com.facebook.drift.codec.ThriftCodec Maven / Gradle / Ivy

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/*
 * Copyright (C) 2012 Facebook, Inc.
 *
 * 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 com.facebook.drift.codec;

import com.facebook.drift.codec.metadata.ThriftType;
import com.facebook.drift.protocol.TProtocolReader;
import com.facebook.drift.protocol.TProtocolWriter;

/**
 * A single type codec for reading and writing in Thrift format.  Each codec is symmetric and
 * therefore only supports a single concrete type.
 * 
 * 
Implementations of this interface are expected to be thread safe.
 *
 * @param  the type this codec supports
 */
public interface ThriftCodec
{
    /**
     * The Thrift type this codec supports.  The Thrift type contains the Java generic Type of the
     * codec.
     */
    ThriftType getType();

    /**
     * Reads a value from supplied Thrift protocol reader.
     *
     * @param protocol the protocol to read from
     * @return the value; not null
     * @throws Exception if any problems occurred when reading or coercing the value
     */
    T read(TProtocolReader protocol)
            throws Exception;

    /**
     * Writes a value to the supplied Thrift protocol writer.
     *
     * @param value the value to write; not null
     * @param protocol the protocol to write to
     * @throws Exception if any problems occurred when writing or coercing the value
     */
    void write(T value, TProtocolWriter protocol)
            throws Exception;

    /**
     * If the value is effectively null and should not be written.
     *
     * @param value the value to test
     * @return true if the value should not be written
     */
    default boolean isNull(T value)
    {
        return value == null;
    }
}