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Lucene example source code file (TSTLookup.java)

This example Lucene source code file (TSTLookup.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

arraylist, arraylist, eq_kid, file, filename, hi_kid, io, ioexception, ioexception, list, lo_kid, override, override, ternarytreenode, ternarytreenode, util

The Lucene TSTLookup.java source code

package org.apache.lucene.search.suggest.tst;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.search.suggest.Lookup;
import org.apache.lucene.search.suggest.SortedTermFreqIteratorWrapper;
import org.apache.lucene.search.spell.SortedIterator;
import org.apache.lucene.search.spell.TermFreqIterator;

public class TSTLookup extends Lookup {
  TernaryTreeNode root = new TernaryTreeNode();
  TSTAutocomplete autocomplete = new TSTAutocomplete();

  @Override
  public void build(TermFreqIterator tfit) throws IOException {
    root = new TernaryTreeNode();
    // buffer first
    if (!(tfit instanceof SortedIterator)) {
      // make sure it's sorted
      tfit = new SortedTermFreqIteratorWrapper(tfit);
    }

    ArrayList<String> tokens = new ArrayList();
    ArrayList<Float> vals = new ArrayList();
    while (tfit.hasNext()) {
      tokens.add(tfit.next());
      vals.add(new Float(tfit.freq()));
    }
    autocomplete.balancedTree(tokens.toArray(), vals.toArray(), 0, tokens.size() - 1, root);
  }

  @Override
  public boolean add(String key, Object value) {
    autocomplete.insert(root, key, value, 0);
    // XXX we don't know if a new node was created
    return true;
  }

  @Override
  public Object get(String key) {
    List<TernaryTreeNode> list = autocomplete.prefixCompletion(root, key, 0);
    if (list == null || list.isEmpty()) {
      return null;
    }
    for (TernaryTreeNode n : list) {
      if (n.token.equals(key)) {
        return n.val;
      }
    }
    return null;
  }

  @Override
  public List<LookupResult> lookup(String key, boolean onlyMorePopular, int num) {
    List<TernaryTreeNode> list = autocomplete.prefixCompletion(root, key, 0);
    List<LookupResult> res = new ArrayList();
    if (list == null || list.size() == 0) {
      return res;
    }
    int maxCnt = Math.min(num, list.size());
    if (onlyMorePopular) {
      LookupPriorityQueue queue = new LookupPriorityQueue(num);
      for (TernaryTreeNode ttn : list) {
        queue.insertWithOverflow(new LookupResult(ttn.token, (Float)ttn.val));
      }
      for (LookupResult lr : queue.getResults()) {
        res.add(lr);
      }
    } else {
      for (int i = 0; i < maxCnt; i++) {
        TernaryTreeNode ttn = list.get(i);
        res.add(new LookupResult(ttn.token, (Float)ttn.val));
      }
    }
    return res;
  }
  
  public static final String FILENAME = "tst.dat";
  
  private static final byte LO_KID = 0x01;
  private static final byte EQ_KID = 0x02;
  private static final byte HI_KID = 0x04;
  private static final byte HAS_TOKEN = 0x08;
  private static final byte HAS_VALUE = 0x10;

  @Override
  public synchronized boolean load(File storeDir) throws IOException {
    File data = new File(storeDir, FILENAME);
    if (!data.exists() || !data.canRead()) {
      return false;
    }
    DataInputStream in = new DataInputStream(new FileInputStream(data));
    root = new TernaryTreeNode();
    try {
      readRecursively(in, root);
    } finally {
      in.close();
    }
    return true;
  }
  
  // pre-order traversal
  private void readRecursively(DataInputStream in, TernaryTreeNode node) throws IOException {
    node.splitchar = in.readChar();
    byte mask = in.readByte();
    if ((mask & HAS_TOKEN) != 0) {
      node.token = in.readUTF();
    }
    if ((mask & HAS_VALUE) != 0) {
      node.val = new Float(in.readFloat());
    }
    if ((mask & LO_KID) != 0) {
      node.loKid = new TernaryTreeNode();
      readRecursively(in, node.loKid);
    }
    if ((mask & EQ_KID) != 0) {
      node.eqKid = new TernaryTreeNode();
      readRecursively(in, node.eqKid);
    }
    if ((mask & HI_KID) != 0) {
      node.hiKid = new TernaryTreeNode();
      readRecursively(in, node.hiKid);
    }
  }

  @Override
  public synchronized boolean store(File storeDir) throws IOException {
    if (!storeDir.exists() || !storeDir.isDirectory() || !storeDir.canWrite()) {
      return false;
    }
    File data = new File(storeDir, FILENAME);
    DataOutputStream out = new DataOutputStream(new FileOutputStream(data));
    try {
      writeRecursively(out, root);
      out.flush();
    } finally {
      out.close();
    }
    return true;
  }
  
  // pre-order traversal
  private void writeRecursively(DataOutputStream out, TernaryTreeNode node) throws IOException {
    // write out the current node
    out.writeChar(node.splitchar);
    // prepare a mask of kids
    byte mask = 0;
    if (node.eqKid != null) mask |= EQ_KID;
    if (node.loKid != null) mask |= LO_KID;
    if (node.hiKid != null) mask |= HI_KID;
    if (node.token != null) mask |= HAS_TOKEN;
    if (node.val != null) mask |= HAS_VALUE;
    out.writeByte(mask);
    if (node.token != null) out.writeUTF(node.token);
    if (node.val != null) out.writeFloat((Float)node.val);
    // recurse and write kids
    if (node.loKid != null) {
      writeRecursively(out, node.loKid);
    }
    if (node.eqKid != null) {
      writeRecursively(out, node.eqKid);
    }
    if (node.hiKid != null) {
      writeRecursively(out, node.hiKid);
    }
  }
}

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene TSTLookup.java source code file:

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