examples/src/joran/calculator/Calculator2.java

/*
 * Copyright 1999,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package joran.calculator;

import java.util.List;

import org.apache.log4j.joran.spi.Interpreter;
import org.apache.log4j.joran.spi.Pattern;
import org.apache.log4j.joran.spi.RuleStore;
import org.apache.log4j.joran.spi.SimpleRuleStore;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;


/**
 * This examples illustrates collaboration between multiple actions through the
 * common execution context stack.
 * 
 * It differs from Calculator1 in that it supoorts arbitrary nesting of 
 * computation elements.
 * 
 * You can test this application with the sample XML file <em>calculator3.xml</em>.
 * 
 * @author Ceki G&uuml;ulc&uuml;
 */
public class Calculator2 {
  public static void main(String[] args) throws Exception {

    RuleStore ruleStore = new SimpleRuleStore();

    // Note the wild card character '*', in the paterns, signifying any level 
    // of nesting.
    ruleStore.addRule(new Pattern("*/computation"), new ComputationAction2());

    ruleStore.addRule(new Pattern("*/computation/literal"), new LiteralAction());
    ruleStore.addRule(new Pattern("*/computation/add"), new AddAction());
    ruleStore.addRule(new Pattern("*/computation/multiply"), new MultiplyAction());
    
    // Create a new Joran Interpreter and hand it our simple rule store.
    Interpreter ji = new Interpreter(ruleStore);

    // Create a SAX parser
    SAXParserFactory spf = SAXParserFactory.newInstance();
    SAXParser saxParser = spf.newSAXParser();

    // Parse the file given as the application's first argument and
    // set the SAX ContentHandler to the Joran Interpreter we just created.
    saxParser.parse(args[0], ji);
    
    // The file has been parsed and interpreted. We now print any errors that 
    // might have occured.
    List errorList = ji.getExecutionContext().getErrorList();
    if(errorList.size() > 0) {
      System.out.println("The following errors occured:");
      for(int i = 0; i < errorList.size(); i++) {
        System.out.println("\t"+errorList.get(i));
      }
    }
  }
}