/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.teiid.query.function.aggregate;

import java.util.List;

import org.teiid.api.exception.query.ExpressionEvaluationException;
import org.teiid.api.exception.query.FunctionExecutionException;
import org.teiid.core.TeiidComponentException;
import org.teiid.query.util.CommandContext;


/**
 */
public class ConstantFunction extends SingleArgumentAggregateFunction {

    private Object value;

    public void reset() {
        this.value = null;
    }
    
    @Override
    public boolean respectsNull() {
    	return true;
    }

    /**
     * @see org.teiid.query.function.aggregate.AggregateFunction#addInputDirect(List, CommandContext, CommandContext)
     */
    public void addInputDirect(Object input, List<?> tuple, CommandContext commandContext)
        throws FunctionExecutionException, ExpressionEvaluationException, TeiidComponentException {
            
        value = input;
    }

    /**
     * @see org.teiid.query.function.aggregate.AggregateFunction#getResult(CommandContext)
     */
    public Object getResult(CommandContext commandContext)
        throws FunctionExecutionException, ExpressionEvaluationException, TeiidComponentException {
            
        return this.value;
    }

}
