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 */ getName()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 */ getSpecified()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 */ getValue()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 */ setValue(String value)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 */ getOwnerElement()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 */ getSchemaTypeInfo()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 */ isId()273 public boolean isId(); 274 275 } 276