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package edu.stanford.nlp.process;
import java.io.*;
import java.util.*;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import java.util.function.Function;
import edu.stanford.nlp.io.IOUtils;
import edu.stanford.nlp.util.XMLUtils;
/**
* Reads XML from an input file or stream and writes XML to an output
* file or stream, while transforming text appearing inside specified
* XML tags by applying a specified {@link Function
* Function}. See TransformXMLApplications for examples.
* Implementation note: This is done using SAX2.
*
* @param The type of the output of the Function (from String to T)
* @author Bill MacCartney
* @author Anna Rafferty (refactoring, making SAXInterface easy to extend elsewhere)
*/
public class TransformXML {
private final SAXParser saxParser;
public SAXInterface buildSaxInterface() { return new SAXInterface<>(); }
public static class SAXInterface extends DefaultHandler {
protected List elementsToBeTransformed;
protected StringBuffer textToBeTransformed;
protected PrintWriter outWriter = new PrintWriter(System.out, true);
protected Function function;
/**
* How far down we are in the nested tags. For example, if we've
* seen <foo> <bar> and "foo" and "bar" are both tags
* we care about, then depth = 2.
*/
protected int depth = 0;
public SAXInterface() {
elementsToBeTransformed = new ArrayList<>();
depth = 0;
openingTag = null;
textToBeTransformed = new StringBuffer();
}
/**
* The first tag from {@link elementsToBeTransformed}
* that we saw the last time {@link depth} was
* 0.
*
* You would expect incoming XML to be well-formatted, but just in
* case it isn't, we keep track of this so we can output the
* correct closing tag.
*/
String openingTag;
private void outputTextAndTag(String qName, Attributes attributes, boolean close) {
// If we're not already in an element to be transformed, first
// echo the previous text...
outWriter.print(XMLUtils.escapeXML(textToBeTransformed.toString()));
textToBeTransformed = new StringBuffer();
// ... then echo the new tag to outStream
outWriter.print('<');
if (close) {
outWriter.print('/');
}
outWriter.print(qName);
if (attributes != null) {
for (int i = 0; i < attributes.getLength(); i++) {
outWriter.print(' ');
outWriter.print(attributes.getQName(i));
outWriter.print("=\"");
outWriter.print(XMLUtils.escapeXML(attributes.getValue(i)));
outWriter.print('"');
}
}
outWriter.print(">\n");
}
@Override
public void endDocument() {
// Theoretically, there shouldn't be anything in the buffer after
// the last closing tag, but if there is, it's probably better to
// echo it than ignore it
outWriter.print(XMLUtils.escapeXML(textToBeTransformed.toString()));
// we need to flush because there are no other ways we
// explicitely flush
outWriter.flush();
}
// Called at the beginning of each element. If the tag is on the
// designated list, set flag to remember that we're in an element
// to be transformed. In either case, echo tag.
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
//System.err.println("start element " + qName);
if (depth == 0) {
outputTextAndTag(qName, attributes, false);
}
if (elementsToBeTransformed.contains(qName)) {
if (depth == 0) {
openingTag = qName;
}
++depth;
}
}
// Called at the end of each element. If the tag is on the
// designated list, apply the designated {@link Function
// Function} to the accumulated text and echo the the
// result. In either case, echo the closing tag.
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException
{
//System.err.println("end element " + qName + "; function is " + function.getClass());
//System.err.println("elementsToBeTransformed is " + elementsToBeTransformed);
//System.err.println("textToBeTransformed is " + textToBeTransformed);
if (depth == 0) {
outputTextAndTag(qName, null, true);
} else {
if (elementsToBeTransformed.contains(qName)) {
--depth;
if (depth == 0) {
String text = textToBeTransformed.toString().trim();
// factored out so subclasses can handle the text differently
processText(text);
textToBeTransformed = new StringBuffer();
outWriter.print("\n");
}
}
// when we're inside a block to be transformed, we ignore
// elements that don't end the block.
}
}
public void processText(String text) {
if (text.length() > 0) {
text = function.apply(text).toString();
outWriter.print(XMLUtils.escapeXML(text));
outWriter.print('\n');
}
}
// Accumulate characters in buffer of text to be transformed
// (SAX may call this after each line break)
@Override
public void characters(char[] buf, int offset, int len) throws SAXException {
// System.err.println("characters |" + new String(buf, offset, len) + "|");
textToBeTransformed.append(buf, offset, len);
}
} // end static class SAXInterface
/**
* This version of the SAXInterface doesn't escape the text produced
* by the function. This is useful in the case where the function
* already produces well-formed XML. One example of this is the
* Tagger, which already escapes the inner text and produces xml
* tags around the words.
*/
public static class NoEscapingSAXInterface extends SAXInterface {
@Override
public void processText(String text) {
if (text.length() > 0) {
text = function.apply(text).toString();
outWriter.print(text);
outWriter.print('\n');
}
}
}
public TransformXML() {
try {
saxParser = SAXParserFactory.newInstance().newSAXParser();
} catch (Exception e) {
System.err.println("Error configuring XML parser: " + e);
throw new RuntimeException(e);
}
}
/**
* Read XML from the specified file and write XML to stdout,
* while transforming text appearing inside the specified XML
* tags by applying the specified {@link Function
* Function}. Note that the Function
* you supply must be prepared to accept Strings as
* input; if your Function doesn't handle
* Strings, you need to write a wrapper for it that
* does.
*
* @param tags an array of Strings, each an XML tag
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the File to read from
*/
public void transformXML(String[] tags, Function fn, File in) {
InputStream ins = null;
try {
ins = new BufferedInputStream(new FileInputStream(in));
transformXML(tags, fn, ins, System.out);
} catch (Exception e) {
System.err.println("Error reading file " + in + ": " + e);
e.printStackTrace();
} finally {
IOUtils.closeIgnoringExceptions(ins);
}
}
/**
* Read XML from the specified file and write XML to specified file,
* while transforming text appearing inside the specified XML tags
* by applying the specified {@link Function Function}.
* Note that the Function you supply must be
* prepared to accept Strings as input; if your
* Function doesn't handle Strings, you
* need to write a wrapper for it that does.
*
* @param tags an array of Strings, each an XML tag
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the File to read from
* @param out the File to write to
*/
public void transformXML(String[] tags, Function fn, File in, File out) {
InputStream ins = null;
OutputStream outs = null;
try {
ins = new BufferedInputStream(new FileInputStream(in));
outs = new BufferedOutputStream(new FileOutputStream(out));
transformXML(tags, fn, ins, outs);
} catch (Exception e) {
System.err.println("Error reading file " + in + " or writing file " + out + ": " + e);
e.printStackTrace();
} finally {
IOUtils.closeIgnoringExceptions(ins);
IOUtils.closeIgnoringExceptions(outs);
}
}
/**
* Read XML from input stream and write XML to stdout, while
* transforming text appearing inside the specified XML tags by
* applying the specified {@link Function Function}.
* Note that the Function you supply must be
* prepared to accept Strings as input; if your
* Function doesn't handle Strings, you
* need to write a wrapper for it that does.
*
* @param tags an array of Strings, each an XML tag
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the InputStream to read from
*/
public void transformXML(String[] tags, Function fn, InputStream in) {
transformXML(tags, fn, in, System.out);
}
/**
* Read XML from input stream and write XML to output stream,
* while transforming text appearing inside the specified XML tags
* by applying the specified {@link Function Function}.
* Note that the Function you supply must be
* prepared to accept Strings as input; if your
* Function doesn't handle Strings, you
* need to write a wrapper for it that does.
*
* @param tags an array of Strings, each an XML tag
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the InputStream to read from
* @param out the OutputStream to write to
*/
public void transformXML(String[] tags, Function fn, InputStream in, OutputStream out) {
transformXML(tags, fn, in, new OutputStreamWriter(out),
buildSaxInterface());
}
/**
* Read XML from input stream and write XML to output stream,
* while transforming text appearing inside the specified XML tags
* by applying the specified {@link Function Function}.
* Note that the Function you supply must be
* prepared to accept Strings as input; if your
* Function doesn't handle Strings, you
* need to write a wrapper for it that does.
* Implementation notes: The InputStream is assumed to already
* be buffered if useful, and we need a stream, so that the XML decoder
* can determine the correct character encoding of the XML file. The output
* is to a Writer, and the provided Writer should again be buffered if
* desirable. Internally, this Writer is wrapped as a PrintWriter.
*
* @param tags an array of Strings, each an XML entity
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the InputStream to read from
* @param w the Writer to write to
*/
public void transformXML(String[] tags, Function fn, InputStream in, Writer w) {
transformXML(tags, fn, in, w, buildSaxInterface());
}
/**
* Calls the fully specified transformXML with an InputSource
* constructed from in.
*/
public void transformXML(String[] tags, Function fn, InputStream in, Writer w, SAXInterface handler) {
transformXML(tags, fn, new InputSource(in), w, handler);
}
/**
* Calls the fully specified transformXML with an InputSource
* constructed from in.
*/
public void transformXML(String[] tags, Function fn, Reader in, Writer w, SAXInterface handler) {
transformXML(tags, fn, new InputSource(in), w, handler);
}
/**
* Read XML from input source and write XML to output writer,
* while transforming text appearing inside the specified XML tags
* by applying the specified {@link Function Function}.
* Note that the Function you supply must be
* prepared to accept Strings as input; if your
* Function doesn't handle Strings, you
* need to write a wrapper for it that does.
*
* Implementation notes: The InputSource is assumed to already
* be buffered if useful, and we need a stream, so that the XML decoder
* can determine the correct character encoding of the XML file.
* TODO: does that mean there's a bug if you send it a Reader
* instead of an InputStream? It seems to work with a Reader...
*
* The output is to a Writer, and the provided Writer should again
* be buffered if desirable. Internally, this Writer is wrapped as
* a PrintWriter.
*
* @param tags an array of Strings, each an XML entity
* within which the transformation should be applied
* @param fn the {@link Function Function} to apply
* @param in the InputStream to read from
* @param w the Writer to write to
* @param saxInterface the sax handler you would like to use (default is SaxInterface, defined in this class, but you may define your own handler)
*/
public void transformXML(String[] tags, Function fn, InputSource in, Writer w, SAXInterface saxInterface) {
saxInterface.outWriter = new PrintWriter(w, true);
saxInterface.function = fn;
saxInterface.elementsToBeTransformed = new ArrayList<>();
saxInterface.elementsToBeTransformed.addAll(Arrays.asList(tags));
try {
saxParser.parse(in, saxInterface);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
} // end class TransformXML