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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 | +} | |