/*
* 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.util.table.writer;
import it.unimi.dsi.fastutil.objects.ObjectArrayList;
import org.grouplens.lenskit.util.table.TableLayout;
import org.grouplens.lenskit.util.table.TableLayoutBuilder;
import java.io.IOException;
import java.util.List;
/**
* A table writer that has the initial column values fixed. It wraps a table
* writer and presents a writer with fewer columns and constant values put in
* for the underlying missing columns. Closing it does nothing.
*
* @author <a href="http://www.grouplens.org">GroupLens Research</a>
*/
class PrefixedTableWriter extends AbstractTableWriter {
private ObjectArrayList<Object> rowData;
private int fixedColumns;
private TableLayout layout;
private TableWriter baseWriter;
/**
* Construct a new prefixed table writer.
*
* @param writer The underlying table writer to write to. This writer is <b>not</b> closed
* when the prefixed writer is closed.
* @param values The initial values to write. Each row written to this table
* writer is written to the base writer with these values prefixed.
*/
public PrefixedTableWriter(TableWriter writer, List<?> values) {
baseWriter = writer;
TableLayout baseLayout = writer.getLayout();
if (values.size() > baseLayout.getColumnCount()) {
throw new IllegalArgumentException("Value array too wide");
}
rowData = new ObjectArrayList<Object>(writer.getLayout().getColumnCount());
rowData.addAll(values);
fixedColumns = values.size();
TableLayoutBuilder bld = new TableLayoutBuilder();
List<String> bheaders = baseLayout.getColumns();
for (String h : bheaders.subList(fixedColumns, bheaders.size())) {
bld.addColumn(h);
}
layout = bld.build();
assert layout.getColumnCount() + rowData.size() == writer.getLayout().getColumnCount();
}
@Override
public TableLayout getLayout() {
return layout;
}
@Override
public synchronized void writeRow(List<?> row) throws IOException {
checkRowWidth(row.size());
// Add the data to the row
assert rowData.size() == fixedColumns;
rowData.addAll(row);
try {
// write the row
baseWriter.writeRow(rowData);
} finally {
// reset the row
rowData.removeElements(fixedColumns, rowData.size());
}
}
}