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    1   // SAX locator interface for document events.
    2   // http://www.saxproject.org
    3   // No warranty; no copyright -- use this as you will.
    4   // $Id: Locator.java 226184 2005-04-08 10:53:24Z neeraj $
    5   
    6   package org.xml.sax;
    7   
    8   
    9   /**
   10    * Interface for associating a SAX event with a document location.
   11    *
   12    * <blockquote>
   13    * <em>This module, both source code and documentation, is in the
   14    * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
   15    * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
   16    * for further information.
   17    * </blockquote>
   18    *
   19    * <p>If a SAX parser provides location information to the SAX
   20    * application, it does so by implementing this interface and then
   21    * passing an instance to the application using the content
   22    * handler's {@link org.xml.sax.ContentHandler#setDocumentLocator
   23    * setDocumentLocator} method.  The application can use the
   24    * object to obtain the location of any other SAX event
   25    * in the XML source document.</p>
   26    *
   27    * <p>Note that the results returned by the object will be valid only
   28    * during the scope of each callback method: the application
   29    * will receive unpredictable results if it attempts to use the
   30    * locator at any other time, or after parsing completes.</p>
   31    *
   32    * <p>SAX parsers are not required to supply a locator, but they are
   33    * very strongly encouraged to do so.  If the parser supplies a
   34    * locator, it must do so before reporting any other document events.
   35    * If no locator has been set by the time the application receives
   36    * the {@link org.xml.sax.ContentHandler#startDocument startDocument}
   37    * event, the application should assume that a locator is not 
   38    * available.</p>
   39    *
   40    * @since SAX 1.0
   41    * @author David Megginson
   42    * @version 2.0.1 (sax2r2)
   43    * @see org.xml.sax.ContentHandler#setDocumentLocator 
   44    */
   45   public interface Locator {
   46       
   47       
   48       /**
   49        * Return the public identifier for the current document event.
   50        *
   51        * <p>The return value is the public identifier of the document
   52        * entity or of the external parsed entity in which the markup
   53        * triggering the event appears.</p>
   54        *
   55        * @return A string containing the public identifier, or
   56        *         null if none is available.
   57        * @see #getSystemId
   58        */
   59       public abstract String getPublicId ();
   60       
   61       
   62       /**
   63        * Return the system identifier for the current document event.
   64        *
   65        * <p>The return value is the system identifier of the document
   66        * entity or of the external parsed entity in which the markup
   67        * triggering the event appears.</p>
   68        *
   69        * <p>If the system identifier is a URL, the parser must resolve it
   70        * fully before passing it to the application.  For example, a file
   71        * name must always be provided as a <em>file:...</em> URL, and other
   72        * kinds of relative URI are also resolved against their bases.</p>
   73        *
   74        * @return A string containing the system identifier, or null
   75        *         if none is available.
   76        * @see #getPublicId
   77        */
   78       public abstract String getSystemId ();
   79       
   80       
   81       /**
   82        * Return the line number where the current document event ends.
   83        * Lines are delimited by line ends, which are defined in
   84        * the XML specification.
   85        *
   86        * <p><strong>Warning:</strong> The return value from the method
   87        * is intended only as an approximation for the sake of diagnostics;
   88        * it is not intended to provide sufficient information
   89        * to edit the character content of the original XML document.
   90        * In some cases, these "line" numbers match what would be displayed
   91        * as columns, and in others they may not match the source text
   92        * due to internal entity expansion.  </p>
   93        *
   94        * <p>The return value is an approximation of the line number
   95        * in the document entity or external parsed entity where the
   96        * markup triggering the event appears.</p>
   97        *
   98        * <p>If possible, the SAX driver should provide the line position 
   99        * of the first character after the text associated with the document 
  100        * event.  The first line is line 1.</p>
  101        *
  102        * @return The line number, or -1 if none is available.
  103        * @see #getColumnNumber
  104        */
  105       public abstract int getLineNumber ();
  106       
  107       
  108       /**
  109        * Return the column number where the current document event ends.
  110        * This is one-based number of Java <code>char</code> values since
  111        * the last line end.
  112        *
  113        * <p><strong>Warning:</strong> The return value from the method
  114        * is intended only as an approximation for the sake of diagnostics;
  115        * it is not intended to provide sufficient information
  116        * to edit the character content of the original XML document.
  117        * For example, when lines contain combining character sequences, wide
  118        * characters, surrogate pairs, or bi-directional text, the value may
  119        * not correspond to the column in a text editor's display. </p>
  120        *
  121        * <p>The return value is an approximation of the column number
  122        * in the document entity or external parsed entity where the
  123        * markup triggering the event appears.</p>
  124        *
  125        * <p>If possible, the SAX driver should provide the line position 
  126        * of the first character after the text associated with the document 
  127        * event.  The first column in each line is column 1.</p>
  128        *
  129        * @return The column number, or -1 if none is available.
  130        * @see #getLineNumber
  131        */
  132       public abstract int getColumnNumber ();
  133       
  134   }
  135   
  136   // end of Locator.java

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