asterix-om/src/main/java/edu/uci/ics/asterix/om/typecomputer/impl/GetItemResultType.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.AbstractCollectionType;
import edu.uci.ics.asterix.om.types.IAType;
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 GetItemResultType implements IResultTypeComputer {

    public static final GetItemResultType INSTANCE = new GetItemResultType();

    private GetItemResultType() {
    }

    @Override
    public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
            IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
        AbstractFunctionCallExpression f = (AbstractFunctionCallExpression) expression;
        Object type0;
        try {
            type0 = env.getType(f.getArguments().get(0).getValue());
        } catch (AlgebricksException e) {
            throw new AlgebricksException(e);
        }
        if (type0 == null) {
            return null;
        }
        AbstractCollectionType t0 = (AbstractCollectionType) type0;
        return t0.getItemType();
    }

}