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63 package org.jaxen.function;
64
65 import java.util.List;
66
67 import org.jaxen.Context;
68 import org.jaxen.Function;
69 import org.jaxen.FunctionCallException;
70 import org.jaxen.Navigator;
71
72 /***
73 * <p><b>4.1</b> <code><i>string</i> local-name(<i>node-set?</i>)</code></p>
74 *
75 *
76 * <blockquote src="http://www.w3.org/TR/xpath">
77 * The <b>local-name</b> function returns the local part of the
78 * expanded-name of the node in the argument node-set that is first in document order.
79 * If the argument node-set is empty or the first node has no expanded-name, an
80 * empty string is returned. If the argument is omitted, it defaults to a node-set with the context node as its only member.
81 *
82 * </blockquote>
83 *
84 * @author bob mcwhirter (bob @ werken.com)
85 * @see <a href="http://www.w3.org/TR/xpath#function-local-name" target="_top">Section 4.1 of the XPath Specification</a>
86 */
87 public class LocalNameFunction implements Function
88 {
89
90 /***
91 * Create a new <code>LocalNameFunction</code> object.
92 */
93 public LocalNameFunction() {}
94
95 /***
96 * Returns the local-name of the specified node or the context node if
97 * no arguments are provided.
98 *
99 * @param context the context at the point in the
100 * expression where the function is called
101 * @param args a <code>List</code> containing zero or one items
102 *
103 * @return a <code>String</code> containing the local-name
104 *
105 * @throws FunctionCallException if <code>args</code> has more than one item
106 */
107 public Object call(Context context,
108 List args) throws FunctionCallException
109 {
110 if ( args.size() == 0 )
111 {
112 return evaluate( context.getNodeSet(),
113 context.getNavigator() );
114 }
115
116 if ( args.size() == 1 )
117 {
118 return evaluate( args,
119 context.getNavigator() );
120 }
121
122 throw new FunctionCallException( "local-name() requires zero or one argument." );
123 }
124
125 /***
126 * Returns the local-name of <code>list.get(0)</code>
127 *
128 * @param list a list of nodes
129 * @param nav the <code>Navigator</code> used to retrieve the local name
130 *
131 * @return the local-name of <code>list.get(0)</code>
132 *
133 * @throws FunctionCallException if <code>list.get(0)</code> is not a node
134 */
135 public static String evaluate(List list,
136 Navigator nav) throws FunctionCallException
137 {
138 if ( ! list.isEmpty() )
139 {
140 Object first = list.get(0);
141
142 if (first instanceof List)
143 {
144 return evaluate( (List) first,
145 nav );
146 }
147 else if ( nav.isElement( first ) )
148 {
149 return nav.getElementName( first );
150 }
151 else if ( nav.isAttribute( first ) )
152 {
153 return nav.getAttributeName( first );
154 }
155 else if ( nav.isProcessingInstruction( first ) )
156 {
157 return nav.getProcessingInstructionTarget( first );
158 }
159 else if ( nav.isNamespace( first ) )
160 {
161 return nav.getNamespacePrefix( first );
162 }
163 else if ( nav.isDocument( first ) )
164 {
165 return "";
166 }
167 else if ( nav.isComment( first ) )
168 {
169 return "";
170 }
171 else if ( nav.isText( first ) )
172 {
173 return "";
174 }
175 else {
176 throw new FunctionCallException("The argument to the local-name function must be a node-set");
177 }
178 }
179
180 return "";
181 }
182
183 }
184