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package it.unimi.dsi.io;
/*
* DSI utilities
*
* Copyright (C) 2005-2009 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.fastutil.objects.AbstractObjectIterator;
import it.unimi.dsi.fastutil.objects.ObjectArrayList;
import it.unimi.dsi.lang.MutableString;
import it.unimi.dsi.logging.ProgressLogger;
import java.io.IOException;
import java.util.List;
import java.util.NoSuchElementException;
/** An adapter that exposes a fast buffered reader as an iterator
* over the returned lines. Since we just actually read a line to know
* whether {@link #hasNext()} should return true, the last line read
* from the underlying fast buffered reader has to be cached.
* Mixing calls to this adapter and to the underlying fast buffered
* reader will not usually give the expected results.
*
* This class reuses the same mutable strings. As a result,
* the comments for {@link FileLinesCollection}
* apply here. If you want just get all the lines, use {@link #allLines()}.
*
*/
public class LineIterator extends AbstractObjectIterator {
/** The underlying fast buffered reader. */
private final FastBufferedReader fastBufferedReader;
/** The mutable strings returned by this iterator. */
private final MutableString[] s = { new MutableString(), new MutableString() };
/** An optional progress meter. */
private final ProgressLogger pl;
/** Whether we must still advance to the next line. */
private boolean toAdvance = true;
/** In case {@link #toAdvance} is false, whether there is a next line. */
private boolean hasNext;
/** Which string in {@link #s} should be returned next. */
private int k;
/** Creates a new line iterator over a specified fast buffered reader.
*
* @param fastBufferedReader the underlying buffered reader.
* @param pl an optional progress logger, or null.
* */
public LineIterator( final FastBufferedReader fastBufferedReader, final ProgressLogger pl ) {
this.fastBufferedReader = fastBufferedReader;
this.pl = pl;
}
/** Creates a new line iterator over a specified fast buffered reader.
*
* @param fastBufferedReader the underlying buffered reader.
*/
public LineIterator( final FastBufferedReader fastBufferedReader ) {
this( fastBufferedReader, null );
}
public boolean hasNext() {
if ( toAdvance ) {
try {
k = 1 - k;
hasNext = fastBufferedReader.readLine( s[ k ] ) != null;
} catch (IOException e) {
throw new RuntimeException( e );
}
toAdvance = false;
}
return hasNext;
}
public MutableString next() {
if ( ! hasNext() ) throw new NoSuchElementException();
toAdvance = true;
if ( pl != null ) pl.update();
return s[ k ];
}
/** Returns all lines remaining in this iterator as a list.
*
* @return all lines remaining in this iterator as a list.
*/
public List allLines() {
final ObjectArrayList result = new ObjectArrayList();
while( hasNext() ) result.add( next().copy() );
return result;
}
}