/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program 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 program 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.data.dao;
import com.google.common.base.Preconditions;
import org.grouplens.lenskit.cursors.AbstractPollingCursor;
import org.grouplens.lenskit.data.event.MutableRating;
import org.grouplens.lenskit.data.event.Rating;
import org.grouplens.lenskit.data.event.Ratings;
import org.grouplens.lenskit.util.DelimitedTextCursor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillCloseWhenClosed;
import java.io.BufferedReader;
/**
* Cursor that parses arbitrary delimited text.
*
* @compat Public
*/
public class DelimitedTextRatingCursor extends AbstractPollingCursor<Rating> {
protected Logger logger = LoggerFactory.getLogger(getClass());
private final String fileName;
private MutableRating rating;
private DelimitedTextCursor rowCursor;
/**
* Construct a rating cursor from a reader.
*
* @param s The reader to read.
* @param name The file name (for error messages).
* @param delimiter The delimiter.
*/
public DelimitedTextRatingCursor(@WillCloseWhenClosed @Nonnull BufferedReader s,
@Nullable String name,
@Nonnull String delimiter) {
fileName = name;
rating = new MutableRating();
rowCursor = new DelimitedTextCursor(s, delimiter);
}
@Override
public void close() {
rowCursor.close();
rating = null;
}
//CHECKSTYLE:OFF MagicNumber
@Override
public Rating poll() {
Preconditions.checkState(rating != null, "cursor is closed");
while (rowCursor.hasNext()) {
String[] fields = rowCursor.next();
if (fields.length < 3) {
logger.error("{}:{}: invalid input, skipping line",
fileName, rowCursor.getLineNumber());
continue;
}
rating.setUserId(Long.parseLong(fields[0].trim()));
rating.setItemId(Long.parseLong(fields[1].trim()));
rating.setRating(Double.parseDouble(fields[2].trim()));
rating.setTimestamp(-1);
if (fields.length >= 4) {
rating.setTimestamp(Long.parseLong(fields[3].trim()));
}
return rating;
}
return null;
}
@Override
public Rating copy(Rating r) {
return Ratings.copyBuilder(r).build();
}
//CHECKSTYLE:ON
}