001// SAX locator interface for document events.
002// http://www.saxproject.org
003// No warranty; no copyright -- use this as you will.
004// $Id: Locator.java,v 1.1 2004/12/23 22:38:42 mark Exp $
005
006package org.xml.sax;
007
008
009/**
010 * Interface for associating a SAX event with a document location.
011 *
012 * <blockquote>
013 * <em>This module, both source code and documentation, is in the
014 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
015 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
016 * for further information.
017 * </blockquote>
018 *
019 * <p>If a SAX parser provides location information to the SAX
020 * application, it does so by implementing this interface and then
021 * passing an instance to the application using the content
022 * handler's {@link org.xml.sax.ContentHandler#setDocumentLocator
023 * setDocumentLocator} method.  The application can use the
024 * object to obtain the location of any other SAX event
025 * in the XML source document.</p>
026 *
027 * <p>Note that the results returned by the object will be valid only
028 * during the scope of each callback method: the application
029 * will receive unpredictable results if it attempts to use the
030 * locator at any other time, or after parsing completes.</p>
031 *
032 * <p>SAX parsers are not required to supply a locator, but they are
033 * very strongly encouraged to do so.  If the parser supplies a
034 * locator, it must do so before reporting any other document events.
035 * If no locator has been set by the time the application receives
036 * the {@link org.xml.sax.ContentHandler#startDocument startDocument}
037 * event, the application should assume that a locator is not
038 * available.</p>
039 *
040 * @since SAX 1.0
041 * @author David Megginson
042 * @version 2.0.1 (sax2r2)
043 * @see org.xml.sax.ContentHandler#setDocumentLocator
044 */
045public interface Locator {
046
047
048    /**
049     * Return the public identifier for the current document event.
050     *
051     * <p>The return value is the public identifier of the document
052     * entity or of the external parsed entity in which the markup
053     * triggering the event appears.</p>
054     *
055     * @return A string containing the public identifier, or
056     *         null if none is available.
057     * @see #getSystemId
058     */
059    public abstract String getPublicId ();
060
061
062    /**
063     * Return the system identifier for the current document event.
064     *
065     * <p>The return value is the system identifier of the document
066     * entity or of the external parsed entity in which the markup
067     * triggering the event appears.</p>
068     *
069     * <p>If the system identifier is a URL, the parser must resolve it
070     * fully before passing it to the application.  For example, a file
071     * name must always be provided as a <em>file:...</em> URL, and other
072     * kinds of relative URI are also resolved against their bases.</p>
073     *
074     * @return A string containing the system identifier, or null
075     *         if none is available.
076     * @see #getPublicId
077     */
078    public abstract String getSystemId ();
079
080
081    /**
082     * Return the line number where the current document event ends.
083     * Lines are delimited by line ends, which are defined in
084     * the XML specification.
085     *
086     * <p><strong>Warning:</strong> The return value from the method
087     * is intended only as an approximation for the sake of diagnostics;
088     * it is not intended to provide sufficient information
089     * to edit the character content of the original XML document.
090     * In some cases, these "line" numbers match what would be displayed
091     * as columns, and in others they may not match the source text
092     * due to internal entity expansion.  </p>
093     *
094     * <p>The return value is an approximation of the line number
095     * in the document entity or external parsed entity where the
096     * markup triggering the event appears.</p>
097     *
098     * <p>If possible, the SAX driver should provide the line position
099     * 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