package edu.uci.ics.hivesterix.runtime.factory.evaluator;

import org.apache.hadoop.hive.ql.plan.ExprNodeConstantDesc;

import edu.uci.ics.hivesterix.logical.expression.ExpressionTranslator;
import edu.uci.ics.hivesterix.runtime.evaluator.ConstantExpressionEvaluator;
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 ConstantExpressionEvaluatorFactory implements ICopyEvaluatorFactory {

    private static final long serialVersionUID = 1L;

    private ExprNodeConstantDesc expr;

    private Schema schema;

    public ConstantExpressionEvaluatorFactory(ILogicalExpression expression, Schema inputSchema,
            IVariableTypeEnvironment env) throws AlgebricksException {
        try {
            expr = (ExprNodeConstantDesc) ExpressionTranslator.getHiveExpression(expression, env);
        } catch (Exception e) {
            throw new AlgebricksException(e.getMessage());
        }
        schema = inputSchema;
    }

    public ICopyEvaluator createEvaluator(IDataOutputProvider output) throws AlgebricksException {
        return new ConstantExpressionEvaluator(expr, schema.toObjectInspector(), output);
    }

    public String toString() {
        return "constant expression evaluator factory: " + expr.toString();
    }

}