net.sf.saxon.event.NamespaceReducer Maven / Gradle / Ivy
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.event;
import net.sf.saxon.expr.parser.Location;
import net.sf.saxon.lib.NamespaceConstant;
import net.sf.saxon.om.NamespaceBinding;
import net.sf.saxon.om.NamespaceResolver;
import net.sf.saxon.om.NodeName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.SchemaType;
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.
*
* 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 NamespaceBinding[] namespaces = new NamespaceBinding[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 NamespaceBinding[] pendingUndeclarations = null;
/**
* Create a NamespaceReducer
*
* @param next the Receiver to which events will be passed after namespace reduction
*/
public NamespaceReducer(Receiver next) {
super(next);
}
/**
* startElement. This call removes redundant namespace declarations, and
* possibly adds an xmlns="" undeclaration.
*/
public void startElement(NodeName elemName, SchemaType typeCode, Location location, int properties) throws XPathException {
nextReceiver.startElement(elemName, typeCode, location, properties);
if ((properties & ReceiverOptions.REFUSE_NAMESPACES) != 0) {
// Typically XQuery: the element does not inherit namespaces from its parent
pendingUndeclarations = new NamespaceBinding[namespacesSize];
System.arraycopy(namespaces, 0, pendingUndeclarations, 0, namespacesSize);
} else if (depth > 0 && disinheritStack[depth - 1]) {
// If the parent element specified inherit=no, keep a list of namespaces that need to be
// undeclared. Note (bug 20340) that namespaces are still inherited from grandparent elements
List undeclarations = new ArrayList(namespacesSize);
int k = namespacesSize;
for (int d = depth-1; d>=0; d--) {
if (!disinheritStack[d]) {
break;
}
for (int i=0; i= 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(elemName.getNamespaceBinding(), 0);
}
}
/**
* Output a namespace node (binding)
*
* @param namespaceBinding the prefix/uri pair to be output
* @param properties the properties of the namespace binding
* @throws XPathException if any downstream error occurs
*/
public void namespace(NamespaceBinding namespaceBinding, int properties) throws XPathException {
// Keep the namespace only if it is actually needed
if (isNeeded(namespaceBinding)) {
addToStack(namespaceBinding);
countStack[depth - 1]++;
nextReceiver.namespace(namespaceBinding, properties);
}
}
/**
* Determine whether a namespace declaration is needed
*
* @param nsBinding the namespace binding
* @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(NamespaceBinding nsBinding) {
if (nsBinding.isXmlNamespace()) {
// Ignore the XML namespace
return false;
}
// First cancel any pending undeclaration of this namespace prefix (there may be more than one)
String prefix = nsBinding.getPrefix();
if (pendingUndeclarations != null) {
for (int p = 0; p < pendingUndeclarations.length; p++) {
NamespaceBinding nb = pendingUndeclarations[p];
if (nb != null && prefix.equals(nb.getPrefix())) {
pendingUndeclarations[p] = null;
//break;
}
}
}
for (int i = namespacesSize - 1; i >= 0; i--) {
if (namespaces[i].equals(nsBinding)) {
// it's a duplicate so we don't need it
return false;
}
if (namespaces[i].getPrefix().equals(nsBinding.getPrefix())) {
// same prefix, different URI.
return true;
}
}
// we need it unless it's a redundant xmlns=""
return !nsBinding.isDefaultUndeclaration();
}
/**
* Add a namespace declaration to the stack
*
* @param nsBinding the namespace code to be added
*/
private void addToStack(NamespaceBinding nsBinding) {
// expand the stack if necessary
if (namespacesSize + 1 >= namespaces.length) {
NamespaceBinding[] newlist = new NamespaceBinding[namespacesSize * 2];
System.arraycopy(namespaces, 0, newlist, 0, namespacesSize);
namespaces = newlist;
}
namespaces[namespacesSize++] = nsBinding;
}
/**
* startContent: Add any namespace undeclarations needed to stop
* namespaces being inherited from parent elements
*/
public void startContent() throws XPathException {
if (pendingUndeclarations != null) {
for (NamespaceBinding ns : pendingUndeclarations) {
if (ns != null) {
namespace(new NamespaceBinding(ns.getPrefix(), ""), 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
*/
/*@Nullable*/
public String getURIForPrefix(String prefix, boolean useDefault) {
if ((prefix.isEmpty()) && !useDefault) {
return NamespaceConstant.NULL;
} else if ("xml".equals(prefix)) {
return NamespaceConstant.XML;
} else {
for (int i = namespacesSize - 1; i >= 0; i--) {
if (namespaces[i].getPrefix().equals(prefix)) {
return namespaces[i].getURI();
}
}
}
return prefix.isEmpty() ? NamespaceConstant.NULL : null;
}
/**
* 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() {
List prefixes = new ArrayList(namespacesSize);
for (int i = namespacesSize - 1; i >= 0; i--) {
String prefix = namespaces[i].getPrefix();
if (!prefixes.contains(prefix)) {
prefixes.add(prefix);
}
}
prefixes.add("xml");
return prefixes.iterator();
}
}
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