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Java > Open Source Codes > org > apache > commons > net > ftp > parser > RegexFTPFileEntryParserImpl


1 /*
2  * Copyright 2004-2005 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.apache.commons.net.ftp.parser;
18 import org.apache.commons.net.ftp.FTPFileEntryParserImpl;
19 import org.apache.oro.text.regex.MalformedPatternException;
20 import org.apache.oro.text.regex.MatchResult;
21 import org.apache.oro.text.regex.Pattern;
22 import org.apache.oro.text.regex.PatternMatcher;
23 import org.apache.oro.text.regex.Perl5Compiler;
24 import org.apache.oro.text.regex.Perl5Matcher;
25
26
27
28 /**
29  * This abstract class implements both the older FTPFileListParser and
30  * newer FTPFileEntryParser interfaces with default functionality.
31  * All the classes in the parser subpackage inherit from this.
32  *
33  * This is the base for all regular based FTPFileEntryParser
34  *
35  * @author Steve Cohen <scohen@apache.org>
36  */
37 public abstract class RegexFTPFileEntryParserImpl extends FTPFileEntryParserImpl
38 {
39     /**
40      * internal pattern the matcher tries to match, representing a file
41      * entry
42      */
43     private Pattern pattern = null;
44
45     /**
46      * internal match result used by the parser
47      */
48     private MatchResult result = null;
49
50     /**
51      * Internal PatternMatcher object used by the parser. It has protected
52      * scope in case subclasses want to make use of it for their own purposes.
53      */
54     protected PatternMatcher _matcher_ = null;
55
56     /**
57      * The constructor for a RegexFTPFileEntryParserImpl object.
58      *
59      * @param regex The regular expression with which this object is
60      * initialized.
61      *
62      * @exception IllegalArgumentException
63      * Thrown if the regular expression is unparseable. Should not be seen in
64      * normal conditions. It it is seen, this is a sign that a subclass has
65      * been created with a bad regular expression. Since the parser must be
66      * created before use, this means that any bad parser subclasses created
67      * from this will bomb very quickly, leading to easy detection.
68      */
69
70     public RegexFTPFileEntryParserImpl(String JavaDoc regex)
71     {
72         super();
73         try
74         {
75             _matcher_ = new Perl5Matcher();
76             pattern = new Perl5Compiler().compile(regex);
77         }
78         catch (MalformedPatternException e)
79         {
80             throw new IllegalArgumentException JavaDoc (
81                "Unparseable regex supplied: " + regex);
82         }
83     }
84
85     /**
86      * Convenience method delegates to the internal MatchResult's matches()
87      * method.
88      *
89      * @param s the String to be matched
90      * @return true if s matches this object's regular expression.
91      */
92
93     public boolean matches(String JavaDoc s)
94     {
95         this.result = null;
96         if (_matcher_.matches(s.trim(), this.pattern))
97         {
98             this.result = _matcher_.getMatch();
99         }
100         return null != this.result;
101     }
102
103
104
105     /**
106      * Convenience method delegates to the internal MatchResult's groups()
107      * method.
108      *
109      * @return the number of groups() in the internal MatchResult.
110      */
111
112     public int getGroupCnt()
113     {
114         if (this.result == null)
115         {
116             return 0;
117         }
118         return this.result.groups();
119     }
120
121
122
123     /**
124      * Convenience method delegates to the internal MatchResult's group()
125      * method.
126      *
127      * @param matchnum match group number to be retrieved
128      *
129      * @return the content of the <code>matchnum'th<code> group of the internal
130      * match or null if this method is called without a match having
131      * been made.
132      */
133     public String JavaDoc group(int matchnum)
134     {
135         if (this.result == null)
136         {
137             return null;
138         }
139         return this.result.group(matchnum);
140     }
141
142     /**
143      * For debugging purposes - returns a string shows each match group by
144      * number.
145      *
146      * @return a string shows each match group by number.
147      */
148
149     public String JavaDoc getGroupsAsString()
150     {
151         StringBuffer JavaDoc b = new StringBuffer JavaDoc();
152         for (int i = 1; i <= this.result.groups(); i++)
153         {
154             b.append(i).append(") ").append(this.result.group(i))
155                 .append(System.getProperty("line.separator"));
156         }
157         return b.toString();
158     }
159     
160 }
161
162
163
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