/**
 * 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 8 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
 * 6. Decimal objects
 * 7. Char objects
 * 8. Varchar 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();

  /**
   * String representing the qualified type name.
   * Qualified types should override this method.
   * @return
   */
  public String getQualifiedName() {
    return getTypeName();
  }

  @Override
  public String toString() {
    return getTypeName();
  }

  @Override
  public abstract boolean equals(Object o);

  @Override
  public abstract int hashCode();

  public boolean accept(TypeInfo other) {
    return this.equals(other);
  }

}
