeException("wrong parser type for getRootContext, expected Rule but got "+parser.getClass().getName());
    } else {
      ExpParser expParser=(ExpParser) parser;
      return expParser.eval();
    }
  }

  @Override
  protected ParseTree parse(ANTLRInputStream in, String inputText)
      throws Exception {
    lexer = new ExpLexer(in);
    parser=new ExpParser(getTokens(lexer));
    ParseTree result=super.parse(lexer,getParser());
    return result;
  }

  @Override
  public void showParseTree() {
    super.showParseTree(getParser());
  }

}

Motivation

• https://github.com/antlr/antlr4/issues/994

Prerequisites

• https://github.com/bkiers/rrd-antlr4