001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 */
017package org.apache.xbean.finder.filter;
018
019import java.util.ArrayList;
020import java.util.Arrays;
021import java.util.Iterator;
022import java.util.LinkedHashSet;
023import java.util.List;
024import java.util.Set;
025
026/**
027 * @version $Rev$ $Date$
028 */
029public class Filters {
030    private static final Filter NONE = new Filter() {
031        public boolean accept(String name) {
032            return false;
033        }
034    };
035
036    public static Filter packages(String... packages) {
037        List<Filter> filters = new ArrayList<Filter>();
038        for (String s : packages) {
039            filters.add(new PackageFilter(s));
040        }
041
042        return optimize(filters);
043    }
044
045    public static Filter classes(String... classes) {
046        List<Filter> filters = new ArrayList<Filter>();
047        for (String s : classes) {
048            filters.add(new ClassFilter(s));
049        }
050
051        return optimize(filters);
052    }
053
054    public static Filter prefixes(String... prefixes) {
055        List<Filter> filters = new ArrayList<Filter>();
056        for (String s : prefixes) {
057            filters.add(new PrefixFilter(s));
058        }
059
060        return optimize(filters);
061    }
062
063    public static Filter tokens(String... tokens) {
064        List<Filter> filters = new ArrayList<Filter>();
065        for (String s : tokens) {
066            filters.add(new ContainsFilter(s));
067        }
068
069        return optimize(filters);
070    }
071
072    public static Filter suffixes(String... suffixes) {
073        List<Filter> filters = new ArrayList<Filter>();
074        for (String s : suffixes) {
075            filters.add(new SuffixFilter(s));
076        }
077
078        return optimize(filters);
079    }
080
081    public static Filter patterns(String... patterns) {
082        List<Filter> filters = new ArrayList<Filter>();
083        for (String s : patterns) {
084            filters.add(new PatternFilter(s));
085        }
086
087        return optimize(filters);
088    }
089
090
091    public static Filter optimize(Filter... filters) {
092        return optimize(Arrays.asList(filters));
093    }
094
095    public static Filter optimize(List<Filter>... filterss) {
096        Set<Filter> unwrapped = new LinkedHashSet<Filter>();
097
098        for (List<Filter> filters : filterss) {
099            unwrap(filters, unwrapped);
100        }
101
102        if (unwrapped.size() > 1) {
103            Iterator<Filter> iterator = unwrapped.iterator();
104            while (iterator.hasNext()) {
105                Filter filter = iterator.next();
106                if (filter == NONE) iterator.remove();
107            }
108        }
109
110        if (unwrapped.size() == 0) return NONE;
111        if (unwrapped.size() == 1) return unwrapped.iterator().next();
112        return new FilterList(unwrapped);
113    }
114
115    /**
116     * Will invert the meaning of this filter by wrapping it with
117     * a filter that negates the return of the accept method.
118     *
119     * If the passed in filter is already wrapped, it will be
120     * unwrapped and returned.  This is to prevent endless wrapping
121     * if the invert method is called many times.
122     * 
123     * @param filter
124     * @return
125     */
126    public static Filter invert(Filter filter) {
127        if (filter instanceof NegativeFilter) {
128            NegativeFilter negativeFilter = (NegativeFilter) filter;
129            return negativeFilter.getFilter();
130        }
131
132        return new NegativeFilter(filter);
133    }
134
135    private static void unwrap(List<Filter> filters, Set<Filter> unwrapped) {
136        for (Filter filter : filters) {
137            if (filter instanceof FilterList) {
138                FilterList filterList = (FilterList) filter;
139                unwrap(filterList.getFilters(), unwrapped);
140            } else {
141                unwrapped.add(filter);
142            }
143        }
144    }
145
146    private static final class NegativeFilter implements Filter {
147        private final Filter filter;
148
149        public NegativeFilter(Filter filter) {
150            this.filter = filter;
151        }
152
153        public boolean accept(String name) {
154            return !filter.accept(name);
155        }
156
157        public Filter getFilter() {
158            return filter;
159        }
160    }
161
162}