content: /*
   * 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.calcite.adapter.hive;
  
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.sql.SqlCallBinding;
  import org.apache.calcite.sql.SqlLiteral;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.SqlOperatorBinding;
  import org.apache.calcite.sql.type.SqlReturnTypeInference;
  
  import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
  import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * A HiveSqlUDFReturnTypeInference can infer the result type of a Hive UDF through
   * {@link GenericUDF#initialize(ObjectInspector[])}
   */
  public class HiveSqlUDFReturnTypeInference implements SqlReturnTypeInference {
  
    public static final HiveSqlUDFReturnTypeInference INSTANCE =
        new HiveSqlUDFReturnTypeInference();
  
    @Override public RelDataType inferReturnType(
        final SqlOperatorBinding opBinding) {
      try {
        SqlOperator sqlOperator = opBinding.getOperator();
        List<RelDataTypeHolder> argsType = new ArrayList<>();
        for (int i = 0; i < opBinding.getOperandCount(); i++) {
          RelDataTypeHolder relDataTypeHolder;
          boolean isSqlCallBinding = opBinding instanceof SqlCallBinding;
          if (isSqlCallBinding) {
            List<SqlNode> operands = ((SqlCallBinding) opBinding).operands();
            if (operands.get(i) instanceof SqlLiteral) {
              relDataTypeHolder = new RelDataTypeHolder(
                  opBinding.getOperandType(i), true,
                  ((SqlLiteral) operands.get(i)).getValue());
            } else {
              relDataTypeHolder = new RelDataTypeHolder(
                  opBinding.getOperandType(i));
            }
  
          } else {
            relDataTypeHolder = new RelDataTypeHolder(
                opBinding.getOperandType(i));
          }
          argsType.add(relDataTypeHolder);
        }
        String opName = sqlOperator.getName();
        GenericUDF udfInstance = HiveUDFImplementor.newGenericUDF(
            opName, sqlOperator.getSyntax());
        ObjectInspector[] inputObjectInspector =
            TypeInferenceUtil.getObjectInspector(
                argsType.toArray(new RelDataTypeHolder[0]));
        ObjectInspector outputObjectInspector = udfInstance.initialize(
            inputObjectInspector);
        RelDataType resultType = TypeInferenceUtil.getRelDataType(
            outputObjectInspector,
            opBinding.getTypeFactory());
        return resultType;
  
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
  }
  
  // End HiveSqlUDFReturnTypeInference.java
  