hivesterix/hivesterix-runtime/src/main/java/edu/uci/ics/hivesterix/runtime/factory/evaluator/NullExpressionEvaluatorFactory.java

/*
 * Copyright 2009-2013 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.hivesterix.runtime.factory.evaluator;

import org.apache.hadoop.hive.ql.plan.ExprNodeNullDesc;

import edu.uci.ics.hivesterix.logical.expression.ExpressionTranslator;
import edu.uci.ics.hivesterix.runtime.evaluator.NullExpressionEvaluator;
import edu.uci.ics.hivesterix.runtime.jobgen.Schema;
import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluator;
import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
import edu.uci.ics.hyracks.data.std.api.IDataOutputProvider;

public class NullExpressionEvaluatorFactory implements ICopyEvaluatorFactory {

    private static final long serialVersionUID = 1L;

    private ExprNodeNullDesc expr;

    private Schema schema;

    public NullExpressionEvaluatorFactory(ILogicalExpression expression, Schema intputSchema,
            IVariableTypeEnvironment env) throws AlgebricksException {
        try {
            expr = (ExprNodeNullDesc) ExpressionTranslator.getHiveExpression(expression, env);
        } catch (Exception e) {
            throw new AlgebricksException(e.getMessage());
        }
        schema = intputSchema;
    }

    public ICopyEvaluator createEvaluator(IDataOutputProvider output) throws AlgebricksException {
        return new NullExpressionEvaluator(expr, schema.toObjectInspector(), output);
    }

    public String toString() {
        return "null expression evaluator factory: " + expr.toString();
    }

}