StringParameterFilter.java

/**
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 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 Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * @author Arne Kepp, The Open Planning Project, Copyright 2009
 */
package org.geowebcache.filter.parameters;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import javax.annotation.Nullable;
import javax.annotation.ParametersAreNonnullByDefault;

import com.google.common.base.Preconditions;
import com.thoughtworks.xstream.annotations.XStreamAlias;

@ParametersAreNonnullByDefault
@XStreamAlias("stringParameterFilter")
public class StringParameterFilter extends CaseNormalizingParameterFilter {

    private static final long serialVersionUID = 7383381085250203901L;

    private List<String> values;
    
    public StringParameterFilter() {
        values = new ArrayList<String>(0);
    }

    protected StringParameterFilter readResolve() {
        super.readResolve();
        if (values == null) {
            values = new ArrayList<String>(0);
        }
        for(String value: values) {
            Preconditions.checkNotNull(value, "Value list included a null pointer.");
        }
        return this;
    }

    @Override
    public String apply(@Nullable String str) throws ParameterException {
        if (str == null || str.length() == 0) {
            return getDefaultValue();
        }
        
        str = getNormalize().apply(str);
        
        if(getLegalValues().contains(str)){
            return str;
        }
        
        throw new ParameterException(str + " violates filter for parameter " + getKey());
    }

    /**
     * @return the values the parameter can take.
     */
    @Override
    public List<String> getValues() {
        return Collections.unmodifiableList(values);
    }

    /**
     * Set the values the parameter can take
     */
    public void setValues(List<String> values) {
        Preconditions.checkNotNull(values);
        for(String value: values) {
            Preconditions.checkNotNull(value, "Value list included a null pointer.");
        }
        this.values = new ArrayList<String>(values);
    }
    
    /**
     * Checks whether a given parameter value applies to this filter.
     *
     * @param parameterValue
     *            the value to check if applies to this parameter filter
     * @return {@code true} if {@code parameterValue} is valid according to this filter,
     *         {@code false} otherwise
     */
    @Override
    public boolean applies(@Nullable String parameterValue) {
        return getLegalValues().contains(getNormalize().apply(parameterValue));
    }

    @Override
    public StringParameterFilter clone() {
        StringParameterFilter clone = new StringParameterFilter();
        clone.setDefaultValue(getDefaultValue());
        clone.setKey(getKey());
        if (values != null) {
            clone.values = new ArrayList<String>(values);
        }
        clone.setNormalize(getNormalize().clone());
        return clone;
    }
}