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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2001, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.misc; | ||
| 27 | import java.io.*; | ||
| 28 | |||
| 29 | /** | ||
| 30 | * A class to represent a pool of regular expressions. A string | ||
| 31 | * can be matched against the whole pool all at once. It is much | ||
| 32 | * faster than doing individual regular expression matches one-by-one. | ||
| 33 | * | ||
| 34 | * @see java.misc.RegexpTarget | ||
| 35 | * @author James Gosling | ||
| 36 | */ | ||
| 37 | |||
| 38 | public class RegexpPool { | ||
| 39 | private RegexpNode prefixMachine = new RegexpNode(); | ||
| 40 | private RegexpNode suffixMachine = new RegexpNode(); | ||
| 41 | private static final int BIG = 0x7FFFFFFF; | ||
| 42 | private int lastDepth = BIG; | ||
| 43 | |||
| 44 | public RegexpPool () { | ||
| 45 | } | ||
| 46 | |||
| 47 | /** | ||
| 48 | * Add a regular expression to the pool of regular expressions. | ||
| 49 | * @param re The regular expression to add to the pool. | ||
| 50 | For now, only handles strings that either begin or end with | ||
| 51 | a '*'. | ||
| 52 | * @param ret The object to be returned when this regular expression is | ||
| 53 | matched. If ret is an instance of the RegexpTarget class, ret.found | ||
| 54 | is called with the string fragment that matched the '*' as its | ||
| 55 | parameter. | ||
| 56 | * @exception REException error | ||
| 57 | */ | ||
| 58 | public void add(String re, Object ret) throws REException { | ||
| 59 | add(re, ret, false); | ||
| 60 | } | ||
| 61 | |||
| 62 | /** | ||
| 63 | * Replace the target for the regular expression with a different | ||
| 64 | * target. | ||
| 65 | * | ||
| 66 | * @param re The regular expression to be replaced in the pool. | ||
| 67 | * For now, only handles strings that either begin or end with | ||
| 68 | * a '*'. | ||
| 69 | * @param ret The object to be returned when this regular expression is | ||
| 70 | * matched. If ret is an instance of the RegexpTarget class, ret.found | ||
| 71 | * is called with the string fragment that matched the '*' as its | ||
| 72 | * parameter. | ||
| 73 | */ | ||
| 74 | public void replace(String re, Object ret) { | ||
| 75 | try { | ||
| 76 | add(re, ret, true); | ||
| 77 | } catch(Exception e) { | ||
| 78 | // should never occur if replace is true | ||
| 79 | } | ||
| 80 | } | ||
| 81 | |||
| 82 | /** | ||
| 83 | * Delete the regular expression and its target. | ||
| 84 | * @param re The regular expression to be deleted from the pool. | ||
| 85 | * must begin or end with a '*' | ||
| 86 | * @return target - the old target. | ||
| 87 | */ | ||
| 88 | public Object delete(String re) { | ||
| 89 | Object o = null; | ||
| 90 | RegexpNode p = prefixMachine; | ||
| 91 | RegexpNode best = p; | ||
| 92 | int len = re.length() - 1; | ||
| 93 | int i; | ||
| 94 | boolean prefix = true; | ||
| 95 | |||
| 96 | if (!re.startsWith("*") || | ||
| 97 | !re.endsWith("*")) | ||
| 98 | len++; | ||
| 99 | |||
| 100 | if (len <= 0) | ||
| 101 | return null; | ||
| 102 | |||
| 103 | /* March forward through the prefix machine */ | ||
| 104 | for (i = 0; p != null; i++) { | ||
| 105 | if (p.result != null && p.depth < BIG | ||
| 106 | && (!p.exact || i == len)) { | ||
| 107 | best = p; | ||
| 108 | } | ||
| 109 | if (i >= len) | ||
| 110 | break; | ||
| 111 | p = p.find(re.charAt(i)); | ||
| 112 | } | ||
| 113 | |||
| 114 | /* march backward through the suffix machine */ | ||
| 115 | p = suffixMachine; | ||
| 116 | for (i = len; --i >= 0 && p != null;) { | ||
| 117 | if (p.result != null && p.depth < BIG) { | ||
| 118 | prefix = false; | ||
| 119 | best = p; | ||
| 120 | } | ||
| 121 | p = p.find(re.charAt(i)); | ||
| 122 | } | ||
| 123 | |||
| 124 | // delete only if there is an exact match | ||
| 125 | if (prefix) { | ||
| 126 | if (re.equals(best.re)) { | ||
| 127 | o = best.result; | ||
| 128 | best.result = null; | ||
| 129 | |||
| 130 | } | ||
| 131 | } else { | ||
| 132 | if (re.equals(best.re)) { | ||
| 133 | o = best.result; | ||
| 134 | best.result = null; | ||
| 135 | } | ||
| 136 | } | ||
| 137 | return o; | ||
| 138 | } | ||
| 139 | |||
| 140 | /** Search for a match to a string & return the object associated | ||
| 141 | with it with the match. When multiple regular expressions | ||
| 142 | would match the string, the best match is returned first. | ||
| 143 | The next best match is returned the next time matchNext is | ||
| 144 | called. | ||
| 145 | @param s The string to match against the regular expressions | ||
| 146 | in the pool. | ||
| 147 | @return null on failure, otherwise the object associated with | ||
| 148 | the regular expression when it was added to the pool. | ||
| 149 | If the object is an instance of RegexpTarget, then | ||
| 150 | the return value is the result from calling | ||
| 151 | return.found(string_that_matched_wildcard). | ||
| 152 | */ | ||
| 153 | public Object match(String s) { | ||
| 154 | return matchAfter(s, BIG); | ||
| 155 | } | ||
| 156 | |||
| 157 | /** Identical to match except that it will only find matches to | ||
| 158 | regular expressions that were added to the pool <i>after</i> | ||
| 159 | the last regular expression that matched in the last call | ||
| 160 | to match() or matchNext() */ | ||
| 161 | public Object matchNext(String s) { | ||
| 162 | return matchAfter(s, lastDepth); | ||
| 163 | } | ||
| 164 | |||
| 165 | private void add(String re, Object ret, boolean replace) throws REException { | ||
| 166 | int len = re.length(); | ||
| 167 | RegexpNode p; | ||
| 168 | if (re.charAt(0) == '*') { | ||
| 169 | p = suffixMachine; | ||
| 170 | while (len > 1) | ||
| 171 | p = p.add(re.charAt(--len)); | ||
| 172 | } else { | ||
| 173 | boolean exact = false; | ||
| 174 | if (re.charAt(len - 1) == '*') | ||
| 175 | len--; | ||
| 176 | else | ||
| 177 | exact = true; | ||
| 178 | p = prefixMachine; | ||
| 179 | for (int i = 0; i < len; i++) | ||
| 180 | p = p.add(re.charAt(i)); | ||
| 181 | p.exact = exact; | ||
| 182 | } | ||
| 183 | |||
| 184 | if (p.result != null && !replace) | ||
| 185 | throw new REException(re + " is a duplicate"); | ||
| 186 | |||
| 187 | p.re = re; | ||
| 188 | p.result = ret; | ||
| 189 | } | ||
| 190 | |||
| 191 | private Object matchAfter(String s, int lastMatchDepth) { | ||
| 192 | RegexpNode p = prefixMachine; | ||
| 193 | RegexpNode best = p; | ||
| 194 | int bst = 0; | ||
| 195 | int bend = 0; | ||
| 196 | int len = s.length(); | ||
| 197 | int i; | ||
| 198 | if (len <= 0) | ||
| 199 | return null; | ||
| 200 | /* March forward through the prefix machine */ | ||
| 201 | for (i = 0; p != null; i++) { | ||
| 202 | if (p.result != null && p.depth < lastMatchDepth | ||
| 203 | && (!p.exact || i == len)) { | ||
| 204 | lastDepth = p.depth; | ||
| 205 | best = p; | ||
| 206 | bst = i; | ||
| 207 | bend = len; | ||
| 208 | } | ||
| 209 | if (i >= len) | ||
| 210 | break; | ||
| 211 | p = p.find(s.charAt(i)); | ||
| 212 | } | ||
| 213 | /* march backward through the suffix machine */ | ||
| 214 | p = suffixMachine; | ||
| 215 | for (i = len; --i >= 0 && p != null;) { | ||
| 216 | if (p.result != null && p.depth < lastMatchDepth) { | ||
| 217 | lastDepth = p.depth; | ||
| 218 | best = p; | ||
| 219 | bst = 0; | ||
| 220 | bend = i+1; | ||
| 221 | } | ||
| 222 | p = p.find(s.charAt(i)); | ||
| 223 | } | ||
| 224 | Object o = best.result; | ||
| 225 | if (o != null && o instanceof RegexpTarget) | ||
| 226 | o = ((RegexpTarget) o).found(s.substring(bst, bend)); | ||
| 227 | return o; | ||
| 228 | } | ||
| 229 | |||
| 230 | /** Resets the pool so that the next call to matchNext looks | ||
| 231 | at all regular expressions in the pool. match(s); is equivalent | ||
| 232 | to reset(); matchNext(s); | ||
| 233 | <p><b>Multithreading note:</b> reset/nextMatch leave state in the | ||
| 234 | regular expression pool. If multiple threads could be using this | ||
| 235 | pool this way, they should be syncronized to avoid race hazards. | ||
| 236 | match() was done in such a way that there are no such race | ||
| 237 | hazards: multiple threads can be matching in the same pool | ||
| 238 | simultaneously. */ | ||
| 239 | public void reset() { | ||
| 240 | lastDepth = BIG; | ||
| 241 | } | ||
| 242 | |||
| 243 | /** Print this pool to standard output */ | ||
| 244 | public void print(PrintStream out) { | ||
| 245 | out.print("Regexp pool:\n"); | ||
| 246 | if (suffixMachine.firstchild != null) { | ||
| 247 | out.print(" Suffix machine: "); | ||
| 248 | suffixMachine.firstchild.print(out); | ||
| 249 | out.print("\n"); | ||
| 250 | } | ||
| 251 | if (prefixMachine.firstchild != null) { | ||
| 252 | out.print(" Prefix machine: "); | ||
| 253 | prefixMachine.firstchild.print(out); | ||
| 254 | out.print("\n"); | ||
| 255 | } | ||
| 256 | } | ||
| 257 | |||
| 258 | } | ||
| 259 | |||
| 260 | /* A node in a regular expression finite state machine. */ | ||
| 261 | class RegexpNode { | ||
| 262 | char c; | ||
| 263 | RegexpNode firstchild; | ||
| 264 | RegexpNode nextsibling; | ||
| 265 | int depth; | ||
| 266 | boolean exact; | ||
| 267 | Object result; | ||
| 268 | String re = null; | ||
| 269 | |||
| 270 | RegexpNode () { | ||
| 271 | c = '#'; | ||
| 272 | depth = 0; | ||
| 273 | } | ||
| 274 | RegexpNode (char C, int depth) { | ||
| 275 | c = C; | ||
| 276 | this.depth = depth; | ||
| 277 | } | ||
| 278 | RegexpNode add(char C) { | ||
| 279 | RegexpNode p = firstchild; | ||
| 280 | if (p == null) | ||
| 281 | p = new RegexpNode (C, depth+1); | ||
| 282 | else { | ||
| 283 | while (p != null) | ||
| 284 | if (p.c == C) | ||
| 285 | return p; | ||
| 286 | else | ||
| 287 | p = p.nextsibling; | ||
| 288 | p = new RegexpNode (C, depth+1); | ||
| 289 | p.nextsibling = firstchild; | ||
| 290 | } | ||
| 291 | firstchild = p; | ||
| 292 | return p; | ||
| 293 | } | ||
| 294 | RegexpNode find(char C) { | ||
| 295 | for (RegexpNode p = firstchild; | ||
| 296 | p != null; | ||
| 297 | p = p.nextsibling) | ||
| 298 | if (p.c == C) | ||
| 299 | return p; | ||
| 300 | return null; | ||
| 301 | } | ||
| 302 | void print(PrintStream out) { | ||
| 303 | if (nextsibling != null) { | ||
| 304 | RegexpNode p = this; | ||
| 305 | out.print("("); | ||
| 306 | while (p != null) { | ||
| 307 | out.write(p.c); | ||
| 308 | if (p.firstchild != null) | ||
| 309 | p.firstchild.print(out); | ||
| 310 | p = p.nextsibling; | ||
| 311 | out.write(p != null ? '|' : ')'); | ||
| 312 | } | ||
| 313 | } else { | ||
| 314 | out.write(c); | ||
| 315 | if (firstchild != null) | ||
| 316 | firstchild.print(out); | ||
| 317 | } | ||
| 318 | } | ||
| 319 | } | ||