jetty-util/src/main/java/org/eclipse/jetty/util/IncludeExclude.java

//
//  ========================================================================
//  Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;

import java.util.HashSet;
import java.util.Set;
import java.util.function.Predicate;


/** Utility class to maintain a set of inclusions and exclusions.
 * <p>Maintains a set of included and excluded elements.  The method {@link #matches(Object)}
 * will return true IFF the passed object is not in the excluded set AND ( either the 
 * included set is empty OR the object is in the included set) 
 * <p>The type of the underlying {@link Set} used may be passed into the 
 * constructor, so special sets like Servlet PathMap may be used.
 * <p>
 * @param <ITEM> The type of element
 */
public class IncludeExclude<ITEM> 
{
    private final Set<ITEM> _includes;
    private final Predicate<ITEM> _includePredicate;
    private final Set<ITEM> _excludes;
    private final Predicate<ITEM> _excludePredicate;
    
    private static class SetContainsPredicate<ITEM> implements Predicate<ITEM>
    {
        private final Set<ITEM> set;
        
        public SetContainsPredicate(Set<ITEM> set)
        {
            this.set = set;
        }
        
        @Override
        public boolean test(ITEM item)
        {
            return set.contains(item);
        }
    }
    
    /**
     * Default constructor over {@link HashSet}
     */
    @SuppressWarnings("unchecked")
    public IncludeExclude()
    {
        this(HashSet.class);
    }
    
    /**
     * Construct an IncludeExclude
     * @param setClass The type of {@link Set} to using internally
     * @param predicate A predicate function to test if a passed ITEM is matched by the passed SET}
     */
    @SuppressWarnings("unchecked")
    public <SET extends Set<ITEM>> IncludeExclude(Class<SET> setClass)
    {
        try
        {
            _includes = setClass.newInstance();
            _excludes = setClass.newInstance();
            
            if(_includes instanceof Predicate) {
                _includePredicate = (Predicate<ITEM>)_includes;
            } else {
                _includePredicate = new SetContainsPredicate<>(_includes);
            }
            
            if(_excludes instanceof Predicate) {
                _excludePredicate = (Predicate<ITEM>)_excludes;
            } else {
                _excludePredicate = new SetContainsPredicate<>(_excludes);
            }
        }
        catch (InstantiationException | IllegalAccessException e)
        {
            throw new RuntimeException(e);
        }
    }
    
    /**
     * Construct an IncludeExclude
     * 
     * @param includeSet the Set of items that represent the included space 
     * @param includePredicate the Predicate for included item testing (null for simple {@link Set#contains(Object)} test)
     * @param excludeSet the Set of items that represent the excluded space
     * @param excludePredicate the Predicate for excluded item testing (null for simple {@link Set#contains(Object)} test)
     */
    public <SET extends Set<ITEM>> IncludeExclude(Set<ITEM> includeSet, Predicate<ITEM> includePredicate, Set<ITEM> excludeSet, Predicate<ITEM> excludePredicate)
    {
        _includes = includeSet;
        _includePredicate = includePredicate;
        _excludes = excludeSet;
        _excludePredicate = excludePredicate;
    }
    
    public void include(ITEM element)
    {
        _includes.add(element);
    }
    
    public void include(@SuppressWarnings("unchecked") ITEM... element)
    {
        for (ITEM e: element)
            _includes.add(e);
    }

    public void exclude(ITEM element)
    {
        _excludes.add(element);
    }
    
    public void exclude(@SuppressWarnings("unchecked") ITEM... element)
    {
        for (ITEM e: element)
            _excludes.add(e);
    }
    
    public boolean matches(ITEM e)
    {
        if (!_includes.isEmpty() && !_includePredicate.test(e))
            return false;
        return !_excludePredicate.test(e);
    }
    
    public int size()
    {
        return _includes.size()+_excludes.size();
    }
    
    public Set<ITEM> getIncluded()
    {
        return _includes;
    }
    
    public Set<ITEM> getExcluded()
    {
        return _excludes;
    }

    public void clear()
    {
        _includes.clear();
        _excludes.clear();
    }

    @Override
    public String toString()
    {
        return String.format("%s@%x{i=%s,ip=%s,e=%s,ep=%s}",this.getClass().getSimpleName(),hashCode(),_includes,_includePredicate,_excludes,_excludePredicate);
    }
}