asterix-external-data/src/main/java/edu/uci/ics/asterix/external/library/ExternalFunctionProvider.java

package edu.uci.ics.asterix.external.library;

import java.util.HashMap;
import java.util.Map;

import edu.uci.ics.asterix.om.functions.IExternalFunctionInfo;
import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
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;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;

public class ExternalFunctionProvider {

    private static Map<IExternalFunctionInfo, ExternalScalarFunction> functionRepo = new HashMap<IExternalFunctionInfo, ExternalScalarFunction>();

    public static IExternalFunction getExternalFunctionEvaluator(IExternalFunctionInfo finfo,
            ICopyEvaluatorFactory args[], IDataOutputProvider outputProvider) throws AlgebricksException {
        switch (finfo.getKind()) {
            case SCALAR:
                ExternalScalarFunction function = functionRepo.get(finfo);
                function = new ExternalScalarFunction(finfo, args, outputProvider);
                // functionRepo.put(finfo, function);
                return function;
            case AGGREGATE:
            case UNNEST:
                throw new IllegalArgumentException(" not supported function kind" + finfo.getKind());
            default:
                throw new IllegalArgumentException(" unknown function kind" + finfo.getKind());
        }
    }
}

class ExternalScalarFunction extends ExternalFunction implements IExternalScalarFunction, ICopyEvaluator {

    public ExternalScalarFunction(IExternalFunctionInfo finfo, ICopyEvaluatorFactory args[],
            IDataOutputProvider outputProvider) throws AlgebricksException {
        super(finfo, args, outputProvider);
        initialize(functionHelper);
    }

    @Override
    public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
        try {
            setArguments(tuple);
            evaluate(functionHelper);
        } catch (Exception e) {
            throw new AlgebricksException(e);
        }
    }

    public void evaluate(IFunctionHelper argumentProvider) throws Exception {
        ((IExternalScalarFunction) externalFunction).evaluate(argumentProvider);
    }

    @Override
    public void initialize(IFunctionHelper functionHelper) {
        ((IExternalScalarFunction) externalFunction).initialize(functionHelper);
    }

}