Tristan Matthews | 0461646 | 2013-11-14 16:09:34 -0500 | [diff] [blame] | 1 | <html> |
| 2 | <head> |
| 3 | <title>pcretest specification</title> |
| 4 | </head> |
| 5 | <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> |
| 6 | <h1>pcretest man page</h1> |
| 7 | <p> |
| 8 | Return to the <a href="index.html">PCRE index page</a>. |
| 9 | </p> |
| 10 | <p> |
| 11 | This page is part of the PCRE HTML documentation. It was generated automatically |
| 12 | from the original man page. If there is any nonsense in it, please consult the |
| 13 | man page, in case the conversion went wrong. |
| 14 | <br> |
| 15 | <ul> |
| 16 | <li><a name="TOC1" href="#SEC1">SYNOPSIS</a> |
| 17 | <li><a name="TOC2" href="#SEC2">COMMAND LINE OPTIONS</a> |
| 18 | <li><a name="TOC3" href="#SEC3">DESCRIPTION</a> |
| 19 | <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a> |
| 20 | <li><a name="TOC5" href="#SEC5">DATA LINES</a> |
| 21 | <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a> |
| 22 | <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a> |
| 23 | <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a> |
| 24 | <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a> |
| 25 | <li><a name="TOC10" href="#SEC10">CALLOUTS</a> |
| 26 | <li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a> |
| 27 | <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a> |
| 28 | <li><a name="TOC13" href="#SEC13">SEE ALSO</a> |
| 29 | <li><a name="TOC14" href="#SEC14">AUTHOR</a> |
| 30 | <li><a name="TOC15" href="#SEC15">REVISION</a> |
| 31 | </ul> |
| 32 | <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br> |
| 33 | <P> |
| 34 | <b>pcretest [options] [input file [output file]]</b> |
| 35 | <br> |
| 36 | <br> |
| 37 | <b>pcretest</b> was written as a test program for the PCRE regular expression |
| 38 | library itself, but it can also be used for experimenting with regular |
| 39 | expressions. This document describes the features of the test program; for |
| 40 | details of the regular expressions themselves, see the |
| 41 | <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| 42 | documentation. For details of the PCRE library function calls and their |
| 43 | options, see the |
| 44 | <a href="pcreapi.html"><b>pcreapi</b></a> |
| 45 | documentation. The input for <b>pcretest</b> is a sequence of regular expression |
| 46 | patterns and strings to be matched, as described below. The output shows the |
| 47 | result of each match. Options on the command line and the patterns control PCRE |
| 48 | options and exactly what is output. |
| 49 | </P> |
| 50 | <br><a name="SEC2" href="#TOC1">COMMAND LINE OPTIONS</a><br> |
| 51 | <P> |
| 52 | <b>-b</b> |
| 53 | Behave as if each pattern has the <b>/B</b> (show byte code) modifier; the |
| 54 | internal form is output after compilation. |
| 55 | </P> |
| 56 | <P> |
| 57 | <b>-C</b> |
| 58 | Output the version number of the PCRE library, and all available information |
| 59 | about the optional features that are included, and then exit. |
| 60 | </P> |
| 61 | <P> |
| 62 | <b>-d</b> |
| 63 | Behave as if each pattern has the <b>/D</b> (debug) modifier; the internal |
| 64 | form and information about the compiled pattern is output after compilation; |
| 65 | <b>-d</b> is equivalent to <b>-b -i</b>. |
| 66 | </P> |
| 67 | <P> |
| 68 | <b>-dfa</b> |
| 69 | Behave as if each data line contains the \D escape sequence; this causes the |
| 70 | alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the |
| 71 | standard <b>pcre_exec()</b> function (more detail is given below). |
| 72 | </P> |
| 73 | <P> |
| 74 | <b>-help</b> |
| 75 | Output a brief summary these options and then exit. |
| 76 | </P> |
| 77 | <P> |
| 78 | <b>-i</b> |
| 79 | Behave as if each pattern has the <b>/I</b> modifier; information about the |
| 80 | compiled pattern is given after compilation. |
| 81 | </P> |
| 82 | <P> |
| 83 | <b>-M</b> |
| 84 | Behave as if each data line contains the \M escape sequence; this causes |
| 85 | PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by |
| 86 | calling <b>pcre_exec()</b> repeatedly with different limits. |
| 87 | </P> |
| 88 | <P> |
| 89 | <b>-m</b> |
| 90 | Output the size of each compiled pattern after it has been compiled. This is |
| 91 | equivalent to adding <b>/M</b> to each regular expression. |
| 92 | </P> |
| 93 | <P> |
| 94 | <b>-o</b> <i>osize</i> |
| 95 | Set the number of elements in the output vector that is used when calling |
| 96 | <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value |
| 97 | is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or |
| 98 | 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be |
| 99 | changed for individual matching calls by including \O in the data line (see |
| 100 | below). |
| 101 | </P> |
| 102 | <P> |
| 103 | <b>-p</b> |
| 104 | Behave as if each pattern has the <b>/P</b> modifier; the POSIX wrapper API is |
| 105 | used to call PCRE. None of the other options has any effect when <b>-p</b> is |
| 106 | set. |
| 107 | </P> |
| 108 | <P> |
| 109 | <b>-q</b> |
| 110 | Do not output the version number of <b>pcretest</b> at the start of execution. |
| 111 | </P> |
| 112 | <P> |
| 113 | <b>-S</b> <i>size</i> |
| 114 | On Unix-like systems, set the size of the run-time stack to <i>size</i> |
| 115 | megabytes. |
| 116 | </P> |
| 117 | <P> |
| 118 | <b>-s</b> or <b>-s+</b> |
| 119 | Behave as if each pattern has the <b>/S</b> modifier; in other words, force each |
| 120 | pattern to be studied. If <b>-s+</b> is used, the PCRE_STUDY_JIT_COMPILE flag is |
| 121 | passed to <b>pcre_study()</b>, causing just-in-time optimization to be set up if |
| 122 | it is available. If the <b>/I</b> or <b>/D</b> option is present on a pattern |
| 123 | (requesting output about the compiled pattern), information about the result of |
| 124 | studying is not included when studying is caused only by <b>-s</b> and neither |
| 125 | <b>-i</b> nor <b>-d</b> is present on the command line. This behaviour means that |
| 126 | the output from tests that are run with and without <b>-s</b> should be |
| 127 | identical, except when options that output information about the actual running |
| 128 | of a match are set. The <b>-M</b>, <b>-t</b>, and <b>-tm</b> options, which give |
| 129 | information about resources used, are likely to produce different output with |
| 130 | and without <b>-s</b>. Output may also differ if the <b>/C</b> option is present |
| 131 | on an individual pattern. This uses callouts to trace the the matching process, |
| 132 | and this may be different between studied and non-studied patterns. If the |
| 133 | pattern contains (*MARK) items there may also be differences, for the same |
| 134 | reason. The <b>-s</b> command line option can be overridden for specific |
| 135 | patterns that should never be studied (see the <b>/S</b> pattern modifier |
| 136 | below). |
| 137 | </P> |
| 138 | <P> |
| 139 | <b>-t</b> |
| 140 | Run each compile, study, and match many times with a timer, and output |
| 141 | resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with |
| 142 | <b>-t</b>, because you will then get the size output a zillion times, and the |
| 143 | timing will be distorted. You can control the number of iterations that are |
| 144 | used for timing by following <b>-t</b> with a number (as a separate item on the |
| 145 | command line). For example, "-t 1000" would iterate 1000 times. The default is |
| 146 | to iterate 500000 times. |
| 147 | </P> |
| 148 | <P> |
| 149 | <b>-tm</b> |
| 150 | This is like <b>-t</b> except that it times only the matching phase, not the |
| 151 | compile or study phases. |
| 152 | </P> |
| 153 | <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br> |
| 154 | <P> |
| 155 | If <b>pcretest</b> is given two filename arguments, it reads from the first and |
| 156 | writes to the second. If it is given only one filename argument, it reads from |
| 157 | that file and writes to stdout. Otherwise, it reads from stdin and writes to |
| 158 | stdout, and prompts for each line of input, using "re>" to prompt for regular |
| 159 | expressions, and "data>" to prompt for data lines. |
| 160 | </P> |
| 161 | <P> |
| 162 | When <b>pcretest</b> is built, a configuration option can specify that it should |
| 163 | be linked with the <b>libreadline</b> library. When this is done, if the input |
| 164 | is from a terminal, it is read using the <b>readline()</b> function. This |
| 165 | provides line-editing and history facilities. The output from the <b>-help</b> |
| 166 | option states whether or not <b>readline()</b> will be used. |
| 167 | </P> |
| 168 | <P> |
| 169 | The program handles any number of sets of input on a single input file. Each |
| 170 | set starts with a regular expression, and continues with any number of data |
| 171 | lines to be matched against the pattern. |
| 172 | </P> |
| 173 | <P> |
| 174 | Each data line is matched separately and independently. If you want to do |
| 175 | multi-line matches, you have to use the \n escape sequence (or \r or \r\n, |
| 176 | etc., depending on the newline setting) in a single line of input to encode the |
| 177 | newline sequences. There is no limit on the length of data lines; the input |
| 178 | buffer is automatically extended if it is too small. |
| 179 | </P> |
| 180 | <P> |
| 181 | An empty line signals the end of the data lines, at which point a new regular |
| 182 | expression is read. The regular expressions are given enclosed in any |
| 183 | non-alphanumeric delimiters other than backslash, for example: |
| 184 | <pre> |
| 185 | /(a|bc)x+yz/ |
| 186 | </pre> |
| 187 | White space before the initial delimiter is ignored. A regular expression may |
| 188 | be continued over several input lines, in which case the newline characters are |
| 189 | included within it. It is possible to include the delimiter within the pattern |
| 190 | by escaping it, for example |
| 191 | <pre> |
| 192 | /abc\/def/ |
| 193 | </pre> |
| 194 | If you do so, the escape and the delimiter form part of the pattern, but since |
| 195 | delimiters are always non-alphanumeric, this does not affect its interpretation. |
| 196 | If the terminating delimiter is immediately followed by a backslash, for |
| 197 | example, |
| 198 | <pre> |
| 199 | /abc/\ |
| 200 | </pre> |
| 201 | then a backslash is added to the end of the pattern. This is done to provide a |
| 202 | way of testing the error condition that arises if a pattern finishes with a |
| 203 | backslash, because |
| 204 | <pre> |
| 205 | /abc\/ |
| 206 | </pre> |
| 207 | is interpreted as the first line of a pattern that starts with "abc/", causing |
| 208 | pcretest to read the next line as a continuation of the regular expression. |
| 209 | </P> |
| 210 | <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br> |
| 211 | <P> |
| 212 | A pattern may be followed by any number of modifiers, which are mostly single |
| 213 | characters. Following Perl usage, these are referred to below as, for example, |
| 214 | "the <b>/i</b> modifier", even though the delimiter of the pattern need not |
| 215 | always be a slash, and no slash is used when writing modifiers. White space may |
| 216 | appear between the final pattern delimiter and the first modifier, and between |
| 217 | the modifiers themselves. |
| 218 | </P> |
| 219 | <P> |
| 220 | The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS, |
| 221 | PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when |
| 222 | <b>pcre_compile()</b> is called. These four modifier letters have the same |
| 223 | effect as they do in Perl. For example: |
| 224 | <pre> |
| 225 | /caseless/i |
| 226 | </pre> |
| 227 | The following table shows additional modifiers for setting PCRE compile-time |
| 228 | options that do not correspond to anything in Perl: |
| 229 | <pre> |
| 230 | <b>/8</b> PCRE_UTF8 |
| 231 | <b>/?</b> PCRE_NO_UTF8_CHECK |
| 232 | <b>/A</b> PCRE_ANCHORED |
| 233 | <b>/C</b> PCRE_AUTO_CALLOUT |
| 234 | <b>/E</b> PCRE_DOLLAR_ENDONLY |
| 235 | <b>/f</b> PCRE_FIRSTLINE |
| 236 | <b>/J</b> PCRE_DUPNAMES |
| 237 | <b>/N</b> PCRE_NO_AUTO_CAPTURE |
| 238 | <b>/U</b> PCRE_UNGREEDY |
| 239 | <b>/W</b> PCRE_UCP |
| 240 | <b>/X</b> PCRE_EXTRA |
| 241 | <b>/Y</b> PCRE_NO_START_OPTIMIZE |
| 242 | <b>/<JS></b> PCRE_JAVASCRIPT_COMPAT |
| 243 | <b>/<cr></b> PCRE_NEWLINE_CR |
| 244 | <b>/<lf></b> PCRE_NEWLINE_LF |
| 245 | <b>/<crlf></b> PCRE_NEWLINE_CRLF |
| 246 | <b>/<anycrlf></b> PCRE_NEWLINE_ANYCRLF |
| 247 | <b>/<any></b> PCRE_NEWLINE_ANY |
| 248 | <b>/<bsr_anycrlf></b> PCRE_BSR_ANYCRLF |
| 249 | <b>/<bsr_unicode></b> PCRE_BSR_UNICODE |
| 250 | </pre> |
| 251 | The modifiers that are enclosed in angle brackets are literal strings as shown, |
| 252 | including the angle brackets, but the letters within can be in either case. |
| 253 | This example sets multiline matching with CRLF as the line ending sequence: |
| 254 | <pre> |
| 255 | /^abc/m<CRLF> |
| 256 | </pre> |
| 257 | As well as turning on the PCRE_UTF8 option, the <b>/8</b> modifier also causes |
| 258 | any non-printing characters in output strings to be printed using the |
| 259 | \x{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE |
| 260 | options are given in the |
| 261 | <a href="pcreapi.html"><b>pcreapi</b></a> |
| 262 | documentation. |
| 263 | </P> |
| 264 | <br><b> |
| 265 | Finding all matches in a string |
| 266 | </b><br> |
| 267 | <P> |
| 268 | Searching for all possible matches within each subject string can be requested |
| 269 | by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called |
| 270 | again to search the remainder of the subject string. The difference between |
| 271 | <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to |
| 272 | <b>pcre_exec()</b> to start searching at a new point within the entire string |
| 273 | (which is in effect what Perl does), whereas the latter passes over a shortened |
| 274 | substring. This makes a difference to the matching process if the pattern |
| 275 | begins with a lookbehind assertion (including \b or \B). |
| 276 | </P> |
| 277 | <P> |
| 278 | If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an |
| 279 | empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and |
| 280 | PCRE_ANCHORED flags set in order to search for another, non-empty, match at the |
| 281 | same point. If this second match fails, the start offset is advanced, and the |
| 282 | normal match is retried. This imitates the way Perl handles such cases when |
| 283 | using the <b>/g</b> modifier or the <b>split()</b> function. Normally, the start |
| 284 | offset is advanced by one character, but if the newline convention recognizes |
| 285 | CRLF as a newline, and the current character is CR followed by LF, an advance |
| 286 | of two is used. |
| 287 | </P> |
| 288 | <br><b> |
| 289 | Other modifiers |
| 290 | </b><br> |
| 291 | <P> |
| 292 | There are yet more modifiers for controlling the way <b>pcretest</b> |
| 293 | operates. |
| 294 | </P> |
| 295 | <P> |
| 296 | The <b>/+</b> modifier requests that as well as outputting the substring that |
| 297 | matched the entire pattern, <b>pcretest</b> should in addition output the |
| 298 | remainder of the subject string. This is useful for tests where the subject |
| 299 | contains multiple copies of the same substring. If the <b>+</b> modifier appears |
| 300 | twice, the same action is taken for captured substrings. In each case the |
| 301 | remainder is output on the following line with a plus character following the |
| 302 | capture number. Note that this modifier must not immediately follow the /S |
| 303 | modifier because /S+ has another meaning. |
| 304 | </P> |
| 305 | <P> |
| 306 | The <b>/=</b> modifier requests that the values of all potential captured |
| 307 | parentheses be output after a match by <b>pcre_exec()</b>. By default, only |
| 308 | those up to the highest one actually used in the match are output |
| 309 | (corresponding to the return code from <b>pcre_exec()</b>). Values in the |
| 310 | offsets vector corresponding to higher numbers should be set to -1, and these |
| 311 | are output as "<unset>". This modifier gives a way of checking that this is |
| 312 | happening. |
| 313 | </P> |
| 314 | <P> |
| 315 | The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b> |
| 316 | output a representation of the compiled byte code after compilation. Normally |
| 317 | this information contains length and offset values; however, if <b>/Z</b> is |
| 318 | also present, this data is replaced by spaces. This is a special feature for |
| 319 | use in the automatic test scripts; it ensures that the same output is generated |
| 320 | for different internal link sizes. |
| 321 | </P> |
| 322 | <P> |
| 323 | The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to |
| 324 | <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers. |
| 325 | </P> |
| 326 | <P> |
| 327 | The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the |
| 328 | fields in the compiled pattern that contain 2-byte and 4-byte numbers. This |
| 329 | facility is for testing the feature in PCRE that allows it to execute patterns |
| 330 | that were compiled on a host with a different endianness. This feature is not |
| 331 | available when the POSIX interface to PCRE is being used, that is, when the |
| 332 | <b>/P</b> pattern modifier is specified. See also the section about saving and |
| 333 | reloading compiled patterns below. |
| 334 | </P> |
| 335 | <P> |
| 336 | The <b>/I</b> modifier requests that <b>pcretest</b> output information about the |
| 337 | compiled pattern (whether it is anchored, has a fixed first character, and |
| 338 | so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a |
| 339 | pattern. If the pattern is studied, the results of that are also output. |
| 340 | </P> |
| 341 | <P> |
| 342 | The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking |
| 343 | control verbs that are returned from calls to <b>pcre_exec()</b>. It causes |
| 344 | <b>pcretest</b> to create a <b>pcre_extra</b> block if one has not already been |
| 345 | created by a call to <b>pcre_study()</b>, and to set the PCRE_EXTRA_MARK flag |
| 346 | and the <b>mark</b> field within it, every time that <b>pcre_exec()</b> is |
| 347 | called. If the variable that the <b>mark</b> field points to is non-NULL for a |
| 348 | match, non-match, or partial match, <b>pcretest</b> prints the string to which |
| 349 | it points. For a match, this is shown on a line by itself, tagged with "MK:". |
| 350 | For a non-match it is added to the message. |
| 351 | </P> |
| 352 | <P> |
| 353 | The <b>/L</b> modifier must be followed directly by the name of a locale, for |
| 354 | example, |
| 355 | <pre> |
| 356 | /pattern/Lfr_FR |
| 357 | </pre> |
| 358 | For this reason, it must be the last modifier. The given locale is set, |
| 359 | <b>pcre_maketables()</b> is called to build a set of character tables for the |
| 360 | locale, and this is then passed to <b>pcre_compile()</b> when compiling the |
| 361 | regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is passed |
| 362 | as the tables pointer; that is, <b>/L</b> applies only to the expression on |
| 363 | which it appears. |
| 364 | </P> |
| 365 | <P> |
| 366 | The <b>/M</b> modifier causes the size of memory block used to hold the compiled |
| 367 | pattern to be output. This does not include the size of the <b>pcre</b> block; |
| 368 | it is just the actual compiled data. If the pattern is successfully studied |
| 369 | with the PCRE_STUDY_JIT_COMPILE option, the size of the JIT compiled code is |
| 370 | also output. |
| 371 | </P> |
| 372 | <P> |
| 373 | If the <b>/S</b> modifier appears once, it causes <b>pcre_study()</b> to be |
| 374 | called after the expression has been compiled, and the results used when the |
| 375 | expression is matched. If <b>/S</b> appears twice, it suppresses studying, even |
| 376 | if it was requested externally by the <b>-s</b> command line option. This makes |
| 377 | it possible to specify that certain patterns are always studied, and others are |
| 378 | never studied, independently of <b>-s</b>. This feature is used in the test |
| 379 | files in a few cases where the output is different when the pattern is studied. |
| 380 | </P> |
| 381 | <P> |
| 382 | If the <b>/S</b> modifier is immediately followed by a + character, the call to |
| 383 | <b>pcre_study()</b> is made with the PCRE_STUDY_JIT_COMPILE option, requesting |
| 384 | just-in-time optimization support if it is available. Note that there is also a |
| 385 | <b>/+</b> modifier; it must not be given immediately after <b>/S</b> because this |
| 386 | will be misinterpreted. If JIT studying is successful, it will automatically be |
| 387 | used when <b>pcre_exec()</b> is run, except when incompatible run-time options |
| 388 | are specified. These include the partial matching options; a complete list is |
| 389 | given in the |
| 390 | <a href="pcrejit.html"><b>pcrejit</b></a> |
| 391 | documentation. See also the <b>\J</b> escape sequence below for a way of |
| 392 | setting the size of the JIT stack. |
| 393 | </P> |
| 394 | <P> |
| 395 | The <b>/T</b> modifier must be followed by a single digit. It causes a specific |
| 396 | set of built-in character tables to be passed to <b>pcre_compile()</b>. It is |
| 397 | used in the standard PCRE tests to check behaviour with different character |
| 398 | tables. The digit specifies the tables as follows: |
| 399 | <pre> |
| 400 | 0 the default ASCII tables, as distributed in |
| 401 | pcre_chartables.c.dist |
| 402 | 1 a set of tables defining ISO 8859 characters |
| 403 | </pre> |
| 404 | In table 1, some characters whose codes are greater than 128 are identified as |
| 405 | letters, digits, spaces, etc. |
| 406 | </P> |
| 407 | <br><b> |
| 408 | Using the POSIX wrapper API |
| 409 | </b><br> |
| 410 | <P> |
| 411 | The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper |
| 412 | API rather than its native API. When <b>/P</b> is set, the following modifiers |
| 413 | set options for the <b>regcomp()</b> function: |
| 414 | <pre> |
| 415 | /i REG_ICASE |
| 416 | /m REG_NEWLINE |
| 417 | /N REG_NOSUB |
| 418 | /s REG_DOTALL ) |
| 419 | /U REG_UNGREEDY ) These options are not part of |
| 420 | /W REG_UCP ) the POSIX standard |
| 421 | /8 REG_UTF8 ) |
| 422 | </pre> |
| 423 | The <b>/+</b> modifier works as described above. All other modifiers are |
| 424 | ignored. |
| 425 | </P> |
| 426 | <br><a name="SEC5" href="#TOC1">DATA LINES</a><br> |
| 427 | <P> |
| 428 | Before each data line is passed to <b>pcre_exec()</b>, leading and trailing |
| 429 | white space is removed, and it is then scanned for \ escapes. Some of these |
| 430 | are pretty esoteric features, intended for checking out some of the more |
| 431 | complicated features of PCRE. If you are just testing "ordinary" regular |
| 432 | expressions, you probably don't need any of these. The following escapes are |
| 433 | recognized: |
| 434 | <pre> |
| 435 | \a alarm (BEL, \x07) |
| 436 | \b backspace (\x08) |
| 437 | \e escape (\x27) |
| 438 | \f form feed (\x0c) |
| 439 | \n newline (\x0a) |
| 440 | \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits) |
| 441 | \r carriage return (\x0d) |
| 442 | \t tab (\x09) |
| 443 | \v vertical tab (\x0b) |
| 444 | \nnn octal character (up to 3 octal digits) |
| 445 | always a byte unless > 255 in UTF-8 mode |
| 446 | \xhh hexadecimal byte (up to 2 hex digits) |
| 447 | \x{hh...} hexadecimal character, any number of digits in UTF-8 mode |
| 448 | \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 449 | \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 450 | \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32) |
| 451 | \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin- |
| 452 | ated by next non alphanumeric character) |
| 453 | \C+ show the current captured substrings at callout time |
| 454 | \C- do not supply a callout function |
| 455 | \C!n return 1 instead of 0 when callout number n is reached |
| 456 | \C!n!m return 1 instead of 0 when callout number n is reached for the nth time |
| 457 | \C*n pass the number n (may be negative) as callout data; this is used as the callout return value |
| 458 | \D use the <b>pcre_dfa_exec()</b> match function |
| 459 | \F only shortest match for <b>pcre_dfa_exec()</b> |
| 460 | \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32) |
| 461 | \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin- |
| 462 | ated by next non-alphanumeric character) |
| 463 | \Jdd set up a JIT stack of dd kilobytes maximum (any number of digits) |
| 464 | \L call pcre_get_substringlist() after a successful match |
| 465 | \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings |
| 466 | \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the |
| 467 | PCRE_NOTEMPTY_ATSTART option |
| 468 | \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits) |
| 469 | \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the |
| 470 | PCRE_PARTIAL_HARD option |
| 471 | \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits) |
| 472 | \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b> |
| 473 | \S output details of memory get/free calls during matching |
| 474 | \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 475 | \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 476 | \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 477 | \>dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i> |
| 478 | argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 479 | \<cr> pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 480 | \<lf> pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 481 | \<crlf> pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 482 | \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 483 | \<any> pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> |
| 484 | </pre> |
| 485 | Note that \xhh always specifies one byte, even in UTF-8 mode; this makes it |
| 486 | possible to construct invalid UTF-8 sequences for testing purposes. On the |
| 487 | other hand, \x{hh} is interpreted as a UTF-8 character in UTF-8 mode, |
| 488 | generating more than one byte if the value is greater than 127. When not in |
| 489 | UTF-8 mode, it generates one byte for values less than 256, and causes an error |
| 490 | for greater values. |
| 491 | </P> |
| 492 | <P> |
| 493 | The escapes that specify line ending sequences are literal strings, exactly as |
| 494 | shown. No more than one newline setting should be present in any data line. |
| 495 | </P> |
| 496 | <P> |
| 497 | A backslash followed by anything else just escapes the anything else. If |
| 498 | the very last character is a backslash, it is ignored. This gives a way of |
| 499 | passing an empty line as data, since a real empty line terminates the data |
| 500 | input. |
| 501 | </P> |
| 502 | <P> |
| 503 | The <b>\J</b> escape provides a way of setting the maximum stack size that is |
| 504 | used by the just-in-time optimization code. It is ignored if JIT optimization |
| 505 | is not being used. Providing a stack that is larger than the default 32K is |
| 506 | necessary only for very complicated patterns. |
| 507 | </P> |
| 508 | <P> |
| 509 | If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with |
| 510 | different values in the <i>match_limit</i> and <i>match_limit_recursion</i> |
| 511 | fields of the <b>pcre_extra</b> data structure, until it finds the minimum |
| 512 | numbers for each parameter that allow <b>pcre_exec()</b> to complete without |
| 513 | error. Because this is testing a specific feature of the normal interpretive |
| 514 | <b>pcre_exec()</b> execution, the use of any JIT optimization that might have |
| 515 | been set up by the <b>/S+</b> qualifier of <b>-s+</b> option is disabled. |
| 516 | </P> |
| 517 | <P> |
| 518 | The <i>match_limit</i> number is a measure of the amount of backtracking |
| 519 | that takes place, and checking it out can be instructive. For most simple |
| 520 | matches, the number is quite small, but for patterns with very large numbers of |
| 521 | matching possibilities, it can become large very quickly with increasing length |
| 522 | of subject string. The <i>match_limit_recursion</i> number is a measure of how |
| 523 | much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is |
| 524 | needed to complete the match attempt. |
| 525 | </P> |
| 526 | <P> |
| 527 | When \O is used, the value specified may be higher or lower than the size set |
| 528 | by the <b>-O</b> command line option (or defaulted to 45); \O applies only to |
| 529 | the call of <b>pcre_exec()</b> for the line in which it appears. |
| 530 | </P> |
| 531 | <P> |
| 532 | If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper |
| 533 | API to be used, the only option-setting sequences that have any effect are \B, |
| 534 | \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively, |
| 535 | to be passed to <b>regexec()</b>. |
| 536 | </P> |
| 537 | <P> |
| 538 | The use of \x{hh...} to represent UTF-8 characters is not dependent on the use |
| 539 | of the <b>/8</b> modifier on the pattern. It is recognized always. There may be |
| 540 | any number of hexadecimal digits inside the braces. The result is from one to |
| 541 | six bytes, encoded according to the original UTF-8 rules of RFC 2279. This |
| 542 | allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are |
| 543 | valid Unicode code points, or indeed valid UTF-8 characters according to the |
| 544 | later rules in RFC 3629. |
| 545 | </P> |
| 546 | <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br> |
| 547 | <P> |
| 548 | By default, <b>pcretest</b> uses the standard PCRE matching function, |
| 549 | <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an |
| 550 | alternative matching function, <b>pcre_dfa_test()</b>, which operates in a |
| 551 | different way, and has some restrictions. The differences between the two |
| 552 | functions are described in the |
| 553 | <a href="pcrematching.html"><b>pcrematching</b></a> |
| 554 | documentation. |
| 555 | </P> |
| 556 | <P> |
| 557 | If a data line contains the \D escape sequence, or if the command line |
| 558 | contains the <b>-dfa</b> option, the alternative matching function is called. |
| 559 | This function finds all possible matches at a given point. If, however, the \F |
| 560 | escape sequence is present in the data line, it stops after the first match is |
| 561 | found. This is always the shortest possible match. |
| 562 | </P> |
| 563 | <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br> |
| 564 | <P> |
| 565 | This section describes the output when the normal matching function, |
| 566 | <b>pcre_exec()</b>, is being used. |
| 567 | </P> |
| 568 | <P> |
| 569 | When a match succeeds, <b>pcretest</b> outputs the list of captured substrings |
| 570 | that <b>pcre_exec()</b> returns, starting with number 0 for the string that |
| 571 | matched the whole pattern. Otherwise, it outputs "No match" when the return is |
| 572 | PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching |
| 573 | substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. (Note that this is |
| 574 | the entire substring that was inspected during the partial match; it may |
| 575 | include characters before the actual match start if a lookbehind assertion, |
| 576 | \K, \b, or \B was involved.) For any other return, <b>pcretest</b> outputs |
| 577 | the PCRE negative error number and a short descriptive phrase. If the error is |
| 578 | a failed UTF-8 string check, the byte offset of the start of the failing |
| 579 | character and the reason code are also output, provided that the size of the |
| 580 | output vector is at least two. Here is an example of an interactive |
| 581 | <b>pcretest</b> run. |
| 582 | <pre> |
| 583 | $ pcretest |
| 584 | PCRE version 8.13 2011-04-30 |
| 585 | |
| 586 | re> /^abc(\d+)/ |
| 587 | data> abc123 |
| 588 | 0: abc123 |
| 589 | 1: 123 |
| 590 | data> xyz |
| 591 | No match |
| 592 | </pre> |
| 593 | Unset capturing substrings that are not followed by one that is set are not |
| 594 | returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In the |
| 595 | following example, there are two capturing substrings, but when the first data |
| 596 | line is matched, the second, unset substring is not shown. An "internal" unset |
| 597 | substring is shown as "<unset>", as for the second data line. |
| 598 | <pre> |
| 599 | re> /(a)|(b)/ |
| 600 | data> a |
| 601 | 0: a |
| 602 | 1: a |
| 603 | data> b |
| 604 | 0: b |
| 605 | 1: <unset> |
| 606 | 2: b |
| 607 | </pre> |
| 608 | If the strings contain any non-printing characters, they are output as \0x |
| 609 | escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the |
| 610 | pattern. See below for the definition of non-printing characters. If the |
| 611 | pattern has the <b>/+</b> modifier, the output for substring 0 is followed by |
| 612 | the the rest of the subject string, identified by "0+" like this: |
| 613 | <pre> |
| 614 | re> /cat/+ |
| 615 | data> cataract |
| 616 | 0: cat |
| 617 | 0+ aract |
| 618 | </pre> |
| 619 | If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive |
| 620 | matching attempts are output in sequence, like this: |
| 621 | <pre> |
| 622 | re> /\Bi(\w\w)/g |
| 623 | data> Mississippi |
| 624 | 0: iss |
| 625 | 1: ss |
| 626 | 0: iss |
| 627 | 1: ss |
| 628 | 0: ipp |
| 629 | 1: pp |
| 630 | </pre> |
| 631 | "No match" is output only if the first match attempt fails. Here is an example |
| 632 | of a failure message (the offset 4 that is specified by \>4 is past the end of |
| 633 | the subject string): |
| 634 | <pre> |
| 635 | re> /xyz/ |
| 636 | data> xyz\>4 |
| 637 | Error -24 (bad offset value) |
| 638 | </PRE> |
| 639 | </P> |
| 640 | <P> |
| 641 | If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a |
| 642 | data line that is successfully matched, the substrings extracted by the |
| 643 | convenience functions are output with C, G, or L after the string number |
| 644 | instead of a colon. This is in addition to the normal full list. The string |
| 645 | length (that is, the return from the extraction function) is given in |
| 646 | parentheses after each string for <b>\C</b> and <b>\G</b>. |
| 647 | </P> |
| 648 | <P> |
| 649 | Note that whereas patterns can be continued over several lines (a plain ">" |
| 650 | prompt is used for continuations), data lines may not. However newlines can be |
| 651 | included in data by means of the \n escape (or \r, \r\n, etc., depending on |
| 652 | the newline sequence setting). |
| 653 | </P> |
| 654 | <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br> |
| 655 | <P> |
| 656 | When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by |
| 657 | means of the \D escape sequence or the <b>-dfa</b> command line option), the |
| 658 | output consists of a list of all the matches that start at the first point in |
| 659 | the subject where there is at least one match. For example: |
| 660 | <pre> |
| 661 | re> /(tang|tangerine|tan)/ |
| 662 | data> yellow tangerine\D |
| 663 | 0: tangerine |
| 664 | 1: tang |
| 665 | 2: tan |
| 666 | </pre> |
| 667 | (Using the normal matching function on this data finds only "tang".) The |
| 668 | longest matching string is always given first (and numbered zero). After a |
| 669 | PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the |
| 670 | partially matching substring. (Note that this is the entire substring that was |
| 671 | inspected during the partial match; it may include characters before the actual |
| 672 | match start if a lookbehind assertion, \K, \b, or \B was involved.) |
| 673 | </P> |
| 674 | <P> |
| 675 | If <b>/g</b> is present on the pattern, the search for further matches resumes |
| 676 | at the end of the longest match. For example: |
| 677 | <pre> |
| 678 | re> /(tang|tangerine|tan)/g |
| 679 | data> yellow tangerine and tangy sultana\D |
| 680 | 0: tangerine |
| 681 | 1: tang |
| 682 | 2: tan |
| 683 | 0: tang |
| 684 | 1: tan |
| 685 | 0: tan |
| 686 | </pre> |
| 687 | Since the matching function does not support substring capture, the escape |
| 688 | sequences that are concerned with captured substrings are not relevant. |
| 689 | </P> |
| 690 | <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br> |
| 691 | <P> |
| 692 | When the alternative matching function has given the PCRE_ERROR_PARTIAL return, |
| 693 | indicating that the subject partially matched the pattern, you can restart the |
| 694 | match with additional subject data by means of the \R escape sequence. For |
| 695 | example: |
| 696 | <pre> |
| 697 | re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ |
| 698 | data> 23ja\P\D |
| 699 | Partial match: 23ja |
| 700 | data> n05\R\D |
| 701 | 0: n05 |
| 702 | </pre> |
| 703 | For further information about partial matching, see the |
| 704 | <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| 705 | documentation. |
| 706 | </P> |
| 707 | <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br> |
| 708 | <P> |
| 709 | If the pattern contains any callout requests, <b>pcretest</b>'s callout function |
| 710 | is called during matching. This works with both matching functions. By default, |
| 711 | the called function displays the callout number, the start and current |
| 712 | positions in the text at the callout time, and the next pattern item to be |
| 713 | tested. For example, the output |
| 714 | <pre> |
| 715 | --->pqrabcdef |
| 716 | 0 ^ ^ \d |
| 717 | </pre> |
| 718 | indicates that callout number 0 occurred for a match attempt starting at the |
| 719 | fourth character of the subject string, when the pointer was at the seventh |
| 720 | character of the data, and when the next pattern item was \d. Just one |
| 721 | circumflex is output if the start and current positions are the same. |
| 722 | </P> |
| 723 | <P> |
| 724 | Callouts numbered 255 are assumed to be automatic callouts, inserted as a |
| 725 | result of the <b>/C</b> pattern modifier. In this case, instead of showing the |
| 726 | callout number, the offset in the pattern, preceded by a plus, is output. For |
| 727 | example: |
| 728 | <pre> |
| 729 | re> /\d?[A-E]\*/C |
| 730 | data> E* |
| 731 | --->E* |
| 732 | +0 ^ \d? |
| 733 | +3 ^ [A-E] |
| 734 | +8 ^^ \* |
| 735 | +10 ^ ^ |
| 736 | 0: E* |
| 737 | </pre> |
| 738 | If a pattern contains (*MARK) items, an additional line is output whenever |
| 739 | a change of latest mark is passed to the callout function. For example: |
| 740 | <pre> |
| 741 | re> /a(*MARK:X)bc/C |
| 742 | data> abc |
| 743 | --->abc |
| 744 | +0 ^ a |
| 745 | +1 ^^ (*MARK:X) |
| 746 | +10 ^^ b |
| 747 | Latest Mark: X |
| 748 | +11 ^ ^ c |
| 749 | +12 ^ ^ |
| 750 | 0: abc |
| 751 | </pre> |
| 752 | The mark changes between matching "a" and "b", but stays the same for the rest |
| 753 | of the match, so nothing more is output. If, as a result of backtracking, the |
| 754 | mark reverts to being unset, the text "<unset>" is output. |
| 755 | </P> |
| 756 | <P> |
| 757 | The callout function in <b>pcretest</b> returns zero (carry on matching) by |
| 758 | default, but you can use a \C item in a data line (as described above) to |
| 759 | change this and other parameters of the callout. |
| 760 | </P> |
| 761 | <P> |
| 762 | Inserting callouts can be helpful when using <b>pcretest</b> to check |
| 763 | complicated regular expressions. For further information about callouts, see |
| 764 | the |
| 765 | <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| 766 | documentation. |
| 767 | </P> |
| 768 | <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br> |
| 769 | <P> |
| 770 | When <b>pcretest</b> is outputting text in the compiled version of a pattern, |
| 771 | bytes other than 32-126 are always treated as non-printing characters are are |
| 772 | therefore shown as hex escapes. |
| 773 | </P> |
| 774 | <P> |
| 775 | When <b>pcretest</b> is outputting text that is a matched part of a subject |
| 776 | string, it behaves in the same way, unless a different locale has been set for |
| 777 | the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b> |
| 778 | function to distinguish printing and non-printing characters. |
| 779 | </P> |
| 780 | <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br> |
| 781 | <P> |
| 782 | The facilities described in this section are not available when the POSIX |
| 783 | interface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is |
| 784 | specified. |
| 785 | </P> |
| 786 | <P> |
| 787 | When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a |
| 788 | compiled pattern to a file, by following the modifiers with > and a file name. |
| 789 | For example: |
| 790 | <pre> |
| 791 | /pattern/im >/some/file |
| 792 | </pre> |
| 793 | See the |
| 794 | <a href="pcreprecompile.html"><b>pcreprecompile</b></a> |
| 795 | documentation for a discussion about saving and re-using compiled patterns. |
| 796 | Note that if the pattern was successfully studied with JIT optimization, the |
| 797 | JIT data cannot be saved. |
| 798 | </P> |
| 799 | <P> |
| 800 | The data that is written is binary. The first eight bytes are the length of the |
| 801 | compiled pattern data followed by the length of the optional study data, each |
| 802 | written as four bytes in big-endian order (most significant byte first). If |
| 803 | there is no study data (either the pattern was not studied, or studying did not |
| 804 | return any data), the second length is zero. The lengths are followed by an |
| 805 | exact copy of the compiled pattern. If there is additional study data, this |
| 806 | (excluding any JIT data) follows immediately after the compiled pattern. After |
| 807 | writing the file, <b>pcretest</b> expects to read a new pattern. |
| 808 | </P> |
| 809 | <P> |
| 810 | A saved pattern can be reloaded into <b>pcretest</b> by specifying < and a file |
| 811 | name instead of a pattern. The name of the file must not contain a < character, |
| 812 | as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by < |
| 813 | characters. |
| 814 | For example: |
| 815 | <pre> |
| 816 | re> </some/file |
| 817 | Compiled pattern loaded from /some/file |
| 818 | No study data |
| 819 | </pre> |
| 820 | If the pattern was previously studied with the JIT optimization, the JIT |
| 821 | information cannot be saved and restored, and so is lost. When the pattern has |
| 822 | been loaded, <b>pcretest</b> proceeds to read data lines in the usual way. |
| 823 | </P> |
| 824 | <P> |
| 825 | You can copy a file written by <b>pcretest</b> to a different host and reload it |
| 826 | there, even if the new host has opposite endianness to the one on which the |
| 827 | pattern was compiled. For example, you can compile on an i86 machine and run on |
| 828 | a SPARC machine. |
| 829 | </P> |
| 830 | <P> |
| 831 | File names for saving and reloading can be absolute or relative, but note that |
| 832 | the shell facility of expanding a file name that starts with a tilde (~) is not |
| 833 | available. |
| 834 | </P> |
| 835 | <P> |
| 836 | The ability to save and reload files in <b>pcretest</b> is intended for testing |
| 837 | and experimentation. It is not intended for production use because only a |
| 838 | single pattern can be written to a file. Furthermore, there is no facility for |
| 839 | supplying custom character tables for use with a reloaded pattern. If the |
| 840 | original pattern was compiled with custom tables, an attempt to match a subject |
| 841 | string using a reloaded pattern is likely to cause <b>pcretest</b> to crash. |
| 842 | Finally, if you attempt to load a file that is not in the correct format, the |
| 843 | result is undefined. |
| 844 | </P> |
| 845 | <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br> |
| 846 | <P> |
| 847 | <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrejit</b>, |
| 848 | <b>pcrematching</b>(3), <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), |
| 849 | <b>pcreprecompile</b>(3). |
| 850 | </P> |
| 851 | <br><a name="SEC14" href="#TOC1">AUTHOR</a><br> |
| 852 | <P> |
| 853 | Philip Hazel |
| 854 | <br> |
| 855 | University Computing Service |
| 856 | <br> |
| 857 | Cambridge CB2 3QH, England. |
| 858 | <br> |
| 859 | </P> |
| 860 | <br><a name="SEC15" href="#TOC1">REVISION</a><br> |
| 861 | <P> |
| 862 | Last updated: 02 December 2011 |
| 863 | <br> |
| 864 | Copyright © 1997-2011 University of Cambridge. |
| 865 | <br> |
| 866 | <p> |
| 867 | Return to the <a href="index.html">PCRE index page</a>. |
| 868 | </p> |