org.gradoop.model.impl.properties.PropertyValueList.java Source code

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Here is the source code for org.gradoop.model.impl.properties.PropertyValueList.java

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/*
 * This file is part of Gradoop.
 *
 * Gradoop is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Gradoop 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 Gradoop. If not, see <http://www.gnu.org/licenses/>.
 */

package org.gradoop.model.impl.properties;

import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.WritableComparable;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;

/**
 * Represents a list of property values.
 */
public class PropertyValueList implements Iterable<PropertyValue>, WritableComparable<PropertyValueList> {

    /**
     * Property values are stored in their byte representation.
     */
    private byte[] bytes;

    /**
     * Default constructor.
     */
    public PropertyValueList() {
    }

    /**
     * Creates a value list from the given bytes.
     *
     * @param bytes byte representation
     */
    private PropertyValueList(byte[] bytes) {
        this.bytes = bytes;
    }

    /**
     * Creates a Property value list from a collection of property values.
     *
     * @param propertyValues property values
     *
     * @return property value list containing the given properties
     */
    public static PropertyValueList fromPropertyValues(Collection<PropertyValue> propertyValues)
            throws IOException {

        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
        DataOutputStream out = new DataOutputStream(byteStream);

        for (PropertyValue propertyValue : propertyValues) {
            propertyValue.write(out);
        }

        out.flush();
        return new PropertyValueList(byteStream.toByteArray());
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof PropertyValueList)) {
            return false;
        }
        PropertyValueList that = (PropertyValueList) o;
        return Arrays.equals(bytes, that.bytes);
    }

    @Override
    public int hashCode() {
        return Arrays.hashCode(bytes);
    }

    @Override
    public Iterator<PropertyValue> iterator() {
        return new PropertyValueListIterator(bytes);
    }

    @Override
    public void write(DataOutput dataOutput) throws IOException {
        dataOutput.writeShort(bytes.length);
        dataOutput.write(bytes);
    }

    @Override
    public void readFields(DataInput dataInput) throws IOException {
        bytes = new byte[dataInput.readShort()];
        dataInput.readFully(bytes);
    }

    @Override
    public int compareTo(PropertyValueList o) {
        return Bytes.compareTo(bytes, o.bytes);
    }

    @Override
    public String toString() {
        return StringUtils.join(iterator(), ',');
    }

    /**
     * Used to iterate over the stored values.
     */
    private static class PropertyValueListIterator implements Iterator<PropertyValue> {

        /**
         * Used to wrap the byte array of PropertyValueList
         */
        private final ByteArrayInputStream byteStream;

        /**
         * Wraps the {@code byteStream} and is used to access the {@code readFields}
         * method of PropertyValue.
         */
        private final DataInputStream in;

        /**
         * Creates new iterator
         *
         * @param rawBytes property value list byte representation
         */
        public PropertyValueListIterator(byte[] rawBytes) {
            if (rawBytes == null) {
                rawBytes = new byte[0];
            }
            byteStream = new ByteArrayInputStream(rawBytes);
            in = new DataInputStream(byteStream);
        }

        @Override
        public boolean hasNext() {
            boolean hasNext;
            if (byteStream.available() > 0) {
                hasNext = true;
            } else {
                // close the stream if no more data is available
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                hasNext = false;
            }
            return hasNext;
        }

        @Override
        public PropertyValue next() {
            PropertyValue nextValue = new PropertyValue();
            try {
                nextValue.readFields(in);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return nextValue;
        }

        @Override
        public void remove() {
        }
    }
}