StringContainsCO.java

// BlogBridge -- RSS feed reader, manager, and web based service
// Copyright (C) 2002-2006 by R. Pito Salas
//
// This program is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free Software Foundation;
// either version 2 of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with this program;
// if not, write to the Free Software Foundation, Inc., 59 Temple Place,
// Suite 330, Boston, MA 02111-1307 USA
//
// Contact: R. Pito Salas
// mailto:pitosalas@users.sourceforge.net
// More information: about BlogBridge
// http://www.blogbridge.com
// http://sourceforge.net/projects/blogbridge
//
// $Id: StringContainsCO.java,v 1.8 2007/03/29 15:14:54 spyromus Exp $
//

package com.salas.bb.domain.query.general;

import com.salas.bb.domain.query.AbstractComparisonOperation;
import com.salas.bb.utils.StringUtils;
import com.salas.bb.utils.i18n.Strings;

import java.util.Map;
import java.util.WeakHashMap;
import java.util.regex.Pattern;

/**
 * Checks if the target value contains one of the space-delimitered words or multi-words
 * enclosed in quotes.
 */
public class StringContainsCO extends AbstractComparisonOperation
{
    /** Instance of this comparison operation. */
    public static final StringContainsCO INSTANCE = new StringContainsCO();

    /**
     * Creates operation.
     */
    public StringContainsCO()
    {
        this(Strings.message("query.operation.contains"), "contains");
    }

    /**
     * Constructor for extensions.
     *
     * @param aName name.
     * @param aDescriptor descriptor.
     */
    protected StringContainsCO(String aName, String aDescriptor)
    {
        super(aName, aDescriptor);
    }

    /**
     * Compares some target value against value for comparison.
     *
     * @param targetValue     target value.
     * @param comparisonValue comparison value.
     *
     * @return TRUE if the target value matches the condition presented by this comparison operation
     *         in conjunction with comparison value.
     */
    public boolean match(String targetValue, String comparisonValue)
    {
        Pattern pattern = preparePattern(comparisonValue);

        return pattern != null && targetValue != null &&
            pattern.matcher(targetValue).find();
    }

    private static final Map<String, Pattern> patterns = new WeakHashMap<String, Pattern>();

    /**
     * Prepares new pattern for matching or takes an old one from the cache.
     *
     * @param comparisonValue comparison value.
     *
     * @return value.
     */
    private static synchronized Pattern preparePattern(String comparisonValue)
    {
        if (comparisonValue == null) return null;

        Pattern pattern = patterns.get(comparisonValue);

        if (pattern == null)
        {
            String[] keys = StringUtils.keywordsToArray(comparisonValue);
            String regex = StringUtils.keywordsToPattern(keys);
            pattern = regex == null ? null : Pattern.compile(regex, Pattern.CASE_INSENSITIVE);

            patterns.put(comparisonValue, pattern);
        }

        return pattern;
    }
}