FileDocCategorySizeDatePackage
DocumentWriter.javaAPI DocApache Lucene 1.4.311783Sat Jul 10 08:19:02 BST 2004org.apache.lucene.index

DocumentWriter

public final class DocumentWriter extends Object
Copyright 2004 The Apache Software Foundation Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Fields Summary
private Analyzer
analyzer
private Directory
directory
private Similarity
similarity
private FieldInfos
fieldInfos
private int
maxFieldLength
private final Hashtable
postingTable
private int[]
fieldLengths
private int[]
fieldPositions
private float[]
fieldBoosts
private final Term
termBuffer
Constructors Summary
DocumentWriter(Directory directory, Analyzer analyzer, Similarity similarity, int maxFieldLength)

param
directory The directory to write the document information to
param
analyzer The analyzer to use for the document
param
similarity The Similarity function
param
maxFieldLength The maximum number of tokens a field may have

    this.directory = directory;
    this.analyzer = analyzer;
    this.similarity = similarity;
    this.maxFieldLength = maxFieldLength;
Methods Summary
final voidaddDocument(java.lang.String segment, org.apache.lucene.document.Document doc)

    // write field names
    fieldInfos = new FieldInfos();
    fieldInfos.add(doc);
    fieldInfos.write(directory, segment + ".fnm");

    // write field values
    FieldsWriter fieldsWriter =
            new FieldsWriter(directory, segment, fieldInfos);
    try {
      fieldsWriter.addDocument(doc);
    } finally {
      fieldsWriter.close();
    }

    // invert doc into postingTable
    postingTable.clear();			  // clear postingTable
    fieldLengths = new int[fieldInfos.size()];    // init fieldLengths
    fieldPositions = new int[fieldInfos.size()];  // init fieldPositions

    fieldBoosts = new float[fieldInfos.size()];	  // init fieldBoosts
    Arrays.fill(fieldBoosts, doc.getBoost());

    invertDocument(doc);

    // sort postingTable into an array
    Posting[] postings = sortPostingTable();

    /*
    for (int i = 0; i < postings.length; i++) {
      Posting posting = postings[i];
      System.out.print(posting.term);
      System.out.print(" freq=" + posting.freq);
      System.out.print(" pos=");
      System.out.print(posting.positions[0]);
      for (int j = 1; j < posting.freq; j++)
	System.out.print("," + posting.positions[j]);
      System.out.println("");
    }
    */

    // write postings
    writePostings(postings, segment);

    // write norms of indexed fields
    writeNorms(doc, segment);
private final voidaddPosition(java.lang.String field, java.lang.String text, int position)

 // avoid consing

           
    termBuffer.set(field, text);
    Posting ti = (Posting) postingTable.get(termBuffer);
    if (ti != null) {				  // word seen before
      int freq = ti.freq;
      if (ti.positions.length == freq) {	  // positions array is full
        int[] newPositions = new int[freq * 2];	  // double size
        int[] positions = ti.positions;
        for (int i = 0; i < freq; i++)		  // copy old positions to new
          newPositions[i] = positions[i];
        ti.positions = newPositions;
      }
      ti.positions[freq] = position;		  // add new position
      ti.freq = freq + 1;			  // update frequency
    } else {					  // word not seen before
      Term term = new Term(field, text, false);
      postingTable.put(term, new Posting(term, position));
    }
private final voidinvertDocument(org.apache.lucene.document.Document doc)


  // Tokenizes the fields of a document into Postings.
      
            
    Enumeration fields = doc.fields();
    while (fields.hasMoreElements()) {
      Field field = (Field) fields.nextElement();
      String fieldName = field.name();
      int fieldNumber = fieldInfos.fieldNumber(fieldName);

      int length = fieldLengths[fieldNumber];     // length of field
      int position = fieldPositions[fieldNumber]; // position in field

      if (field.isIndexed()) {
        if (!field.isTokenized()) {		  // un-tokenized field
          addPosition(fieldName, field.stringValue(), position++);
          length++;
        } else {
          Reader reader;			  // find or make Reader
          if (field.readerValue() != null)
            reader = field.readerValue();
          else if (field.stringValue() != null)
            reader = new StringReader(field.stringValue());
          else
            throw new IllegalArgumentException
                    ("field must have either String or Reader value");

          // Tokenize field and add to postingTable
          TokenStream stream = analyzer.tokenStream(fieldName, reader);
          try {
            for (Token t = stream.next(); t != null; t = stream.next()) {
              position += (t.getPositionIncrement() - 1);
              addPosition(fieldName, t.termText(), position++);
              if (++length > maxFieldLength) break;
            }
          } finally {
            stream.close();
          }
        }

        fieldLengths[fieldNumber] = length;	  // save field length
        fieldPositions[fieldNumber] = position;	  // save field position
        fieldBoosts[fieldNumber] *= field.getBoost();
      }
    }
private static final voidquickSort(org.apache.lucene.index.Posting[] postings, int lo, int hi)

    if (lo >= hi)
      return;

    int mid = (lo + hi) / 2;

    if (postings[lo].term.compareTo(postings[mid].term) > 0) {
      Posting tmp = postings[lo];
      postings[lo] = postings[mid];
      postings[mid] = tmp;
    }

    if (postings[mid].term.compareTo(postings[hi].term) > 0) {
      Posting tmp = postings[mid];
      postings[mid] = postings[hi];
      postings[hi] = tmp;

      if (postings[lo].term.compareTo(postings[mid].term) > 0) {
        Posting tmp2 = postings[lo];
        postings[lo] = postings[mid];
        postings[mid] = tmp2;
      }
    }

    int left = lo + 1;
    int right = hi - 1;

    if (left >= right)
      return;

    Term partition = postings[mid].term;

    for (; ;) {
      while (postings[right].term.compareTo(partition) > 0)
        --right;

      while (left < right && postings[left].term.compareTo(partition) <= 0)
        ++left;

      if (left < right) {
        Posting tmp = postings[left];
        postings[left] = postings[right];
        postings[right] = tmp;
        --right;
      } else {
        break;
      }
    }

    quickSort(postings, lo, left);
    quickSort(postings, left + 1, hi);
private final org.apache.lucene.index.Posting[]sortPostingTable()

    // copy postingTable into an array
    Posting[] array = new Posting[postingTable.size()];
    Enumeration postings = postingTable.elements();
    for (int i = 0; postings.hasMoreElements(); i++)
      array[i] = (Posting) postings.nextElement();

    // sort the array
    quickSort(array, 0, array.length - 1);

    return array;
private final voidwriteNorms(org.apache.lucene.document.Document doc, java.lang.String segment)

 
    for(int n = 0; n < fieldInfos.size(); n++){
      FieldInfo fi = fieldInfos.fieldInfo(n);
      if(fi.isIndexed){
        float norm = fieldBoosts[n] * similarity.lengthNorm(fi.name, fieldLengths[n]);
        OutputStream norms = directory.createFile(segment + ".f" + n);
        try {
          norms.writeByte(Similarity.encodeNorm(norm));
        } finally {
          norms.close();
        }
      }
    }
private final voidwritePostings(org.apache.lucene.index.Posting[] postings, java.lang.String segment)

    OutputStream freq = null, prox = null;
    TermInfosWriter tis = null;
    TermVectorsWriter termVectorWriter = null;
    try {
      //open files for inverse index storage
      freq = directory.createFile(segment + ".frq");
      prox = directory.createFile(segment + ".prx");
      tis = new TermInfosWriter(directory, segment, fieldInfos);
      TermInfo ti = new TermInfo();
      String currentField = null;

      for (int i = 0; i < postings.length; i++) {
        Posting posting = postings[i];

        // add an entry to the dictionary with pointers to prox and freq files
        ti.set(1, freq.getFilePointer(), prox.getFilePointer(), -1);
        tis.add(posting.term, ti);

        // add an entry to the freq file
        int postingFreq = posting.freq;
        if (postingFreq == 1)				  // optimize freq=1
          freq.writeVInt(1);			  // set low bit of doc num.
        else {
          freq.writeVInt(0);			  // the document number
          freq.writeVInt(postingFreq);			  // frequency in doc
        }

        int lastPosition = 0;			  // write positions
        int[] positions = posting.positions;
        for (int j = 0; j < postingFreq; j++) {		  // use delta-encoding
          int position = positions[j];
          prox.writeVInt(position - lastPosition);
          lastPosition = position;
        }
        // check to see if we switched to a new field
        String termField = posting.term.field();
        if (currentField != termField) {
          // changing field - see if there is something to save
          currentField = termField;
          FieldInfo fi = fieldInfos.fieldInfo(currentField);
          if (fi.storeTermVector) {
            if (termVectorWriter == null) {
              termVectorWriter =
                new TermVectorsWriter(directory, segment, fieldInfos);
              termVectorWriter.openDocument();
            }
            termVectorWriter.openField(currentField);
          } else if (termVectorWriter != null) {
            termVectorWriter.closeField();
          }
        }
        if (termVectorWriter != null && termVectorWriter.isFieldOpen()) {
          termVectorWriter.addTerm(posting.term.text(), postingFreq);
        }
      }
      if (termVectorWriter != null)
        termVectorWriter.closeDocument();
    } finally {
      // make an effort to close all streams we can but remember and re-throw
      // the first exception encountered in this process
      IOException keep = null;
      if (freq != null) try { freq.close(); } catch (IOException e) { if (keep == null) keep = e; }
      if (prox != null) try { prox.close(); } catch (IOException e) { if (keep == null) keep = e; }
      if (tis  != null) try {  tis.close(); } catch (IOException e) { if (keep == null) keep = e; }
      if (termVectorWriter  != null) try {  termVectorWriter.close(); } catch (IOException e) { if (keep == null) keep = e; }
      if (keep != null) throw (IOException) keep.fillInStackTrace();
    }