phoenix-core/src/main/java/org/apache/phoenix/execute/TupleProjectionPlan.java

/*
 * 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.phoenix.execute;

import java.sql.SQLException;
import java.util.List;

import org.apache.hadoop.hbase.client.Scan;
import org.apache.phoenix.compile.ExplainPlan;
import org.apache.phoenix.compile.QueryPlan;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.iterate.DelegateResultIterator;
import org.apache.phoenix.iterate.FilterResultIterator;
import org.apache.phoenix.iterate.ParallelScanGrouper;
import org.apache.phoenix.iterate.ResultIterator;
import org.apache.phoenix.schema.tuple.Tuple;

import com.google.common.collect.Lists;

public class TupleProjectionPlan extends DelegateQueryPlan {
    private final TupleProjector tupleProjector;
    private final Expression postFilter;

    public TupleProjectionPlan(QueryPlan plan, TupleProjector tupleProjector, Expression postFilter) {
        super(plan);
        if (tupleProjector == null) throw new IllegalArgumentException("tupleProjector is null");
        this.tupleProjector = tupleProjector;
        this.postFilter = postFilter;
    }

    @Override
    public ExplainPlan getExplainPlan() throws SQLException {
        List<String> planSteps = Lists.newArrayList(delegate.getExplainPlan().getPlanSteps());
        if (postFilter != null) {
            planSteps.add("CLIENT FILTER BY " + postFilter.toString());
        }

        return new ExplainPlan(planSteps);
    }

    @Override
    public ResultIterator iterator(ParallelScanGrouper scanGrouper, Scan scan) throws SQLException {
        ResultIterator iterator = new DelegateResultIterator(delegate.iterator(scanGrouper, scan)) {
            
            @Override
            public Tuple next() throws SQLException {
                Tuple tuple = super.next();
                if (tuple == null)
                    return null;
                
                return tupleProjector.projectResults(tuple);
            }

            @Override
            public String toString() {
                return "TupleProjectionResultIterator [projector=" + tupleProjector + "]";
            }            
        };
        
        if (postFilter != null) {
            iterator = new FilterResultIterator(iterator, postFilter);
        }
        
        return iterator;
    }
}