asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/CreatePolygonDescriptor.java

package edu.uci.ics.asterix.runtime.evaluators.functions;

import java.io.DataOutput;
import java.io.IOException;

import edu.uci.ics.asterix.common.functions.FunctionConstants;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
import edu.uci.ics.asterix.om.types.ATypeTag;
import edu.uci.ics.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
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.data.std.util.ArrayBackedValueStorage;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;

public class CreatePolygonDescriptor extends AbstractScalarFunctionDynamicDescriptor {

    private static final long serialVersionUID = 1L;
    public final static FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "create-polygon",
            FunctionIdentifier.VARARGS);
    public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
        public IFunctionDescriptor createFunctionDescriptor() {
            return new CreatePolygonDescriptor();
        }
    };

    @Override
    public ICopyEvaluatorFactory createEvaluatorFactory(final ICopyEvaluatorFactory[] args) throws AlgebricksException {
        return new ICopyEvaluatorFactory() {
            private static final long serialVersionUID = 1L;

            private DataOutput out;
            private ArrayBackedValueStorage outInput;

            @Override
            public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {

                final ICopyEvaluator[] argEvals = new ICopyEvaluator[args.length];
                out = output.getDataOutput();

                outInput = new ArrayBackedValueStorage();

                for (int i = 0; i < args.length; i++) {
                    argEvals[i] = args[i].createEvaluator(outInput);
                }

                return new ICopyEvaluator() {

                    @Override
                    public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
                        try {
                            out.writeByte(ATypeTag.POLYGON.serialize());
                            out.writeShort(args.length);
                        } catch (IOException e) {
                            throw new AlgebricksException(e);
                        }

                        for (int i = 0; i < argEvals.length; i++) {
                            outInput.reset();
                            argEvals[i].evaluate(tuple);
                            try {
                                out.write(outInput.getByteArray(), outInput.getStartOffset() + 1,
                                        outInput.getLength() - 1);
                            } catch (IOException e) {
                                throw new AlgebricksException(e);
                            }
                        }
                    }
                };
            }
        };
    }

    @Override
    public FunctionIdentifier getIdentifier() {
        return FID;
    }

}