asterix-om/src/main/java/edu/uci/ics/asterix/om/typecomputer/impl/BinaryBooleanOrNullFunctionTypeComputer.java

package edu.uci.ics.asterix.om.typecomputer.impl;


import edu.uci.ics.asterix.om.typecomputer.base.IResultTypeComputer;
import edu.uci.ics.asterix.om.types.ATypeTag;
import edu.uci.ics.asterix.om.types.AUnionType;
import edu.uci.ics.asterix.om.types.BuiltinType;
import edu.uci.ics.asterix.om.types.IAType;
import edu.uci.ics.asterix.om.types.TypeHelper;
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.AbstractFunctionCallExpression;
import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;

public class BinaryBooleanOrNullFunctionTypeComputer implements IResultTypeComputer {

    public static final BinaryBooleanOrNullFunctionTypeComputer INSTANCE = new BinaryBooleanOrNullFunctionTypeComputer();

    private BinaryBooleanOrNullFunctionTypeComputer() {
    }

    @Override
    public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
            IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
        AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) expression;
        ILogicalExpression arg0 = fce.getArguments().get(0).getValue();
        ILogicalExpression arg1 = fce.getArguments().get(1).getValue();
        IAType t0, t1;
        try {
            t0 = (IAType) env.getType(arg0);
            t1 = (IAType) env.getType(arg1);
        } catch (AlgebricksException e) {
            throw new AlgebricksException(e);
        }
        if (t0.getTypeTag() == ATypeTag.NULL && t1.getTypeTag() == ATypeTag.NULL) {
            return BuiltinType.ANULL;
        }
        if (TypeHelper.canBeNull(t0) || TypeHelper.canBeNull(t1)) {
            return AUnionType.createNullableType(BuiltinType.ABOOLEAN);
        }
        return BuiltinType.ABOOLEAN;
    }
}