source: trunk/indexers/lucene-gs/src/org/greenstone/LuceneWrapper/Indexer.java@ 12257

package org.nzdl.gsdl.LuceneWrap;


import org.xml.sax.Attributes;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.analysis.standard.StandardAnalyzer;

import java.util.Stack;
import java.io.FileInputStream;
import java.io.File;
import java.io.StringReader;
import java.net.URL;



public class Indexer extends DefaultHandler 
{
    IndexWriter writer_   = null;
    SAXParser sax_parser_ = null;
    String doc_tag_level_ = null;

    Stack stack_ = null;
    String path_ = "";

    Document current_doc_ = null;
    String current_node_ = "";
    String indexable_current_node_ = "";
    String current_contents_ = "";

    protected String file_id_ = null;

    /** pass in true if want to create a new index, false if want to use the existing one */
    public Indexer (String doc_tag_level, File index_dir, boolean create) 
    {
    doc_tag_level_ = doc_tag_level;

    try {
        stack_ = new Stack();
        SAXParserFactory sax_factory = SAXParserFactory.newInstance();
        sax_parser_ = sax_factory.newSAXParser();

        XMLReader reader = sax_parser_.getXMLReader(); 
        reader.setFeature("http://xml.org/sax/features/validation", false);

        writer_ = new IndexWriter(index_dir.getPath(), new StandardAnalyzer(), create);
        // by default, will only index 10,000 words per document
        // Can throw out_of_memory errors
        writer_.setMaxFieldLength(Integer.MAX_VALUE);
        if (create) {
        writer_.optimize();
        }

    } catch (Exception e) {
        // do nothing!
    }
    }

    /** index one document */
    public void index (String file_id, File file) 
    {
    file_id_ = file_id;
    path_ = "";
    String base_path = file.getPath();
    base_path = base_path.substring(0, base_path.lastIndexOf(File.separatorChar));

    try {       
            sax_parser_.parse(new InputSource(new FileInputStream(file)), this);
        }
        catch (Exception e) {
        println("parse error:");
            e.printStackTrace();
    }
    }

    /** index one document stored as string*/
    public void index (String xml_text) 
    {
    file_id_ = "<xml doc on stdin>";
    path_ = "";

    try {
            sax_parser_.parse(new InputSource(new StringReader(xml_text)), this);
        }
        catch (Exception e) {
        println("parse error:");
            e.printStackTrace();
    }
    }
    
    public void finish() 
    {
    /** optimise the index */
    try {
        writer_.optimize();
        writer_.close();
    } 
    catch (Exception e) {
    }
    }

    protected void print(String s) 
    { 
    System.out.print(s); 
    }

    protected void println(String s) 
    { 
    System.out.println(s); 
    }

    public void startDocument() throws SAXException 
    {
        println("Starting to index " + file_id_);
        print("[");
    }

    public void endDocument() throws SAXException 
    {
        println("]");
        println("... indexing finished.");
    }

    public void startElement(String uri, String localName, String qName, Attributes atts) 
    throws SAXException 
    {
    path_ = appendPathLink(path_, qName, atts);

    if (qName.equals(doc_tag_level_)) {
        pushOnStack(); // start new doc
        current_node_ = qName;
        String node_id = atts.getValue("gs2:id");

        print(" " + qName + ": " + node_id );
        current_doc_.add(new Field("nodeID", node_id, Field.Store.YES, Field.Index.NO));
    }

    if (XMLTagInfo.isIndexable(atts)) {
        indexable_current_node_ = qName;    
    }
    else {
        indexable_current_node_ = "";
    }

    }
    public void endElement(String uri, String localName, String qName) throws SAXException 
    {
    if (qName.equals(indexable_current_node_)) {
        current_doc_.add(new Field(qName, current_contents_, Field.Store.NO, Field.Index.TOKENIZED));
        current_contents_ = "";
    }

    if (qName.equals(doc_tag_level_)) {
        try {
        writer_.addDocument(current_doc_);
        } 
        catch (java.io.IOException e) {
        e.printStackTrace();
        }
        popOffStack(); // end document
    }
    
    path_ = removePathLink(path_);
    }

    public void characters(char ch[], int start, int length) throws SAXException 
    {
    String data = new String(ch, start, length).trim();
    if (data.length() > 0 ) {
        current_contents_ += data;
    }
    }
    
    protected String appendPathLink(String path, String qName, Attributes atts) 
    {

    path = path + "/"+qName;
    if (atts.getLength()>0) {
        String id = atts.getValue("gs2:id");
        if (id != null) {
        path +=  "[@gs2:id='"+id+"']";
        }
        else {
        id = atts.getValue("gs3:id");
        if (id != null) {
            path +=  "[@gs3:id='"+id+"']";
        }
        }
    }
    return path;
    }
    protected String  removePathLink(String path) 
    {

    int i=path.lastIndexOf('/');
    if (i==-1) {
        path="";
    } else {
        path = path.substring(0, i);
    }
    return path;
    }
    /** these are what we save on the stack */
    private class MyDocument 
    {
    public Document doc = null;
    public String contents = null;
    public String tagname = "";
    
    }

    protected void pushOnStack() 
    {
    if (current_doc_ != null) {
        MyDocument save = new MyDocument();
        save.doc = current_doc_;
        save.contents = current_contents_;
        save.tagname = current_node_;
        stack_.push(save);
    }
    current_doc_ = new Document();
    current_contents_ = "";
    current_node_ = "";
    }

    protected void popOffStack() 
    {
    if (!stack_.empty()) {
        MyDocument saved = (MyDocument)stack_.pop();
        current_doc_ = saved.doc;
        current_contents_ = saved.contents;
        current_node_ = saved.tagname;
    } else {
        current_doc_ = new Document();
        current_contents_ = "";
        current_node_ = "";
    }
    }


}