/tags/release-0.1-rc2/hive/external/serde/src/java/org/apache/hadoop/hive/serde2/typeinfo/TypeInfo.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.hadoop.hive.serde2.typeinfo;



import java.io.Serializable;



import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector.Category;



/**

 * Stores information about a type. Always use the TypeInfoFactory to create new

 * TypeInfo objects.

 *

 * We support 5 categories of types: 1. Primitive objects (String, Number, etc)

 * 2. List objects (a list of objects of a single type) 3. Map objects (a map

 * from objects of one type to objects of another type) 4. Struct objects (a

 * list of fields with names and their own types) 5. Union objects

 */

public abstract class TypeInfo implements Serializable {



  private static final long serialVersionUID = 1L;



  protected TypeInfo() {

  }



  /**

   * The Category of this TypeInfo. Possible values are Primitive, List, Map,

   * Struct and Union, which corresponds to the 5 sub-classes of TypeInfo.

   */

  public abstract Category getCategory();



  /**

   * A String representation of the TypeInfo.

   */

  public abstract String getTypeName();



  @Override

  public String toString() {

    return getTypeName();

  }



  @Override

  public abstract boolean equals(Object o);



  @Override

  public abstract int hashCode();

}