MastiffExprEvaluatorFactory.java

package org.apache.hadoop.hive.mastiff;

import org.apache.hadoop.hive.ql.exec.ExprNodeColumnEvaluator;
import org.apache.hadoop.hive.ql.exec.ExprNodeConstantEvaluator;
import org.apache.hadoop.hive.ql.exec.ExprNodeEvaluator;
import org.apache.hadoop.hive.ql.exec.ExprNodeFieldEvaluator;
import org.apache.hadoop.hive.ql.exec.ExprNodeNullEvaluator;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.plan.ExprNodeColumnDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeConstantDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeFieldDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeNullDesc;

public final class MastiffExprEvaluatorFactory {

  private MastiffExprEvaluatorFactory() {
  }

  public static ExprNodeEvaluator get(ExprNodeDesc desc) throws HiveException {
    // Constant node
    if (desc instanceof ExprNodeConstantDesc) {
      return new ExprNodeConstantEvaluator((ExprNodeConstantDesc) desc);
    }
    // Column-reference node, e.g. a column in the input row
    if (desc instanceof ExprNodeColumnDesc) {
      return new ExprNodeColumnEvaluator((ExprNodeColumnDesc) desc);
    }
    // Generic Function node, e.g. CASE, an operator or a UDF node
    if (desc instanceof ExprNodeGenericFuncDesc) {
      return new MastiffExprNodeGenericFuncEvaluator((ExprNodeGenericFuncDesc) desc);
    }
    // Field node, e.g. get a.myfield1 from a
    if (desc instanceof ExprNodeFieldDesc) {
      return new ExprNodeFieldEvaluator((ExprNodeFieldDesc) desc);
    }
    // Null node, a constant node with value NULL and no type information
    if (desc instanceof ExprNodeNullDesc) {
      return new ExprNodeNullEvaluator((ExprNodeNullDesc) desc);
    }

    throw new RuntimeException(
        "Cannot find ExprNodeEvaluator for the exprNodeDesc = " + desc);
  }
}