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

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

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/**
 * Copyright  2014 - 2018 Leipzig University (Database Research Group)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.gradoop.common.model.impl.properties;

import org.apache.commons.lang.StringUtils;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataInputViewStreamWrapper;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.core.memory.DataOutputViewStreamWrapper;
import org.apache.flink.types.Value;
import org.apache.hadoop.hbase.util.Bytes;

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

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

    /**
     * Class version for serialization.
     */
    private static final long serialVersionUID = 1L;

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

    /**
     * Default constructor (used for (de-)serialization.
     */
    public PropertyValueList() {
    }

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

    /**
     * Creates a new property value list containing no elements.
     *
     * @return empty property value list
     */
    public static PropertyValueList createEmptyList() {
        return new PropertyValueList(new byte[0]);
    }

    /**
     * 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 outputStream = new DataOutputStream(byteStream);
        DataOutputView outputView = new DataOutputViewStreamWrapper(outputStream);

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

        outputStream.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(DataOutputView dataOutput) throws IOException {
        dataOutput.writeShort(bytes.length);
        dataOutput.write(bytes);
    }

    @Override
    public void read(DataInputView 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 read}
         * method of PropertyValue.
         */
        private final DataInputStream inputStream;

        /**
         * Creates new iterator
         *
         * @param rawBytes property value list byte representation
         */
        PropertyValueListIterator(byte[] rawBytes) {
            if (rawBytes == null) {
                rawBytes = new byte[0];
            }
            byteStream = new ByteArrayInputStream(rawBytes);
            inputStream = 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 {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                hasNext = false;
            }
            return hasNext;
        }

        @Override
        public PropertyValue next() {
            PropertyValue nextValue = new PropertyValue();
            try {
                DataInputView inputView = new DataInputViewStreamWrapper(inputStream);
                nextValue.read(inputView);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return nextValue;
        }

        @Override
        public void remove() {
        }
    }
}