1 /*
2 * Copyright (c) 2004 World Wide Web Consortium,
3 *
4 * (Massachusetts Institute of Technology, European Research Consortium for
5 * Informatics and Mathematics, Keio University). All Rights Reserved. This
6 * work is distributed under the W3C(r) Software License [1] in the hope that
7 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
8 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
9 *
10 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
11 */
12
13 package org.w3c.dom;
14
15 /**
16 * The <code>Attr</code> interface represents an attribute in an
17 * <code>Element</code> object. Typically the allowable values for the
18 * attribute are defined in a schema associated with the document.
19 * <p><code>Attr</code> objects inherit the <code>Node</code> interface, but
20 * since they are not actually child nodes of the element they describe, the
21 * DOM does not consider them part of the document tree. Thus, the
22 * <code>Node</code> attributes <code>parentNode</code>,
23 * <code>previousSibling</code>, and <code>nextSibling</code> have a
24 * <code>null</code> value for <code>Attr</code> objects. The DOM takes the
25 * view that attributes are properties of elements rather than having a
26 * separate identity from the elements they are associated with; this should
27 * make it more efficient to implement such features as default attributes
28 * associated with all elements of a given type. Furthermore,
29 * <code>Attr</code> nodes may not be immediate children of a
30 * <code>DocumentFragment</code>. However, they can be associated with
31 * <code>Element</code> nodes contained within a
32 * <code>DocumentFragment</code>. In short, users and implementors of the
33 * DOM need to be aware that <code>Attr</code> nodes have some things in
34 * common with other objects inheriting the <code>Node</code> interface, but
35 * they also are quite distinct.
36 * <p>The attribute's effective value is determined as follows: if this
37 * attribute has been explicitly assigned any value, that value is the
38 * attribute's effective value; otherwise, if there is a declaration for
39 * this attribute, and that declaration includes a default value, then that
40 * default value is the attribute's effective value; otherwise, the
41 * attribute does not exist on this element in the structure model until it
42 * has been explicitly added. Note that the <code>Node.nodeValue</code>
43 * attribute on the <code>Attr</code> instance can also be used to retrieve
44 * the string version of the attribute's value(s).
45 * <p> If the attribute was not explicitly given a value in the instance
46 * document but has a default value provided by the schema associated with
47 * the document, an attribute node will be created with
48 * <code>specified</code> set to <code>false</code>. Removing attribute
49 * nodes for which a default value is defined in the schema generates a new
50 * attribute node with the default value and <code>specified</code> set to
51 * <code>false</code>. If validation occurred while invoking
52 * <code>Document.normalizeDocument()</code>, attribute nodes with
53 * <code>specified</code> equals to <code>false</code> are recomputed
54 * according to the default attribute values provided by the schema. If no
55 * default value is associate with this attribute in the schema, the
56 * attribute node is discarded.
57 * <p>In XML, where the value of an attribute can contain entity references,
58 * the child nodes of the <code>Attr</code> node may be either
59 * <code>Text</code> or <code>EntityReference</code> nodes (when these are
60 * in use; see the description of <code>EntityReference</code> for
61 * discussion).
62 * <p>The DOM Core represents all attribute values as simple strings, even if
63 * the DTD or schema associated with the document declares them of some
64 * specific type such as tokenized.
65 * <p>The way attribute value normalization is performed by the DOM
66 * implementation depends on how much the implementation knows about the
67 * schema in use. Typically, the <code>value</code> and
68 * <code>nodeValue</code> attributes of an <code>Attr</code> node initially
69 * returns the normalized value given by the parser. It is also the case
70 * after <code>Document.normalizeDocument()</code> is called (assuming the
71 * right options have been set). But this may not be the case after
72 * mutation, independently of whether the mutation is performed by setting
73 * the string value directly or by changing the <code>Attr</code> child
74 * nodes. In particular, this is true when <a href='http://www.w3.org/TR/2004/REC-xml-20040204#dt-charref'>character
75 * references</a> are involved, given that they are not represented in the DOM and they
76 * impact attribute value normalization. On the other hand, if the
77 * implementation knows about the schema in use when the attribute value is
78 * changed, and it is of a different type than CDATA, it may normalize it
79 * again at that time. This is especially true of specialized DOM
80 * implementations, such as SVG DOM implementations, which store attribute
81 * values in an internal form different from a string.
82 * <p>The following table gives some examples of the relations between the
83 * attribute value in the original document (parsed attribute), the value as
84 * exposed in the DOM, and the serialization of the value:
85 * <table border='1' cellpadding='3'>
86 * <tr>
87 * <th>Examples</th>
88 * <th>Parsed
89 * attribute value</th>
90 * <th>Initial <code>Attr.value</code></th>
91 * <th>Serialized attribute value</th>
92 * </tr>
93 * <tr>
94 * <td valign='top' rowspan='1' colspan='1'>
95 * Character reference</td>
96 * <td valign='top' rowspan='1' colspan='1'>
97 * <pre>"x&#178;=5"</pre>
98 * </td>
99 * <td valign='top' rowspan='1' colspan='1'>
100 * <pre>"x\u00b2=5"</pre>
101 * </td>
102 * <td valign='top' rowspan='1' colspan='1'>
103 * <pre>"x&#178;=5"</pre>
104 * </td>
105 * </tr>
106 * <tr>
107 * <td valign='top' rowspan='1' colspan='1'>Built-in
108 * character entity</td>
109 * <td valign='top' rowspan='1' colspan='1'>
110 * <pre>"y&lt;6"</pre>
111 * </td>
112 * <td valign='top' rowspan='1' colspan='1'>
113 * <pre>"y<6"</pre>
114 * </td>
115 * <td valign='top' rowspan='1' colspan='1'>
116 * <pre>"y&lt;6"</pre>
117 * </td>
118 * </tr>
119 * <tr>
120 * <td valign='top' rowspan='1' colspan='1'>Literal newline between</td>
121 * <td valign='top' rowspan='1' colspan='1'>
122 * <pre>
123 * "x=5&#10;y=6"</pre>
124 * </td>
125 * <td valign='top' rowspan='1' colspan='1'>
126 * <pre>"x=5 y=6"</pre>
127 * </td>
128 * <td valign='top' rowspan='1' colspan='1'>
129 * <pre>"x=5&#10;y=6"</pre>
130 * </td>
131 * </tr>
132 * <tr>
133 * <td valign='top' rowspan='1' colspan='1'>Normalized newline between</td>
134 * <td valign='top' rowspan='1' colspan='1'>
135 * <pre>"x=5
136 * y=6"</pre>
137 * </td>
138 * <td valign='top' rowspan='1' colspan='1'>
139 * <pre>"x=5 y=6"</pre>
140 * </td>
141 * <td valign='top' rowspan='1' colspan='1'>
142 * <pre>"x=5 y=6"</pre>
143 * </td>
144 * </tr>
145 * <tr>
146 * <td valign='top' rowspan='1' colspan='1'>Entity <code>e</code> with literal newline</td>
147 * <td valign='top' rowspan='1' colspan='1'>
148 * <pre>
149 * <!ENTITY e '...&#10;...'> [...]> "x=5&e;y=6"</pre>
150 * </td>
151 * <td valign='top' rowspan='1' colspan='1'><em>Dependent on Implementation and Load Options</em></td>
152 * <td valign='top' rowspan='1' colspan='1'><em>Dependent on Implementation and Load/Save Options</em></td>
153 * </tr>
154 * </table>
155 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407'>Document Object Model (DOM) Level 3 Core Specification</a>.
156 */
157 public interface Attr extends Node {
158 /**
159 * Returns the name of this attribute. If <code>Node.localName</code> is
160 * different from <code>null</code>, this attribute is a qualified name.
161 */
162 public String getName();
163
164 /**
165 * <code>True</code> if this attribute was explicitly given a value in
166 * the instance document, <code>false</code> otherwise. If the
167 * application changed the value of this attribute node (even if it ends
168 * up having the same value as the default value) then it is set to
169 * <code>true</code>. The implementation may handle attributes with
170 * default values from other schemas similarly but applications should
171 * use <code>Document.normalizeDocument()</code> to guarantee this
172 * information is up-to-date.
173 */
174 public boolean getSpecified();
175
176 /**
177 * On retrieval, the value of the attribute is returned as a string.
178 * Character and general entity references are replaced with their
179 * values. See also the method <code>getAttribute</code> on the
180 * <code>Element</code> interface.
181 * <br>On setting, this creates a <code>Text</code> node with the unparsed
182 * contents of the string, i.e. any characters that an XML processor
183 * would recognize as markup are instead treated as literal text. See
184 * also the method <code>Element.setAttribute()</code>.
185 * <br> Some specialized implementations, such as some [<a href='http://www.w3.org/TR/2003/REC-SVG11-20030114/'>SVG 1.1</a>]
186 * implementations, may do normalization automatically, even after
187 * mutation; in such case, the value on retrieval may differ from the
188 * value on setting.
189 */
190 public String getValue();
191 /**
192 * On retrieval, the value of the attribute is returned as a string.
193 * Character and general entity references are replaced with their
194 * values. See also the method <code>getAttribute</code> on the
195 * <code>Element</code> interface.
196 * <br>On setting, this creates a <code>Text</code> node with the unparsed
197 * contents of the string, i.e. any characters that an XML processor
198 * would recognize as markup are instead treated as literal text. See
199 * also the method <code>Element.setAttribute()</code>.
200 * <br> Some specialized implementations, such as some [<a href='http://www.w3.org/TR/2003/REC-SVG11-20030114/'>SVG 1.1</a>]
201 * implementations, may do normalization automatically, even after
202 * mutation; in such case, the value on retrieval may differ from the
203 * value on setting.
204 * @exception DOMException
205 * NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
206 */
207 public void setValue(String value)
208 throws DOMException;
209
210 /**
211 * The <code>Element</code> node this attribute is attached to or
212 * <code>null</code> if this attribute is not in use.
213 * @since DOM Level 2
214 */
215 public Element getOwnerElement();
216
217 /**
218 * The type information associated with this attribute. While the type
219 * information contained in this attribute is guarantee to be correct
220 * after loading the document or invoking
221 * <code>Document.normalizeDocument()</code>, <code>schemaTypeInfo</code>
222 * may not be reliable if the node was moved.
223 * @since DOM Level 3
224 */
225 public TypeInfo getSchemaTypeInfo();
226
227 /**
228 * Returns whether this attribute is known to be of type ID (i.e. to
229 * contain an identifier for its owner element) or not. When it is and
230 * its value is unique, the <code>ownerElement</code> of this attribute
231 * can be retrieved using the method <code>Document.getElementById</code>
232 * . The implementation could use several ways to determine if an
233 * attribute node is known to contain an identifier:
234 * <ul>
235 * <li> If validation
236 * occurred using an XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>]
237 * while loading the document or while invoking
238 * <code>Document.normalizeDocument()</code>, the post-schema-validation
239 * infoset contributions (PSVI contributions) values are used to
240 * determine if this attribute is a schema-determined ID attribute using
241 * the <a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/#term-sdi'>
242 * schema-determined ID</a> definition in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
243 * .
244 * </li>
245 * <li> If validation occurred using a DTD while loading the document or
246 * while invoking <code>Document.normalizeDocument()</code>, the infoset <b>[type definition]</b> value is used to determine if this attribute is a DTD-determined ID
247 * attribute using the <a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/#term-ddi'>
248 * DTD-determined ID</a> definition in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
249 * .
250 * </li>
251 * <li> from the use of the methods <code>Element.setIdAttribute()</code>,
252 * <code>Element.setIdAttributeNS()</code>, or
253 * <code>Element.setIdAttributeNode()</code>, i.e. it is an
254 * user-determined ID attribute;
255 * <p ><b>Note:</b> XPointer framework (see section 3.2 in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
256 * ) consider the DOM user-determined ID attribute as being part of the
257 * XPointer externally-determined ID definition.
258 * </li>
259 * <li> using mechanisms that
260 * are outside the scope of this specification, it is then an
261 * externally-determined ID attribute. This includes using schema
262 * languages different from XML schema and DTD.
263 * </li>
264 * </ul>
265 * <br> If validation occurred while invoking
266 * <code>Document.normalizeDocument()</code>, all user-determined ID
267 * attributes are reset and all attribute nodes ID information are then
268 * reevaluated in accordance to the schema used. As a consequence, if
269 * the <code>Attr.schemaTypeInfo</code> attribute contains an ID type,
270 * <code>isId</code> will always return true.
271 * @since DOM Level 3
272 */
273 public boolean isId();
274
275 }