rangequery.java

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package org.apache.lucene.search;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 *
 * 5. Products derived from this software may not be called "Apache",
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 *
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.IndexReader;

/** A Query that matches documents within an exclusive range. */
public final class RangeQuery extends Query
{
    private Term lowerTerm;
    private Term upperTerm;
    private boolean inclusive;
    private IndexReader reader;
    private BooleanQuery query;
    
    /** Constructs a query selecting all terms greater than 
     * <code>lowerTerm</code> but less than <code>upperTerm</code>.
     * There must be at least one term and either term may be null--
     * in which case there is no bound on that side, but if there are 
     * two term, both terms <b>must</b> be for the same field.
     */
    public RangeQuery(Term lowerTerm, Term upperTerm, boolean inclusive)
    {
        if (lowerTerm == null && upperTerm == null)
        {
            throw new IllegalArgumentException("At least one term must be non-null");
        }
        if (lowerTerm != null && upperTerm != null && lowerTerm.field() != upperTerm.field())
        {
            throw new IllegalArgumentException("Both terms must be for the same field");
        }
        this.lowerTerm = lowerTerm;
        this.upperTerm = upperTerm;
        this.inclusive = inclusive;
    }
    
    final void prepare(IndexReader reader)
    {
        this.query = null;
        this.reader = reader;
    }
    
    final float sumOfSquaredWeights(Searcher searcher) throws IOException
    {
        return getQuery().sumOfSquaredWeights(searcher);
    }
    
    void normalize(float norm)
    {
        try
        {
            getQuery().normalize(norm);
        } 
        catch (IOException e)
        {
            throw new RuntimeException(e.toString());
        }
    }
    
    Scorer scorer(IndexReader reader) throws IOException
    {
        return getQuery().scorer(reader);
    }
    
    private BooleanQuery getQuery() throws IOException
    {
        if (query == null)
        {
            BooleanQuery q = new BooleanQuery();
            // if we have a lowerTerm, start there. otherwise, start at beginning
            if (lowerTerm == null) lowerTerm = new Term(getField(), "");
            TermEnum enum = reader.terms(lowerTerm);
            try
            {
                String lowerText = null;
                String field;
                boolean checkLower = false;
                if (!inclusive) // make adjustments to set to exclusive
                {
                    if (lowerTerm != null)
                    {
                        lowerText = lowerTerm.text();
                        checkLower = true;
                    }
                    if (upperTerm != null)
                    {
                        // set upperTerm to an actual term in the index
                        TermEnum uppEnum = reader.terms(upperTerm);
                        upperTerm = uppEnum.term();
                    }
                }
                String testField = getField();
                do
                {
                    Term term = enum.term();
                    if (term != null && term.field() == testField)
                    {
                        if (!checkLower || term.text().compareTo(lowerText) > 0) 
                        {
                            checkLower = false;
                            if (upperTerm != null)
                            {
                                int compare = upperTerm.compareTo(term);
                                /* if beyond the upper term, or is exclusive and
                                 * this is equal to the upper term, break out */
                                if ((compare < 0) || (!inclusive && compare == 0)) break;
                            }
                            TermQuery tq = new TermQuery(term);	  // found a match
                            tq.setBoost(boost);               // set the boost
                            q.add(tq, false, false);		  // add to q
                        }
                    } 
                    else
                    {
                        break;
                    }
                }
                while (enum.next());
            } 
            finally
            {
                enum.close();
            }
            query = q;
        }
        return query;
    }
    
    private String getField()
    {
        return (lowerTerm != null ? lowerTerm.field() : upperTerm.field());
    }
    
    /** Prints a user-readable version of this query. */
    public String toString(String field)
    {
        StringBuffer buffer = new StringBuffer();
        if (!getField().equals(field))
        {
            buffer.append(getField());
            buffer.append(":");
        }
        buffer.append(inclusive ? "[" : "{");
        buffer.append(lowerTerm != null ? lowerTerm.text() : "null");
        buffer.append("-");
        buffer.append(upperTerm != null ? upperTerm.text() : "null");
        buffer.append(inclusive ? "]" : "}");
        if (boost != 1.0f)
        {
            buffer.append("^");
            buffer.append(Float.toString(boost));
        }
        return buffer.toString();
    }
}