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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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// NamespaceSupport.java - generic Namespace support for SAX.
// http://www.saxproject.org
// Written by David Megginson
// This class is in the Public Domain.  NO WARRANTY!
// $Id: NamespaceSupport.java,v 1.5 2004/11/03 22:53:09 jsuttor Exp $

package org.xml.sax.helpers;

import java.util.ArrayList;
import java.util.Collections;
import java.util.EmptyStackException;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;



Encapsulate Namespace logic for use by applications using SAX,
or internally by SAX drivers.


This module, both source code and documentation, is in the
Public Domain, and comes with NO WARRANTY.
See http://www.saxproject.org
for further information.



This class encapsulates the logic of Namespace processing: it
tracks the declarations currently in force for each context and
automatically processes qualified XML names into their Namespace
parts; it can also be used in reverse for generating XML qnames
from Namespaces.


Namespace support objects are reusable, but the reset method
must be invoked between each session.


Here is a simple session:


String parts[] = new String[3];
NamespaceSupport support = new NamespaceSupport();
support.pushContext();
support.declarePrefix("", "http://www.w3.org/1999/xhtml");
support.declarePrefix("dc", "http://www.purl.org/dc#");
parts = support.processName("p", parts, false);
System.out.println("Namespace URI: " + parts[0]);
System.out.println("Local name: " + parts[1]);
System.out.println("Raw name: " + parts[2]);
parts = support.processName("dc:title", parts, false);
System.out.println("Namespace URI: " + parts[0]);
System.out.println("Local name: " + parts[1]);
System.out.println("Raw name: " + parts[2]);
support.popContext();



Note that this class is optimized for the use case where most
elements do not contain Namespace declarations: if the same
prefix/URI mapping is repeated for each context (for example), this
class will be somewhat less efficient.


Although SAX drivers (parsers) may choose to use this class to
implement namespace handling, they are not required to do so.
Applications must track namespace information themselves if they
want to use namespace information.

Author:David Megginson
Since:1.4, SAX 2.0
/**
 * Encapsulate Namespace logic for use by applications using SAX,
 * or internally by SAX drivers.
 *
 * <blockquote>
 * <em>This module, both source code and documentation, is in the
 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
 * for further information.
 * </blockquote>
 *
 * <p>This class encapsulates the logic of Namespace processing: it
 * tracks the declarations currently in force for each context and
 * automatically processes qualified XML names into their Namespace
 * parts; it can also be used in reverse for generating XML qnames
 * from Namespaces.</p>
 *
 * <p>Namespace support objects are reusable, but the reset method
 * must be invoked between each session.</p>
 *
 * <p>Here is a simple session:</p>
 *
 * <pre>
 * String parts[] = new String[3];
 * NamespaceSupport support = new NamespaceSupport();
 *
 * support.pushContext();
 * support.declarePrefix("", "http://www.w3.org/1999/xhtml");
 * support.declarePrefix("dc", "http://www.purl.org/dc#");
 *
 * parts = support.processName("p", parts, false);
 * System.out.println("Namespace URI: " + parts[0]);
 * System.out.println("Local name: " + parts[1]);
 * System.out.println("Raw name: " + parts[2]);
 *
 * parts = support.processName("dc:title", parts, false);
 * System.out.println("Namespace URI: " + parts[0]);
 * System.out.println("Local name: " + parts[1]);
 * System.out.println("Raw name: " + parts[2]);
 *
 * support.popContext();
 * </pre>
 *
 * <p>Note that this class is optimized for the use case where most
 * elements do not contain Namespace declarations: if the same
 * prefix/URI mapping is repeated for each context (for example), this
 * class will be somewhat less efficient.</p>
 *
 * <p>Although SAX drivers (parsers) may choose to use this class to
 * implement namespace handling, they are not required to do so.
 * Applications must track namespace information themselves if they
 * want to use namespace information.
 *
 * @since 1.4, SAX 2.0
 * @author David Megginson
 */
public class NamespaceSupport
{


    ////////////////////////////////////////////////////////////////////
    // Constants.
    ////////////////////////////////////////////////////////////////////


    
The XML Namespace URI as a constant.
The value is http://www.w3.org/XML/1998/namespace
as defined in the "Namespaces in XML" * recommendation.

This is the Namespace URI that is automatically mapped
to the "xml" prefix.


/**
     * The XML Namespace URI as a constant.
     * The value is <code>http://www.w3.org/XML/1998/namespace</code>
     * as defined in the "Namespaces in XML" * recommendation.
     *
     * <p>This is the Namespace URI that is automatically mapped
     * to the "xml" prefix.</p>
     */
    public final static String XMLNS =
        "http://www.w3.org/XML/1998/namespace";


    
The namespace declaration URI as a constant.
The value is http://www.w3.org/xmlns/2000/, as defined
in a backwards-incompatible erratum to the "Namespaces in XML"
recommendation.  Because that erratum postdated SAX2, SAX2 defaults
to the original recommendation, and does not normally use this URI.

This is the Namespace URI that is optionally applied to
xmlns and xmlns:* attributes, which are used to
declare namespaces.  


See Also:
Since:1.5, SAX 2.1alpha
/**
     * The namespace declaration URI as a constant.
     * The value is <code>http://www.w3.org/xmlns/2000/</code>, as defined
     * in a backwards-incompatible erratum to the "Namespaces in XML"
     * recommendation.  Because that erratum postdated SAX2, SAX2 defaults
     * to the original recommendation, and does not normally use this URI.
     *
     *
     * <p>This is the Namespace URI that is optionally applied to
     * <em>xmlns</em> and <em>xmlns:*</em> attributes, which are used to
     * declare namespaces.  </p>
     *
     * @since 1.5, SAX 2.1alpha
     * @see #setNamespaceDeclUris
     * @see #isNamespaceDeclUris
     */
    public final static String NSDECL =
        "http://www.w3.org/xmlns/2000/";


    
An empty enumeration.

/**
     * An empty enumeration.
     */
    private final static Enumeration EMPTY_ENUMERATION =
            Collections.enumeration(new ArrayList<String>());


    ////////////////////////////////////////////////////////////////////
    // Constructor.
    ////////////////////////////////////////////////////////////////////


    
Create a new Namespace support object.

/**
     * Create a new Namespace support object.
     */
    public NamespaceSupport ()
    {
        reset();
    }



    ////////////////////////////////////////////////////////////////////
    // Context management.
    ////////////////////////////////////////////////////////////////////


    
Reset this Namespace support object for reuse.

It is necessary to invoke this method before reusing the
Namespace support object for a new session.  If namespace
declaration URIs are to be supported, that flag must also
be set to a non-default value.



See Also:
  • setNamespaceDeclUris
/**
     * Reset this Namespace support object for reuse.
     *
     * <p>It is necessary to invoke this method before reusing the
     * Namespace support object for a new session.  If namespace
     * declaration URIs are to be supported, that flag must also
     * be set to a non-default value.
     * </p>
     *
     * @see #setNamespaceDeclUris
     */
    public void reset ()
    {
        contexts = new Context[32];
        namespaceDeclUris = false;
        contextPos = 0;
        contexts[contextPos] = currentContext = new Context();
        currentContext.declarePrefix("xml", XMLNS);
    }


    
Start a new Namespace context.
The new context will automatically inherit
the declarations of its parent context, but it will also keep
track of which declarations were made within this context.

Event callback code should start a new context once per element.
This means being ready to call this in either of two places.
For elements that don't include namespace declarations, the
ContentHandler.startElement() callback is the right place.
For elements with such a declaration, it'd done in the first
ContentHandler.startPrefixMapping() callback.
A boolean flag can be used to
track whether a context has been started yet.  When either of
those methods is called, it checks the flag to see if a new context
needs to be started.  If so, it starts the context and sets the
flag.  After ContentHandler.startElement()
does that, it always clears the flag.

Normally, SAX drivers would push a new context at the beginning
of each XML element.  Then they perform a first pass over the
attributes to process all namespace declarations, making
ContentHandler.startPrefixMapping() callbacks.
Then a second pass is made, to determine the namespace-qualified
names for all attributes and for the element name.
Finally all the information for the
ContentHandler.startElement() callback is available,
so it can then be made.

The Namespace support object always starts with a base context
already in force: in this context, only the "xml" prefix is
declared.


See Also:
/**
     * Start a new Namespace context.
     * The new context will automatically inherit
     * the declarations of its parent context, but it will also keep
     * track of which declarations were made within this context.
     *
     * <p>Event callback code should start a new context once per element.
     * This means being ready to call this in either of two places.
     * For elements that don't include namespace declarations, the
     * <em>ContentHandler.startElement()</em> callback is the right place.
     * For elements with such a declaration, it'd done in the first
     * <em>ContentHandler.startPrefixMapping()</em> callback.
     * A boolean flag can be used to
     * track whether a context has been started yet.  When either of
     * those methods is called, it checks the flag to see if a new context
     * needs to be started.  If so, it starts the context and sets the
     * flag.  After <em>ContentHandler.startElement()</em>
     * does that, it always clears the flag.
     *
     * <p>Normally, SAX drivers would push a new context at the beginning
     * of each XML element.  Then they perform a first pass over the
     * attributes to process all namespace declarations, making
     * <em>ContentHandler.startPrefixMapping()</em> callbacks.
     * Then a second pass is made, to determine the namespace-qualified
     * names for all attributes and for the element name.
     * Finally all the information for the
     * <em>ContentHandler.startElement()</em> callback is available,
     * so it can then be made.
     *
     * <p>The Namespace support object always starts with a base context
     * already in force: in this context, only the "xml" prefix is
     * declared.</p>
     *
     * @see org.xml.sax.ContentHandler
     * @see #popContext
     */
    public void pushContext ()
    {
        int max = contexts.length;

        contextPos++;

                                // Extend the array if necessary
        if (contextPos >= max) {
            Context newContexts[] = new Context[max*2];
            System.arraycopy(contexts, 0, newContexts, 0, max);
            max *= 2;
            contexts = newContexts;
        }

                                // Allocate the context if necessary.
        currentContext = contexts[contextPos];
        if (currentContext == null) {
            contexts[contextPos] = currentContext = new Context();
        }

                                // Set the parent, if any.
        if (contextPos > 0) {
            currentContext.setParent(contexts[contextPos - 1]);
        }
    }


    
Revert to the previous Namespace context.

Normally, you should pop the context at the end of each
XML element.  After popping the context, all Namespace prefix
mappings that were previously in force are restored.


You must not attempt to declare additional Namespace
prefixes after popping a context, unless you push another
context first.


See Also:
  • pushContext
/**
     * Revert to the previous Namespace context.
     *
     * <p>Normally, you should pop the context at the end of each
     * XML element.  After popping the context, all Namespace prefix
     * mappings that were previously in force are restored.</p>
     *
     * <p>You must not attempt to declare additional Namespace
     * prefixes after popping a context, unless you push another
     * context first.</p>
     *
     * @see #pushContext
     */
    public void popContext ()
    {
        contexts[contextPos].clear();
        contextPos--;
        if (contextPos < 0) {
            throw new EmptyStackException();
        }
        currentContext = contexts[contextPos];
    }



    ////////////////////////////////////////////////////////////////////
    // Operations within a context.
    ////////////////////////////////////////////////////////////////////


    
Declare a Namespace prefix. All prefixes must be declared before they are referenced. For example, a SAX driver (parser) would scan an element's attributes in two passes: first for namespace declarations, then a second pass using processName() to interpret prefixes against (potentially redefined) prefixes. 
This method declares a prefix in the current Namespace
context; the prefix will remain in force until this context
is popped, unless it is shadowed in a descendant context.


To declare the default element Namespace, use the empty string as
the prefix.


Note that there is an asymmetry in this library: getPrefix will not return the "" prefix, even if you have declared a default element namespace. To check for a default namespace, you have to look it up explicitly using getURI. This asymmetry exists to make it easier to look up prefixes for attribute names, where the default prefix is not allowed.


Params:
  • prefix – The prefix to declare, or the empty string to
 indicate the default element namespace.  This may never have
 the value "xml" or "xmlns".
  • uri – The Namespace URI to associate with the prefix.
See Also:
Returns:true if the prefix was legal, false otherwise
/**
     * Declare a Namespace prefix.  All prefixes must be declared
     * before they are referenced.  For example, a SAX driver (parser)
     * would scan an element's attributes
     * in two passes:  first for namespace declarations,
     * then a second pass using {@link #processName processName()} to
     * interpret prefixes against (potentially redefined) prefixes.
     *
     * <p>This method declares a prefix in the current Namespace
     * context; the prefix will remain in force until this context
     * is popped, unless it is shadowed in a descendant context.</p>
     *
     * <p>To declare the default element Namespace, use the empty string as
     * the prefix.</p>
     *
     * <p>Note that there is an asymmetry in this library: {@link
     * #getPrefix getPrefix} will not return the "" prefix,
     * even if you have declared a default element namespace.
     * To check for a default namespace,
     * you have to look it up explicitly using {@link #getURI getURI}.
     * This asymmetry exists to make it easier to look up prefixes
     * for attribute names, where the default prefix is not allowed.</p>
     *
     * @param prefix The prefix to declare, or the empty string to
     *  indicate the default element namespace.  This may never have
     *  the value "xml" or "xmlns".
     * @param uri The Namespace URI to associate with the prefix.
     * @return true if the prefix was legal, false otherwise
     *
     * @see #processName
     * @see #getURI
     * @see #getPrefix
     */
    public boolean declarePrefix (String prefix, String uri)
    {
        if (prefix.equals("xml") || prefix.equals("xmlns")) {
            return false;
        } else {
            currentContext.declarePrefix(prefix, uri);
            return true;
        }
    }


    
Process a raw XML qualified name, after all declarations in the current context have been handled by 
declarePrefix(). 
This method processes a raw XML qualified name in the
current context by removing the prefix and looking it up among
the prefixes currently declared.  The return value will be the
array supplied by the caller, filled in as follows:




parts[0]


The Namespace URI, or an empty string if none is
 in use.


parts[1]


The local name (without prefix).


parts[2]


The original raw name.




All of the strings in the array will be internalized.  If
the raw name has a prefix that has not been declared, then
the return value will be null.


Note that attribute names are processed differently than
element names: an unprefixed element name will receive the
default Namespace (if any), while an unprefixed attribute name
will not.


Params:
  • qName – The XML qualified name to be processed.
  • parts – An array supplied by the caller, capable of
       holding at least three members.
  • isAttribute – A flag indicating whether this is an
       attribute name (true) or an element name (false).
See Also:
Returns:The supplied array holding three internalized strings
       representing the Namespace URI (or empty string), the
       local name, and the XML qualified name; or null if there
       is an undeclared prefix.
/**
     * Process a raw XML qualified name, after all declarations in the
     * current context have been handled by {@link #declarePrefix
     * declarePrefix()}.
     *
     * <p>This method processes a raw XML qualified name in the
     * current context by removing the prefix and looking it up among
     * the prefixes currently declared.  The return value will be the
     * array supplied by the caller, filled in as follows:</p>
     *
     * <dl>
     * <dt>parts[0]</dt>
     * <dd>The Namespace URI, or an empty string if none is
     *  in use.</dd>
     * <dt>parts[1]</dt>
     * <dd>The local name (without prefix).</dd>
     * <dt>parts[2]</dt>
     * <dd>The original raw name.</dd>
     * </dl>
     *
     * <p>All of the strings in the array will be internalized.  If
     * the raw name has a prefix that has not been declared, then
     * the return value will be null.</p>
     *
     * <p>Note that attribute names are processed differently than
     * element names: an unprefixed element name will receive the
     * default Namespace (if any), while an unprefixed attribute name
     * will not.</p>
     *
     * @param qName The XML qualified name to be processed.
     * @param parts An array supplied by the caller, capable of
     *        holding at least three members.
     * @param isAttribute A flag indicating whether this is an
     *        attribute name (true) or an element name (false).
     * @return The supplied array holding three internalized strings
     *        representing the Namespace URI (or empty string), the
     *        local name, and the XML qualified name; or null if there
     *        is an undeclared prefix.
     * @see #declarePrefix
     * @see java.lang.String#intern */
    public String [] processName (String qName, String parts[],
                                  boolean isAttribute)
    {
        String myParts[] = currentContext.processName(qName, isAttribute);
        if (myParts == null) {
            return null;
        } else {
            parts[0] = myParts[0];
            parts[1] = myParts[1];
            parts[2] = myParts[2];
            return parts;
        }
    }


    
Look up a prefix and get the currently-mapped Namespace URI.

This method looks up the prefix in the current context.
Use the empty string ("") for the default Namespace.


Params:
  • prefix – The prefix to look up.
See Also:
Returns:The associated Namespace URI, or null if the prefix
        is undeclared in this context.
/**
     * Look up a prefix and get the currently-mapped Namespace URI.
     *
     * <p>This method looks up the prefix in the current context.
     * Use the empty string ("") for the default Namespace.</p>
     *
     * @param prefix The prefix to look up.
     * @return The associated Namespace URI, or null if the prefix
     *         is undeclared in this context.
     * @see #getPrefix
     * @see #getPrefixes
     */
    public String getURI (String prefix)
    {
        return currentContext.getURI(prefix);
    }


    
Return an enumeration of all prefixes whose declarations are
active in the current context.
This includes declarations from parent contexts that have
not been overridden.

Note: if there is a default prefix, it will not be returned in this enumeration; check for the default prefix using the getURI with an argument of "".


See Also:
Returns:An enumeration of prefixes (never empty).
/**
     * Return an enumeration of all prefixes whose declarations are
     * active in the current context.
     * This includes declarations from parent contexts that have
     * not been overridden.
     *
     * <p><strong>Note:</strong> if there is a default prefix, it will not be
     * returned in this enumeration; check for the default prefix
     * using the {@link #getURI getURI} with an argument of "".</p>
     *
     * @return An enumeration of prefixes (never empty).
     * @see #getDeclaredPrefixes
     * @see #getURI
     */
    public Enumeration getPrefixes ()
    {
        return currentContext.getPrefixes();
    }


    
Return one of the prefixes mapped to a Namespace URI.

If more than one prefix is currently mapped to the same URI, this method will make an arbitrary selection; if you want all of the prefixes, use the getPrefixes method instead.


Note: this will never return the empty (default) prefix; to check for a default prefix, use the getURI method with an argument of "".


Params:
  • uri – the namespace URI
See Also:
Returns:one of the prefixes currently mapped to the URI supplied,
        or null if none is mapped or if the URI is assigned to
        the default namespace
/**
     * Return one of the prefixes mapped to a Namespace URI.
     *
     * <p>If more than one prefix is currently mapped to the same
     * URI, this method will make an arbitrary selection; if you
     * want all of the prefixes, use the {@link #getPrefixes}
     * method instead.</p>
     *
     * <p><strong>Note:</strong> this will never return the empty (default) prefix;
     * to check for a default prefix, use the {@link #getURI getURI}
     * method with an argument of "".</p>
     *
     * @param uri the namespace URI
     * @return one of the prefixes currently mapped to the URI supplied,
     *         or null if none is mapped or if the URI is assigned to
     *         the default namespace
     * @see #getPrefixes(java.lang.String)
     * @see #getURI
     */
    public String getPrefix (String uri)
    {
        return currentContext.getPrefix(uri);
    }


    
Return an enumeration of all prefixes for a given URI whose
declarations are active in the current context.
This includes declarations from parent contexts that have
not been overridden.

This method returns prefixes mapped to a specific Namespace URI. The xml: prefix will be included. If you want only one prefix that's mapped to the Namespace URI, and you don't care which one you get, use the getPrefix method instead.


Note: the empty (default) prefix is never included in this enumeration; to check for the presence of a default Namespace, use the getURI method with an argument of "".


Params:
  • uri – The Namespace URI.
See Also:
Returns:An enumeration of prefixes (never empty).
/**
     * Return an enumeration of all prefixes for a given URI whose
     * declarations are active in the current context.
     * This includes declarations from parent contexts that have
     * not been overridden.
     *
     * <p>This method returns prefixes mapped to a specific Namespace
     * URI.  The xml: prefix will be included.  If you want only one
     * prefix that's mapped to the Namespace URI, and you don't care
     * which one you get, use the {@link #getPrefix getPrefix}
     *  method instead.</p>
     *
     * <p><strong>Note:</strong> the empty (default) prefix is <em>never</em> included
     * in this enumeration; to check for the presence of a default
     * Namespace, use the {@link #getURI getURI} method with an
     * argument of "".</p>
     *
     * @param uri The Namespace URI.
     * @return An enumeration of prefixes (never empty).
     * @see #getPrefix
     * @see #getDeclaredPrefixes
     * @see #getURI
     */
    public Enumeration getPrefixes (String uri)
    {
        List<String> prefixes = new ArrayList<>();
        Enumeration allPrefixes = getPrefixes();
        while (allPrefixes.hasMoreElements()) {
            String prefix = (String)allPrefixes.nextElement();
            if (uri.equals(getURI(prefix))) {
                prefixes.add(prefix);
            }
        }
        return Collections.enumeration(prefixes);
    }


    
Return an enumeration of all prefixes declared in this context.

The empty (default) prefix will be included in this enumeration; note that this behaviour differs from that of getPrefix and getPrefixes.


See Also:
Returns:An enumeration of all prefixes declared in this
        context.
/**
     * Return an enumeration of all prefixes declared in this context.
     *
     * <p>The empty (default) prefix will be included in this
     * enumeration; note that this behaviour differs from that of
     * {@link #getPrefix} and {@link #getPrefixes}.</p>
     *
     * @return An enumeration of all prefixes declared in this
     *         context.
     * @see #getPrefixes
     * @see #getURI
     */
    public Enumeration getDeclaredPrefixes ()
    {
        return currentContext.getDeclaredPrefixes();
    }

    
Controls whether namespace declaration attributes are placed into the NSDECL namespace by processName(). This may only be changed before any contexts have been pushed. 
Throws:
Since:1.5, SAX 2.1alpha
/**
     * Controls whether namespace declaration attributes are placed
     * into the {@link #NSDECL NSDECL} namespace
     * by {@link #processName processName()}.  This may only be
     * changed before any contexts have been pushed.
     *
     * @since 1.5, SAX 2.1alpha
     *
     * @exception IllegalStateException when attempting to set this
     *  after any context has been pushed.
     */
    public void setNamespaceDeclUris (boolean value)
    {
        if (contextPos != 0)
            throw new IllegalStateException ();
        if (value == namespaceDeclUris)
            return;
        namespaceDeclUris = value;
        if (value)
            currentContext.declarePrefix ("xmlns", NSDECL);
        else {
            contexts[contextPos] = currentContext = new Context();
            currentContext.declarePrefix("xml", XMLNS);
        }
    }

    
Returns true if namespace declaration attributes are placed into
a namespace.  This behavior is not the default.

Since:1.5, SAX 2.1alpha
/**
     * Returns true if namespace declaration attributes are placed into
     * a namespace.  This behavior is not the default.
     *
     * @since 1.5, SAX 2.1alpha
     */
    public boolean isNamespaceDeclUris ()
        { return namespaceDeclUris; }



    ////////////////////////////////////////////////////////////////////
    // Internal state.
    ////////////////////////////////////////////////////////////////////

    private Context contexts[];
    private Context currentContext;
    private int contextPos;
    private boolean namespaceDeclUris;


    ////////////////////////////////////////////////////////////////////
    // Internal classes.
    ////////////////////////////////////////////////////////////////////

    
Internal class for a single Namespace context.

This module caches and reuses Namespace contexts,
so the number allocated
will be equal to the element depth of the document, not to the total
number of elements (i.e. 5-10 rather than tens of thousands).
Also, data structures used to represent contexts are shared when
possible (child contexts without declarations) to further reduce
the amount of memory that's consumed.



/**
     * Internal class for a single Namespace context.
     *
     * <p>This module caches and reuses Namespace contexts,
     * so the number allocated
     * will be equal to the element depth of the document, not to the total
     * number of elements (i.e. 5-10 rather than tens of thousands).
     * Also, data structures used to represent contexts are shared when
     * possible (child contexts without declarations) to further reduce
     * the amount of memory that's consumed.
     * </p>
     */
    final class Context {

        
Create the root-level Namespace context.

/**
         * Create the root-level Namespace context.
         */
        Context ()
        {
            copyTables();
        }


        
(Re)set the parent of this Namespace context.
The context must either have been freshly constructed,
or must have been cleared.

Params:
  • context – The parent Namespace context object.
/**
         * (Re)set the parent of this Namespace context.
         * The context must either have been freshly constructed,
         * or must have been cleared.
         *
         * @param context The parent Namespace context object.
         */
        void setParent (Context parent)
        {
            this.parent = parent;
            declarations = null;
            prefixTable = parent.prefixTable;
            uriTable = parent.uriTable;
            elementNameTable = parent.elementNameTable;
            attributeNameTable = parent.attributeNameTable;
            defaultNS = parent.defaultNS;
            declSeen = false;
        }

        
Makes associated state become collectible, invalidating this context. setParent must be called before this context may be used again. 
/**
         * Makes associated state become collectible,
         * invalidating this context.
         * {@link #setParent} must be called before
         * this context may be used again.
         */
        void clear ()
        {
            parent = null;
            prefixTable = null;
            uriTable = null;
            elementNameTable = null;
            attributeNameTable = null;
            defaultNS = null;
        }


        
Declare a Namespace prefix for this context.

Params:
  • prefix – The prefix to declare.
  • uri – The associated Namespace URI.
See Also:
/**
         * Declare a Namespace prefix for this context.
         *
         * @param prefix The prefix to declare.
         * @param uri The associated Namespace URI.
         * @see org.xml.sax.helpers.NamespaceSupport#declarePrefix
         */
        void declarePrefix (String prefix, String uri)
        {
                                // Lazy processing...
//          if (!declsOK)
//              throw new IllegalStateException (
//                  "can't declare any more prefixes in this context");
            if (!declSeen) {
                copyTables();
            }
            if (declarations == null) {
                declarations = new ArrayList<>();
            }

            prefix = prefix.intern();
            uri = uri.intern();
            if ("".equals(prefix)) {
                if ("".equals(uri)) {
                    defaultNS = null;
                } else {
                    defaultNS = uri;
                }
            } else {
                prefixTable.put(prefix, uri);
                uriTable.put(uri, prefix); // may wipe out another prefix
            }
            declarations.add(prefix);
        }


        
Process an XML qualified name in this context.

Params:
  • qName – The XML qualified name.
  • isAttribute – true if this is an attribute name.
See Also:
Returns:An array of three strings containing the
        URI part (or empty string), the local part,
        and the raw name, all internalized, or null
        if there is an undeclared prefix.
/**
         * Process an XML qualified name in this context.
         *
         * @param qName The XML qualified name.
         * @param isAttribute true if this is an attribute name.
         * @return An array of three strings containing the
         *         URI part (or empty string), the local part,
         *         and the raw name, all internalized, or null
         *         if there is an undeclared prefix.
         * @see org.xml.sax.helpers.NamespaceSupport#processName
         */
        String [] processName (String qName, boolean isAttribute)
        {
            String name[];
            Map<String, String[]> table;

            // Select the appropriate table.
            if (isAttribute) {
                table = attributeNameTable;
            } else {
                table = elementNameTable;
            }

            // Start by looking in the cache, and
            // return immediately if the name
            // is already known in this content
            name = (String[])table.get(qName);
            if (name != null) {
                return name;
            }

            // We haven't seen this name in this
            // context before.  Maybe in the parent
            // context, but we can't assume prefix
            // bindings are the same.
            name = new String[3];
            name[2] = qName.intern();
            int index = qName.indexOf(':');


            // No prefix.
            if (index == -1) {
                if (isAttribute) {
                    if (qName == "xmlns" && namespaceDeclUris)
                        name[0] = NSDECL;
                    else
                        name[0] = "";
                } else if (defaultNS == null) {
                    name[0] = "";
                } else {
                    name[0] = defaultNS;
                }
                name[1] = name[2];
            }

            // Prefix
            else {
                String prefix = qName.substring(0, index);
                String local = qName.substring(index+1);
                String uri;
                if ("".equals(prefix)) {
                    uri = defaultNS;
                } else {
                    uri = (String)prefixTable.get(prefix);
                }
                if (uri == null
                        || (!isAttribute && "xmlns".equals (prefix))) {
                    return null;
                }
                name[0] = uri;
                name[1] = local.intern();
            }

            // Save in the cache for future use.
            // (Could be shared with parent context...)
            table.put(name[2], name);
            return name;
        }


        
Look up the URI associated with a prefix in this context.

Params:
  • prefix – The prefix to look up.
See Also:
Returns:The associated Namespace URI, or null if none is
        declared.
/**
         * Look up the URI associated with a prefix in this context.
         *
         * @param prefix The prefix to look up.
         * @return The associated Namespace URI, or null if none is
         *         declared.
         * @see org.xml.sax.helpers.NamespaceSupport#getURI
         */
        String getURI (String prefix)
        {
            if ("".equals(prefix)) {
                return defaultNS;
            } else if (prefixTable == null) {
                return null;
            } else {
                return (String)prefixTable.get(prefix);
            }
        }


        
Look up one of the prefixes associated with a URI in this context.

Since many prefixes may be mapped to the same URI,
the return value may be unreliable.


Params:
  • uri – The URI to look up.
See Also:
Returns:The associated prefix, or null if none is declared.
/**
         * Look up one of the prefixes associated with a URI in this context.
         *
         * <p>Since many prefixes may be mapped to the same URI,
         * the return value may be unreliable.</p>
         *
         * @param uri The URI to look up.
         * @return The associated prefix, or null if none is declared.
         * @see org.xml.sax.helpers.NamespaceSupport#getPrefix
         */
        String getPrefix (String uri)
        {
            if (uriTable == null) {
                return null;
            } else {
                return (String)uriTable.get(uri);
            }
        }


        
Return an enumeration of prefixes declared in this context.

See Also:
Returns:An enumeration of prefixes (possibly empty).
/**
         * Return an enumeration of prefixes declared in this context.
         *
         * @return An enumeration of prefixes (possibly empty).
         * @see org.xml.sax.helpers.NamespaceSupport#getDeclaredPrefixes
         */
        Enumeration getDeclaredPrefixes ()
        {
            if (declarations == null) {
                return EMPTY_ENUMERATION;
            } else {
                return Collections.enumeration(declarations);
            }
        }

        
Return an enumeration of all prefixes currently in force.

The default prefix, if in force, is not
returned, and will have to be checked for separately.


See Also:
Returns:An enumeration of prefixes (never empty).
/**
         * Return an enumeration of all prefixes currently in force.
         *
         * <p>The default prefix, if in force, is <em>not</em>
         * returned, and will have to be checked for separately.</p>
         *
         * @return An enumeration of prefixes (never empty).
         * @see org.xml.sax.helpers.NamespaceSupport#getPrefixes
         */
        Enumeration getPrefixes ()
        {
            if (prefixTable == null) {
                return EMPTY_ENUMERATION;
            } else {
                return Collections.enumeration(prefixTable.keySet());
            }
        }



        ////////////////////////////////////////////////////////////////
        // Internal methods.
        ////////////////////////////////////////////////////////////////


        
Copy on write for the internal tables in this context.

This class is optimized for the normal case where most
elements do not contain Namespace declarations.


/**
         * Copy on write for the internal tables in this context.
         *
         * <p>This class is optimized for the normal case where most
         * elements do not contain Namespace declarations.</p>
         */
        private void copyTables ()
        {
            if (prefixTable != null) {
                prefixTable = new HashMap<>(prefixTable);
            } else {
                prefixTable = new HashMap<>();
            }
            if (uriTable != null) {
                uriTable = new HashMap<>(uriTable);
            } else {
                uriTable = new HashMap<>();
            }
            elementNameTable = new HashMap<>();
            attributeNameTable = new HashMap<>();
            declSeen = true;
        }



        ////////////////////////////////////////////////////////////////
        // Protected state.
        ////////////////////////////////////////////////////////////////

        Map<String, String> prefixTable;
        Map<String, String> uriTable;
        Map<String, String[]> elementNameTable;
        Map<String, String[]> attributeNameTable;
        String defaultNS = null;



        ////////////////////////////////////////////////////////////////
        // Internal state.
        ////////////////////////////////////////////////////////////////

        private List<String> declarations = null;
        private boolean declSeen = false;
        private Context parent = null;
    }
}

// end of NamespaceSupport.java