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StdXMLBuilder.java

/*
 * StdXMLBuilder.java NanoXML/Java $Revision: 1.3 $ $Date: 2002/01/04 21:03:28 $
 * $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 org.freeplane.core.io.xml;

import java.io.IOException;
import java.io.Reader;
import java.util.Stack;

import org.freeplane.n3.nanoxml.IXMLBuilder;
import org.freeplane.n3.nanoxml.XMLElement;
import org.freeplane.n3.nanoxml.XMLParseException;

/**
 * StdXMLBuilder is a concrete implementation of IXMLBuilder which creates a
 * tree of IXMLElement from an XML data source.
 * 
 * @see org.freeplane.n3.nanoxml.XMLElement
 * @author Marc De Scheemaecker
 * @version $Name: RELEASE_2_2_1 $, $Revision: 1.3 $ Modified by Dimitry
 *          Polivaev: method getLastBuiltElement added
 */
00036 class StdXMLBuilder implements IXMLBuilder {
      /**
       * The last built element of the parsed XML tree.
       */
00040       private XMLElement last;
      /**
       * Prototype element for creating the tree.
       */
00044       private XMLElement prototype;
      /**
       * The root element of the parsed XML tree.
       */
00048       private XMLElement root;
      /**
       * This stack contains the current element and its parents.
       */
00052       private Stack stack;

      /**
       * Creates the builder.
       */
00057       public StdXMLBuilder() {
            this(new XMLElement());
      }

      /**
       * Creates the builder.
       * 
       * @param prototype
       *            the prototype to use when building the tree.
       */
00067       public StdXMLBuilder(final XMLElement prototype) {
            stack = null;
            root = null;
            last = null;
            this.prototype = prototype;
      }

      /**
       * This method is called when a new attribute of an XML element is
       * encountered.
       * 
       * @param key
       *            the key (name) of the attribute.
       * @param nsPrefix
       *            the prefix used to identify the namespace. If no namespace has
       *            been specified, this parameter is null.
       * @param nsURI
       *            the URI associated with the namespace. If no namespace has
       *            been specified, or no URI is associated with nsPrefix, this
       *            parameter is null.
       * @param value
       *            the value of the attribute.
       * @param type
       *            the type of the attribute. If no type is known, "CDATA" is
       *            returned.
       * @throws java.lang.Exception
       *             If an exception occurred while processing the event.
       */
00095       public void addAttribute(final String key, final String nsPrefix, final String nsURI, final String value,
                               final String type) throws Exception {
            String fullName = key;
            if (nsPrefix != null) {
                  fullName = nsPrefix + ':' + key;
            }
            final XMLElement top = (XMLElement) stack.peek();
            if (top.hasAttribute(fullName)) {
                  throw new XMLParseException(top.getSystemID(), top.getLineNr(), "Duplicate attribute: " + key);
            }
            if (nsPrefix != null) {
                  top.setAttribute(fullName, nsURI, value);
            }
            else {
                  top.setAttribute(fullName, value);
            }
      }

      /**
       * This method is called when a PCDATA element is encountered. A Java reader
       * is supplied from which you can read the data. The reader will only read
       * the data of the element. You don't need to check for boundaries. If you
       * don't read the full element, the rest of the data is skipped. You also
       * don't have to care about entities; they are resolved by the parser.
       * 
       * @param reader
       *            the Java reader from which you can retrieve the data.
       * @param systemID
       *            the system ID of the XML data source.
       * @param lineNr
       *            the line in the source where the element starts.
       */
00127       public void addPCData(final Reader reader, final String systemID, final int lineNr) {
            int bufSize = 2048;
            int sizeRead = 0;
            final StringBuilder str = new StringBuilder(bufSize);
            final char[] buf = new char[bufSize];
            for (;;) {
                  if (sizeRead >= bufSize) {
                        bufSize *= 2;
                        str.ensureCapacity(bufSize);
                  }
                  int size;
                  try {
                        size = reader.read(buf);
                  }
                  catch (final IOException e) {
                        break;
                  }
                  if (size < 0) {
                        break;
                  }
                  str.append(buf, 0, size);
                  sizeRead += size;
            }
            final XMLElement elt = prototype.createElement(null, systemID, lineNr);
            elt.setContent(str.toString());
            if (!stack.empty()) {
                  final XMLElement top = (XMLElement) stack.peek();
                  top.addChild(elt);
            }
      }

      /**
       * This method is called when the attributes of an XML element have been
       * processed.
       * 
       * @see #startElement
       * @see #addAttribute
       * @param name
       *            the name of the element.
       * @param nsPrefix
       *            the prefix used to identify the namespace. If no namespace has
       *            been specified, this parameter is null.
       * @param nsURI
       *            the URI associated with the namespace. If no namespace has
       *            been specified, or no URI is associated with nsPrefix, this
       *            parameter is null.
       */
00174       public void elementAttributesProcessed(final String name, final String nsPrefix, final String nsURI) {
      }

      /**
       * This method is called when the end of an XML elemnt is encountered.
       * 
       * @see #startElement
       * @param name
       *            the name of the element.
       * @param nsPrefix
       *            the prefix used to identify the namespace. If no namespace has
       *            been specified, this parameter is null.
       * @param nsURI
       *            the URI associated with the namespace. If no namespace has
       *            been specified, or no URI is associated with nsPrefix, this
       *            parameter is null.
       */
00191       public void endElement(final String name, final String nsPrefix, final String nsURI) {
            final XMLElement elt = (XMLElement) stack.pop();
            if (elt.getChildrenCount() == 1) {
                  final XMLElement child = elt.getChildAtIndex(0);
                  if (child.getName() == null) {
                        elt.setContent(child.getContent());
                        elt.removeChildAtIndex(0);
                  }
            }
      }

      /**
       * Cleans up the object when it's destroyed.
       */
      @Override
00206       protected void finalize() throws Throwable {
            prototype = null;
            root = null;
            last = null;
            stack.clear();
            stack = null;
            super.finalize();
      }

      public XMLElement getLastBuiltElement() {
            return last;
      }

      public XMLElement getParentElement() {
            return root != null ? (XMLElement) stack.peek() : null;
      }

      /**
       * Returns the result of the building process. This method is called just
       * before the <I>parse</I> method of IXMLParser returns.
       * 
       * @see org.freeplane.n3.nanoxml.IXMLParser#parse
       * @return the result of the building process.
       */
00230       public Object getResult() {
            return root;
      }

      /**
       * This method is called when a processing instruction is encountered. PIs
       * with target "xml" are handled by the parser.
       * 
       * @param target
       *            the PI target.
       * @param reader
       *            to read the data from the PI.
       */
00243       public void newProcessingInstruction(final String target, final Reader reader) {
      }

      /**
       * This method is called before the parser starts processing its input.
       * 
       * @param systemID
       *            the system ID of the XML data source.
       * @param lineNr
       *            the line on which the parsing starts.
       */
00254       public void startBuilding(final String systemID, final int lineNr) {
            stack = new Stack();
            root = null;
            last = null;
      }

      /**
       * This method is called when a new XML element is encountered.
       * 
       * @see #endElement
       * @param name
       *            the name of the element.
       * @param nsPrefix
       *            the prefix used to identify the namespace. If no namespace has
       *            been specified, this parameter is null.
       * @param nsURI
       *            the URI associated with the namespace. If no namespace has
       *            been specified, or no URI is associated with nsPrefix, this
       *            parameter is null.
       * @param systemID
       *            the system ID of the XML data source.
       * @param lineNr
       *            the line in the source where the element starts.
       */
00278       public void startElement(final String name, final String nsPrefix, final String nsURI, final String systemID,
                               final int lineNr) {
            String fullName = name;
            if (nsPrefix != null) {
                  fullName = nsPrefix + ':' + name;
            }
            final XMLElement elt = prototype.createElement(fullName, nsURI, systemID, lineNr);
            last = elt;
            if (stack.empty()) {
                  root = elt;
            }
            else {
                  final XMLElement top = (XMLElement) stack.peek();
                  top.addChild(elt);
            }
            stack.push(elt);
      }
}

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