package LBJ2.nlp;

import LBJ2.parse.LinkedVector;
import LBJ2.parse.Parser;


/**
  * This parser takes the plain, unannotated {@link Sentence}s returned by
  * another parser (e.g., {@link SentenceSplitter}) and splits them into
  * {@link Word} objects.  Entire sentences now represented as
  * {@link LBJ2.parse.LinkedVector}s are then returned one at a time by calls
  * to the <code>next()</code> method.
  *
  * <p> A {@link #main(String[])} method is also implemented which applies
  * this class to plain text in a straight-forward way.
  *
  * @author Nick Rizzolo
 **/
public class WordSplitter implements Parser
{
  /**
    * Run this program on a file containing plain text, and it will produce
    * the same text on <code>STDOUT</code> rearranged so that each line
    * contains exactly one sentence, and so that character sequences deemed to
    * be "words" are delimited by whitespace.
    *
    * <p> Usage:
    * <code> java LBJ2.nlp.WordSplitter <file name> </code>
    *
    * @param args The command line arguments.
   **/
  public static void main(String[] args) {
    String filename = null;

    try {
      filename = args[0];
      if (args.length > 1) throw new Exception();
    }
    catch (Exception e) {
      System.err.println("usage: java LBJ2.nlp.WordSplitter <file name>");
      System.exit(1);
    }

    WordSplitter splitter = new WordSplitter(new SentenceSplitter(filename));

    for (LinkedVector s = (LinkedVector) splitter.next(); s != null;
         s = (LinkedVector) splitter.next()) {
      if (s.size() > 0) {
        Word w = (Word) s.get(0);
        System.out.print(w.form);
        for (w = (Word) w.next ; w != null; w = (Word) w.next)
          System.out.print(" " + w.form);
      }

      System.out.println();
    }
  }


  /** The {@link Sentence} returning parser. */
  protected Parser parser;


  /**
    * Initializing constructor.
    *
    * @param p  The {@link Sentence} returning parser.
   **/
  public WordSplitter(Parser p) { parser = p; }


  /**
    * Returns {@link LBJ2.parse.LinkedVector}s of {@link Word} objects one at
    * a time.
   **/
  public Object next() {
    Sentence sentence = (Sentence) parser.next();
    if (sentence == null) return null;
    return sentence.wordSplit();
  }


  /** Sets this parser back to the beginning of the raw data. */
  public void reset() { parser.reset(); }


  /** Frees any resources this parser may be holding. */
  public void close() { parser.close(); }
}