XMLValidator.java

/* NonValidator.java                                               NanoXML/Java
 *
 * $Revision: 1.4 $
 * $Date: 2002/02/03 21:19:38 $
 * $Name: RELEASE_2_2_1 $
 *
 * This file is part of NanoXML 2 for Java.
 * Copyright (C) 2000-2002 Marc De Scheemaecker, All Rights Reserved.
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from the
 * use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software in
 *     a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *
 *  3. This notice may not be removed or altered from any source distribution.
 */

package processing.xml;


import java.io.Reader;
import java.io.StringReader;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import java.util.Stack;


/**
 * XMLValidator implementation based on NonValidator (which implemented 
 * IXMLValidator in the original NanoXML).
 * This implementation processes the DTD and handles entity definitions. 
 * It does not do any validation itself.
 *
 * @author Marc De Scheemaecker
 * @author processing.org
 */
public class XMLValidator
{

   /**
    * The parameter entity resolver.
    */
   protected XMLEntityResolver parameterEntityResolver;


   /**
    * Contains the default values for attributes for the different element
    * types.
    */
   protected Hashtable<String, Properties> attributeDefaultValues;


   /**
    * The stack of elements to be processed.
    */
   protected Stack<Properties> currentElements;


   /**
    * Creates the &quot;validator&quot;.
    */
   public XMLValidator()
   {
      this.attributeDefaultValues = new Hashtable<String, Properties>();
      this.currentElements = new Stack<Properties>();
      this.parameterEntityResolver = new XMLEntityResolver();
   }


   /**
    * Cleans up the object when it's destroyed.
    */
   protected void finalize()
      throws Throwable
   {
      this.parameterEntityResolver = null;
      this.attributeDefaultValues.clear();
      this.attributeDefaultValues = null;
      this.currentElements.clear();
      this.currentElements = null;
      super.finalize();
   }


   /**
    * Sets the parameter entity resolver.
    *
    * @param resolver the entity resolver.
    */
   public void setParameterEntityResolver(XMLEntityResolver resolver)
   {
      this.parameterEntityResolver = resolver;
   }


   /**
    * Returns the parameter entity resolver.
    *
    * @return the entity resolver.
    */
   public XMLEntityResolver getParameterEntityResolver()
   {
      return this.parameterEntityResolver;
   }


   /**
    * Parses the DTD. The validator object is responsible for reading the
    * full DTD.
    *
    * @param publicID       the public ID, which may be null.
    * @param reader         the reader to read the DTD from.
    * @param entityResolver the entity resolver.
    * @param external       true if the DTD is external.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   public void parseDTD(String             publicID,
                        StdXMLReader         reader,
                        XMLEntityResolver entityResolver,
                        boolean            external)
      throws Exception
   {
      XMLUtil.skipWhitespace(reader, null);
      int origLevel = reader.getStreamLevel();

      for (;;) {
         String str = XMLUtil.read(reader, '%');
         char ch = str.charAt(0);

         if (ch == '%') {
            XMLUtil.processEntity(str, reader,
                                  this.parameterEntityResolver);
            continue;
         } else if (ch == '<') {
            this.processElement(reader, entityResolver);
         } else if (ch == ']') {
            return; // end internal DTD
         } else {
            XMLUtil.errorInvalidInput(reader.getSystemID(),
                                      reader.getLineNr(),
                                      str);
         }

         do {
            ch = reader.read();

            if (external && (reader.getStreamLevel() < origLevel)) {
               reader.unread(ch);
               return; // end external DTD
            }
         } while ((ch == ' ') || (ch == '\t') || (ch == '\n')
                  || (ch == '\r'));

         reader.unread(ch);
      }
   }


   /**
    * Processes an element in the DTD.
    *
    * @param reader         the reader to read data from.
    * @param entityResolver the entity resolver.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   protected void processElement(StdXMLReader         reader,
                                 XMLEntityResolver entityResolver)
      throws Exception
   {
      String str = XMLUtil.read(reader, '%');
      char ch = str.charAt(0);

      if (ch != '!') {
         XMLUtil.skipTag(reader);
         return;
      }

      str = XMLUtil.read(reader, '%');
      ch = str.charAt(0);

      switch (ch) {
         case '-':
            XMLUtil.skipComment(reader);
            break;

         case '[':
            this.processConditionalSection(reader, entityResolver);
            break;

         case 'E':
            this.processEntity(reader, entityResolver);
            break;

         case 'A':
            this.processAttList(reader, entityResolver);
            break;

         default:
            XMLUtil.skipTag(reader);
      }
   }


   /**
    * Processes a conditional section.
    *
    * @param reader         the reader to read data from.
    * @param entityResolver the entity resolver.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   protected void processConditionalSection(StdXMLReader         reader,
                                            XMLEntityResolver entityResolver)
      throws Exception
   {
      XMLUtil.skipWhitespace(reader, null);

      String str = XMLUtil.read(reader, '%');
      char ch = str.charAt(0);

      if (ch != 'I') {
         XMLUtil.skipTag(reader);
         return;
      }

      str = XMLUtil.read(reader, '%');
      ch = str.charAt(0);

      switch (ch) {
         case 'G':
            this.processIgnoreSection(reader, entityResolver);
            return;

         case 'N':
            break;

         default:
            XMLUtil.skipTag(reader);
            return;
      }

      if (! XMLUtil.checkLiteral(reader, "CLUDE")) {
         XMLUtil.skipTag(reader);
         return;
      }

      XMLUtil.skipWhitespace(reader, null);

      str = XMLUtil.read(reader, '%');
      ch = str.charAt(0);

      if (ch != '[') {
         XMLUtil.skipTag(reader);
         return;
      }

      Reader subreader = new CDATAReader(reader);
      StringBuffer buf = new StringBuffer(1024);

      for (;;) {
         int ch2 = subreader.read();

         if (ch2 < 0) {
            break;
         }

         buf.append((char) ch2);
      }

      subreader.close();
      reader.startNewStream(new StringReader(buf.toString()));
   }


   /**
    * Processes an ignore section.
    *
    * @param reader         the reader to read data from.
    * @param entityResolver the entity resolver.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   protected void processIgnoreSection(StdXMLReader         reader,
                                       XMLEntityResolver entityResolver)
      throws Exception
   {
      if (! XMLUtil.checkLiteral(reader, "NORE")) {
         XMLUtil.skipTag(reader);
         return;
      }

      XMLUtil.skipWhitespace(reader, null);

      String str = XMLUtil.read(reader, '%');
      char ch = str.charAt(0);

      if (ch != '[') {
         XMLUtil.skipTag(reader);
         return;
      }

      Reader subreader = new CDATAReader(reader);
      subreader.close();
   }


   /**
    * Processes an ATTLIST element.
    *
    * @param reader         the reader to read data from.
    * @param entityResolver the entity resolver.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   protected void processAttList(StdXMLReader         reader,
                                 XMLEntityResolver entityResolver)
      throws Exception
   {
      if (! XMLUtil.checkLiteral(reader,  "TTLIST")) {
         XMLUtil.skipTag(reader);
         return;
      }

      XMLUtil.skipWhitespace(reader, null);
      String str = XMLUtil.read(reader, '%');
      char ch = str.charAt(0);
      while (ch == '%') {
         XMLUtil.processEntity(str, reader,
                               this.parameterEntityResolver);
         str = XMLUtil.read(reader, '%');
         ch = str.charAt(0);
      }
      reader.unread(ch);
      String elementName = XMLUtil.scanIdentifier(reader);
      XMLUtil.skipWhitespace(reader, null);
      
      str = XMLUtil.read(reader, '%');
      ch = str.charAt(0);
      while (ch == '%') {
         XMLUtil.processEntity(str, reader,
                               this.parameterEntityResolver);
         str = XMLUtil.read(reader, '%');
         ch = str.charAt(0);
      }

      Properties props = new Properties();

      while (ch != '>') {
         reader.unread(ch);
         String attName = XMLUtil.scanIdentifier(reader);
         XMLUtil.skipWhitespace(reader, null);
         str = XMLUtil.read(reader, '%');
         ch = str.charAt(0);
         while (ch == '%') {
             XMLUtil.processEntity(str, reader,
                                   this.parameterEntityResolver);
             str = XMLUtil.read(reader, '%');
             ch = str.charAt(0);
         }

         if (ch == '(') {
             while (ch != ')') {
                 str = XMLUtil.read(reader, '%');
                 ch = str.charAt(0);
                 while (ch == '%') {
                     XMLUtil.processEntity(str, reader,
                                           this.parameterEntityResolver);
                     str = XMLUtil.read(reader, '%');
                     ch = str.charAt(0);
                 }
             }
         } else {
            reader.unread(ch);
            XMLUtil.scanIdentifier(reader);
         }

         XMLUtil.skipWhitespace(reader, null);
         str = XMLUtil.read(reader, '%');
         ch = str.charAt(0);
         while (ch == '%') {
             XMLUtil.processEntity(str, reader,
                                   this.parameterEntityResolver);
             str = XMLUtil.read(reader, '%');
             ch = str.charAt(0);
         }
         
         if (ch == '#') {
            str = XMLUtil.scanIdentifier(reader);
            XMLUtil.skipWhitespace(reader, null);

            if (! str.equals("FIXED")) {
               XMLUtil.skipWhitespace(reader, null);

               str = XMLUtil.read(reader, '%');
               ch = str.charAt(0);
               while (ch == '%') {
                  XMLUtil.processEntity(str, reader,
                                        this.parameterEntityResolver);
                  str = XMLUtil.read(reader, '%');
                  ch = str.charAt(0);
               }

               continue;
            }
         } else {
            reader.unread(ch);
         }

         String value = XMLUtil.scanString(reader, '%',
                                           this.parameterEntityResolver);
         props.put(attName, value);
         XMLUtil.skipWhitespace(reader, null);

         str = XMLUtil.read(reader, '%');
         ch = str.charAt(0);
         while (ch == '%') {
            XMLUtil.processEntity(str, reader,
                                  this.parameterEntityResolver);
            str = XMLUtil.read(reader, '%');
            ch = str.charAt(0);
         }
      }

      if (! props.isEmpty()) {
         this.attributeDefaultValues.put(elementName, props);
      }
   }


   /**
    * Processes an ENTITY element.
    *
    * @param reader         the reader to read data from.
    * @param entityResolver the entity resolver.
    *
    * @throws java.lang.Exception
    *     If something went wrong.
    */
   protected void processEntity(StdXMLReader         reader,
                                XMLEntityResolver entityResolver)
      throws Exception
   {
      if (! XMLUtil.checkLiteral(reader, "NTITY")) {
         XMLUtil.skipTag(reader);
         return;
      }

      XMLUtil.skipWhitespace(reader, null);
      char ch = XMLUtil.readChar(reader, '\0');

      if (ch == '%') {
         XMLUtil.skipWhitespace(reader, null);
         entityResolver = this.parameterEntityResolver;
      } else {
         reader.unread(ch);
      }

      String key = XMLUtil.scanIdentifier(reader);
      XMLUtil.skipWhitespace(reader, null);
      ch = XMLUtil.readChar(reader, '%');
      String systemID = null;
      String publicID = null;

      switch (ch) {
         case 'P':
            if (! XMLUtil.checkLiteral(reader, "UBLIC")) {
               XMLUtil.skipTag(reader);
               return;
            }

            XMLUtil.skipWhitespace(reader, null);
            publicID = XMLUtil.scanString(reader, '%',
                                          this.parameterEntityResolver);
            XMLUtil.skipWhitespace(reader, null);
            systemID = XMLUtil.scanString(reader, '%',
                                          this.parameterEntityResolver);
            XMLUtil.skipWhitespace(reader, null);
            XMLUtil.readChar(reader, '%');
            break;

         case 'S':
            if (! XMLUtil.checkLiteral(reader, "YSTEM")) {
               XMLUtil.skipTag(reader);
               return;
            }

            XMLUtil.skipWhitespace(reader, null);
            systemID = XMLUtil.scanString(reader, '%',
                                          this.parameterEntityResolver);
            XMLUtil.skipWhitespace(reader, null);
            XMLUtil.readChar(reader, '%');
            break;

         case '"':
         case '\'':
            reader.unread(ch);
            String value = XMLUtil.scanString(reader, '%',
                                              this.parameterEntityResolver);
            entityResolver.addInternalEntity(key, value);
            XMLUtil.skipWhitespace(reader, null);
            XMLUtil.readChar(reader, '%');
            break;

         default:
            XMLUtil.skipTag(reader);
      }

      if (systemID != null) {
         entityResolver.addExternalEntity(key, publicID, systemID);
      }
   }


   /**
    * Indicates that an element has been started.
    *
    * @param name       the name of the element.
    * @param systemId   the system ID of the XML data of the element.
    * @param lineNr     the line number in the XML data of the element.
    */
   public void elementStarted(String name,
                              String systemId,
                              int    lineNr)
   {
      Properties attribs
         = (Properties) this.attributeDefaultValues.get(name);

      if (attribs == null) {
         attribs = new Properties();
      } else {
         attribs = (Properties) attribs.clone();
      }

      this.currentElements.push(attribs);
   }


   /**
    * Indicates that the current element has ended.
    *
    * @param name       the name of the element.
    * @param systemId   the system ID of the XML data of the element.
    * @param lineNr     the line number in the XML data of the element.
    */
   public void elementEnded(String name,
                            String systemId,
                            int    lineNr)
   {
      // nothing to do
   }


   /**
    * This method is called when the attributes of an XML element have been
    * processed.
    * If there are attributes with a default value which have not been
    * specified yet, they have to be put into <I>extraAttributes</I>.
    *
    * @param name            the name of the element.
    * @param extraAttributes where to put extra attributes.
    * @param systemId        the system ID of the XML data of the element.
    * @param lineNr          the line number in the XML data of the element.
    */
   public void elementAttributesProcessed(String     name,
                                          Properties extraAttributes,
                                          String     systemId,
                                          int        lineNr)
   {
      Properties props = (Properties) this.currentElements.pop();
      Enumeration<?> en = props.keys();

      while (en.hasMoreElements()) {
         String key = (String) en.nextElement();
         extraAttributes.put(key, props.get(key));
      }
   }


   /**
    * Indicates that an attribute has been added to the current element.
    *
    * @param key        the name of the attribute.
    * @param value      the value of the attribute.
    * @param systemId   the system ID of the XML data of the element.
    * @param lineNr     the line number in the XML data of the element.
    */
   public void attributeAdded(String key,
                              String value,
                              String systemId,
                              int    lineNr)
   {
      Properties props = (Properties) this.currentElements.peek();

      if (props.containsKey(key)) {
         props.remove(key);
      }
   }


   /**
    * Indicates that a new #PCDATA element has been encountered.
    *
    * @param systemId the system ID of the XML data of the element.
    * @param lineNr   the line number in the XML data of the element.
    */
   public void PCDataAdded(String systemId,
                           int    lineNr)
   {
      // nothing to do
   }

}