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49 package org.jaxen.function;
50
51 import java.util.List;
52
53 import org.jaxen.Context;
54 import org.jaxen.Function;
55 import org.jaxen.FunctionCallException;
56 import org.jaxen.Navigator;
57
58 /***
59 * <p><b>4.1</b> <code><i>string</i> local-name(<i>node-set?</i>)</code></p>
60 *
61 *
62 * <blockquote src="http://www.w3.org/TR/xpath">
63 * The <b>local-name</b> function returns the local part of the
64 * expanded-name of the node in the argument node-set that is first in document order.
65 * If the argument node-set is empty or the first node has no expanded-name, an
66 * empty string is returned. If the argument is omitted, it defaults to a node-set with the context node as its only member.
67 *
68 * </blockquote>
69 *
70 * @author bob mcwhirter (bob @ werken.com)
71 * @see <a href="http://www.w3.org/TR/xpath#function-local-name" target="_top">Section 4.1 of the XPath Specification</a>
72 */
73 public class LocalNameFunction implements Function
74 {
75
76 /***
77 * Create a new <code>LocalNameFunction</code> object.
78 */
79 public LocalNameFunction() {}
80
81 /***
82 * Returns the local-name of the specified node or the context node if
83 * no arguments are provided.
84 *
85 * @param context the context at the point in the
86 * expression where the function is called
87 * @param args a <code>List</code> containing zero or one items
88 *
89 * @return a <code>String</code> containing the local-name
90 *
91 * @throws FunctionCallException if <code>args</code> has more than one item
92 */
93 public Object call(Context context,
94 List args) throws FunctionCallException
95 {
96 if ( args.size() == 0 )
97 {
98 return evaluate( context.getNodeSet(),
99 context.getNavigator() );
100 }
101
102 if ( args.size() == 1 )
103 {
104 return evaluate( args,
105 context.getNavigator() );
106 }
107
108 throw new FunctionCallException( "local-name() requires zero or one argument." );
109 }
110
111 /***
112 * Returns the local-name of <code>list.get(0)</code>
113 *
114 * @param list a list of nodes
115 * @param nav the <code>Navigator</code> used to retrieve the local name
116 *
117 * @return the local-name of <code>list.get(0)</code>
118 *
119 * @throws FunctionCallException if <code>list.get(0)</code> is not a node
120 */
121 public static String evaluate(List list,
122 Navigator nav) throws FunctionCallException
123 {
124 if ( ! list.isEmpty() )
125 {
126 Object first = list.get(0);
127
128 if (first instanceof List)
129 {
130 return evaluate( (List) first,
131 nav );
132 }
133 else if ( nav.isElement( first ) )
134 {
135 return nav.getElementName( first );
136 }
137 else if ( nav.isAttribute( first ) )
138 {
139 return nav.getAttributeName( first );
140 }
141 else if ( nav.isProcessingInstruction( first ) )
142 {
143 return nav.getProcessingInstructionTarget( first );
144 }
145 else if ( nav.isNamespace( first ) )
146 {
147 return nav.getNamespacePrefix( first );
148 }
149 else if ( nav.isDocument( first ) )
150 {
151 return "";
152 }
153 else if ( nav.isComment( first ) )
154 {
155 return "";
156 }
157 else if ( nav.isText( first ) )
158 {
159 return "";
160 }
161 else {
162 throw new FunctionCallException("The argument to the local-name function must be a node-set");
163 }
164 }
165
166 return "";
167 }
168
169 }
170