ConditionProcessor.java

/*
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version. You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

package org.aitools.programd.processor.aiml;

import java.util.List;

import org.aitools.programd.Core;
import org.aitools.programd.parser.TemplateParser;
import org.aitools.programd.processor.ProcessorException;
import org.aitools.programd.util.NotAnAIMLPatternException;
import org.aitools.programd.util.PatternArbiter;
import org.jdom.Element;

/**
 * Handles a <code><a href="http://aitools.org/aiml/TR/2001/WD-aiml/#section-condition">condition</a></code> element.
 * 
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class ConditionProcessor extends AIMLProcessor {

  /** The wo types of <code>condition</code> that have <code>li</code> children. */
  public static enum NonBlockConditionType {
    /** A <code>singlePredicateCondition</code>. */
    SINGLE_PREDICATE,

    /** A <code>multiPredicateCondition</code>. */
    MULTI_PREDICATE
  }

  /** The label (as required by the registration scheme). */
  public static final String label = "condition";

  /**
   * Creates a new ConditionProcessor using the given Core.
   * 
   * @param core the Core object to use
   */
  public ConditionProcessor(Core core) {
    super(core);
  }

  /**
   * @throws ProcessorException
   * @see AIMLProcessor#process(Element, TemplateParser)
   */
  @SuppressWarnings("unchecked")
  @Override
  public String process(Element element, TemplateParser parser) throws ProcessorException {
    String name = element.getAttributeValue("name");
    String value = element.getAttributeValue("value");

    try {
      /*
       * Process a blockCondition: <condition name="xxx" value="yyy"> ... </condition>
       */
      if (name != null && value != null) {
        if (PatternArbiter.matches(
            parser.getCore().getPredicateMaster().get(name, parser.getUserID(), parser.getBotID()), value, true)) {
          return parser.evaluate(element.getContent());
        }
        return "";
      }

      /*
       * Process a multiPredicateCondition: <condition> <li name="xxx" value="xxx"> ... </li><li> ... </li> </condition>
       */
      if (name == null && value == null) {
        return this.processMultiPredicateListItems(parser, element);
      }

      /*
       * Process a singlePredicateCondition: <condition name="xxx"> <li value="yyy"> ... </li><li> ... </li>
       * </condition>
       */
      if (name != null && value == null) {
        return this.processSinglePredicateListItems(parser, element, name);
      }
    }
    catch (NotAnAIMLPatternException e) {
      logger.warn("ConditionProcessor got a non-AIML pattern in a value attribute.", e);
      return "";
    }

    // In other cases, return an empty string.
    return "";
  }

  /**
   * Evaluates all the <li/> elements inside a multi-predicate <condition/>.
   * 
   * @param parser the TemplateParser object responsible for this
   * @param condition the parent condition
   * @return the result of processing this <li/>
   * @throws ProcessorException
   * @throws NotAnAIMLPatternException
   */
  @SuppressWarnings("unchecked")
  protected String processMultiPredicateListItems(TemplateParser parser, Element condition) throws ProcessorException,
      NotAnAIMLPatternException {
    List<Element> listItems = condition.getChildren();

    int lastLI = listItems.size() - 1;
    for (int index = 0; index <= lastLI; index++) {
      Element listItem = listItems.get(index);
      String liValue = listItem.getAttributeValue("value");
      String liName = listItem.getAttributeValue("name");

      if (liName != null && liValue != null) {
        if (PatternArbiter.matches(this._core.getPredicateMaster().get(liName, parser.getUserID(), parser.getBotID()),
            liValue, true)) {
          return parser.evaluate(listItem.getContent());
        }
      }
      else if (index == lastLI && liName == null && liValue == null) {
        return parser.evaluate(listItem.getContent());
      }
    }
    return "";
  }

  /**
   * Evaluates all the <li/> elements inside a single-predicate <condition/>.
   * 
   * @param parser the TemplateParser object responsible for this
   * @param condition the parent condition
   * @param name the name attribute of the <li/> (if applicable)
   * @return the result of processing this <li/>
   * @throws ProcessorException
   * @throws NotAnAIMLPatternException
   */
  @SuppressWarnings("unchecked")
  protected String processSinglePredicateListItems(TemplateParser parser, Element condition, String name)
      throws ProcessorException, NotAnAIMLPatternException {
    List<Element> listItems = condition.getChildren();

    int lastLI = listItems.size() - 1;
    for (int index = 0; index <= lastLI; index++) {
      Element listItem = listItems.get(index);
      String liValue = listItem.getAttributeValue("value");
      String predicateValue = this._core.getPredicateMaster().get(name, parser.getUserID(), parser.getBotID());
      if (liValue != null) {
        if (PatternArbiter.matches(predicateValue, liValue, true)) {
          return parser.evaluate(listItem.getContent());
        }
      }
      else if (index == lastLI) {
        return parser.evaluate(listItem.getContent());
      }
    }
    return "";
  }
}