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1   // SAX default implementation for AttributeList.
2   // http://www.saxproject.org
3   // No warranty; no copyright -- use this as you will.
4   // $Id: AttributeListImpl.java,v 1.5 2004/03/19 20:17:54 maartenc Exp $
5   
6   package org.xml.sax.helpers;
7   
8   import org.xml.sax.AttributeList;
9   
10  import java.util.Vector;
11  
12  
13  /***
14   * Default implementation for AttributeList.
15   *
16   * <blockquote>
17   * <em>This module, both source code and documentation, is in the
18   * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
19   * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
20   * for further information.
21   * </blockquote>
22   *
23   * <p>AttributeList implements the deprecated SAX1 {@link
24   * org.xml.sax.AttributeList AttributeList} interface, and has been
25   * replaced by the new SAX2 {@link org.xml.sax.helpers.AttributesImpl
26   * AttributesImpl} interface.</p>
27   *
28   * <p>This class provides a convenience implementation of the SAX
29   * {@link org.xml.sax.AttributeList AttributeList} interface.  This 
30   * implementation is useful both for SAX parser writers, who can use 
31   * it to provide attributes to the application, and for SAX application 
32   * writers, who can use it to create a persistent copy of an element's 
33   * attribute specifications:</p>
34   *
35   * <pre>
36   * private AttributeList myatts;
37   *
38   * public void startElement (String name, AttributeList atts)
39   * {
40   *              // create a persistent copy of the attribute list
41   *              // for use outside this method
42   *   myatts = new AttributeListImpl(atts);
43   *   [...]
44   * }
45   * </pre>
46   *
47   * <p>Please note that SAX parsers are not required to use this
48   * class to provide an implementation of AttributeList; it is
49   * supplied only as an optional convenience.  In particular, 
50   * parser writers are encouraged to invent more efficient
51   * implementations.</p>
52   *
53   * @deprecated This class implements a deprecated interface,
54   *             {@link org.xml.sax.AttributeList AttributeList};
55   *             that interface has been replaced by
56   *             {@link org.xml.sax.Attributes Attributes},
57   *             which is implemented in the
58   *             {@link org.xml.sax.helpers.AttributesImpl 
59   *            AttributesImpl} helper class.
60   * @since SAX 1.0
61   * @author David Megginson
62   * @version 2.0.1 (sax2r2)
63   * @see org.xml.sax.AttributeList
64   * @see org.xml.sax.DocumentHandler#startElement 
65   */
66  public class AttributeListImpl implements AttributeList
67  {
68      
69      /***
70       * Create an empty attribute list.
71       *
72       * <p>This constructor is most useful for parser writers, who
73       * will use it to create a single, reusable attribute list that
74       * can be reset with the clear method between elements.</p>
75       *
76       * @see #addAttribute
77       * @see #clear
78       */
79      public AttributeListImpl ()
80      {
81      }
82      
83      
84      /***
85       * Construct a persistent copy of an existing attribute list.
86       *
87       * <p>This constructor is most useful for application writers,
88       * who will use it to create a persistent copy of an existing
89       * attribute list.</p>
90       *
91       * @param atts The attribute list to copy
92       * @see org.xml.sax.DocumentHandler#startElement
93       */
94      public AttributeListImpl (AttributeList atts)
95      {
96  	setAttributeList(atts);
97      }
98      
99      
100 
101     ////////////////////////////////////////////////////////////////////
102     // Methods specific to this class.
103     ////////////////////////////////////////////////////////////////////
104     
105     
106     /***
107      * Set the attribute list, discarding previous contents.
108      *
109      * <p>This method allows an application writer to reuse an
110      * attribute list easily.</p>
111      *
112      * @param atts The attribute list to copy.
113      */
114     public void setAttributeList (AttributeList atts)
115     {
116 	int count = atts.getLength();
117 	
118 	clear();
119 	
120 	for (int i = 0; i < count; i++) {
121 	    addAttribute(atts.getName(i), atts.getType(i), atts.getValue(i));
122 	}
123     }
124     
125     
126     /***
127      * Add an attribute to an attribute list.
128      *
129      * <p>This method is provided for SAX parser writers, to allow them
130      * to build up an attribute list incrementally before delivering
131      * it to the application.</p>
132      *
133      * @param name The attribute name.
134      * @param type The attribute type ("NMTOKEN" for an enumeration).
135      * @param value The attribute value (must not be null).
136      * @see #removeAttribute
137      * @see org.xml.sax.DocumentHandler#startElement
138      */
139     public void addAttribute (String name, String type, String value)
140     {
141 	names.addElement(name);
142 	types.addElement(type);
143 	values.addElement(value);
144     }
145     
146     
147     /***
148      * Remove an attribute from the list.
149      *
150      * <p>SAX application writers can use this method to filter an
151      * attribute out of an AttributeList.  Note that invoking this
152      * method will change the length of the attribute list and
153      * some of the attribute's indices.</p>
154      *
155      * <p>If the requested attribute is not in the list, this is
156      * a no-op.</p>
157      *
158      * @param name The attribute name.
159      * @see #addAttribute
160      */
161     public void removeAttribute (String name)
162     {
163 	int i = names.indexOf(name);
164 	
165 	if (i >= 0) {
166 	    names.removeElementAt(i);
167 	    types.removeElementAt(i);
168 	    values.removeElementAt(i);
169 	}
170     }
171     
172     
173     /***
174      * Clear the attribute list.
175      *
176      * <p>SAX parser writers can use this method to reset the attribute
177      * list between DocumentHandler.startElement events.  Normally,
178      * it will make sense to reuse the same AttributeListImpl object
179      * rather than allocating a new one each time.</p>
180      *
181      * @see org.xml.sax.DocumentHandler#startElement
182      */
183     public void clear ()
184     {
185 	names.removeAllElements();
186 	types.removeAllElements();
187 	values.removeAllElements();
188     }
189     
190     
191 
192     ////////////////////////////////////////////////////////////////////
193     // Implementation of org.xml.sax.AttributeList
194     ////////////////////////////////////////////////////////////////////
195     
196     
197     /***
198      * Return the number of attributes in the list.
199      *
200      * @return The number of attributes in the list.
201      * @see org.xml.sax.AttributeList#getLength
202      */
203     public int getLength ()
204     {
205 	return names.size();
206     }
207     
208     
209     /***
210      * Get the name of an attribute (by position).
211      *
212      * @param i The position of the attribute in the list.
213      * @return The attribute name as a string, or null if there
214      *         is no attribute at that position.
215      * @see org.xml.sax.AttributeList#getName(int)
216      */
217     public String getName (int i)
218     {
219 	if (i < 0) {
220 	    return null;
221 	}
222 	try {
223 	    return (String)names.elementAt(i);
224 	} catch (ArrayIndexOutOfBoundsException e) {
225 	    return null;
226 	}
227     }
228     
229     
230     /***
231      * Get the type of an attribute (by position).
232      *
233      * @param i The position of the attribute in the list.
234      * @return The attribute type as a string ("NMTOKEN" for an
235      *         enumeration, and "CDATA" if no declaration was
236      *         read), or null if there is no attribute at
237      *         that position.
238      * @see org.xml.sax.AttributeList#getType(int)
239      */
240     public String getType (int i)
241     {
242 	if (i < 0) {
243 	    return null;
244 	}
245 	try {
246 	    return (String)types.elementAt(i);
247 	} catch (ArrayIndexOutOfBoundsException e) {
248 	    return null;
249 	}
250     }
251     
252     
253     /***
254      * Get the value of an attribute (by position).
255      *
256      * @param i The position of the attribute in the list.
257      * @return The attribute value as a string, or null if
258      *         there is no attribute at that position.
259      * @see org.xml.sax.AttributeList#getValue(int)
260      */
261     public String getValue (int i)
262     {
263 	if (i < 0) {
264 	    return null;
265 	}
266 	try {
267 	    return (String)values.elementAt(i);
268 	} catch (ArrayIndexOutOfBoundsException e) {
269 	    return null;
270 	}
271     }
272     
273     
274     /***
275      * Get the type of an attribute (by name).
276      *
277      * @param name The attribute name.
278      * @return The attribute type as a string ("NMTOKEN" for an
279      *         enumeration, and "CDATA" if no declaration was
280      *         read).
281      * @see org.xml.sax.AttributeList#getType(java.lang.String)
282      */
283     public String getType (String name)
284     {
285 	return getType(names.indexOf(name));
286     }
287     
288     
289     /***
290      * Get the value of an attribute (by name).
291      *
292      * @param name The attribute name.
293      * @see org.xml.sax.AttributeList#getValue(java.lang.String)
294      */
295     public String getValue (String name)
296     {
297 	return getValue(names.indexOf(name));
298     }
299     
300     
301 
302     ////////////////////////////////////////////////////////////////////
303     // Internal state.
304     ////////////////////////////////////////////////////////////////////
305 
306     Vector names = new Vector();
307     Vector types = new Vector();
308     Vector values = new Vector();
309 
310 }
311 
312 // end of AttributeListImpl.java