001// SAX Attribute List Interface.
002// No warranty; no copyright -- use this as you will.
003// $Id: AttributeList.java,v 1.1 2001/03/05 21:40:05 jstrachan Exp $
004
005package org.xml.sax;
006
007/**
008 * Interface for an element's attribute specifications.
009 *
010 * <blockquote>
011 * <em>This module, both source code and documentation, is in the
012 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
013 * </blockquote>
014 *
015 * <p>This is the original SAX1 interface for reporting an element's
016 * attributes.  Unlike the new {@link org.xml.sax.Attributes Attributes}
017 * interface, it does not support Namespace-related information.</p>
018 *
019 * <p>When an attribute list is supplied as part of a
020 * {@link org.xml.sax.DocumentHandler#startElement startElement}
021 * event, the list will return valid results only during the
022 * scope of the event; once the event handler returns control
023 * to the parser, the attribute list is invalid.  To save a
024 * persistent copy of the attribute list, use the SAX1
025 * {@link org.xml.sax.helpers.AttributeListImpl AttributeListImpl}
026 * helper class.</p>
027 *
028 * <p>An attribute list includes only attributes that have been
029 * specified or defaulted: #IMPLIED attributes will not be included.</p>
030 *
031 * <p>There are two ways for the SAX application to obtain information
032 * from the AttributeList.  First, it can iterate through the entire
033 * list:</p>
034 *
035 * <pre>
036 * public void startElement (String name, AttributeList atts) {
037 *   for (int i = 0; i < atts.getLength(); i++) {
038 *     String name = atts.getName(i);
039 *     String type = atts.getType(i);
040 *     String value = atts.getValue(i);
041 *     [...]
042 *   }
043 * }
044 * </pre>
045 *
046 * <p>(Note that the result of getLength() will be zero if there
047 * are no attributes.)
048 *
049 * <p>As an alternative, the application can request the value or
050 * type of specific attributes:</p>
051 *
052 * <pre>
053 * public void startElement (String name, AttributeList atts) {
054 *   String identifier = atts.getValue("id");
055 *   String label = atts.getValue("label");
056 *   [...]
057 * }
058 * </pre>
059 *
060 * @deprecated This interface has been replaced by the SAX2
061 *             {@link org.xml.sax.Attributes Attributes}
062 *             interface, which includes Namespace support.
063 * @since SAX 1.0
064 * @author David Megginson, 
065 *         <a href="mailto:sax@megginson.com">sax@megginson.com</a>
066 * @version 2.0
067 * @see org.xml.sax.DocumentHandler#startElement startElement
068 * @see org.xml.sax.helpers.AttributeListImpl AttributeListImpl
069 */
070public interface AttributeList {
071
072
073    ////////////////////////////////////////////////////////////////////
074    // Iteration methods.
075    ////////////////////////////////////////////////////////////////////
076    
077
078    /**
079     * Return the number of attributes in this list.
080     *
081     * <p>The SAX parser may provide attributes in any
082     * arbitrary order, regardless of the order in which they were
083     * declared or specified.  The number of attributes may be
084     * zero.</p>
085     *
086     * @return The number of attributes in the list.  
087     */
088    public abstract int getLength ();
089    
090    
091    /**
092     * Return the name of an attribute in this list (by position).
093     *
094     * <p>The names must be unique: the SAX parser shall not include the
095     * same attribute twice.  Attributes without values (those declared
096     * #IMPLIED without a value specified in the start tag) will be
097     * omitted from the list.</p>
098     *
099     * <p>If the attribute name has a namespace prefix, the prefix
100     * will still be attached.</p>
101     *
102     * @param i The index of the attribute in the list (starting at 0).
103     * @return The name of the indexed attribute, or null
104     *         if the index is out of range.
105     * @see #getLength 
106     */
107    public abstract String getName (int i);
108    
109    
110    /**
111     * Return the type of an attribute in the list (by position).
112     *
113     * <p>The attribute type is one of the strings "CDATA", "ID",
114     * "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES",
115     * or "NOTATION" (always in upper case).</p>
116     *
117     * <p>If the parser has not read a declaration for the attribute,
118     * or if the parser does not report attribute types, then it must
119     * return the value "CDATA" as stated in the XML 1.0 Recommentation
120     * (clause 3.3.3, "Attribute-Value Normalization").</p>
121     *
122     * <p>For an enumerated attribute that is not a notation, the
123     * parser will report the type as "NMTOKEN".</p>
124     *
125     * @param i The index of the attribute in the list (starting at 0).
126     * @return The attribute type as a string, or
127     *         null if the index is out of range.
128     * @see #getLength 
129     * @see #getType(java.lang.String)
130     */
131    public abstract String getType (int i);
132    
133    
134    /**
135     * Return the value of an attribute in the list (by position).
136     *
137     * <p>If the attribute value is a list of tokens (IDREFS,
138     * ENTITIES, or NMTOKENS), the tokens will be concatenated
139     * into a single string separated by whitespace.</p>
140     *
141     * @param i The index of the attribute in the list (starting at 0).
142     * @return The attribute value as a string, or
143     *         null if the index is out of range.
144     * @see #getLength
145     * @see #getValue(java.lang.String)
146     */
147    public abstract String getValue (int i);
148
149
150
151    ////////////////////////////////////////////////////////////////////
152    // Lookup methods.
153    ////////////////////////////////////////////////////////////////////
154    
155    
156    /**
157     * Return the type of an attribute in the list (by name).
158     *
159     * <p>The return value is the same as the return value for
160     * getType(int).</p>
161     *
162     * <p>If the attribute name has a namespace prefix in the document,
163     * the application must include the prefix here.</p>
164     *
165     * @param name The name of the attribute.
166     * @return The attribute type as a string, or null if no
167     *         such attribute exists.
168     * @see #getType(int)
169     */
170    public abstract String getType (String name);
171    
172    
173    /**
174     * Return the value of an attribute in the list (by name).
175     *
176     * <p>The return value is the same as the return value for
177     * getValue(int).</p>
178     *
179     * <p>If the attribute name has a namespace prefix in the document,
180     * the application must include the prefix here.</p>
181     *
182     * @param i The index of the attribute in the list.
183     * @return The attribute value as a string, or null if
184     *         no such attribute exists.
185     * @see #getValue(int)
186     */
187    public abstract String getValue (String name);
188    
189}
190
191// end of AttributeList.java