Source Code Cross Referenced for WildcardMatcherHelper.java in  » Content-Management-System » apache-lenya-2.0 » org » apache » cocoon » util » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Content Management System » apache lenya 2.0 » org.apache.cocoon.util 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


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:         */
017:        package org.apache.cocoon.util;
018:
019:        import org.apache.regexp.RE;
020:        import org.apache.regexp.RECompiler;
021:        import org.apache.regexp.REProgram;
022:
023:        import java.util.HashMap;
024:        import java.util.Map;
025:
026:        /**
027:         * This class is an utility class that perform wildcard-patterns matching and isolation.
028:         *
029:         * @version $Id: WildcardMatcherHelper.java 448573 2006-09-21 14:52:23Z anathaniel $
030:         */
031:        public class WildcardMatcherHelper {
032:            //~ Static fields/initializers -----------------------------------------------------------------
033:
034:            /** Default path separator: "/" */
035:            public static final char ESC = '\\';
036:
037:            /** Default path separator: "/" */
038:            public static final char PATHSEP = '/';
039:
040:            /** Default path separator: "/" */
041:            public static final char STAR = '*';
042:
043:            //~ Methods ------------------------------------------------------------------------------------
044:
045:            /**
046:             * Match a pattern agains a string and isolates wildcard replacement into a <code>Map</code>.
047:             * <br>
048:             * Here is how the matching algorithm works:
049:             *
050:             * <ul>
051:             *   <li>
052:             *     The '*' character, meaning that zero or more characters (excluding the path separator '/')
053:             *     are to be matched.
054:             *   </li>
055:             *   <li>
056:             *     The '**' sequence, meaning that zero or more characters (including the path separator '/')
057:             *     are to be matched.
058:             *   </li>
059:             *   <li>
060:             *     The '\*' sequence is honored as a litteral '*' character, not a wildcard
061:             *   </li>
062:             * </ul>
063:             * <br>
064:             * When more than two '*' characters, not separated by another character, are found their value is
065:             * considered as '**' and immediate succeeding '*' are skipped.
066:             * <br>
067:             * The '**' wildcard is greedy and thus the following sample matches as {"foo/bar","baz","bug"}:
068:             * <dl>
069:             *   <dt>pattern</dt>
070:             *   <dd>STAR,STAR,PATHSEP,STAR,PATHSEP,STAR,STAR (why can't I express it litterally?)</dt>
071:             *   <dt>string</dt>
072:             *   <dd>foo/bar/baz/bug</dt>
073:             * </dl>
074:             * The first '**' in the pattern will suck up as much as possible without making the match fail.
075:             * 
076:             * @param pat The pattern string.
077:             * @param str The string to math agains the pattern
078:             *
079:             * @return a <code>Map</code> containing the representation of the extracted pattern. The extracted patterns are
080:             *         keys in the <code>Map</code> from left to right beginning with "1" for te left most, "2" for the next,
081:             *         a.s.o. The key "0" is the string itself. If the return value is null, string does not match to the
082:             *         pattern .
083:             */
084:            public static Map match(final String pat, final String str) {
085:                Matcher matcher;
086:                synchronized (cache) {
087:                    matcher = (Matcher) cache.get(pat);
088:                    if (matcher == null) {
089:                        matcher = new Matcher(pat);
090:                        cache.put(pat, matcher);
091:                    }
092:                }
093:
094:                String[] list = matcher.getMatches(str);
095:                if (list == null)
096:                    return null;
097:
098:                int n = list.length;
099:                Map map = new HashMap(n * 2 + 1);
100:                for (int i = 0; i < n; i++) {
101:                    map.put(String.valueOf(i), list[i]);
102:                }
103:
104:                return map;
105:            }
106:
107:            /** Cache for compiled pattern matchers */
108:            private static final Map cache = new HashMap();
109:
110:            //~ Inner Classes ------------------------------------------------------------------------------
111:
112:            /**
113:             * The private matcher class
114:             */
115:            private static class Matcher {
116:
117:                /** Regexp to split constant parts from front and back leaving wildcards in the middle. */
118:                private static final REProgram splitter;
119:
120:                static {
121:                    final String fixedRE = "([^*\\\\]*)";
122:                    final String wcardRE = "(.*[*\\\\])";
123:                    final String splitRE = "^" + fixedRE + wcardRE + fixedRE
124:                            + "$";
125:                    splitter = new RECompiler().compile(splitRE);
126:                }
127:
128:                /** Wildcard types to short-cut simple '*' and "**' matches. */
129:                private static final int WC_CONST = 0;
130:                private static final int WC_STAR = 1;
131:                private static final int WC_STARSTAR = 2;
132:                private static final int WC_REGEXP = 3;
133:
134:                //~ Instance fields ------------------------------------------------------------------------
135:
136:                // All fields declared final to emphasize requirement to be thread-safe.
137:
138:                /** Fixed text at start of pattern. */
139:                private final String prefix;
140:
141:                /** Fixed text at end of pattern. */
142:                private final String suffix;
143:
144:                /** Length of prefix and suffix. */
145:                private final int fixlen;
146:
147:                /** Wildcard type of pattern. */
148:                private final int wctype;
149:
150:                /** Compiled regexp equivalent to wildcard pattern between prefix and suffix. */
151:                private final REProgram regexp;
152:
153:                //~ Constructors ---------------------------------------------------------------------------
154:
155:                /**
156:                 * Creates a new Matcher object.
157:                 *
158:                 * @param pat The pattern
159:                 * @param str The string
160:                 */
161:                Matcher(final String pat) {
162:                    RE re = new RE(splitter);
163:
164:                    if (re.match(pat)) {
165:
166:                        // Split pattern into (foo/)(*)(/bar).
167:
168:                        prefix = re.getParen(1);
169:                        String wildcard = re.getParen(2);
170:                        String tail = re.getParen(3);
171:
172:                        // If wildcard ends with \ then add the first char of postfix to wildcard.
173:                        if (tail.length() != 0
174:                                && wildcard.charAt(wildcard.length() - 1) == ESC) {
175:                            wildcard = wildcard + tail.substring(0, 1);
176:                            suffix = tail.substring(1);
177:                        } else {
178:                            suffix = tail;
179:                        }
180:
181:                        // Use short-cuts for single * or ** wildcards
182:
183:                        if (wildcard.equals("*")) {
184:                            wctype = WC_STAR;
185:                            regexp = null;
186:                        } else if (wildcard.equals("**")) {
187:                            wctype = WC_STARSTAR;
188:                            regexp = null;
189:                        } else {
190:                            wctype = WC_REGEXP;
191:                            regexp = compileRegexp(wildcard);
192:                        }
193:                    } else {
194:                        // Pattern is a constant without '*' or '\'.
195:                        prefix = pat;
196:                        suffix = "";
197:                        wctype = WC_CONST;
198:                        regexp = null;
199:                    }
200:
201:                    fixlen = prefix.length() + suffix.length();
202:                }
203:
204:                //~ Methods --------------------------------------------------------------------------------
205:
206:                /**
207:                 * Match string against pattern.
208:                 * 
209:                 * @param str The string
210:                 * @return list of wildcard matches, null if match failed
211:                 */
212:                String[] getMatches(final String str) {
213:
214:                    // Protect against 'foo' matching 'foo*foo'.
215:                    if (str.length() < fixlen)
216:                        return null;
217:
218:                    if (!str.startsWith(prefix))
219:                        return null;
220:
221:                    if (!str.endsWith(suffix))
222:                        return null;
223:
224:                    String infix = str.substring(prefix.length(), str.length()
225:                            - suffix.length());
226:
227:                    if (wctype == WC_REGEXP) {
228:                        RE re = new RE(regexp);
229:                        if (!re.match(infix))
230:                            return null;
231:
232:                        int n = re.getParenCount();
233:                        String[] list = new String[n];
234:                        list[0] = str;
235:                        for (int i = 1; i < n; i++)
236:                            list[i] = re.getParen(i);
237:                        return list;
238:                    }
239:
240:                    if (wctype == WC_CONST) {
241:                        if (infix.length() != 0)
242:                            return null;
243:                        return new String[] { str };
244:                    }
245:
246:                    if (wctype == WC_STAR) {
247:                        if (infix.indexOf(PATHSEP) != -1)
248:                            return null;
249:                    }
250:
251:                    return new String[] { str, infix };
252:                }
253:            }
254:
255:            /**
256:             * Compile wildcard pattern into regexp pattern.
257:             * 
258:             * @param pat The wildcard pattern
259:             * @return compiled regexp program.
260:             */
261:            private static REProgram compileRegexp(String pat) {
262:                StringBuffer repat = new StringBuffer(pat.length() * 6);
263:                repat.append('^');
264:
265:                // Add an extra character to allow unchecked wcpat[i+1] accesses.
266:                // Unterminated ESC sequences are silently handled as '\\'.
267:                char[] wcpat = (pat + ESC).toCharArray();
268:                for (int i = 0, n = pat.length(); i < n; i++) {
269:                    char ch = wcpat[i];
270:
271:                    if (ch == STAR) {
272:                        if (wcpat[i + 1] != STAR) {
273:                            repat.append("([^/]*)");
274:                            continue;
275:                        }
276:
277:                        // Handle two and more '*' as single '**'.
278:                        while (wcpat[i + 1] == STAR)
279:                            i++;
280:                        repat.append("(.*)");
281:                        continue;
282:                    }
283:
284:                    // Match ESC+ESC and ESC+STAR as literal ESC and STAR which needs to be escaped
285:                    // in regexp. Match ESC+other as two characters ESC+other where other may also
286:                    // need to be escaped in regexp.
287:                    if (ch == ESC) {
288:                        ch = wcpat[++i];
289:                        if (ch != ESC && ch != STAR)
290:                            repat.append("\\\\");
291:                    }
292:
293:                    if (ch >= 'a' && ch <= 'z' || ch >= 'A' && ch <= 'Z'
294:                            || ch >= '0' && ch <= '9' || ch == '/') {
295:                        repat.append(ch);
296:                        continue;
297:                    }
298:
299:                    repat.append('\\');
300:                    repat.append(ch);
301:                }
302:                repat.append('$');
303:
304:                return new RECompiler().compile(repat.toString());
305:            }
306:        }
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