NamespaceContext


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57  
58  package com.sun.org.apache.xerces.internal.xni;
59  
60  import java.util.Enumeration  ;
61  
62  /**
63   * Represents an interface to query namespace information.
64   * <p>
65   * The prefix and namespace must be identical references for equal strings, thus
66   * each string should be internalized (@see String.intern()) 
67   * or added to the <code>SymbolTable</code>
68   *
69   * @see <a HREF="../../../../../xerces2/com/sun/org/apache/xerces/internal/util/SymbolTable.html">
70   * com.sun.org.apache.xerces.internal.util.SymbolTable</a>
71   *
72   * @author Andy Clark, IBM
73   *
74   * @version $Id: NamespaceContext.java,v 1.10 2003/01/23 17:27:12 sandygao Exp $
75   */
76  public interface NamespaceContext {
77  
78      //
79      // Constants
80      //
81  
82      /**
83       * The XML Namespace ("http://www.w3.org/XML/1998/namespace"). This is
84       * the Namespace URI that is automatically mapped to the "xml" prefix.
85       */
86      public final static String   XML_URI = "http://www.w3.org/XML/1998/namespace".intern();
87  
88      /**
89       * XML Information Set REC
90       * all namespace attributes (including those named xmlns, 
91       * whose [prefix] property has no value) have a namespace URI of http://www.w3.org/2000/xmlns/
92       */
93      public final static String   XMLNS_URI = "http://www.w3.org/2000/xmlns/".intern();
94  
95      //
96      // NamespaceContext methods
97      //
98          
99      /**
100      * Start a new Namespace context.
101      * <p>
102      * A new context should be pushed at the beginning
103      * of each XML element: the new context will automatically inherit
104      * the declarations of its parent context, but it will also keep
105      * track of which declarations were made within this context.
106      * <p>
107      *
108      * @see #popContext
109      */
110     public void pushContext();
111 
112    /**
113      * Revert to the previous Namespace context.
114      * <p>
115      * The context should be popped at the end of each
116      * XML element.  After popping the context, all Namespace prefix
117      * mappings that were previously in force are restored.
118      * <p>
119      * Users must not attempt to declare additional Namespace
120      * prefixes after popping a context, unless you push another
121      * context first.
122      *
123      * @see #pushContext
124      */
125     public void popContext();
126 
127     /**
128      * Declare a Namespace prefix.
129      * <p>
130      * This method declares a prefix in the current Namespace
131      * context; the prefix will remain in force until this context
132      * is popped, unless it is shadowed in a descendant context.
133      * <p>
134      * Note that to declare a default Namespace, use the empty string.  
135      * The prefixes "xml" and "xmlns" can't be rebound.
136      * <p>
137      * Note that you must <em>not</em> declare a prefix after
138      * you've pushed and popped another Namespace.
139      *
140      * @param prefix The prefix to declare, or null for the empty
141      *        string. 
142      * @param uri The Namespace URI to associate with the prefix.
143      *
144      * @return true if the prefix was legal, false otherwise
145      *
146      * @see #getURI
147      * @see #getDeclaredPrefixAt
148      */
149     public boolean declarePrefix(String   prefix, String   uri);
150     
151 
152     /**
153      * Look up a prefix and get the currently-mapped Namespace URI.
154      * <p>
155      * This method looks up the prefix in the current context. If no mapping 
156      * is found, this methods will continue lookup in the parent context(s).
157      * Use the empty string ("") for the default Namespace.
158      *
159      * @param prefix The prefix to look up. 
160      *
161      * @return The associated Namespace URI, or null if the prefix
162      *         is undeclared in this context.
163      */
164     public String   getURI(String   prefix);
165     
166     /**
167      * Look up a namespace URI and get one of the mapped prefix.
168      * <p>
169      * This method looks up the namespace URI in the current context.
170      * If more than one prefix is currently mapped to the same URI, 
171      * this method will make an arbitrary selection
172      * If no mapping is found, this methods will continue lookup in the 
173      * parent context(s).
174      *
175      * @param uri The namespace URI to look up.
176      *
177      * @return One of the associated prefixes, or null if the uri
178      *         does not map to any prefix.
179      *
180      * @see #getPrefix
181      */
182     public String   getPrefix(String   uri);
183     
184     /**
185      * Return a count of locally declared prefixes, including
186      * the default prefix if bound.
187      */
188     public int getDeclaredPrefixCount();
189 
190     /** 
191      * Returns the prefix at the specified index in the current context.
192      */
193     public String   getDeclaredPrefixAt(int index);
194 
195     /**
196      * Return an enumeration of all prefixes whose declarations are active 
197      * in the current context. This includes declarations from parent contexts 
198      * that have not been overridden.
199      * @return Enumeration
200      */
201     public Enumeration   getAllPrefixes();
202     
203     /**
204      * Reset this Namespace support object for reuse.
205      *
206      * <p>It is necessary to invoke this method before reusing the
207      * Namespace support object for a new session.</p>
208      * 
209      * <p>Note that implementations of this method need to ensure that
210      * the declaration of the prefixes "xmlns" and "xml" are available.</p>
211      */
212     public void reset();
213     
214 
215 
216 } // interface NamespaceContext
217
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