org.exist.xquery.modules.compression.GZipFunction.java Source code

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Here is the source code for org.exist.xquery.modules.compression.GZipFunction.java

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/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-09 The eXist Project
 *  http://exist-db.org
 *
 *  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
 *  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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * $Id$
 */
package org.exist.xquery.modules.compression;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;

import org.apache.commons.io.output.ByteArrayOutputStream;

import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.Base64BinaryValueType;
import org.exist.xquery.value.BinaryValue;
import org.exist.xquery.value.BinaryValueFromInputStream;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

/**
 * Compression into a GZip file
 * 
 * @author Adam Retter <adam@exist-db.org>
 * @version 1.1
 */
public class GZipFunction extends BasicFunction {
    public final static FunctionSignature signatures[] = { new FunctionSignature(
            new QName("gzip", CompressionModule.NAMESPACE_URI, CompressionModule.PREFIX), "GZip's data",
            new SequenceType[] { new FunctionParameterSequenceType("data", Type.BASE64_BINARY,
                    Cardinality.EXACTLY_ONE, "The data to GZip") },
            new SequenceType(Type.BASE64_BINARY, Cardinality.ZERO_OR_ONE)) };

    public GZipFunction(XQueryContext context, FunctionSignature signature) {
        super(context, signature);
    }

    @Override
    public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
        // is there some data to GZip?
        if (args[0].isEmpty())
            return Sequence.EMPTY_SEQUENCE;

        BinaryValue bin = (BinaryValue) args[0].itemAt(0);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        // gzip the data
        try {
            GZIPOutputStream gzos = new GZIPOutputStream(baos);
            bin.streamTo(gzos);
            gzos.close();

            return BinaryValueFromInputStream.getInstance(context, new Base64BinaryValueType(),
                    new ByteArrayInputStream(baos.toByteArray()));
        } catch (IOException ioe) {
            throw new XPathException(this, ioe.getMessage());
        }
    }
}