AIMLReader.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.parser;

import java.net.URL;

import org.aitools.programd.Bot;
import org.aitools.programd.graph.Graphmapper;
import org.aitools.programd.processor.aiml.AIMLProcessorRegistry;
import org.aitools.util.xml.Characters;
import org.aitools.util.xml.SAX;
import org.jdom.IllegalNameException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.ext.DefaultHandler2;

/**
 * This reads in standard AIML and delivers categories to the Graphmapper.
 * 
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class AIMLReader extends DefaultHandler2 {

  private String _defaultNamespaceURI;

  private Graphmapper _graphmapper;

  private URL _path;

  private Bot _bot;

  /** The most recently collected <pattern></pattern> contents. */
  private StringBuilder patternBuffer;

  /** The most recently collected <that></that> contents. */
  private StringBuilder thatBuffer;

  /** The most recently collected <template></template> contents. */
  private StringBuilder templateBuffer;

  /** A pointer to the current buffer. */
  private StringBuilder currentBuffer;

  /** The finalized <pattern></pattern> contents. */
  private String pattern;

  /** The finalized <that></that> contents. */
  private String that;

  /** The finalized <topic></topic> contents. */
  private String topic;

  /** The finalized <template></template> contents. */
  private String template;

  /** The start of a template element. */
  private String templateStartTag;

  /**
   * Creates a new AIMLReader.
   * 
   * @param graphmapper the <code>Graphmapper</code> into which new categories are to be loaded.
   * @param path the path that is being read
   * @param bot the bot itself
   */
  public AIMLReader(Graphmapper graphmapper, URL path, Bot bot) {
    this._graphmapper = graphmapper;
    this._path = path;
    this._bot = bot;
    this.templateStartTag = String.format("<template xmlns=\"%s\">", AIMLProcessorRegistry.XMLNS);
    this.topic = "*";
  }

  /**
   * @see org.xml.sax.ContentHandler#characters(char[], int, int)
   */
  @Override
  public void characters(char[] ch, int start, int length) {
    if (this.currentBuffer != null) {
      this.currentBuffer.append(Characters.escapeXMLChars(ch, start, length));
    }
  }

  /**
   * @see org.xml.sax.ext.DefaultHandler2#endCDATA()
   */
  @Override
  public void endCDATA() {
    assert this.currentBuffer != null : "Got CDATA end outside of a known element!";
    this.currentBuffer.append("]]>");
  }

  /**
   * @see org.xml.sax.ContentHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
   */
  @Override
  @SuppressWarnings({ "boxing" })
  public void endElement(String uri, String localName, String qName) {
    String elementName;
    if ("".equals(localName)) {
      elementName = qName;
    }
    else {
      elementName = localName;
    }

    if (this.currentBuffer != null && this.currentBuffer == this.patternBuffer) {
      this.pattern = this.patternBuffer.toString();
      this.currentBuffer = null;
    }
    else if (this.currentBuffer != null && this.currentBuffer == this.thatBuffer) {
      this.that = this.thatBuffer.toString();
      this.currentBuffer = null;
    }
    else if (elementName.equals("template")) {
      // Whitespace-normalize the template contents.
      this.template = String.format("%s%s</template>", this.templateStartTag, this.templateBuffer.toString());
      // Finally, deliver the newly defined category to the Graphmapper.
      this._graphmapper.addCategory(this.pattern, this.that, this.topic, this.template, this._bot, this._path);
      // Reset the pattern, that and template.
      this.pattern = this.that = this.template = null;
      this.currentBuffer = this.patternBuffer = this.thatBuffer = this.templateBuffer = null;
    }
    else if (this.currentBuffer != null && this.currentBuffer == this.templateBuffer) {
      // See if we are ending an empty element.
      boolean makeClosingTag = true;

      // Get the template length (just once).
      int templateLength = this.templateBuffer.length();
      // If the last char of the template string is a '>',
      if (this.templateBuffer.substring(templateLength - 1).equals('>')) {
        // and if the next to last char is *not* a '/',
        if (!this.templateBuffer.substring(templateLength - 2, templateLength - 1).equals('/')) {
          // then if the name of the last tag is the same as this one,
          // this is an empty element.
          int lastMarkerStart = this.templateBuffer.lastIndexOf("<");
          if (this.templateBuffer.indexOf(elementName, lastMarkerStart) == lastMarkerStart + 1) {
            // So just insert a '/' before the '>'.
            this.templateBuffer.insert(templateLength - 1, '/');
            makeClosingTag = false;
          }
        }
      }
      // Otherwise, make a closing tag.
      if (makeClosingTag) {
        this.templateBuffer.append(String.format("</%s>", elementName));
      }
    }
    else if (elementName.equals("topic")) {
      this.topic = "*";
    }
  }

  /**
   * @see org.xml.sax.helpers.DefaultHandler#error(org.xml.sax.SAXParseException)
   */
  @Override
  public void error(SAXParseException e) throws SAXException {
    throw e;
  }

  /**
   * @see org.xml.sax.ext.DefaultHandler2#startCDATA()
   */
  @Override
  public void startCDATA() {
    assert this.currentBuffer != null : "Got CDATA start outside of a known element!";
    this.currentBuffer.append("<![CDATA[");
  }

  /**
   * @see org.xml.sax.ContentHandler#startElement(java.lang.String, java.lang.String, java.lang.String,
   *      org.xml.sax.Attributes)
   */
  @Override
  public void startElement(String uri, String localName, String qName, Attributes attributes) {
    String elementName;
    if ("".equals(localName)) {
      elementName = qName;
    }
    else {
      elementName = localName;
    }
    if (elementName.equals("pattern")) {
      this.currentBuffer = this.patternBuffer = new StringBuilder();
    }
    else if (elementName.equals("bot") && this.currentBuffer != null && this.currentBuffer == this.patternBuffer) {
      // Insert the value of the given bot predicate (no warning if doesn't exist!).
      this.patternBuffer.append(this._bot.getPropertyValue(attributes.getValue("name")));
    }
    else if (elementName.equals("that") && this.currentBuffer == null || this.currentBuffer != this.templateBuffer) {
      this.currentBuffer = this.thatBuffer = new StringBuilder();
    }
    else if (elementName.equals("template")) {
      this.currentBuffer = this.templateBuffer = new StringBuilder();
    }
    else if (this.currentBuffer != null && this.currentBuffer == this.templateBuffer) {
      /*
       * We don't want to parse the template into some big memory structure, since it may never be used. So we just
       * reconstitute the XML text for later processing.
       */
      try {
        this.templateBuffer.append(SAX.renderStartTag(elementName, attributes, !uri.equals(this._defaultNamespaceURI),
            uri));
      }
      catch (IllegalNameException e) {
        assert false: "The SAX parser is not performing namespace processing correctly.";
      }
    }
    else if (elementName.equals("topic")) {
      // We don't check that it's valid, because it's supposed to have been schema-validated already!
      this.topic = attributes.getValue("name");
    }
  }
}