/**
 * 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.ql.plan;

import java.io.Serializable;
import java.util.List;

import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoUtils;

/**
 * ExprNodeDesc.
 *
 */
public abstract class ExprNodeDesc implements Serializable, Node {
  private static final long serialVersionUID = 1L;
  TypeInfo typeInfo;

  public ExprNodeDesc() {
  }

  public ExprNodeDesc(TypeInfo typeInfo) {
    this.typeInfo = typeInfo;
    if (typeInfo == null) {
      throw new RuntimeException("typeInfo cannot be null!");
    }
  }

  @Override
  public abstract ExprNodeDesc clone();

  // Cant use equals because the walker depends on them being object equal
  // The default graph walker processes a node after its kids have been
  // processed. That comparison needs
  // object equality - isSame means that the objects are semantically equal.
  public abstract boolean isSame(Object o);

  public TypeInfo getTypeInfo() {
    return typeInfo;
  }

  public void setTypeInfo(TypeInfo typeInfo) {
    this.typeInfo = typeInfo;
  }

  public String getExprString() {
    assert (false);
    return null;
  }

  public ObjectInspector getWritableObjectInspector() {
    return TypeInfoUtils
      .getStandardWritableObjectInspectorFromTypeInfo(typeInfo);
  }

  @Explain(displayName = "type")
  public String getTypeString() {
    return typeInfo.getTypeName();
  }

  public List<String> getCols() {
    return null;
  }

  @Override
  public List<ExprNodeDesc> getChildren() {
    return null;
  }

  @Override
  public String getName() {
    return this.getClass().getName();
  }

  // This wraps an instance of an ExprNodeDesc, and makes equals work like isSame, see comment on
  // isSame
  public static class ExprNodeDescEqualityWrapper {
    private ExprNodeDesc exprNodeDesc;

    public ExprNodeDescEqualityWrapper(ExprNodeDesc exprNodeDesc) {
      this.exprNodeDesc = exprNodeDesc;
    }

    public ExprNodeDesc getExprNodeDesc() {
      return exprNodeDesc;
    }

    public void setExprNodeDesc(ExprNodeDesc exprNodeDesc) {
      this.exprNodeDesc = exprNodeDesc;
    }

    @Override
    public boolean equals(Object other) {

      if (other == null || !(other instanceof ExprNodeDescEqualityWrapper)) {
        return false;
      }

      return this.exprNodeDesc.isSame(((ExprNodeDescEqualityWrapper)other).getExprNodeDesc());
    }
  }
}