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001// Attributes.java - attribute list with Namespace support
002// http://www.saxproject.org
003// Written by David Megginson
004// NO WARRANTY!  This class is in the public domain.
005// $Id: Attributes.java,v 1.2 2004/11/03 22:44:51 jsuttor Exp $
006
007package org.xml.sax;
008
009
010/**
011 * Interface for a list of XML attributes.
012 *
013 * <blockquote>
014 * <em>This module, both source code and documentation, is in the
015 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
016 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
017 * for further information.
018 * </blockquote>
019 *
020 * <p>This interface allows access to a list of attributes in
021 * three different ways:</p>
022 *
023 * <ol>
024 * <li>by attribute index;</li>
025 * <li>by Namespace-qualified name; or</li>
026 * <li>by qualified (prefixed) name.</li>
027 * </ol>
028 *
029 * <p>The list will not contain attributes that were declared
030 * #IMPLIED but not specified in the start tag.  It will also not
031 * contain attributes used as Namespace declarations (xmlns*) unless
032 * the <code>http://xml.org/sax/features/namespace-prefixes</code> 
033 * feature is set to <var>true</var> (it is <var>false</var> by 
034 * default).
035 * Because SAX2 conforms to the original "Namespaces in XML"
036 * recommendation, it normally does not
037 * give namespace declaration attributes a namespace URI.
038 * </p>
039 *
040 * <p>Some SAX2 parsers may support using an optional feature flag
041 * (<code>http://xml.org/sax/features/xmlns-uris</code>) to request
042 * that those attributes be given URIs, conforming to a later
043 * backwards-incompatible revision of that recommendation.  (The
044 * attribute's "local name" will be the prefix, or "xmlns" when
045 * defining a default element namespace.)  For portability, handler
046 * code should always resolve that conflict, rather than requiring
047 * parsers that can change the setting of that feature flag.  </p>
048 *
049 * <p>If the namespace-prefixes feature (see above) is
050 * <var>false</var>, access by qualified name may not be available; if
051 * the <code>http://xml.org/sax/features/namespaces</code> feature is
052 * <var>false</var>, access by Namespace-qualified names may not be
053 * available.</p>
054 *
055 * <p>This interface replaces the now-deprecated SAX1 {@link
056 * org.xml.sax.AttributeList AttributeList} interface, which does not 
057 * contain Namespace support.  In addition to Namespace support, it 
058 * adds the <var>getIndex</var> methods (below).</p>
059 *
060 * <p>The order of attributes in the list is unspecified, and will
061 * vary from implementation to implementation.</p>
062 *
063 * @since SAX 2.0
064 * @author David Megginson
065 * @version 2.0.1 (sax2r2)
066 * @see org.xml.sax.helpers.AttributesImpl
067 * @see org.xml.sax.ext.DeclHandler#attributeDecl
068 */
069public interface Attributes
070{
071
072
073    ////////////////////////////////////////////////////////////////////
074    // Indexed access.
075    ////////////////////////////////////////////////////////////////////
076
077
078    /**
079     * Return the number of attributes in the list.
080     *
081     * <p>Once you know the number of attributes, you can iterate
082     * through the list.</p>
083     *
084     * @return The number of attributes in the list.
085     * @see #getURI(int)
086     * @see #getLocalName(int)
087     * @see #getQName(int)
088     * @see #getType(int)
089     * @see #getValue(int)
090     */
091    public abstract int getLength ();
092
093
094    /**
095     * Look up an attribute's Namespace URI by index.
096     *
097     * @param index The attribute index (zero-based).
098     * @return The Namespace URI, or the empty string if none
099     *         is available, or null if the index is out of
100     *         range.
101     * @see #getLength
102     */
103    public abstract String getURI (int index);
104
105
106    /**
107     * Look up an attribute's local name by index.
108     *
109     * @param index The attribute index (zero-based).
110     * @return The local name, or the empty string if Namespace
111     *         processing is not being performed, or null
112     *         if the index is out of range.
113     * @see #getLength
114     */
115    public abstract String getLocalName (int index);
116
117
118    /**
119     * Look up an attribute's XML qualified (prefixed) name by index.
120     *
121     * @param index The attribute index (zero-based).
122     * @return The XML qualified name, or the empty string
123     *         if none is available, or null if the index
124     *         is out of range.
125     * @see #getLength
126     */
127    public abstract String getQName (int index);
128
129
130    /**
131     * Look up an attribute's type by index.
132     *
133     * <p>The attribute type is one of the strings "CDATA", "ID",
134     * "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES",
135     * or "NOTATION" (always in upper case).</p>
136     *
137     * <p>If the parser has not read a declaration for the attribute,
138     * or if the parser does not report attribute types, then it must
139     * return the value "CDATA" as stated in the XML 1.0 Recommendation
140     * (clause 3.3.3, "Attribute-Value Normalization").</p>
141     *
142     * <p>For an enumerated attribute that is not a notation, the
143     * parser will report the type as "NMTOKEN".</p>
144     *
145     * @param index The attribute index (zero-based).
146     * @return The attribute's type as a string, or null if the
147     *         index is out of range.
148     * @see #getLength
149     */
150    public abstract String getType (int index);
151
152
153    /**
154     * Look up an attribute's value by index.
155     *
156     * <p>If the attribute value is a list of tokens (IDREFS,
157     * ENTITIES, or NMTOKENS), the tokens will be concatenated
158     * into a single string with each token separated by a
159     * single space.</p>
160     *
161     * @param index The attribute index (zero-based).
162     * @return The attribute's value as a string, or null if the
163     *         index is out of range.
164     * @see #getLength
165     */
166    public abstract String getValue (int index);
167
168
169
170    ////////////////////////////////////////////////////////////////////
171    // Name-based query.
172    ////////////////////////////////////////////////////////////////////
173
174
175    /**
176     * Look up the index of an attribute by Namespace name.
177     *
178     * @param uri The Namespace URI, or the empty string if
179     *        the name has no Namespace URI.
180     * @param localName The attribute's local name.
181     * @return The index of the attribute, or -1 if it does not
182     *         appear in the list.
183     */
184    public int getIndex (String uri, String localName);
185
186
187    /**
188     * Look up the index of an attribute by XML qualified (prefixed) name.
189     *
190     * @param qName The qualified (prefixed) name.
191     * @return The index of the attribute, or -1 if it does not
192     *         appear in the list.
193     */
194    public int getIndex (String qName);
195
196
197    /**
198     * Look up an attribute's type by Namespace name.
199     *
200     * <p>See {@link #getType(int) getType(int)} for a description
201     * of the possible types.</p>
202     *
203     * @param uri The Namespace URI, or the empty String if the
204     *        name has no Namespace URI.
205     * @param localName The local name of the attribute.
206     * @return The attribute type as a string, or null if the
207     *         attribute is not in the list or if Namespace
208     *         processing is not being performed.
209     */
210    public abstract String getType (String uri, String localName);
211
212
213    /**
214     * Look up an attribute's type by XML qualified (prefixed) name.
215     *
216     * <p>See {@link #getType(int) getType(int)} for a description
217     * of the possible types.</p>
218     *
219     * @param qName The XML qualified name.
220     * @return The attribute type as a string, or null if the
221     *         attribute is not in the list or if qualified names
222     *         are not available.
223     */
224    public abstract String getType (String qName);
225
226
227    /**
228     * Look up an attribute's value by Namespace name.
229     *
230     * <p>See {@link #getValue(int) getValue(int)} for a description
231     * of the possible values.</p>
232     *
233     * @param uri The Namespace URI, or the empty String if the
234     *        name has no Namespace URI.
235     * @param localName The local name of the attribute.
236     * @return The attribute value as a string, or null if the
237     *         attribute is not in the list.
238     */
239    public abstract String getValue (String uri, String localName);
240
241
242    /**
243     * Look up an attribute's value by XML qualified (prefixed) name.
244     *
245     * <p>See {@link #getValue(int) getValue(int)} for a description
246     * of the possible values.</p>
247     *
248     * @param qName The XML qualified name.
249     * @return The attribute value as a string, or null if the
250     *         attribute is not in the list or if qualified names
251     *         are not available.
252     */
253    public abstract String getValue (String qName);
254
255}
256
257// end of Attributes.java