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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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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.
*
* <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 SAX 2.0
* @author David Megginson
*/
public class
NamespaceSupport
{
////////////////////////////////////////////////////////////////////
// Constants.
////////////////////////////////////////////////////////////////////
/**
* 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 <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 SAX 2.1alpha
* @see #setNamespaceDeclUris
* @see #isNamespaceDeclUris
*/
public final static
String NSDECL =
"http://www.w3.org/xmlns/2000/";
/**
* An empty enumeration.
*/
private final static
Enumeration EMPTY_ENUMERATION =
Collections.
enumeration(new
ArrayList<
String>());
////////////////////////////////////////////////////////////////////
// Constructor.
////////////////////////////////////////////////////////////////////
/**
* Create a new Namespace support object.
*/
public
NamespaceSupport ()
{
reset();
}
////////////////////////////////////////////////////////////////////
// Context management.
////////////////////////////////////////////////////////////////////
/**
* 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.
*
* <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.
*
* <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 {@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 {@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.
*
* <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.
*
* <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.
*
* <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.
*
* <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.
*
* <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 {@link #NSDECL NSDECL} namespace
* by {@link #processName processName()}. This may only be
* changed before any contexts have been pushed.
*
* @since 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 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.
*
* <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.
*/
Context ()
{
copyTables();
}
/**
* (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.
* {@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.
*
* @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.
*
* @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.
*
* @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.
*
* <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
Collections.
enumeration(
declarations);
}
}
/**
* 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.
*
* <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