package net.sf.saxon.event;
import net.sf.saxon.om.NamePool;
import net.sf.saxon.om.NamespaceConstant;
import net.sf.saxon.om.NamespaceResolver;
import net.sf.saxon.trans.XPathException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* NamespaceReducer is a ProxyReceiver responsible for removing duplicate namespace
* declarations. It also ensures that an xmlns="" undeclaration is output when
* necessary. Used on its own, the NamespaceReducer simply eliminates unwanted
* namespace declarations. It can also be subclassed, in which case the subclass
* can use the services of the NamespaceReducer to resolve QNames.
* <p>
* The NamespaceReducer also validates namespace-sensitive content.
*/
public class NamespaceReducer extends ProxyReceiver implements NamespaceResolver
{
// We keep track of namespaces to avoid outputting duplicate declarations. The namespaces
// array holds a list of all namespaces currently declared (organised as pairs of entries,
// prefix followed by URI). The countStack contains an entry for each element currently open; the
// value on the stack is an integer giving the number of namespaces added to the main
// namespace stack by that element.
private int[] namespaces = new int[50]; // all namespace codes currently declared
private int namespacesSize = 0; // all namespaces currently declared
private int[] countStack = new int[50];
private int depth = 0;
// Creating an element does not automatically inherit the namespaces of the containing element.
// When the DISINHERIT property is set on startElement(), this indicates that the namespaces
// on that element are not to be automatically inherited by its children. So startElement()
// stacks a boolean flag indicating whether the children are to disinherit the parent's namespaces.
private boolean[] disinheritStack = new boolean[50];
// When a child element does not inherit the namespaces of its parent, it acquires undeclarations
// to indicate this fact. This array keeps track of the undeclarations that need to be added to the
// current child element.
private int[] pendingUndeclarations = null;
/**
* Create a NamespaceReducer
*/
public NamespaceReducer() {}
/**
* Create a NamespaceReducer with a given destination Receiver
* @param base the Receiver to which events will be passed after namespace reduction
*/
public NamespaceReducer(Receiver base) {
setUnderlyingReceiver(base);
if (pipelineConfiguration == null) {
pipelineConfiguration = base.getPipelineConfiguration();
}
}
/**
* startElement. This call removes redundant namespace declarations, and
* possibly adds an xmlns="" undeclaration.
*/
public void startElement(int nameCode, int typeCode, int locationId, int properties) throws XPathException {
nextReceiver.startElement(nameCode, typeCode, locationId, properties);
// If the parent element specified inherit=no, keep a list of namespaces that need to be
// undeclared
if (depth>0 && disinheritStack[depth-1]) {
pendingUndeclarations = new int[namespacesSize];
System.arraycopy(namespaces, 0, pendingUndeclarations, 0, namespacesSize);
} else {
pendingUndeclarations = null;
}
// Record the current height of the namespace list so it can be reset at endElement time
countStack[depth] = 0;
disinheritStack[depth] = (properties & ReceiverOptions.DISINHERIT_NAMESPACES) != 0;
if (++depth >= countStack.length) {
int[] newstack = new int[depth*2];
System.arraycopy(countStack, 0, newstack, 0, depth);
boolean[] disStack2 = new boolean[depth*2];
System.arraycopy(disinheritStack, 0, disStack2, 0, depth);
countStack = newstack;
disinheritStack = disStack2;
}
// Ensure that the element namespace is output, unless this is done
// automatically by the caller (which is true, for example, for a literal
// result element).
if ((properties & ReceiverOptions.NAMESPACE_OK) == 0) {
namespace(getNamePool().getNamespaceCode(nameCode), 0);
}
}
/**
* Output a namespace node (binding)
* @param namespaceCode encapsulates the prefix and URI
* @param properties the properties of the namespace binding
* @throws XPathException
*/
public void namespace(int namespaceCode, int properties) throws XPathException {
// Keep the namespace only if it is actually needed
if (isNeeded(namespaceCode)) {
addToStack(namespaceCode);
countStack[depth - 1]++;
nextReceiver.namespace(namespaceCode, properties);
}
}
/**
* Determine whether a namespace declaration is needed
* @param nscode the namespace code
* @return true if the namespace is needed: that is, if it not the XML namespace, is not a duplicate,
* and is not a redundant xmlns="".
*/
private boolean isNeeded(int nscode) {
if (nscode==NamespaceConstant.XML_NAMESPACE_CODE) {
// Ignore the XML namespace
return false;
}
// First cancel any pending undeclaration of this namespace prefix (there may be more than one)
if (pendingUndeclarations != null) {
for (int p=0; p<pendingUndeclarations.length; p++) {
if ((nscode>>16) == (pendingUndeclarations[p]>>16)) {
pendingUndeclarations[p] = -1;
//break;
}
}
}
for (int i=namespacesSize-1; i>=0; i--) {
if (namespaces[i]==nscode) {
// it's a duplicate so we don't need it
return false;
}
if ((namespaces[i]>>16) == (nscode>>16)) {
// same prefix, different URI.
return true;
}
}
// we need it unless it's a redundant xmlns=""
return (nscode != NamespaceConstant.NULL_NAMESPACE_CODE);
}
/**
* Add a namespace declaration to the stack
* @param nscode the namespace code to be added
*/
private void addToStack(int nscode) {
// expand the stack if necessary
if (namespacesSize+1 >= namespaces.length) {
int[] newlist = new int[namespacesSize*2];
System.arraycopy(namespaces, 0, newlist, 0, namespacesSize);
namespaces = newlist;
}
namespaces[namespacesSize++] = nscode;
}
/**
* startContent: Add any namespace undeclarations needed to stop
* namespaces being inherited from parent elements
*/
public void startContent() throws XPathException {
if (pendingUndeclarations != null) {
for (int i=0; i<pendingUndeclarations.length; i++) {
int nscode = pendingUndeclarations[i];
if (nscode != -1) {
namespace(nscode & 0xffff0000, 0);
// relies on the namespace() method to prevent duplicate undeclarations
}
}
}
pendingUndeclarations = null;
nextReceiver.startContent();
}
/**
* endElement: Discard the namespaces declared on this element.
*/
public void endElement () throws XPathException
{
if (depth-- == 0) {
throw new IllegalStateException("Attempt to output end tag with no matching start tag");
}
namespacesSize -= countStack[depth];
nextReceiver.endElement();
}
/**
* Get the URI code corresponding to a given prefix code, by searching the
* in-scope namespaces. This is a service provided to subclasses.
* @param prefixCode the 16-bit prefix code required
* @return the 16-bit URI code, or -1 if the prefix is not found
*/
protected short getURICode(short prefixCode) {
for (int i=namespacesSize-1; i>=0; i--) {
if ((namespaces[i]>>16) == (prefixCode)) {
return (short)(namespaces[i]&0xffff);
}
}
if (prefixCode == 0) {
return 0; // by default, no prefix means no namespace URI
} else {
return -1;
}
}
/**
* Get the namespace URI corresponding to a given prefix. Return null
* if the prefix is not in scope.
*
* @param prefix the namespace prefix
* @param useDefault true if the default namespace is to be used when the
* prefix is ""
* @return the uri for the namespace, or null if the prefix is not in scope
*/
public String getURIForPrefix(String prefix, boolean useDefault) {
NamePool pool = getNamePool();
if ((prefix==null || prefix.length()==0) && !useDefault) {
return "";
} else if ("xml".equals(prefix)) {
return NamespaceConstant.XML;
} else {
short prefixCode = pool.getCodeForPrefix(prefix);
short uriCode = getURICode(prefixCode);
if (uriCode == -1) {
return null;
}
return pool.getURIFromURICode(uriCode);
}
}
/**
* Get an iterator over all the prefixes declared in this namespace context. This will include
* the default namespace (prefix="") and the XML namespace where appropriate
*/
public Iterator iteratePrefixes() {
NamePool pool = getNamePool();
List prefixes = new ArrayList(namespacesSize);
for (int i=namespacesSize-1; i>=0; i--) {
String prefix = pool.getPrefixFromNamespaceCode(namespaces[i]);
if (!prefixes.contains(prefix)) {
prefixes.add(prefix);
}
}
prefixes.add("xml");
return prefixes.iterator();
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//