/*--
$Id: Namespace.java,v 1.41 2004/02/27 11:32:57 jhunter Exp $
Copyright (C) 2000-2004 Jason Hunter & Brett McLaughlin.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
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2. Redistributions in binary form must reproduce the above copyright
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provided with the distribution.
3. The name "JDOM" must not be used to endorse or promote products
derived from this software without prior written permission. For
written permission, please contact <request_AT_jdom_DOT_org>.
4. Products derived from this software may not be called "JDOM", nor
may "JDOM" appear in their name, without prior written permission
from the JDOM Project Management <request_AT_jdom_DOT_org>.
In addition, we request (but do not require) that you include in the
end-user documentation provided with the redistribution and/or in the
software itself an acknowledgement equivalent to the following:
"This product includes software developed by the
JDOM Project (http://www.jdom.org/)."
Alternatively, the acknowledgment may be graphical using the logos
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THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE JDOM AUTHORS OR THE PROJECT
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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SUCH DAMAGE.
This software consists of voluntary contributions made by many
individuals on behalf of the JDOM Project and was originally
created by Jason Hunter <jhunter_AT_jdom_DOT_org> and
Brett McLaughlin <brett_AT_jdom_DOT_org>. For more information
on the JDOM Project, please see <http://www.jdom.org/>.
*/
package org.jdom;
import java.util.*;
/**
* An XML namespace representation, as well as a factory for creating XML
* namespace objects. Namespaces are not Serializable, however objects that use
* namespaces have special logic to handle serialization manually. These classes
* call the getNamespace() method on deserialization to ensure there is one
* unique Namespace object for any unique prefix/uri pair.
*
* @version $Revision: 1.41 $, $Date: 2004/02/27 11:32:57 $
* @author Brett McLaughlin
* @author Elliotte Rusty Harold
* @author Jason Hunter
* @author Wesley Biggs
*/
public final class Namespace {
// XXX May want to use weak references to keep the maps from growing
// large with extended use
// XXX We may need to make the namespaces HashMap synchronized with
// reader/writer locks or perhaps make Namespace no longer a flyweight.
// As written, multiple put() calls may happen from different threads
// concurrently and cause a ConcurrentModificationException. See
// http://lists.denveronline.net/lists/jdom-interest/2000-September/003009.html.
// No one has ever reported this over the many years, so don't worry yet.
private static final String CVS_ID =
"@(#) $RCSfile: Namespace.java,v $ $Revision: 1.41 $ $Date: 2004/02/27 11:32:57 $ $Name: jdom_1_0 $";
/**
* Factory list of namespaces.
* Keys are <i>prefix</i>&<i>URI</i>.
* Values are Namespace objects
*/
private static HashMap namespaces;
/** Define a <code>Namespace</code> for when <i>not</i> in a namespace */
public static final Namespace NO_NAMESPACE = new Namespace("", "");
/** Define a <code>Namespace</code> for the standard xml prefix. */
public static final Namespace XML_NAMESPACE =
new Namespace("xml", "http://www.w3.org/XML/1998/namespace");
/** The prefix mapped to this namespace */
private String prefix;
/** The URI for this namespace */
private String uri;
/**
* This static initializer acts as a factory contructor.
* It sets up storage and required initial values.
*/
static {
namespaces = new HashMap();
// Add the "empty" namespace
namespaces.put("&", NO_NAMESPACE);
namespaces.put("xml&http://www.w3.org/XML/1998/namespace",
XML_NAMESPACE);
}
/**
* This will retrieve (if in existence) or create (if not) a
* <code>Namespace</code> for the supplied prefix and URI.
*
* @param prefix <code>String</code> prefix to map to
* <code>Namespace</code>.
* @param uri <code>String</code> URI of new <code>Namespace</code>.
* @return <code>Namespace</code> - ready to use namespace.
* @throws IllegalNameException if the given prefix and uri make up
* an illegal namespace name.
*/
public static Namespace getNamespace(String prefix, String uri) {
// Sanity checking
if ((prefix == null) || (prefix.trim().equals(""))) {
prefix = "";
}
if ((uri == null) || (uri.trim().equals(""))) {
uri = "";
}
// Return existing namespace if found. The preexisting namespaces
// should all be legal. In other words, an illegal namespace won't
// have been placed in this. Thus we can do this test before
// verifying the URI and prefix.
String lookup = new StringBuffer(64)
.append(prefix).append('&').append(uri).toString();
Namespace preexisting = (Namespace) namespaces.get(lookup);
if (preexisting != null) {
return preexisting;
}
// Ensure proper naming
String reason;
if ((reason = Verifier.checkNamespacePrefix(prefix)) != null) {
throw new IllegalNameException(prefix, "Namespace prefix", reason);
}
if ((reason = Verifier.checkNamespaceURI(uri)) != null) {
throw new IllegalNameException(uri, "Namespace URI", reason);
}
// Unless the "empty" Namespace (no prefix and no URI), require a URI
if ((!prefix.equals("")) && (uri.equals(""))) {
throw new IllegalNameException("", "namespace",
"Namespace URIs must be non-null and non-empty Strings");
}
// Handle XML namespace mislabels. If the user requested the correct
// namespace and prefix -- xml, http://www.w3.org/XML/1998/namespace
// -- then it was already returned from the preexisting namespaces.
// Thus any use of the xml prefix or the
// http://www.w3.org/XML/1998/namespace URI at this point must be
// incorrect.
if (prefix.equals("xml")) {
throw new IllegalNameException(prefix, "Namespace prefix",
"The xml prefix can only be bound to " +
"http://www.w3.org/XML/1998/namespace");
}
// The erratum to Namespaces in XML 1.0 that suggests this
// next check is controversial. Not everyone accepts it.
if (uri.equals("http://www.w3.org/XML/1998/namespace")) {
throw new IllegalNameException(uri, "Namespace URI",
"The http://www.w3.org/XML/1998/namespace must be bound to " +
"the xml prefix.");
}
// Finally, store and return
Namespace ns = new Namespace(prefix, uri);
namespaces.put(lookup, ns);
return ns;
}
/**
* This will retrieve (if in existence) or create (if not) a
* <code>Namespace</code> for the supplied URI, and make it usable
* as a default namespace, as no prefix is supplied.
*
* @param uri <code>String</code> URI of new <code>Namespace</code>.
* @return <code>Namespace</code> - ready to use namespace.
*/
public static Namespace getNamespace(String uri) {
return getNamespace("", uri);
}
/**
* This constructor handles creation of a <code>Namespace</code> object
* with a prefix and URI; it is intentionally left <code>private</code>
* so that it cannot be invoked by external programs/code.
*
* @param prefix <code>String</code> prefix to map to this namespace.
* @param uri <code>String</code> URI for namespace.
*/
private Namespace(String prefix, String uri) {
this.prefix = prefix;
this.uri = uri;
}
/**
* This returns the prefix mapped to this <code>Namespace</code>.
*
* @return <code>String</code> - prefix for this <code>Namespace</code>.
*/
public String getPrefix() {
return prefix;
}
/**
* This returns the namespace URI for this <code>Namespace</code>.
*
* @return <code>String</code> - URI for this <code>Namespace</code>.
*/
public String getURI() {
return uri;
}
/**
* This tests for equality - Two <code>Namespaces</code>
* are equal if and only if their URIs are byte-for-byte equals.
*
* @param ob <code>Object</code> to compare to this <code>Namespace</code>.
* @return <code>boolean</code> - whether the supplied object is equal to
* this <code>Namespace</code>.
*/
public boolean equals(Object ob) {
if (this == ob) {
return true;
}
if (ob instanceof Namespace) { // instanceof returns false if null
return uri.equals(((Namespace)ob).uri);
}
return false;
}
/**
* This returns a <code>String</code> representation of this
* <code>Namespace</code>, suitable for use in debugging.
*
* @return <code>String</code> - information about this instance.
*/
public String toString() {
return "[Namespace: prefix \"" + prefix + "\" is mapped to URI \"" +
uri + "\"]";
}
/**
* This returns a probably unique hash code for the <code>Namespace</code>.
* If two namespaces have the same URI, they are equal and have the same
* hash code, even if they have different prefixes.
*
* @return <code>int</code> - hash code for this <code>Namespace</code>.
*/
public int hashCode() {
return uri.hashCode();
}
}