aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.xml.internal.bind.v2.runtime.output;
aoqi@0: 
aoqi@0: import java.io.IOException;
aoqi@0: import java.util.Collections;
aoqi@0: import java.util.Iterator;
aoqi@0: 
aoqi@0: import javax.xml.XMLConstants;
aoqi@0: import javax.xml.stream.XMLStreamException;
aoqi@0: 
aoqi@0: import com.sun.istack.internal.NotNull;
aoqi@0: import com.sun.istack.internal.Nullable;
aoqi@0: import com.sun.xml.internal.bind.marshaller.NamespacePrefixMapper;
aoqi@0: import com.sun.xml.internal.bind.v2.WellKnownNamespace;
aoqi@0: import com.sun.xml.internal.bind.v2.runtime.Name;
aoqi@0: import com.sun.xml.internal.bind.v2.runtime.NamespaceContext2;
aoqi@0: import com.sun.xml.internal.bind.v2.runtime.XMLSerializer;
aoqi@0: 
aoqi@0: import org.xml.sax.SAXException;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * Keeps track of in-scope namespace bindings for the marshaller.
aoqi@0:  *
aoqi@0:  * <p>
aoqi@0:  * This class is also used to keep track of tag names for each element
aoqi@0:  * for the marshaller (for the performance reason.)
aoqi@0:  *
aoqi@0:  * @author Kohsuke Kawaguchi
aoqi@0:  */
aoqi@0: public final class NamespaceContextImpl implements NamespaceContext2 {
aoqi@0:     private final XMLSerializer owner;
aoqi@0: 
aoqi@0:     private String[] prefixes = new String[4];
aoqi@0:     private String[] nsUris = new String[4];
aoqi@0: //    /**
aoqi@0: //     * True if the correponding namespace declaration is an authentic one that should be printed.
aoqi@0: //     *
aoqi@0: //     * False if it's a re-discovered in-scope namespace binding available at the ancestor elements
aoqi@0: //     * outside this marhsalling. The false value is used to incorporate the in-scope namespace binding
aoqi@0: //     * information from {@link #inscopeNamespaceContext}. When false, such a declaration does not need
aoqi@0: //     * to be printed, as it's already available in ancestors.
aoqi@0: //     */
aoqi@0: //    private boolean[] visible = new boolean[4];
aoqi@0: //
aoqi@0: //    /**
aoqi@0: //     * {@link NamespaceContext} that informs this {@link XMLSerializer} about the
aoqi@0: //     * in-scope namespace bindings of the ancestor elements outside this marshalling.
aoqi@0: //     *
aoqi@0: //     * <p>
aoqi@0: //     * This is used when the marshaller is marshalling into a subtree that has ancestor
aoqi@0: //     * elements created outside the JAXB marshaller.
aoqi@0: //     *
aoqi@0: //     * Its {@link NamespaceContext#getPrefix(String)} is used to discover in-scope namespace
aoqi@0: //     * binding,
aoqi@0: //     */
aoqi@0: //    private final NamespaceContext inscopeNamespaceContext;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Number of URIs declared. Identifies the valid portion of
aoqi@0:      * the {@link #prefixes} and {@link #nsUris} arrays.
aoqi@0:      */
aoqi@0:     private int size;
aoqi@0: 
aoqi@0:     private Element current;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * This is the {@link Element} whose prev==null.
aoqi@0:      * This element is used to hold the contextual namespace bindings
aoqi@0:      * that are assumed to be outside of the document we are marshalling.
aoqi@0:      * Specifically the xml prefix and any other user-specified bindings.
aoqi@0:      *
aoqi@0:      * @see NamespacePrefixMapper#getPreDeclaredNamespaceUris()
aoqi@0:      */
aoqi@0:     private final Element top;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Never null.
aoqi@0:      */
aoqi@0:     private NamespacePrefixMapper prefixMapper = defaultNamespacePrefixMapper;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * True to allow new URIs to be declared. False otherwise.
aoqi@0:      */
aoqi@0:     public boolean collectionMode;
aoqi@0: 
aoqi@0: 
aoqi@0:     public NamespaceContextImpl(XMLSerializer owner) {
aoqi@0:         this.owner = owner;
aoqi@0: 
aoqi@0:         current = top = new Element(this,null);
aoqi@0:         // register namespace URIs that are implicitly bound
aoqi@0:         put(XMLConstants.XML_NS_URI,XMLConstants.XML_NS_PREFIX);
aoqi@0:     }
aoqi@0: 
aoqi@0:     public void setPrefixMapper( NamespacePrefixMapper mapper ) {
aoqi@0:         if(mapper==null)
aoqi@0:             mapper = defaultNamespacePrefixMapper;
aoqi@0:         this.prefixMapper = mapper;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public NamespacePrefixMapper getPrefixMapper() {
aoqi@0:         return prefixMapper;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public void reset() {
aoqi@0:         current = top;
aoqi@0:         size = 1;
aoqi@0:         collectionMode = false;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns the prefix index to the specified URI.
aoqi@0:      * This method allocates a new URI if necessary.
aoqi@0:      */
aoqi@0:     public int declareNsUri( String uri, String preferedPrefix, boolean requirePrefix ) {
aoqi@0:         preferedPrefix = prefixMapper.getPreferredPrefix(uri,preferedPrefix,requirePrefix);
aoqi@0: 
aoqi@0:         if(uri.length()==0) {
aoqi@0:             for( int i=size-1; i>=0; i-- ) {
aoqi@0:                 if(nsUris[i].length()==0)
aoqi@0:                     return i; // already declared
aoqi@0:                 if(prefixes[i].length()==0) {
aoqi@0:                     // the default prefix is already taken.
aoqi@0:                     // move that URI to another prefix, then assign "" to the default prefix.
aoqi@0:                     assert current.defaultPrefixIndex==-1 && current.oldDefaultNamespaceUriIndex==-1;
aoqi@0: 
aoqi@0:                     String oldUri = nsUris[i];
aoqi@0:                     String[] knownURIs = owner.nameList.namespaceURIs;
aoqi@0: 
aoqi@0:                     if(current.baseIndex<=i) {
aoqi@0:                         // this default prefix is declared in this context. just reassign it
aoqi@0: 
aoqi@0:                         nsUris[i] = "";
aoqi@0: 
aoqi@0:                         int subst = put(oldUri,null);
aoqi@0: 
aoqi@0:                         // update uri->prefix table if necessary
aoqi@0:                         for( int j=knownURIs.length-1; j>=0; j-- ) {
aoqi@0:                             if(knownURIs[j].equals(oldUri)) {
aoqi@0:                                 owner.knownUri2prefixIndexMap[j] = subst;
aoqi@0:                                 break;
aoqi@0:                             }
aoqi@0:                         }
aoqi@0:                         if (current.elementLocalName != null) {
aoqi@0:                             current.setTagName(subst, current.elementLocalName, current.getOuterPeer());
aoqi@0:                         }
aoqi@0:                         return i;
aoqi@0:                     } else {
aoqi@0:                         // first, if the previous URI assigned to "" is
aoqi@0:                         // a "known URI", remember what we've reallocated
aoqi@0:                         // so that we can fix it when this context pops.
aoqi@0:                         for( int j=knownURIs.length-1; j>=0; j-- ) {
aoqi@0:                             if(knownURIs[j].equals(oldUri)) {
aoqi@0:                                 current.defaultPrefixIndex = i;
aoqi@0:                                 current.oldDefaultNamespaceUriIndex = j;
aoqi@0:                                 // assert commented out; too strict/not valid any more
aoqi@0:                                 // assert owner.knownUri2prefixIndexMap[j]==current.defaultPrefixIndex;
aoqi@0:                                 // update the table to point to the prefix we'll declare
aoqi@0:                                 owner.knownUri2prefixIndexMap[j] = size;
aoqi@0:                                 break;
aoqi@0:                             }
aoqi@0:                         }
aoqi@0:                         if (current.elementLocalName!=null) {
aoqi@0:                                                 current.setTagName(size, current.elementLocalName, current.getOuterPeer());
aoqi@0:                         }
aoqi@0: 
aoqi@0:                         put(nsUris[i],null);
aoqi@0:                         return put("", "");
aoqi@0:                     }
aoqi@0:                 }
aoqi@0:             }
aoqi@0: 
aoqi@0:             // "" isn't in use
aoqi@0:             return put("", "");
aoqi@0:         } else {
aoqi@0:             // check for the existing binding
aoqi@0:             for( int i=size-1; i>=0; i-- ) {
aoqi@0:                 String p = prefixes[i];
aoqi@0:                 if(nsUris[i].equals(uri)) {
aoqi@0:                     if (!requirePrefix || p.length()>0)
aoqi@0:                         return i;
aoqi@0:                     // declared but this URI is bound to empty. Look further
aoqi@0:                 }
aoqi@0:                 if(p.equals(preferedPrefix)) {
aoqi@0:                     // the suggested prefix is already taken. can't use it
aoqi@0:                     preferedPrefix = null;
aoqi@0:                 }
aoqi@0:             }
aoqi@0: 
aoqi@0:             if(preferedPrefix==null && requirePrefix)
aoqi@0:                 // we know we can't bind to "", but we don't have any possible name at hand.
aoqi@0:                 // generate it here to avoid this namespace to be bound to "".
aoqi@0:                 preferedPrefix = makeUniquePrefix();
aoqi@0: 
aoqi@0:             // haven't been declared. allocate a new one
aoqi@0:             // if the preferred prefix is already in use, it should have been set to null by this time
aoqi@0:             return put(uri, preferedPrefix);
aoqi@0:         }
aoqi@0:     }
aoqi@0: 
aoqi@0:     public int force(@NotNull String uri, @NotNull String prefix) {
aoqi@0:         // check for the existing binding
aoqi@0: 
aoqi@0:         for( int i=size-1; i>=0; i-- ) {
aoqi@0:             if(prefixes[i].equals(prefix)) {
aoqi@0:                 if(nsUris[i].equals(uri))
aoqi@0:                     return i;   // found duplicate
aoqi@0:                 else
aoqi@0:                     // the prefix is used for another namespace. we need to declare it
aoqi@0:                     break;
aoqi@0:             }
aoqi@0:         }
aoqi@0: 
aoqi@0:         return put(uri, prefix);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Puts this new binding into the declared prefixes list
aoqi@0:      * without doing any duplicate check.
aoqi@0:      *
aoqi@0:      * This can be used to forcibly set namespace declarations.
aoqi@0:      *
aoqi@0:      * <p>
aoqi@0:      * Most of the time {@link #declareNamespace(String, String, boolean)} shall be used.
aoqi@0:      *
aoqi@0:      * @return
aoqi@0:      *      the index of this new binding.
aoqi@0:      */
aoqi@0:     public int put(@NotNull String uri, @Nullable String prefix) {
aoqi@0:         if(size==nsUris.length) {
aoqi@0:             // reallocate
aoqi@0:             String[] u = new String[nsUris.length*2];
aoqi@0:             String[] p = new String[prefixes.length*2];
aoqi@0:             System.arraycopy(nsUris,0,u,0,nsUris.length);
aoqi@0:             System.arraycopy(prefixes,0,p,0,prefixes.length);
aoqi@0:             nsUris = u;
aoqi@0:             prefixes = p;
aoqi@0:         }
aoqi@0:         if(prefix==null) {
aoqi@0:             if(size==1)
aoqi@0:                 prefix = "";    // if this is the first user namespace URI we see, use "".
aoqi@0:             else {
aoqi@0:                 // otherwise make up an unique name
aoqi@0:                 prefix = makeUniquePrefix();
aoqi@0:             }
aoqi@0:         }
aoqi@0:         nsUris[size] = uri;
aoqi@0:         prefixes[size] = prefix;
aoqi@0: 
aoqi@0:         return size++;
aoqi@0:     }
aoqi@0: 
aoqi@0:     private String makeUniquePrefix() {
aoqi@0:         String prefix;
aoqi@0:         prefix = new StringBuilder(5).append("ns").append(size).toString();
aoqi@0:         while(getNamespaceURI(prefix)!=null) {
aoqi@0:             prefix += '_';  // under a rare circumstance there might be existing 'nsNNN', so rename them
aoqi@0:         }
aoqi@0:         return prefix;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     public Element getCurrent() {
aoqi@0:         return current;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns the prefix index of the specified URI.
aoqi@0:      * It is an error if the URI is not declared.
aoqi@0:      */
aoqi@0:     public int getPrefixIndex( String uri ) {
aoqi@0:         for( int i=size-1; i>=0; i-- ) {
aoqi@0:                 if(nsUris[i].equals(uri))
aoqi@0:                     return i;
aoqi@0:         }
aoqi@0:         throw new IllegalStateException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Gets the prefix from a prefix index.
aoqi@0:      *
aoqi@0:      * The behavior is undefined if the index is out of range.
aoqi@0:      */
aoqi@0:     public String getPrefix(int prefixIndex) {
aoqi@0:         return prefixes[prefixIndex];
aoqi@0:     }
aoqi@0: 
aoqi@0:     public String getNamespaceURI(int prefixIndex) {
aoqi@0:         return nsUris[prefixIndex];
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Gets the namespace URI that is bound to the specified prefix.
aoqi@0:      *
aoqi@0:      * @return null
aoqi@0:      *      if the prefix is unbound.
aoqi@0:      */
aoqi@0:     public String getNamespaceURI(String prefix) {
aoqi@0:         for( int i=size-1; i>=0; i-- )
aoqi@0:             if(prefixes[i].equals(prefix))
aoqi@0:                 return nsUris[i];
aoqi@0:         return null;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns the prefix of the specified URI,
aoqi@0:      * or null if none exists.
aoqi@0:      */
aoqi@0:     public String getPrefix( String uri ) {
aoqi@0:         if(collectionMode) {
aoqi@0:             return declareNamespace(uri,null,false);
aoqi@0:         } else {
aoqi@0:             for( int i=size-1; i>=0; i-- )
aoqi@0:                 if(nsUris[i].equals(uri))
aoqi@0:                     return prefixes[i];
aoqi@0:             return null;
aoqi@0:         }
aoqi@0:     }
aoqi@0: 
aoqi@0:     public Iterator<String> getPrefixes(String uri) {
aoqi@0:         String prefix = getPrefix(uri);
aoqi@0:         if(prefix==null)
aoqi@0:             return Collections.<String>emptySet().iterator();
aoqi@0:         else
aoqi@0:             return Collections.singleton(uri).iterator();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public String declareNamespace(String namespaceUri, String preferedPrefix, boolean requirePrefix) {
aoqi@0:         int idx = declareNsUri(namespaceUri,preferedPrefix,requirePrefix);
aoqi@0:         return getPrefix(idx);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Number of total bindings declared.
aoqi@0:      */
aoqi@0:     public int count() {
aoqi@0:         return size;
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * This model of namespace declarations maintain the following invariants.
aoqi@0:      *
aoqi@0:      * <ul>
aoqi@0:      *  <li>If a non-empty prefix is declared, it will never be reassigned to different namespace URIs.
aoqi@0:      *  <li>
aoqi@0:      */
aoqi@0:     public final class Element {
aoqi@0: 
aoqi@0:         public final NamespaceContextImpl context;
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * {@link Element}s form a doubly-linked list.
aoqi@0:          */
aoqi@0:         private final Element prev;
aoqi@0:         private Element next;
aoqi@0: 
aoqi@0:         private int oldDefaultNamespaceUriIndex;
aoqi@0:         private int defaultPrefixIndex;
aoqi@0: 
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * The numbe of prefixes declared by ancestor {@link Element}s.
aoqi@0:          */
aoqi@0:         private int baseIndex;
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * The depth of the {@link Element}.
aoqi@0:          *
aoqi@0:          * This value is equivalent as the result of the following computation.
aoqi@0:          *
aoqi@0:          * <pre>
aoqi@0:          * int depth() {
aoqi@0:          *   int i=-1;
aoqi@0:          *   for(Element e=this; e!=null;e=e.prev)
aoqi@0:          *     i++;
aoqi@0:          *   return i;
aoqi@0:          * }
aoqi@0:          * </pre>
aoqi@0:          */
aoqi@0:         private final int depth;
aoqi@0: 
aoqi@0: 
aoqi@0: 
aoqi@0:         private int elementNamePrefix;
aoqi@0:         private String elementLocalName;
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Tag name of this element.
aoqi@0:          * Either this field is used or the {@link #elementNamePrefix} and {@link #elementLocalName} pair.
aoqi@0:          */
aoqi@0:         private Name elementName;
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Used for the binder. The JAXB object that corresponds to this element.
aoqi@0:          */
aoqi@0:         private Object outerPeer;
aoqi@0:         private Object innerPeer;
aoqi@0: 
aoqi@0: 
aoqi@0:         private Element(NamespaceContextImpl context,Element prev) {
aoqi@0:             this.context = context;
aoqi@0:             this.prev = prev;
aoqi@0:             this.depth = (prev==null) ? 0 : prev.depth+1;
aoqi@0:         }
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Returns true if this {@link Element} represents the root element that
aoqi@0:          * we are marshalling.
aoqi@0:          */
aoqi@0:         public boolean isRootElement() {
aoqi@0:             return depth==1;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public Element push() {
aoqi@0:             if(next==null)
aoqi@0:                 next = new Element(context,this);
aoqi@0:             next.onPushed();
aoqi@0:             return next;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public Element pop() {
aoqi@0:             if(oldDefaultNamespaceUriIndex>=0) {
aoqi@0:                 // restore the old default namespace URI binding
aoqi@0:                 context.owner.knownUri2prefixIndexMap[oldDefaultNamespaceUriIndex] = defaultPrefixIndex;
aoqi@0:             }
aoqi@0:             context.size = baseIndex;
aoqi@0:             context.current = prev;
aoqi@0:             // release references to user objects
aoqi@0:             outerPeer = innerPeer = null;
aoqi@0:             return prev;
aoqi@0:         }
aoqi@0: 
aoqi@0:         private void onPushed() {
aoqi@0:             oldDefaultNamespaceUriIndex = defaultPrefixIndex = -1;
aoqi@0:             baseIndex = context.size;
aoqi@0:             context.current = this;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public void setTagName( int prefix, String localName, Object outerPeer ) {
aoqi@0:             assert localName!=null;
aoqi@0:             this.elementNamePrefix = prefix;
aoqi@0:             this.elementLocalName = localName;
aoqi@0:             this.elementName = null;
aoqi@0:             this.outerPeer = outerPeer;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public void setTagName( Name tagName, Object outerPeer ) {
aoqi@0:             assert tagName!=null;
aoqi@0:             this.elementName = tagName;
aoqi@0:             this.outerPeer = outerPeer;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public void startElement(XmlOutput out, Object innerPeer) throws IOException, XMLStreamException {
aoqi@0:             this.innerPeer = innerPeer;
aoqi@0:             if(elementName!=null) {
aoqi@0:                 out.beginStartTag(elementName);
aoqi@0:             } else {
aoqi@0:                 out.beginStartTag(elementNamePrefix,elementLocalName);
aoqi@0:             }
aoqi@0:         }
aoqi@0: 
aoqi@0:         public void endElement(XmlOutput out) throws IOException, SAXException, XMLStreamException {
aoqi@0:             if(elementName!=null) {
aoqi@0:                 out.endTag(elementName);
aoqi@0:                 elementName = null;
aoqi@0:             } else {
aoqi@0:                 out.endTag(elementNamePrefix,elementLocalName);
aoqi@0:             }
aoqi@0:         }
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Gets the number of bindings declared on this element.
aoqi@0:          */
aoqi@0:         public final int count() {
aoqi@0:             return context.size-baseIndex;
aoqi@0:         }
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Gets the prefix declared in this context.
aoqi@0:          *
aoqi@0:          * @param idx
aoqi@0:          *      between 0 and {@link #count()}
aoqi@0:          */
aoqi@0:         public final String getPrefix(int idx) {
aoqi@0:             return context.prefixes[baseIndex+idx];
aoqi@0:         }
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Gets the namespace URI declared in this context.
aoqi@0:          *
aoqi@0:          * @param idx
aoqi@0:          *      between 0 and {@link #count()}
aoqi@0:          */
aoqi@0:         public final String getNsUri(int idx) {
aoqi@0:             return context.nsUris[baseIndex+idx];
aoqi@0:         }
aoqi@0: 
aoqi@0:         public int getBase() {
aoqi@0:             return baseIndex;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public Object getOuterPeer() {
aoqi@0:             return outerPeer;
aoqi@0:         }
aoqi@0: 
aoqi@0:         public Object getInnerPeer() {
aoqi@0:             return innerPeer;
aoqi@0:         }
aoqi@0: 
aoqi@0:         /**
aoqi@0:          * Gets the parent {@link Element}.
aoqi@0:          */
aoqi@0:         public Element getParent() {
aoqi@0:             return prev;
aoqi@0:         }
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Default {@link NamespacePrefixMapper} implementation used when
aoqi@0:      * it is not specified by the user.
aoqi@0:      */
aoqi@0:     private static final NamespacePrefixMapper defaultNamespacePrefixMapper = new NamespacePrefixMapper() {
aoqi@0:         public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
aoqi@0:             if( namespaceUri.equals(WellKnownNamespace.XML_SCHEMA_INSTANCE) )
aoqi@0:                 return "xsi";
aoqi@0:             if( namespaceUri.equals(WellKnownNamespace.XML_SCHEMA) )
aoqi@0:                 return "xs";
aoqi@0:             if( namespaceUri.equals(WellKnownNamespace.XML_MIME_URI) )
aoqi@0:                 return "xmime";
aoqi@0:             return suggestion;
aoqi@0:         }
aoqi@0:     };
aoqi@0: }