com.sun.tools.xjc.util.SubtreeCutter Maven / Gradle / Ivy
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package com.sun.tools.xjc.util;
import org.xml.sax.helpers.XMLFilterImpl;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.XMLFilter;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.Attributes;
/**
* {@link XMLFilter} that can cut sub-trees.
*
* @author Kohsuke Kawaguchi
*/
public abstract class SubtreeCutter extends XMLFilterImpl {
/**
* When we are pruning a sub tree, this field holds the depth of
* elements that are being cut. Used to resume event forwarding.
*
* As long as this value is 0, we will pass through data.
*/
private int cutDepth=0;
/**
* This object will receive SAX events while a sub tree is being
* pruned.
*/
private static final ContentHandler stub = new DefaultHandler();
/**
* This field remembers the user-specified ContentHandler.
* So that we can restore it once the sub tree is completely pruned.
*/
private ContentHandler next;
public void startDocument() throws SAXException {
cutDepth=0;
super.startDocument();
}
public boolean isCutting() {
return cutDepth>0;
}
/**
* Starts cutting a sub-tree. Should be called from within the
* {@link #startElement(String, String, String, Attributes)} implementation
* before the execution is passed to {@link SubtreeCutter#startElement(String, String, String, Attributes)} .
* The current element will be cut.
*/
public void startCutting() {
super.setContentHandler(stub);
cutDepth=1;
}
public void setContentHandler(ContentHandler handler) {
next = handler;
// changes take effect immediately unless the sub-tree is being pruned
if(getContentHandler()!=stub)
super.setContentHandler(handler);
}
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
if(cutDepth>0)
cutDepth++;
super.startElement(uri, localName, qName, atts);
}
public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
super.endElement(namespaceURI, localName, qName);
if( cutDepth!=0 ) {
cutDepth--;
if( cutDepth == 1 ) {
// pruning completed. restore the user handler
super.setContentHandler(next);
cutDepth=0;
}
}
}
}