mirror of git://gcc.gnu.org/git/gcc.git
690 lines
20 KiB
Java
690 lines
20 KiB
Java
// NamespaceSupport.java - generic Namespace support for SAX.
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// Written by David Megginson, sax@megginson.com
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// This class is in the Public Domain. NO WARRANTY!
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// $Id: NamespaceSupport.java,v 1.1 2000/10/02 02:43:20 sboag Exp $
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package org.xml.sax.helpers;
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import java.util.EmptyStackException;
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import java.util.Enumeration;
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import java.util.Hashtable;
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import java.util.Vector;
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/**
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* Encapsulate Namespace logic for use by SAX drivers.
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*
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* <blockquote>
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* <em>This module, both source code and documentation, is in the
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* Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
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* </blockquote>
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*
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* <p>This class encapsulates the logic of Namespace processing:
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* it tracks the declarations currently in force for each context
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* and automatically processes qualified XML 1.0 names into their
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* Namespace parts; it can also be used in reverse for generating
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* XML 1.0 from Namespaces.</p>
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*
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* <p>Namespace support objects are reusable, but the reset method
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* must be invoked between each session.</p>
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*
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* <p>Here is a simple session:</p>
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*
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* <pre>
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* String parts[] = new String[3];
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* NamespaceSupport support = new NamespaceSupport();
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*
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* support.pushContext();
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* support.declarePrefix("", "http://www.w3.org/1999/xhtml");
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* support.declarePrefix("dc", "http://www.purl.org/dc#");
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*
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* String parts[] = support.processName("p", parts, false);
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* System.out.println("Namespace URI: " + parts[0]);
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* System.out.println("Local name: " + parts[1]);
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* System.out.println("Raw name: " + parts[2]);
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* String parts[] = support.processName("dc:title", parts, false);
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* System.out.println("Namespace URI: " + parts[0]);
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* System.out.println("Local name: " + parts[1]);
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* System.out.println("Raw name: " + parts[2]);
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* support.popContext();
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* </pre>
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*
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* <p>Note that this class is optimized for the use case where most
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* elements do not contain Namespace declarations: if the same
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* prefix/URI mapping is repeated for each context (for example), this
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* class will be somewhat less efficient.</p>
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*
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* @since SAX 2.0
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* @author David Megginson,
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* <a href="mailto:sax@megginson.com">sax@megginson.com</a>
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* @version 2.0
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*/
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public class NamespaceSupport
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{
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////////////////////////////////////////////////////////////////////
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// Constants.
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////////////////////////////////////////////////////////////////////
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/**
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* The XML Namespace as a constant.
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*
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* <p>This is the Namespace URI that is automatically mapped
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* to the "xml" prefix.</p>
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*/
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public final static String XMLNS =
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"http://www.w3.org/XML/1998/namespace";
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/**
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* An empty enumeration.
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*/
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private final static Enumeration EMPTY_ENUMERATION =
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new Vector().elements();
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////////////////////////////////////////////////////////////////////
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// Constructor.
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////////////////////////////////////////////////////////////////////
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/**
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* Create a new Namespace support object.
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*/
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public NamespaceSupport ()
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{
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reset();
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}
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////////////////////////////////////////////////////////////////////
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// Context management.
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////////////////////////////////////////////////////////////////////
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/**
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* Reset this Namespace support object for reuse.
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*
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* <p>It is necessary to invoke this method before reusing the
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* Namespace support object for a new session.</p>
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*/
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public void reset ()
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{
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contexts = new Context[32];
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contextPos = 0;
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contexts[contextPos] = currentContext = new Context();
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currentContext.declarePrefix("xml", XMLNS);
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}
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/**
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* Start a new Namespace context.
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*
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* <p>Normally, you should push a new context at the beginning
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* of each XML element: the new context will automatically inherit
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* the declarations of its parent context, but it will also keep
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* track of which declarations were made within this context.</p>
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*
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* <p>The Namespace support object always starts with a base context
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* already in force: in this context, only the "xml" prefix is
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* declared.</p>
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*
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* @see #popContext
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*/
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public void pushContext ()
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{
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int max = contexts.length;
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contextPos++;
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// Extend the array if necessary
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if (contextPos >= max) {
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Context newContexts[] = new Context[max*2];
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System.arraycopy(contexts, 0, newContexts, 0, max);
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max *= 2;
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contexts = newContexts;
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}
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// Allocate the context if necessary.
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currentContext = contexts[contextPos];
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if (currentContext == null) {
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contexts[contextPos] = currentContext = new Context();
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}
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// Set the parent, if any.
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if (contextPos > 0) {
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currentContext.setParent(contexts[contextPos - 1]);
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}
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}
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/**
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* Revert to the previous Namespace context.
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*
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* <p>Normally, you should pop the context at the end of each
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* XML element. After popping the context, all Namespace prefix
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* mappings that were previously in force are restored.</p>
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*
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* <p>You must not attempt to declare additional Namespace
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* prefixes after popping a context, unless you push another
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* context first.</p>
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*
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* @see #pushContext
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*/
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public void popContext ()
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{
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contextPos--;
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if (contextPos < 0) {
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throw new EmptyStackException();
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}
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currentContext = contexts[contextPos];
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}
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////////////////////////////////////////////////////////////////////
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// Operations within a context.
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////////////////////////////////////////////////////////////////////
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/**
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* Declare a Namespace prefix.
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*
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* <p>This method declares a prefix in the current Namespace
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* context; the prefix will remain in force until this context
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* is popped, unless it is shadowed in a descendant context.</p>
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*
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* <p>To declare a default Namespace, use the empty string. The
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* prefix must not be "xml" or "xmlns".</p>
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*
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* <p>Note that you must <em>not</em> declare a prefix after
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* you've pushed and popped another Namespace.</p>
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*
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* <p>Note that there is an asymmetry in this library: while {@link
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* #getPrefix getPrefix} will not return the default "" prefix,
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* even if you have declared one; to check for a default prefix,
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* you have to look it up explicitly using {@link #getURI getURI}.
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* This asymmetry exists to make it easier to look up prefixes
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* for attribute names, where the default prefix is not allowed.</p>
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*
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* @param prefix The prefix to declare, or null for the empty
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* string.
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* @param uri The Namespace URI to associate with the prefix.
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* @return true if the prefix was legal, false otherwise
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* @see #processName
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* @see #getURI
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* @see #getPrefix
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*/
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public boolean declarePrefix (String prefix, String uri)
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{
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if (prefix.equals("xml") || prefix.equals("xmlns")) {
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return false;
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} else {
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currentContext.declarePrefix(prefix, uri);
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return true;
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}
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}
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/**
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* Process a raw XML 1.0 name.
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*
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* <p>This method processes a raw XML 1.0 name in the current
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* context by removing the prefix and looking it up among the
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* prefixes currently declared. The return value will be the
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* array supplied by the caller, filled in as follows:</p>
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*
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* <dl>
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* <dt>parts[0]</dt>
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* <dd>The Namespace URI, or an empty string if none is
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* in use.</dd>
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* <dt>parts[1]</dt>
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* <dd>The local name (without prefix).</dd>
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* <dt>parts[2]</dt>
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* <dd>The original raw name.</dd>
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* </dl>
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*
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* <p>All of the strings in the array will be internalized. If
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* the raw name has a prefix that has not been declared, then
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* the return value will be null.</p>
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*
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* <p>Note that attribute names are processed differently than
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* element names: an unprefixed element name will received the
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* default Namespace (if any), while an unprefixed element name
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* will not.</p>
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*
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* @param qName The raw XML 1.0 name to be processed.
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* @param parts An array supplied by the caller, capable of
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* holding at least three members.
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* @param isAttribute A flag indicating whether this is an
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* attribute name (true) or an element name (false).
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* @return The supplied array holding three internalized strings
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* representing the Namespace URI (or empty string), the
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* local name, and the raw XML 1.0 name; or null if there
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* is an undeclared prefix.
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* @see #declarePrefix
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* @see java.lang.String#intern */
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public String [] processName (String qName, String parts[],
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boolean isAttribute)
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{
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String myParts[] = currentContext.processName(qName, isAttribute);
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if (myParts == null) {
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return null;
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} else {
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parts[0] = myParts[0];
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parts[1] = myParts[1];
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parts[2] = myParts[2];
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return parts;
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}
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}
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/**
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* Look up a prefix and get the currently-mapped Namespace URI.
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*
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* <p>This method looks up the prefix in the current context.
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* Use the empty string ("") for the default Namespace.</p>
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*
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* @param prefix The prefix to look up.
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* @return The associated Namespace URI, or null if the prefix
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* is undeclared in this context.
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* @see #getPrefix
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* @see #getPrefixes
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*/
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public String getURI (String prefix)
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{
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return currentContext.getURI(prefix);
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}
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/**
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* Return an enumeration of all prefixes currently declared.
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*
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* <p><strong>Note:</strong> if there is a default prefix, it will not be
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* returned in this enumeration; check for the default prefix
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* using the {@link #getURI getURI} with an argument of "".</p>
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*
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* @return An enumeration of all prefixes declared in the
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* current context except for the empty (default)
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* prefix.
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* @see #getDeclaredPrefixes
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* @see #getURI
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*/
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public Enumeration getPrefixes ()
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{
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return currentContext.getPrefixes();
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}
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/**
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* Return one of the prefixes mapped to a Namespace URI.
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*
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* <p>If more than one prefix is currently mapped to the same
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* URI, this method will make an arbitrary selection; if you
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* want all of the prefixes, use the {@link #getPrefixes}
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* method instead.</p>
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*
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* <p><strong>Note:</strong> this will never return the empty (default) prefix;
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* to check for a default prefix, use the {@link #getURI getURI}
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* method with an argument of "".</p>
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*
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* @param uri The Namespace URI.
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* @param isAttribute true if this prefix is for an attribute
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* (and the default Namespace is not allowed).
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* @return One of the prefixes currently mapped to the URI supplied,
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* or null if none is mapped or if the URI is assigned to
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* the default Namespace.
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* @see #getPrefixes(java.lang.String)
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* @see #getURI
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*/
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public String getPrefix (String uri)
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{
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return currentContext.getPrefix(uri);
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}
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/**
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* Return an enumeration of all prefixes currently declared for a URI.
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*
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* <p>This method returns prefixes mapped to a specific Namespace
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* URI. The xml: prefix will be included. If you want only one
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* prefix that's mapped to the Namespace URI, and you don't care
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* which one you get, use the {@link #getPrefix getPrefix}
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* method instead.</p>
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*
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* <p><strong>Note:</strong> the empty (default) prefix is <em>never</em> included
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* in this enumeration; to check for the presence of a default
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* Namespace, use the {@link #getURI getURI} method with an
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* argument of "".</p>
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*
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* @param uri The Namespace URI.
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* @return An enumeration of all prefixes declared in the
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* current context.
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* @see #getPrefix
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* @see #getDeclaredPrefixes
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* @see #getURI
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*/
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public Enumeration getPrefixes (String uri)
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{
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Vector prefixes = new Vector();
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Enumeration allPrefixes = getPrefixes();
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while (allPrefixes.hasMoreElements()) {
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String prefix = (String)allPrefixes.nextElement();
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if (uri.equals(getURI(prefix))) {
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prefixes.addElement(prefix);
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}
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}
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return prefixes.elements();
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}
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/**
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* Return an enumeration of all prefixes declared in this context.
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*
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* <p>The empty (default) prefix will be included in this
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* enumeration; note that this behaviour differs from that of
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* {@link #getPrefix} and {@link #getPrefixes}.</p>
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*
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* @return An enumeration of all prefixes declared in this
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* context.
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* @see #getPrefixes
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* @see #getURI
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*/
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public Enumeration getDeclaredPrefixes ()
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{
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return currentContext.getDeclaredPrefixes();
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}
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////////////////////////////////////////////////////////////////////
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// Internal state.
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////////////////////////////////////////////////////////////////////
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private Context contexts[];
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private Context currentContext;
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private int contextPos;
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////////////////////////////////////////////////////////////////////
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// Internal classes.
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////////////////////////////////////////////////////////////////////
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/**
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* Internal class for a single Namespace context.
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*
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* <p>This module caches and reuses Namespace contexts, so the number allocated
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* will be equal to the element depth of the document, not to the total
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* number of elements (i.e. 5-10 rather than tens of thousands).</p>
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*/
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final class Context {
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/**
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* Create the root-level Namespace context.
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*/
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Context ()
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{
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copyTables();
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}
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/**
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* (Re)set the parent of this Namespace context.
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*
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* @param context The parent Namespace context object.
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*/
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void setParent (Context parent)
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{
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this.parent = parent;
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declarations = null;
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prefixTable = parent.prefixTable;
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uriTable = parent.uriTable;
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elementNameTable = parent.elementNameTable;
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attributeNameTable = parent.attributeNameTable;
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defaultNS = parent.defaultNS;
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tablesDirty = false;
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}
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/**
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* Declare a Namespace prefix for this context.
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*
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* @param prefix The prefix to declare.
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* @param uri The associated Namespace URI.
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* @see org.xml.sax.helpers.NamespaceSupport#declarePrefix
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*/
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void declarePrefix (String prefix, String uri)
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{
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// Lazy processing...
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if (!tablesDirty) {
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copyTables();
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}
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if (declarations == null) {
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declarations = new Vector();
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}
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prefix = prefix.intern();
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uri = uri.intern();
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if ("".equals(prefix)) {
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if ("".equals(uri)) {
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defaultNS = null;
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} else {
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defaultNS = uri;
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}
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} else {
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prefixTable.put(prefix, uri);
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uriTable.put(uri, prefix); // may wipe out another prefix
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}
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declarations.addElement(prefix);
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}
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/**
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* Process a raw XML 1.0 name in this context.
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*
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* @param qName The raw XML 1.0 name.
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* @param isAttribute true if this is an attribute name.
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* @return An array of three strings containing the
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* URI part (or empty string), the local part,
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* and the raw name, all internalized, or null
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* if there is an undeclared prefix.
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* @see org.xml.sax.helpers.NamespaceSupport#processName
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*/
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String [] processName (String qName, boolean isAttribute)
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{
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String name[];
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Hashtable table;
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// Select the appropriate table.
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if (isAttribute) {
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table = elementNameTable;
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} else {
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table = attributeNameTable;
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}
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// Start by looking in the cache, and
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// return immediately if the name
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// is already known in this content
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name = (String[])table.get(qName);
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if (name != null) {
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return name;
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}
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// We haven't seen this name in this
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// context before.
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name = new String[3];
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int index = qName.indexOf(':');
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// No prefix.
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if (index == -1) {
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if (isAttribute || defaultNS == null) {
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name[0] = "";
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} else {
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name[0] = defaultNS;
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}
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name[1] = qName.intern();
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name[2] = name[1];
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}
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// Prefix
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else {
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String prefix = qName.substring(0, index);
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String local = qName.substring(index+1);
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String uri;
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if ("".equals(prefix)) {
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uri = defaultNS;
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} else {
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uri = (String)prefixTable.get(prefix);
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}
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if (uri == null) {
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return null;
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}
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name[0] = uri;
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name[1] = local.intern();
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name[2] = qName.intern();
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}
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// Save in the cache for future use.
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table.put(name[2], name);
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tablesDirty = true;
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return name;
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}
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/**
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* Look up the URI associated with a prefix in this context.
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*
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* @param prefix The prefix to look up.
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* @return The associated Namespace URI, or null if none is
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* declared.
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* @see org.xml.sax.helpers.NamespaceSupport#getURI
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*/
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String getURI (String prefix)
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{
|
||
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.
|
||
*
|
||
* <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.
|
||
*
|
||
* @return An enumeration of prefixes (possibly empty).
|
||
* @see org.xml.sax.helpers.NamespaceSupport#getDeclaredPrefixes
|
||
*/
|
||
Enumeration getDeclaredPrefixes ()
|
||
{
|
||
if (declarations == null) {
|
||
return EMPTY_ENUMERATION;
|
||
} else {
|
||
return declarations.elements();
|
||
}
|
||
}
|
||
|
||
|
||
/**
|
||
* 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 prefixTable.keys();
|
||
}
|
||
}
|
||
|
||
|
||
|
||
////////////////////////////////////////////////////////////////
|
||
// Internal methods.
|
||
////////////////////////////////////////////////////////////////
|
||
|
||
|
||
/**
|
||
* 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 = (Hashtable)prefixTable.clone();
|
||
} else {
|
||
prefixTable = new Hashtable();
|
||
}
|
||
if (uriTable != null) {
|
||
uriTable = (Hashtable)uriTable.clone();
|
||
} else {
|
||
uriTable = new Hashtable();
|
||
}
|
||
elementNameTable = new Hashtable();
|
||
attributeNameTable = new Hashtable();
|
||
tablesDirty = true;
|
||
}
|
||
|
||
|
||
|
||
////////////////////////////////////////////////////////////////
|
||
// Protected state.
|
||
////////////////////////////////////////////////////////////////
|
||
|
||
Hashtable prefixTable;
|
||
Hashtable uriTable;
|
||
Hashtable elementNameTable;
|
||
Hashtable attributeNameTable;
|
||
String defaultNS = null;
|
||
|
||
|
||
|
||
////////////////////////////////////////////////////////////////
|
||
// Internal state.
|
||
////////////////////////////////////////////////////////////////
|
||
|
||
private Vector declarations = null;
|
||
private boolean tablesDirty = false;
|
||
private Context parent = null;
|
||
}
|
||
}
|
||
|
||
// end of NamespaceSupport.java
|