1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu)
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21package proguard.util;
22
23import java.util.List;
24
25/**
26 * This StringParser can create StringMatcher instances for regular expressions.
27 * The regular expressions are either presented as a list, or they are
28 * interpreted as comma-separated lists, optionally prefixed with '!' negators.
29 * If an entry with a negator matches, a negative match is returned, without
30 * considering any subsequent entries in the list. The creation of StringMatcher
31 * instances  for the entries is delegated to the given StringParser.
32 *
33 * @author Eric Lafortune
34 */
35public class ListParser implements StringParser
36{
37    private final StringParser stringParser;
38
39
40    /**
41     * Creates a new ListParser that parses individual elements in the
42     * comma-separated list with the given StringParser.
43     */
44    public ListParser(StringParser stringParser)
45    {
46        this.stringParser = stringParser;
47    }
48
49
50    // Implementations for StringParser.
51
52    public StringMatcher parse(String regularExpression)
53    {
54        // Does the regular expression contain a ',' list separator?
55        return parse(ListUtil.commaSeparatedList(regularExpression));
56    }
57
58
59    /**
60     * Creates a StringMatcher for the given regular expression, which can
61     * be a list of optionally negated simple entries.
62     * <p>
63     * An empty list results in a StringMatcher that matches any string.
64     */
65    public StringMatcher parse(List regularExpressions)
66    {
67        StringMatcher listMatcher = null;
68
69        // Loop over all simple regular expressions, backward, creating a
70        // linked list of matchers.
71        for (int index = regularExpressions.size()-1; index >=0; index--)
72        {
73            String regularExpression = (String)regularExpressions.get(index);
74
75            StringMatcher entryMatcher = parseEntry(regularExpression);
76
77            // Prepend the entry matcher.
78            listMatcher =
79                listMatcher == null ?
80                    (StringMatcher)entryMatcher :
81                isNegated(regularExpression) ?
82                    (StringMatcher)new AndMatcher(entryMatcher, listMatcher) :
83                    (StringMatcher)new OrMatcher(entryMatcher, listMatcher);
84        }
85
86        return listMatcher != null ? listMatcher : new ConstantMatcher(true);
87    }
88
89
90    // Small utility methods.
91
92    /**
93     * Creates a StringMatcher for the given regular expression, which is a
94     * an optionally negated simple expression.
95     */
96    private StringMatcher parseEntry(String regularExpression)
97    {
98        // Wrap the matcher if the regular expression starts with a '!' negator.
99        return isNegated(regularExpression) ?
100          new NotMatcher(stringParser.parse(regularExpression.substring(1))) :
101          stringParser.parse(regularExpression);
102    }
103
104
105    /**
106     * Returns whether the given simple regular expression is negated.
107     */
108    private boolean isNegated(String regularExpression)
109    {
110        return regularExpression.length() > 0 &&
111               regularExpression.charAt(0) == '!';
112    }
113
114
115    /**
116     * A main method for testing name matching.
117     */
118    public static void main(String[] args)
119    {
120        try
121        {
122            System.out.println("Regular expression ["+args[0]+"]");
123            ListParser parser  = new ListParser(new NameParser());
124            StringMatcher  matcher = parser.parse(args[0]);
125            for (int index = 1; index < args.length; index++)
126            {
127                String string = args[index];
128                System.out.print("String             ["+string+"]");
129                System.out.println(" -> match = "+matcher.matches(args[index]));
130            }
131        }
132        catch (Exception ex)
133        {
134            ex.printStackTrace();
135        }
136    }
137}
138