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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.cassandra.cql3.selection;

import java.nio.ByteBuffer;
import java.util.List;

import org.apache.cassandra.cql3.QueryOptions;
import org.apache.cassandra.cql3.Tuples;
import org.apache.cassandra.db.filter.ColumnFilter.Builder;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.TupleType;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.transport.ProtocolVersion;

/**
 * Selector for literal tuples (e.g. (min(value), max(value), count(value))).
 *
 */
final class TupleSelector extends Selector
{
    /**
     * The tuple type.
     */
    private final AbstractType type;

    /**
     * The tuple elements
     */
    private final List elements;

    public static Factory newFactory(final AbstractType type, final SelectorFactories factories)
    {
        return new CollectionFactory(type, factories)
        {
            protected String getColumnName()
            {
                return Tuples.tupleToString(factories, Factory::getColumnName);
            }

            public Selector newInstance(final QueryOptions options)
            {
                return new TupleSelector(type, factories.newInstances(options));
            }
        };
    }

    @Override
    public void addFetchedColumns(Builder builder)
    {
        for (int i = 0, m = elements.size(); i < m; i++)
            elements.get(i).addFetchedColumns(builder);
    }

    public void addInput(ProtocolVersion protocolVersion, ResultSetBuilder rs) throws InvalidRequestException
    {
        for (int i = 0, m = elements.size(); i < m; i++)
            elements.get(i).addInput(protocolVersion, rs);
    }

    public ByteBuffer getOutput(ProtocolVersion protocolVersion) throws InvalidRequestException
    {
        ByteBuffer[] buffers = new ByteBuffer[elements.size()];
        for (int i = 0, m = elements.size(); i < m; i++)
        {
            buffers[i] = elements.get(i).getOutput(protocolVersion);
        }
        return TupleType.buildValue(buffers);
    }

    public void reset()
    {
        for (int i = 0, m = elements.size(); i < m; i++)
            elements.get(i).reset();
    }

    public AbstractType getType()
    {
        return type;
    }

    @Override
    public String toString()
    {
        return Tuples.tupleToString(elements);
    }

    private TupleSelector(AbstractType type, List elements)
    {
        this.type = type;
        this.elements = elements;
    }
}