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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   * This code is free software; you can redistribute it and/or modify it
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   * published by the Free Software Foundation.  Oracle designates this
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   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
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  // ContentHandler.java - handle main document content.
  // http://www.saxproject.org
  // Written by David Megginson
  // NO WARRANTY!  This class is in the public domain.
  // $Id: ContentHandler.java,v 1.2 2004/11/03 22:44:51 jsuttor Exp $
  
  package org.xml.sax;
  
  
  import org.xml.sax.Attributes;
  import org.xml.sax.Locator;
  import org.xml.sax.SAXException;
  
  /**
   * Receive notification of the logical content of a document.
   *
   * <blockquote>
   * <em>This module, both source code and documentation, is in the
   * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
   * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
   * for further information.
   * </blockquote>
   *
   * <p>This is the main interface that most SAX applications
   * implement: if the application needs to be informed of basic parsing
   * events, it implements this interface and registers an instance with
   * the SAX parser using the {@link org.xml.sax.XMLReader#setContentHandler
   * setContentHandler} method.  The parser uses the instance to report
   * basic document-related events like the start and end of elements
   * and character data.</p>
   *
   * <p>The order of events in this interface is very important, and
   * mirrors the order of information in the document itself.  For
   * example, all of an element's content (character data, processing
   * instructions, and/or subelements) will appear, in order, between
   * the startElement event and the corresponding endElement event.</p>
   *
   * <p>This interface is similar to the now-deprecated SAX 1.0
   * DocumentHandler interface, but it adds support for Namespaces
   * and for reporting skipped entities (in non-validating XML
   * processors).</p>
   *
   * <p>Implementors should note that there is also a
   * <code>ContentHandler</code> class in the <code>java.net</code>
   * package; that means that it's probably a bad idea to do</p>
   *
   * <pre>import java.net.*;
   * import org.xml.sax.*;
   * </pre>
   *
   * <p>In fact, "import ...*" is usually a sign of sloppy programming
   * anyway, so the user should consider this a feature rather than a
   * bug.</p>
   *
   * @since SAX 2.0
   * @author David Megginson
   * @see org.xml.sax.XMLReader
   * @see org.xml.sax.DTDHandler
   * @see org.xml.sax.ErrorHandler
   */
  public interface ContentHandler
  {
  
      /**
       * Receive an object for locating the origin of SAX document events.
       *
       * <p>SAX parsers are strongly encouraged (though not absolutely
       * required) to supply a locator: if it does so, it must supply
       * the locator to the application by invoking this method before
       * invoking any of the other methods in the ContentHandler
       * interface.</p>
       *
       * <p>The locator allows the application to determine the end
       * position of any document-related event, even if the parser is
       * not reporting an error.  Typically, the application will
       * use this information for reporting its own errors (such as
       * character content that does not match an application's
       * business rules).  The information returned by the locator
       * is probably not sufficient for use with a search engine.</p>
       *
       * <p>Note that the locator will return correct information only
       * during the invocation SAX event callbacks after
       * {@link #startDocument startDocument} returns and before
       * {@link #endDocument endDocument} is called.  The
       * application should not attempt to use it at any other time.</p>
       *
       * @param locator an object that can return the location of
       *                any SAX document event
       * @see org.xml.sax.Locator
       */
      public void setDocumentLocator (Locator locator);
  
  
      /**
       * Receive notification of the beginning of a document.
       *
       * <p>The SAX parser will invoke this method only once, before any
       * other event callbacks (except for {@link #setDocumentLocator
       * setDocumentLocator}).</p>
       *
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       * @see #endDocument
       */
      public void startDocument ()
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of the end of a document.
       *
       * <p><strong>There is an apparent contradiction between the
       * documentation for this method and the documentation for {@link
       * org.xml.sax.ErrorHandler#fatalError}.  Until this ambiguity is
       * resolved in a future major release, clients should make no
       * assumptions about whether endDocument() will or will not be
       * invoked when the parser has reported a fatalError() or thrown
       * an exception.</strong></p>
       *
       * <p>The SAX parser will invoke this method only once, and it will
       * be the last method invoked during the parse.  The parser shall
       * not invoke this method until it has either abandoned parsing
       * (because of an unrecoverable error) or reached the end of
       * input.</p>
       *
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       * @see #startDocument
       */
      public void endDocument()
          throws org.xml.sax.SAXException;
  
  
      /**
       * Begin the scope of a prefix-URI Namespace mapping.
       *
       * <p>The information from this event is not necessary for
       * normal Namespace processing: the SAX XML reader will
       * automatically replace prefixes for element and attribute
       * names when the <code>http://xml.org/sax/features/namespaces</code>
       * feature is <var>true</var> (the default).</p>
       *
       * <p>There are cases, however, when applications need to
       * use prefixes in character data or in attribute values,
       * where they cannot safely be expanded automatically; the
       * start/endPrefixMapping event supplies the information
       * to the application to expand prefixes in those contexts
       * itself, if necessary.</p>
       *
       * <p>Note that start/endPrefixMapping events are not
       * guaranteed to be properly nested relative to each other:
       * all startPrefixMapping events will occur immediately before the
       * corresponding {@link #startElement startElement} event,
       * and all {@link #endPrefixMapping endPrefixMapping}
       * events will occur immediately after the corresponding
       * {@link #endElement endElement} event,
       * but their order is not otherwise
       * guaranteed.</p>
       *
       * <p>There should never be start/endPrefixMapping events for the
       * "xml" prefix, since it is predeclared and immutable.</p>
       *
       * @param prefix the Namespace prefix being declared.
       *  An empty string is used for the default element namespace,
       *  which has no prefix.
       * @param uri the Namespace URI the prefix is mapped to
       * @throws org.xml.sax.SAXException the client may throw
       *            an exception during processing
       * @see #endPrefixMapping
       * @see #startElement
       */
      public void startPrefixMapping (String prefix, String uri)
          throws org.xml.sax.SAXException;
  
  
      /**
       * End the scope of a prefix-URI mapping.
       *
       * <p>See {@link #startPrefixMapping startPrefixMapping} for
       * details.  These events will always occur immediately after the
       * corresponding {@link #endElement endElement} event, but the order of
       * {@link #endPrefixMapping endPrefixMapping} events is not otherwise
       * guaranteed.</p>
       *
       * @param prefix the prefix that was being mapped.
       *  This is the empty string when a default mapping scope ends.
       * @throws org.xml.sax.SAXException the client may throw
       *            an exception during processing
       * @see #startPrefixMapping
       * @see #endElement
       */
      public void endPrefixMapping (String prefix)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of the beginning of an element.
       *
       * <p>The Parser will invoke this method at the beginning of every
       * element in the XML document; there will be a corresponding
       * {@link #endElement endElement} event for every startElement event
       * (even when the element is empty). All of the element's content will be
       * reported, in order, before the corresponding endElement
       * event.</p>
       *
       * <p>This event allows up to three name components for each
       * element:</p>
       *
       * <ol>
       * <li>the Namespace URI;</li>
       * <li>the local name; and</li>
       * <li>the qualified (prefixed) name.</li>
       * </ol>
       *
       * <p>Any or all of these may be provided, depending on the
       * values of the <var>http://xml.org/sax/features/namespaces</var>
       * and the <var>http://xml.org/sax/features/namespace-prefixes</var>
       * properties:</p>
       *
       * <ul>
       * <li>the Namespace URI and local name are required when
       * the namespaces property is <var>true</var> (the default), and are
       * optional when the namespaces property is <var>false</var> (if one is
       * specified, both must be);</li>
       * <li>the qualified name is required when the namespace-prefixes property
       * is <var>true</var>, and is optional when the namespace-prefixes property
       * is <var>false</var> (the default).</li>
       * </ul>
       *
       * <p>Note that the attribute list provided will contain only
       * attributes with explicit values (specified or defaulted):
       * #IMPLIED attributes will be omitted.  The attribute list
       * will contain attributes used for Namespace declarations
       * (xmlns* attributes) only if the
       * <code>http://xml.org/sax/features/namespace-prefixes</code>
       * property is true (it is false by default, and support for a
       * true value is optional).</p>
       *
       * <p>Like {@link #characters characters()}, attribute values may have
       * characters that need more than one <code>char</code> value.  </p>
       *
       * @param uri the Namespace URI, or the empty string if the
       *        element has no Namespace URI or if Namespace
       *        processing is not being performed
       * @param localName the local name (without prefix), or the
       *        empty string if Namespace processing is not being
       *        performed
       * @param qName the qualified name (with prefix), or the
       *        empty string if qualified names are not available
       * @param atts the attributes attached to the element.  If
       *        there are no attributes, it shall be an empty
       *        Attributes object.  The value of this object after
       *        startElement returns is undefined
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       * @see #endElement
       * @see org.xml.sax.Attributes
       * @see org.xml.sax.helpers.AttributesImpl
       */
      public void startElement (String uri, String localName,
                                String qName, Attributes atts)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of the end of an element.
       *
       * <p>The SAX parser will invoke this method at the end of every
       * element in the XML document; there will be a corresponding
       * {@link #startElement startElement} event for every endElement
       * event (even when the element is empty).</p>
       *
       * <p>For information on the names, see startElement.</p>
       *
       * @param uri the Namespace URI, or the empty string if the
       *        element has no Namespace URI or if Namespace
       *        processing is not being performed
       * @param localName the local name (without prefix), or the
       *        empty string if Namespace processing is not being
       *        performed
       * @param qName the qualified XML name (with prefix), or the
       *        empty string if qualified names are not available
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       */
      public void endElement (String uri, String localName,
                              String qName)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of character data.
       *
       * <p>The Parser will call this method to report each chunk of
       * character data.  SAX parsers may return all contiguous character
       * data in a single chunk, or they may split it into several
       * chunks; however, all of the characters in any single event
       * must come from the same external entity so that the Locator
       * provides useful information.</p>
       *
       * <p>The application must not attempt to read from the array
       * outside of the specified range.</p>
       *
       * <p>Individual characters may consist of more than one Java
       * <code>char</code> value.  There are two important cases where this
       * happens, because characters can't be represented in just sixteen bits.
       * In one case, characters are represented in a <em>Surrogate Pair</em>,
       * using two special Unicode values. Such characters are in the so-called
       * "Astral Planes", with a code point above U+FFFF.  A second case involves
       * composite characters, such as a base character combining with one or
       * more accent characters. </p>
       *
       * <p> Your code should not assume that algorithms using
       * <code>char</code>-at-a-time idioms will be working in character
       * units; in some cases they will split characters.  This is relevant
       * wherever XML permits arbitrary characters, such as attribute values,
       * processing instruction data, and comments as well as in data reported
       * from this method.  It's also generally relevant whenever Java code
       * manipulates internationalized text; the issue isn't unique to XML.</p>
       *
       * <p>Note that some parsers will report whitespace in element
       * content using the {@link #ignorableWhitespace ignorableWhitespace}
       * method rather than this one (validating parsers <em>must</em>
       * do so).</p>
       *
       * @param ch the characters from the XML document
       * @param start the start position in the array
       * @param length the number of characters to read from the array
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       * @see #ignorableWhitespace
       * @see org.xml.sax.Locator
       */
      public void characters (char ch[], int start, int length)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of ignorable whitespace in element content.
       *
       * <p>Validating Parsers must use this method to report each chunk
       * of whitespace in element content (see the W3C XML 1.0
       * recommendation, section 2.10): non-validating parsers may also
       * use this method if they are capable of parsing and using
       * content models.</p>
       *
       * <p>SAX parsers may return all contiguous whitespace in a single
       * chunk, or they may split it into several chunks; however, all of
       * the characters in any single event must come from the same
       * external entity, so that the Locator provides useful
       * information.</p>
       *
       * <p>The application must not attempt to read from the array
       * outside of the specified range.</p>
       *
       * @param ch the characters from the XML document
       * @param start the start position in the array
       * @param length the number of characters to read from the array
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       * @see #characters
       */
      public void ignorableWhitespace (char ch[], int start, int length)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of a processing instruction.
       *
       * <p>The Parser will invoke this method once for each processing
       * instruction found: note that processing instructions may occur
       * before or after the main document element.</p>
       *
       * <p>A SAX parser must never report an XML declaration (XML 1.0,
       * section 2.8) or a text declaration (XML 1.0, section 4.3.1)
       * using this method.</p>
       *
       * <p>Like {@link #characters characters()}, processing instruction
       * data may have characters that need more than one <code>char</code>
       * value. </p>
       *
       * @param target the processing instruction target
       * @param data the processing instruction data, or null if
       *        none was supplied.  The data does not include any
       *        whitespace separating it from the target
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       */
      public void processingInstruction (String target, String data)
          throws org.xml.sax.SAXException;
  
  
      /**
       * Receive notification of a skipped entity.
       * This is not called for entity references within markup constructs
       * such as element start tags or markup declarations.  (The XML
       * recommendation requires reporting skipped external entities.
       * SAX also reports internal entity expansion/non-expansion, except
       * within markup constructs.)
       *
       * <p>The Parser will invoke this method each time the entity is
       * skipped.  Non-validating processors may skip entities if they
       * have not seen the declarations (because, for example, the
       * entity was declared in an external DTD subset).  All processors
       * may skip external entities, depending on the values of the
       * <code>http://xml.org/sax/features/external-general-entities</code>
       * and the
       * <code>http://xml.org/sax/features/external-parameter-entities</code>
       * properties.</p>
       *
       * @param name the name of the skipped entity.  If it is a
       *        parameter entity, the name will begin with '%', and if
       *        it is the external DTD subset, it will be the string
       *        "[dtd]"
       * @throws org.xml.sax.SAXException any SAX exception, possibly
       *            wrapping another exception
       */
      public void skippedEntity (String name)
          throws SAXException;
  }
  
  // end of ContentHandler.java
  