src/java/org/apache/hcatalog/data/ReaderWriter.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hcatalog.data;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.hadoop.io.VIntWritable;
import org.apache.hadoop.io.VLongWritable;


public abstract class ReaderWriter {

    private static final String UTF8 = "UTF-8";

    public static Object readDatum(DataInput in) throws IOException {

        byte type = in.readByte();
        switch (type) {

        case DataType.STRING:
            byte[] buffer = new byte[in.readInt()];
            in.readFully(buffer);
            return new String(buffer, UTF8);

        case DataType.INTEGER:
            VIntWritable vint = new VIntWritable();
            vint.readFields(in);
            return vint.get();

        case DataType.LONG:
            VLongWritable vlong = new VLongWritable();
            vlong.readFields(in);
            return vlong.get();

        case DataType.FLOAT:
            return in.readFloat();

        case DataType.DOUBLE:
            return in.readDouble();

        case DataType.BOOLEAN:
            return in.readBoolean();

        case DataType.BYTE:
            return in.readByte();

        case DataType.SHORT:
            return in.readShort();

        case DataType.NULL:
            return null;

        case DataType.BINARY:
            int len = in.readInt();
            byte[] ba = new byte[len];
            in.readFully(ba);
            return ba;

        case DataType.MAP:
            int size = in.readInt();
            Map<Object, Object> m = new HashMap<Object, Object>(size);
            for (int i = 0; i < size; i++) {
                m.put(readDatum(in), readDatum(in));
            }
            return m;

        case DataType.LIST:
            int sz = in.readInt();
            List<Object> list = new ArrayList<Object>(sz);
            for (int i = 0; i < sz; i++) {
                list.add(readDatum(in));
            }
            return list;

        default:
            throw new IOException("Unexpected data type " + type +
                " found in stream.");
        }
    }

    public static void writeDatum(DataOutput out, Object val) throws IOException {
        // write the data type
        byte type = DataType.findType(val);
        switch (type) {
        case DataType.LIST:
            out.writeByte(DataType.LIST);
            List<?> list = (List<?>) val;
            int sz = list.size();
            out.writeInt(sz);
            for (int i = 0; i < sz; i++) {
                writeDatum(out, list.get(i));
            }
            return;

        case DataType.MAP:
            out.writeByte(DataType.MAP);
            Map<?, ?> m = (Map<?, ?>) val;
            out.writeInt(m.size());
            Iterator<?> i =
                m.entrySet().iterator();
            while (i.hasNext()) {
                Entry<?, ?> entry = (Entry<?, ?>) i.next();
                writeDatum(out, entry.getKey());
                writeDatum(out, entry.getValue());
            }
            return;

        case DataType.INTEGER:
            out.writeByte(DataType.INTEGER);
            new VIntWritable((Integer) val).write(out);
            return;

        case DataType.LONG:
            out.writeByte(DataType.LONG);
            new VLongWritable((Long) val).write(out);
            return;

        case DataType.FLOAT:
            out.writeByte(DataType.FLOAT);
            out.writeFloat((Float) val);
            return;

        case DataType.DOUBLE:
            out.writeByte(DataType.DOUBLE);
            out.writeDouble((Double) val);
            return;

        case DataType.BOOLEAN:
            out.writeByte(DataType.BOOLEAN);
            out.writeBoolean((Boolean) val);
            return;

        case DataType.BYTE:
            out.writeByte(DataType.BYTE);
            out.writeByte((Byte) val);
            return;

        case DataType.SHORT:
            out.writeByte(DataType.SHORT);
            out.writeShort((Short) val);
            return;

        case DataType.STRING:
            String s = (String) val;
            byte[] utfBytes = s.getBytes(ReaderWriter.UTF8);
            out.writeByte(DataType.STRING);
            out.writeInt(utfBytes.length);
            out.write(utfBytes);
            return;

        case DataType.BINARY:
            byte[] ba = (byte[]) val;
            out.writeByte(DataType.BINARY);
            out.writeInt(ba.length);
            out.write(ba);
            return;

        case DataType.NULL:
            out.writeByte(DataType.NULL);
            return;

        default:
            throw new IOException("Unexpected data type " + type +
                " found in stream.");
        }
    }
}