com.bah.culvert.constraints.IndexRangeConstraint.java Source code

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Here is the source code for com.bah.culvert.constraints.IndexRangeConstraint.java

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/**
 * Copyright 2011 Booz Allen Hamilton.
 * 
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership. Booz Allen Hamilton
 * 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 com.bah.culvert.constraints;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.ObjectWritable;
import org.apache.hadoop.io.Writable;

import com.bah.culvert.data.CRange;
import com.bah.culvert.data.index.Index;
import com.bah.culvert.iterators.SeekingCurrentIterator;

/**
 * A constraint that only returns results over the specified indexes.
 */
public final class IndexRangeConstraint extends Constraint implements Writable {

    private CRange range = new CRange();
    private Index index;

    /**
     * Create an index range where all the indexes are [minimum, maximum)
     * 
     * @param index
     *          to examine
     * @param range
     *          to iterate over
     */
    public IndexRangeConstraint(Index index, CRange range) {
        this.range = range;
        this.index = index;
    }

    /**
     * Create an empty range constraint.
     */
    public IndexRangeConstraint() {
        // TODO Auto-generated constructor stub
    }

    /** 
     * Uses the Index's handleGet method to parse for the row id.
     * @see com.bah.culvert.constraints.Constraint#getResultIterator(com.bah.culvert.adapter.TableAdapter)
     * 
     */
    @Override
    public SeekingCurrentIterator getResultIterator() {
        return index.handleGet(range.getStart(), range.getEnd());
    }

    /**
     * @return the range for this constraint
     */
    public CRange getRange() {
        return range;
    }

    @Override
    public String toString() {
        boolean startNotNull = false;
        StringBuilder sb = new StringBuilder();
        sb.append("IndexRangeConstraint(");

        if (range != null && range.getStart() != null) {
            sb.append(range.getStart().hashCode());
            startNotNull = true;
        }

        if (range != null && range.getEnd() != null) {
            if (startNotNull) {
                sb.append(", ");
            }
            sb.append(range.getEnd().hashCode());
        }
        sb.append(")");
        return sb.toString();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.hadoop.io.Writable#readFields(java.io.DataInput)
     */
    @Override
    public void readFields(DataInput in) throws IOException {
        range.readFields(in);
        ObjectWritable ow = new ObjectWritable();
        Configuration conf = new Configuration();
        ow.setConf(conf);
        ow.readFields(in);
        this.index = (Index) ow.get();
    }

    @Override
    public void write(DataOutput out) throws IOException {
        range.write(out);
        new ObjectWritable(this.index).write(out);
    }

    @Override
    public boolean equals(Object compareto) {
        if (!(compareto instanceof IndexRangeConstraint) || compareto == null) {
            return false;
        }

        IndexRangeConstraint compare = (IndexRangeConstraint) compareto;

        if (range == null && compare.getRange() != null) {
            return false;
        }

        if (range == null && compare.getRange() == null) {
            return true;
        }

        if (range != null && compare.getRange() == null) {
            return false;
        }

        return range.equals(compare.getRange());
    }

    @Override
    public int hashCode() {
        int i = 0;
        if (range != null) {
            i = range.hashCode();
        }
        return i;
    }

    public Index getIndex() {
        return index;
    }

}