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package org.apache.lucene.analysis.synonym;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

import java.io.IOException;
import java.io.LineNumberReader;
import java.io.Reader;
import java.text.ParseException;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.util.CharsRef;

/**
 * Parser for wordnet prolog format
 * 
 * See http://wordnet.princeton.edu/man/prologdb.5WN.html for a description of the format.
 * @lucene.experimental
 */
// TODO: allow you to specify syntactic categories (e.g. just nouns, etc)
public class WordnetSynonymParser extends SynonymMap.Parser {
  private final boolean expand;
  
  public WordnetSynonymParser(boolean dedup, boolean expand, Analyzer analyzer) {
    super(dedup, analyzer);
    this.expand = expand;
  }

  @Override
  public void parse(Reader in) throws IOException, ParseException {
    LineNumberReader br = new LineNumberReader(in);
    try {
      String line = null;
      String lastSynSetID = "";
      CharsRef synset[] = new CharsRef[8];
      int synsetSize = 0;
      
      while ((line = br.readLine()) != null) {
        String synSetID = line.substring(2, 11);

        if (!synSetID.equals(lastSynSetID)) {
          addInternal(synset, synsetSize);
          synsetSize = 0;
        }

        if (synset.length <= synsetSize+1) {
          CharsRef larger[] = new CharsRef[synset.length * 2];
          System.arraycopy(synset, 0, larger, 0, synsetSize);
          synset = larger;
        }
        
        synset[synsetSize] = parseSynonym(line, synset[synsetSize]);
        synsetSize++;
        lastSynSetID = synSetID;
      }
      
      // final synset in the file
      addInternal(synset, synsetSize);
    } catch (IllegalArgumentException e) {
      ParseException ex = new ParseException("Invalid synonym rule at line " + br.getLineNumber(), 0);
      ex.initCause(e);
      throw ex;
    } finally {
      br.close();
    }
  }
 
  private CharsRef parseSynonym(String line, CharsRef reuse) throws IOException {
    if (reuse == null) {
      reuse = new CharsRef(8);
    }
    
    int start = line.indexOf('\'')+1;
    int end = line.lastIndexOf('\'');
    
    String text = line.substring(start, end).replace("''", "'");
    return analyze(text, reuse);
  }
  
  private void addInternal(CharsRef synset[], int size) {
    if (size <= 1) {
      return; // nothing to do
    }
    
    if (expand) {
      for (int i = 0; i < size; i++) {
        for (int j = 0; j < size; j++) {
          add(synset[i], synset[j], false);
        }
      }
    } else {
      for (int i = 0; i < size; i++) {
        add(synset[i], synset[0], false);
      }
    }
  }
}