1// LexicalHandler.java - optional handler for lexical parse events.
2// http://www.saxproject.org
3// Public Domain: no warranty.
4// $Id: LexicalHandler.java,v 1.5 2002/01/30 21:00:44 dbrownell Exp $
5
6package org.xml.sax.ext;
7
8import org.xml.sax.SAXException;
9
10/**
11 * SAX2 extension handler for lexical events.
12 *
13 * <blockquote>
14 * <em>This module, both source code and documentation, is in the
15 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
16 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
17 * for further information.
18 * </blockquote>
19 *
20 * <p>This is an optional extension handler for SAX2 to provide
21 * lexical information about an XML document, such as comments
22 * and CDATA section boundaries.
23 * XML readers are not required to recognize this handler, and it
24 * is not part of core-only SAX2 distributions.</p>
25 *
26 * <p>The events in the lexical handler apply to the entire document,
27 * not just to the document element, and all lexical handler events
28 * must appear between the content handler's startDocument and
29 * endDocument events.</p>
30 *
31 * <p>To set the LexicalHandler for an XML reader, use the
32 * {@link org.xml.sax.XMLReader#setProperty setProperty} method
33 * with the property name
34 * <code>http://xml.org/sax/properties/lexical-handler</code>
35 * and an object implementing this interface (or null) as the value.
36 * If the reader does not report lexical events, it will throw a
37 * {@link org.xml.sax.SAXNotRecognizedException SAXNotRecognizedException}
38 * when you attempt to register the handler.</p>
39 *
40 * @since SAX 2.0 (extensions 1.0)
41 * @author David Megginson
42 * @version 2.0.1 (sax2r2)
43 */
44public interface LexicalHandler
45{
46
47    /**
48     * Report the start of DTD declarations, if any.
49     *
50     * <p>This method is intended to report the beginning of the
51     * DOCTYPE declaration; if the document has no DOCTYPE declaration,
52     * this method will not be invoked.</p>
53     *
54     * <p>All declarations reported through
55     * {@link org.xml.sax.DTDHandler DTDHandler} or
56     * {@link org.xml.sax.ext.DeclHandler DeclHandler} events must appear
57     * between the startDTD and {@link #endDTD endDTD} events.
58     * Declarations are assumed to belong to the internal DTD subset
59     * unless they appear between {@link #startEntity startEntity}
60     * and {@link #endEntity endEntity} events.  Comments and
61     * processing instructions from the DTD should also be reported
62     * between the startDTD and endDTD events, in their original
63     * order of (logical) occurrence; they are not required to
64     * appear in their correct locations relative to DTDHandler
65     * or DeclHandler events, however.</p>
66     *
67     * <p>Note that the start/endDTD events will appear within
68     * the start/endDocument events from ContentHandler and
69     * before the first
70     * {@link org.xml.sax.ContentHandler#startElement startElement}
71     * event.</p>
72     *
73     * @param name The document type name.
74     * @param publicId The declared public identifier for the
75     *        external DTD subset, or null if none was declared.
76     * @param systemId The declared system identifier for the
77     *        external DTD subset, or null if none was declared.
78     *        (Note that this is not resolved against the document
79     *        base URI.)
80     * @exception SAXException The application may raise an
81     *            exception.
82     * @see #endDTD
83     * @see #startEntity
84     */
85    public abstract void startDTD (String name, String publicId,
86                   String systemId)
87    throws SAXException;
88
89
90    /**
91     * Report the end of DTD declarations.
92     *
93     * <p>This method is intended to report the end of the
94     * DOCTYPE declaration; if the document has no DOCTYPE declaration,
95     * this method will not be invoked.</p>
96     *
97     * @exception SAXException The application may raise an exception.
98     * @see #startDTD
99     */
100    public abstract void endDTD ()
101    throws SAXException;
102
103
104    /**
105     * Report the beginning of some internal and external XML entities.
106     *
107     * <p>The reporting of parameter entities (including
108     * the external DTD subset) is optional, and SAX2 drivers that
109     * report LexicalHandler events may not implement it; you can use the
110     * <code
111     * >http://xml.org/sax/features/lexical-handler/parameter-entities</code>
112     * feature to query or control the reporting of parameter entities.</p>
113     *
114     * <p>General entities are reported with their regular names,
115     * parameter entities have '%' prepended to their names, and
116     * the external DTD subset has the pseudo-entity name "[dtd]".</p>
117     *
118     * <p>When a SAX2 driver is providing these events, all other
119     * events must be properly nested within start/end entity
120     * events.  There is no additional requirement that events from
121     * {@link org.xml.sax.ext.DeclHandler DeclHandler} or
122     * {@link org.xml.sax.DTDHandler DTDHandler} be properly ordered.</p>
123     *
124     * <p>Note that skipped entities will be reported through the
125     * {@link org.xml.sax.ContentHandler#skippedEntity skippedEntity}
126     * event, which is part of the ContentHandler interface.</p>
127     *
128     * <p>Because of the streaming event model that SAX uses, some
129     * entity boundaries cannot be reported under any
130     * circumstances:</p>
131     *
132     * <ul>
133     * <li>general entities within attribute values</li>
134     * <li>parameter entities within declarations</li>
135     * </ul>
136     *
137     * <p>These will be silently expanded, with no indication of where
138     * the original entity boundaries were.</p>
139     *
140     * <p>Note also that the boundaries of character references (which
141     * are not really entities anyway) are not reported.</p>
142     *
143     * <p>All start/endEntity events must be properly nested.
144     *
145     * @param name The name of the entity.  If it is a parameter
146     *        entity, the name will begin with '%', and if it is the
147     *        external DTD subset, it will be "[dtd]".
148     * @exception SAXException The application may raise an exception.
149     * @see #endEntity
150     * @see org.xml.sax.ext.DeclHandler#internalEntityDecl
151     * @see org.xml.sax.ext.DeclHandler#externalEntityDecl
152     */
153    public abstract void startEntity (String name)
154    throws SAXException;
155
156
157    /**
158     * Report the end of an entity.
159     *
160     * @param name The name of the entity that is ending.
161     * @exception SAXException The application may raise an exception.
162     * @see #startEntity
163     */
164    public abstract void endEntity (String name)
165    throws SAXException;
166
167
168    /**
169     * Report the start of a CDATA section.
170     *
171     * <p>The contents of the CDATA section will be reported through
172     * the regular {@link org.xml.sax.ContentHandler#characters
173     * characters} event; this event is intended only to report
174     * the boundary.</p>
175     *
176     * @exception SAXException The application may raise an exception.
177     * @see #endCDATA
178     */
179    public abstract void startCDATA ()
180    throws SAXException;
181
182
183    /**
184     * Report the end of a CDATA section.
185     *
186     * @exception SAXException The application may raise an exception.
187     * @see #startCDATA
188     */
189    public abstract void endCDATA ()
190    throws SAXException;
191
192
193    /**
194     * Report an XML comment anywhere in the document.
195     *
196     * <p>This callback will be used for comments inside or outside the
197     * document element, including comments in the external DTD
198     * subset (if read).  Comments in the DTD must be properly
199     * nested inside start/endDTD and start/endEntity events (if
200     * used).</p>
201     *
202     * @param ch An array holding the characters in the comment.
203     * @param start The starting position in the array.
204     * @param length The number of characters to use from the array.
205     * @exception SAXException The application may raise an exception.
206     */
207    public abstract void comment (char ch[], int start, int length)
208    throws SAXException;
209
210}
211
212// end of LexicalHandler.java
213