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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

 *

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package org.xml.sax;

/**

 * Interface for associating a SAX event with a document location.

 *

 * <p>If a SAX parser provides location information to the SAX

 * application, it does so by implementing this interface and then

 * passing an instance to the application using the content

 * handler's {@link org.xml.sax.ContentHandler#setDocumentLocator

 * setDocumentLocator} method.  The application can use the

 * object to obtain the location of any other SAX event

 * in the XML source document.</p>

 *

 * <p>Note that the results returned by the object will be valid only

 * during the scope of each callback method: the application

 * will receive unpredictable results if it attempts to use the

 * locator at any other time, or after parsing completes.</p>

 *

 * <p>SAX parsers are not required to supply a locator, but they are

 * very strongly encouraged to do so.  If the parser supplies a

 * locator, it must do so before reporting any other document events.

 * If no locator has been set by the time the application receives

 * the {@link org.xml.sax.ContentHandler#startDocument startDocument}

 * event, the application should assume that a locator is not

 * available.</p>

 *

 * @since 1.4, SAX 1.0

 * @author David Megginson

 * @see org.xml.sax.ContentHandler#setDocumentLocator

 */

public interface Locator {

    /**

     * Return the public identifier for the current document event.

     *

     * <p>The return value is the public identifier of the document

     * entity or of the external parsed entity in which the markup

     * triggering the event appears.</p>

     *

     * @return A string containing the public identifier, or

     *         null if none is available.

     * @see #getSystemId

     */

    public abstract String getPublicId ();

    /**

     * Return the system identifier for the current document event.

     *

     * <p>The return value is the system identifier of the document

     * entity or of the external parsed entity in which the markup

     * triggering the event appears.</p>

     *

     * <p>If the system identifier is a URL, the parser must resolve it

     * fully before passing it to the application.  For example, a file

     * name must always be provided as a <em>file:...</em> URL, and other

     * kinds of relative URI are also resolved against their bases.</p>

     *

     * @return A string containing the system identifier, or null

     *         if none is available.

     * @see #getPublicId

     */

    public abstract String getSystemId ();

    /**

     * Return the line number where the current document event ends.

     * Lines are delimited by line ends, which are defined in

     * the XML specification.

     *

     * <p><strong>Warning:</strong> The return value from the method

     * is intended only as an approximation for the sake of diagnostics;

     * it is not intended to provide sufficient information

     * to edit the character content of the original XML document.

     * In some cases, these "line" numbers match what would be displayed

     * as columns, and in others they may not match the source text

     * due to internal entity expansion.  </p>

     *

     * <p>The return value is an approximation of the line number

     * in the document entity or external parsed entity where the

     * markup triggering the event appears.</p>

     *

     * <p>If possible, the SAX driver should provide the line position

     * of the first character after the text associated with the document

     * event.  The first line is line 1.</p>

     *

     * @return The line number, or -1 if none is available.

     * @see #getColumnNumber

     */

    public abstract int getLineNumber ();

    /**

     * Return the column number where the current document event ends.

     * This is one-based number of Java <code>char</code> values since

     * the last line end.

     *

     * <p><strong>Warning:</strong> The return value from the method

     * is intended only as an approximation for the sake of diagnostics;

     * it is not intended to provide sufficient information

     * to edit the character content of the original XML document.

     * For example, when lines contain combining character sequences, wide

     * characters, surrogate pairs, or bi-directional text, the value may

     * not correspond to the column in a text editor's display. </p>

     *

     * <p>The return value is an approximation of the column number

     * in the document entity or external parsed entity where the

     * markup triggering the event appears.</p>

     *

     * <p>If possible, the SAX driver should provide the line position

     * of the first character after the text associated with the document

     * event.  The first column in each line is column 1.</p>

     *

     * @return The column number, or -1 if none is available.

     * @see #getLineNumber

     */

    public abstract int getColumnNumber ();

}

// end of Locator.java