phoenix-core/src/main/java/org/apache/phoenix/iterate/MaterializedComparableResultIterator.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.iterate;

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

import org.apache.phoenix.schema.tuple.Tuple;

/**
 * Fully materialized comparable result iterator backed by the result iterator provided with
 * comparator. No copy is made of the backing results iterator.
 */
public class MaterializedComparableResultIterator
        implements PeekingResultIterator, Comparable<MaterializedComparableResultIterator> {

    private PeekingResultIterator delegate;
    private Comparator<? super Tuple> comparator;
    private Tuple current;

    public Tuple getCurrent() {
        return current;
    }

    public MaterializedComparableResultIterator(PeekingResultIterator delegate,
            Comparator<? super Tuple> c) throws SQLException {
        this.delegate = delegate;
        this.comparator = c;
        this.current = delegate.peek();
    }

    @Override
    public Tuple next() throws SQLException {
        Tuple next = delegate.next();
        this.current = delegate.peek();
        return next;
    }

    @Override
    public Tuple peek() throws SQLException {
        return delegate.peek();
    }

    @Override
    public void close() throws SQLException {
        delegate.close();
    }

    @Override
    public int compareTo(MaterializedComparableResultIterator o) {
        return comparator.compare(this.getCurrent(), o.getCurrent());

    }

    @Override
    public void explain(List<String> planSteps) {
        delegate.explain(planSteps);
    }
}