package it.unimi.dsi.io;
/*
* DSI utilities
*
* Copyright (C) 2005-2009 Paolo Boldi and Sebastiano Vigna
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
import it.unimi.dsi.lang.MutableString;
import java.io.IOException;
import java.io.Reader;
import java.io.Serializable;
/** An interface providing methods to break the input from a reader into words.
*
* <p>The intended implementations of this interface should decorate
* a given reader (see, for instance, {@link it.unimi.dsi.io.FastBufferedReader}).
* The reader can be changed at any time using {@link #setReader(Reader)}.
*
* <p>This interface is heavily oriented towards reusability and
* streaming. It is conceived so that at most one method call has
* to be performed per <em>word</em>, rather than per <em>character</em>,
* and that implementations may completely avoid object creation by
* {@linkplain #setReader(Reader) setting explicitly the underlying reader}.
*
* <p>The standard implementation ({@link it.unimi.dsi.io.FastBufferedReader}) breaks
* words in the trivial way. More complex implementations (e.g., for languages requiring
* segmentation) can subclass {@link it.unimi.dsi.io.FastBufferedReader} or provide their
* own implementation.
*/
public interface WordReader extends Serializable {
/** Extracts the next word and non-word.
*
* <p>If this method returns true, a new non-empty word, and possibly
* a new non-word, have been extracted. It is acceptable
* that the <em>first</em> call to this method after creation
* or after a call to {@link #setReader(Reader)} returns an empty
* word. In other words <em>both <code>word</code> and <code>nonWord</code> are maximal</em>.
*
* @param word the next word returned by the underlying reader.
* @param nonWord the nonword following the next word returned by the underlying reader.
* @return true if a new word was processed, false otherwise (in which
* case both <code>word</code> and <code>nonWord</code> are unchanged).
*/
public abstract boolean next( MutableString word, MutableString nonWord ) throws IOException;
/** Resets the internal state of this word reader, which will start again reading from the given reader.
*
* @param reader the new reader providing characters.
* @return this word reader.
*/
public abstract WordReader setReader( Reader reader );
/** Returns a copy of this word reader.
*
* <p>This method must return a word reader with a behaviour that
* matches exactly that of this word reader.
*
* @return a copy of this word reader.
*/
public abstract WordReader copy();
}