# Contents of /code/trunk/doc/pcretest.1

Thu Aug 9 09:52:43 2007 UTC (6 years, 7 months ago) by ph10
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Update UTF-8 validity check and documentation.


 1 .TH PCRETEST 1 2 .SH NAME 3 pcretest - a program for testing Perl-compatible regular expressions. 4 .SH SYNOPSIS 5 .rs 6 .sp 7 .B pcretest "[options] [source] [destination]" 8 .sp 9 \fBpcretest\fP was written as a test program for the PCRE regular expression 10 library itself, but it can also be used for experimenting with regular 11 expressions. This document describes the features of the test program; for 12 details of the regular expressions themselves, see the 13 .\" HREF 14 \fBpcrepattern\fP 15 .\" 16 documentation. For details of the PCRE library function calls and their 17 options, see the 18 .\" HREF 19 \fBpcreapi\fP 20 .\" 21 documentation. 22 . 23 . 24 .SH OPTIONS 25 .rs 26 .TP 10 27 \fB-b\fP 28 Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal 29 form is output after compilation. 30 .TP 10 31 \fB-C\fP 32 Output the version number of the PCRE library, and all available information 33 about the optional features that are included, and then exit. 34 .TP 10 35 \fB-d\fP 36 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal 37 form and information about the compiled pattern is output after compilation; 38 \fB-d\fP is equivalent to \fB-b -i\fP. 39 .TP 10 40 \fB-dfa\fP 41 Behave as if each data line contains the \eD escape sequence; this causes the 42 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the 43 standard \fBpcre_exec()\fP function (more detail is given below). 44 .TP 10 45 \fB-help\fP 46 Output a brief summary these options and then exit. 47 .TP 10 48 \fB-i\fP 49 Behave as if each regex has the \fB/I\fP modifier; information about the 50 compiled pattern is given after compilation. 51 .TP 10 52 \fB-m\fP 53 Output the size of each compiled pattern after it has been compiled. This is 54 equivalent to adding \fB/M\fP to each regular expression. For compatibility 55 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP. 56 .TP 10 57 \fB-o\fP \fIosize\fP 58 Set the number of elements in the output vector that is used when calling 59 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value 60 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or 61 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be 62 changed for individual matching calls by including \eO in the data line (see 63 below). 64 .TP 10 65 \fB-p\fP 66 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is 67 used to call PCRE. None of the other options has any effect when \fB-p\fP is 68 set. 69 .TP 10 70 \fB-q\fP 71 Do not output the version number of \fBpcretest\fP at the start of execution. 72 .TP 10 73 \fB-S\fP \fIsize\fP 74 On Unix-like systems, set the size of the runtime stack to \fIsize\fP 75 megabytes. 76 .TP 10 77 \fB-t\fP 78 Run each compile, study, and match many times with a timer, and output 79 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with 80 \fB-t\fP, because you will then get the size output a zillion times, and the 81 timing will be distorted. You can control the number of iterations that are 82 used for timing by following \fB-t\fP with a number (as a separate item on the 83 command line). For example, "-t 1000" would iterate 1000 times. The default is 84 to iterate 500000 times. 85 .TP 10 86 \fB-tm\fP 87 This is like \fB-t\fP except that it times only the matching phase, not the 88 compile or study phases. 89 . 90 . 91 .SH DESCRIPTION 92 .rs 93 .sp 94 If \fBpcretest\fP is given two filename arguments, it reads from the first and 95 writes to the second. If it is given only one filename argument, it reads from 96 that file and writes to stdout. Otherwise, it reads from stdin and writes to 97 stdout, and prompts for each line of input, using "re>" to prompt for regular 98 expressions, and "data>" to prompt for data lines. 99 .P 100 The program handles any number of sets of input on a single input file. Each 101 set starts with a regular expression, and continues with any number of data 102 lines to be matched against the pattern. 103 .P 104 Each data line is matched separately and independently. If you want to do 105 multi-line matches, you have to use the \en escape sequence (or \er or \er\en, 106 etc., depending on the newline setting) in a single line of input to encode the 107 newline sequences. There is no limit on the length of data lines; the input 108 buffer is automatically extended if it is too small. 109 .P 110 An empty line signals the end of the data lines, at which point a new regular 111 expression is read. The regular expressions are given enclosed in any 112 non-alphanumeric delimiters other than backslash, for example: 113 .sp 114 /(a|bc)x+yz/ 115 .sp 116 White space before the initial delimiter is ignored. A regular expression may 117 be continued over several input lines, in which case the newline characters are 118 included within it. It is possible to include the delimiter within the pattern 119 by escaping it, for example 120 .sp 121 /abc\e/def/ 122 .sp 123 If you do so, the escape and the delimiter form part of the pattern, but since 124 delimiters are always non-alphanumeric, this does not affect its interpretation. 125 If the terminating delimiter is immediately followed by a backslash, for 126 example, 127 .sp 128 /abc/\e 129 .sp 130 then a backslash is added to the end of the pattern. This is done to provide a 131 way of testing the error condition that arises if a pattern finishes with a 132 backslash, because 133 .sp 134 /abc\e/ 135 .sp 136 is interpreted as the first line of a pattern that starts with "abc/", causing 137 pcretest to read the next line as a continuation of the regular expression. 138 . 139 . 140 .SH "PATTERN MODIFIERS" 141 .rs 142 .sp 143 A pattern may be followed by any number of modifiers, which are mostly single 144 characters. Following Perl usage, these are referred to below as, for example, 145 "the \fB/i\fP modifier", even though the delimiter of the pattern need not 146 always be a slash, and no slash is used when writing modifiers. Whitespace may 147 appear between the final pattern delimiter and the first modifier, and between 148 the modifiers themselves. 149 .P 150 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS, 151 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when 152 \fBpcre_compile()\fP is called. These four modifier letters have the same 153 effect as they do in Perl. For example: 154 .sp 155 /caseless/i 156 .sp 157 The following table shows additional modifiers for setting PCRE options that do 158 not correspond to anything in Perl: 159 .sp 160 \fB/A\fP PCRE_ANCHORED 161 \fB/C\fP PCRE_AUTO_CALLOUT 162 \fB/E\fP PCRE_DOLLAR_ENDONLY 163 \fB/f\fP PCRE_FIRSTLINE 164 \fB/J\fP PCRE_DUPNAMES 165 \fB/N\fP PCRE_NO_AUTO_CAPTURE 166 \fB/U\fP PCRE_UNGREEDY 167 \fB/X\fP PCRE_EXTRA 168 \fB/\fP PCRE_NEWLINE_CR 169 \fB/\fP PCRE_NEWLINE_LF 170 \fB/\fP PCRE_NEWLINE_CRLF 171 \fB/\fP PCRE_NEWLINE_ANYCRLF 172 \fB/\fP PCRE_NEWLINE_ANY 173 .sp 174 Those specifying line ending sequencess are literal strings as shown. This 175 example sets multiline matching with CRLF as the line ending sequence: 176 .sp 177 /^abc/m 178 .sp 179 Details of the meanings of these PCRE options are given in the 180 .\" HREF 181 \fBpcreapi\fP 182 .\" 183 documentation. 184 . 185 . 186 .SS "Finding all matches in a string" 187 .rs 188 .sp 189 Searching for all possible matches within each subject string can be requested 190 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called 191 again to search the remainder of the subject string. The difference between 192 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to 193 \fBpcre_exec()\fP to start searching at a new point within the entire string 194 (which is in effect what Perl does), whereas the latter passes over a shortened 195 substring. This makes a difference to the matching process if the pattern 196 begins with a lookbehind assertion (including \eb or \eB). 197 .P 198 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an 199 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED 200 flags set in order to search for another, non-empty, match at the same point. 201 If this second match fails, the start offset is advanced by one, and the normal 202 match is retried. This imitates the way Perl handles such cases when using the 203 \fB/g\fP modifier or the \fBsplit()\fP function. 204 . 205 . 206 .SS "Other modifiers" 207 .rs 208 .sp 209 There are yet more modifiers for controlling the way \fBpcretest\fP 210 operates. 211 .P 212 The \fB/+\fP modifier requests that as well as outputting the substring that 213 matched the entire pattern, pcretest should in addition output the remainder of 214 the subject string. This is useful for tests where the subject contains 215 multiple copies of the same substring. 216 .P 217 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP 218 output a representation of the compiled byte code after compilation. Normally 219 this information contains length and offset values; however, if \fB/Z\fP is 220 also present, this data is replaced by spaces. This is a special feature for 221 use in the automatic test scripts; it ensures that the same output is generated 222 for different internal link sizes. 223 .P 224 The \fB/L\fP modifier must be followed directly by the name of a locale, for 225 example, 226 .sp 227 /pattern/Lfr_FR 228 .sp 229 For this reason, it must be the last modifier. The given locale is set, 230 \fBpcre_maketables()\fP is called to build a set of character tables for the 231 locale, and this is then passed to \fBpcre_compile()\fP when compiling the 232 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables 233 pointer; that is, \fB/L\fP applies only to the expression on which it appears. 234 .P 235 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the 236 compiled pattern (whether it is anchored, has a fixed first character, and 237 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a 238 pattern. If the pattern is studied, the results of that are also output. 239 .P 240 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to 241 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers. 242 .P 243 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the 244 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This 245 facility is for testing the feature in PCRE that allows it to execute patterns 246 that were compiled on a host with a different endianness. This feature is not 247 available when the POSIX interface to PCRE is being used, that is, when the 248 \fB/P\fP pattern modifier is specified. See also the section about saving and 249 reloading compiled patterns below. 250 .P 251 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the 252 expression has been compiled, and the results used when the expression is 253 matched. 254 .P 255 The \fB/M\fP modifier causes the size of memory block used to hold the compiled 256 pattern to be output. 257 .P 258 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper 259 API rather than its native API. When this is done, all other modifiers except 260 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is 261 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions 262 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. 263 .P 264 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8 265 option set. This turns on support for UTF-8 character handling in PCRE, 266 provided that it was compiled with this support enabled. This modifier also 267 causes any non-printing characters in output strings to be printed using the 268 \ex{hh...} notation if they are valid UTF-8 sequences. 269 .P 270 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to 271 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the 272 checking of the string for UTF-8 validity. 273 . 274 . 275 .SH "DATA LINES" 276 .rs 277 .sp 278 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing 279 whitespace is removed, and it is then scanned for \e escapes. Some of these are 280 pretty esoteric features, intended for checking out some of the more 281 complicated features of PCRE. If you are just testing "ordinary" regular 282 expressions, you probably don't need any of these. The following escapes are 283 recognized: 284 .sp 285 \ea alarm (BEL, \ex07) 286 \eb backspace (\ex08) 287 \ee escape (\ex27) 288 \ef formfeed (\ex0c) 289 \en newline (\ex0a) 290 .\" JOIN 291 \eqdd set the PCRE_MATCH_LIMIT limit to dd 292 (any number of digits) 293 \er carriage return (\ex0d) 294 \et tab (\ex09) 295 \ev vertical tab (\ex0b) 296 \ennn octal character (up to 3 octal digits) 297 \exhh hexadecimal character (up to 2 hex digits) 298 .\" JOIN 299 \ex{hh...} hexadecimal character, any number of digits 300 in UTF-8 mode 301 .\" JOIN 302 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP 303 or \fBpcre_dfa_exec()\fP 304 .\" JOIN 305 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP 306 or \fBpcre_dfa_exec()\fP 307 .\" JOIN 308 \eCdd call pcre_copy_substring() for substring dd 309 after a successful match (number less than 32) 310 .\" JOIN 311 \eCname call pcre_copy_named_substring() for substring 312 "name" after a successful match (name termin- 313 ated by next non alphanumeric character) 314 .\" JOIN 315 \eC+ show the current captured substrings at callout 316 time 317 \eC- do not supply a callout function 318 .\" JOIN 319 \eC!n return 1 instead of 0 when callout number n is 320 reached 321 .\" JOIN 322 \eC!n!m return 1 instead of 0 when callout number n is 323 reached for the nth time 324 .\" JOIN 325 \eC*n pass the number n (may be negative) as callout 326 data; this is used as the callout return value 327 \eD use the \fBpcre_dfa_exec()\fP match function 328 \eF only shortest match for \fBpcre_dfa_exec()\fP 329 .\" JOIN 330 \eGdd call pcre_get_substring() for substring dd 331 after a successful match (number less than 32) 332 .\" JOIN 333 \eGname call pcre_get_named_substring() for substring 334 "name" after a successful match (name termin- 335 ated by next non-alphanumeric character) 336 .\" JOIN 337 \eL call pcre_get_substringlist() after a 338 successful match 339 .\" JOIN 340 \eM discover the minimum MATCH_LIMIT and 341 MATCH_LIMIT_RECURSION settings 342 .\" JOIN 343 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP 344 or \fBpcre_dfa_exec()\fP 345 .\" JOIN 346 \eOdd set the size of the output vector passed to 347 \fBpcre_exec()\fP to dd (any number of digits) 348 .\" JOIN 349 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP 350 or \fBpcre_dfa_exec()\fP 351 .\" JOIN 352 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd 353 (any number of digits) 354 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP 355 \eS output details of memory get/free calls during matching 356 .\" JOIN 357 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP 358 or \fBpcre_dfa_exec()\fP 359 .\" JOIN 360 \e? pass the PCRE_NO_UTF8_CHECK option to 361 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP 362 \e>dd start the match at offset dd (any number of digits); 363 .\" JOIN 364 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP 365 or \fBpcre_dfa_exec()\fP 366 .\" JOIN 367 \e pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP 368 or \fBpcre_dfa_exec()\fP 369 .\" JOIN 370 \e pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP 371 or \fBpcre_dfa_exec()\fP 372 .\" JOIN 373 \e pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP 374 or \fBpcre_dfa_exec()\fP 375 .\" JOIN 376 \e pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP 377 or \fBpcre_dfa_exec()\fP 378 .\" JOIN 379 \e pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP 380 or \fBpcre_dfa_exec()\fP 381 .sp 382 The escapes that specify line ending sequences are literal strings, exactly as 383 shown. No more than one newline setting should be present in any data line. 384 .P 385 A backslash followed by anything else just escapes the anything else. If 386 the very last character is a backslash, it is ignored. This gives a way of 387 passing an empty line as data, since a real empty line terminates the data 388 input. 389 .P 390 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with 391 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP 392 fields of the \fBpcre_extra\fP data structure, until it finds the minimum 393 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The 394 \fImatch_limit\fP number is a measure of the amount of backtracking that takes 395 place, and checking it out can be instructive. For most simple matches, the 396 number is quite small, but for patterns with very large numbers of matching 397 possibilities, it can become large very quickly with increasing length of 398 subject string. The \fImatch_limit_recursion\fP number is a measure of how much 399 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed 400 to complete the match attempt. 401 .P 402 When \eO is used, the value specified may be higher or lower than the size set 403 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to 404 the call of \fBpcre_exec()\fP for the line in which it appears. 405 .P 406 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper 407 API to be used, the only option-setting sequences that have any effect are \eB 408 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to 409 \fBregexec()\fP. 410 .P 411 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use 412 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be 413 any number of hexadecimal digits inside the braces. The result is from one to 414 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This 415 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are 416 valid Unicode code points, or indeed valid UTF-8 characters according to the 417 later rules in RFC 3629. 418 . 419 . 420 .SH "THE ALTERNATIVE MATCHING FUNCTION" 421 .rs 422 .sp 423 By default, \fBpcretest\fP uses the standard PCRE matching function, 424 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an 425 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a 426 different way, and has some restrictions. The differences between the two 427 functions are described in the 428 .\" HREF 429 \fBpcrematching\fP 430 .\" 431 documentation. 432 .P 433 If a data line contains the \eD escape sequence, or if the command line 434 contains the \fB-dfa\fP option, the alternative matching function is called. 435 This function finds all possible matches at a given point. If, however, the \eF 436 escape sequence is present in the data line, it stops after the first match is 437 found. This is always the shortest possible match. 438 . 439 . 440 .SH "DEFAULT OUTPUT FROM PCRETEST" 441 .rs 442 .sp 443 This section describes the output when the normal matching function, 444 \fBpcre_exec()\fP, is being used. 445 .P 446 When a match succeeds, pcretest outputs the list of captured substrings that 447 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched 448 the whole pattern. Otherwise, it outputs "No match" or "Partial match" 449 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, 450 respectively, and otherwise the PCRE negative error number. Here is an example 451 of an interactive \fBpcretest\fP run. 452 .sp 453 $pcretest 454 PCRE version 7.0 30-Nov-2006 455 .sp 456 re> /^abc(\ed+)/ 457 data> abc123 458 0: abc123 459 1: 123 460 data> xyz 461 No match 462 .sp 463 If the strings contain any non-printing characters, they are output as \e0x 464 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the 465 pattern. See below for the definition of non-printing characters. If the 466 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by 467 the the rest of the subject string, identified by "0+" like this: 468 .sp 469 re> /cat/+ 470 data> cataract 471 0: cat 472 0+ aract 473 .sp 474 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive 475 matching attempts are output in sequence, like this: 476 .sp 477 re> /\eBi(\ew\ew)/g 478 data> Mississippi 479 0: iss 480 1: ss 481 0: iss 482 1: ss 483 0: ipp 484 1: pp 485 .sp 486 "No match" is output only if the first match attempt fails. 487 .P 488 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a 489 data line that is successfully matched, the substrings extracted by the 490 convenience functions are output with C, G, or L after the string number 491 instead of a colon. This is in addition to the normal full list. The string 492 length (that is, the return from the extraction function) is given in 493 parentheses after each string for \fB\eC\fP and \fB\eG\fP. 494 .P 495 Note that whereas patterns can be continued over several lines (a plain ">" 496 prompt is used for continuations), data lines may not. However newlines can be 497 included in data by means of the \en escape (or \er, \er\en, etc., depending on 498 the newline sequence setting). 499 . 500 . 501 . 502 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION" 503 .rs 504 .sp 505 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by 506 means of the \eD escape sequence or the \fB-dfa\fP command line option), the 507 output consists of a list of all the matches that start at the first point in 508 the subject where there is at least one match. For example: 509 .sp 510 re> /(tang|tangerine|tan)/ 511 data> yellow tangerine\eD 512 0: tangerine 513 1: tang 514 2: tan 515 .sp 516 (Using the normal matching function on this data finds only "tang".) The 517 longest matching string is always given first (and numbered zero). 518 .P 519 If \fB/g\fP is present on the pattern, the search for further matches resumes 520 at the end of the longest match. For example: 521 .sp 522 re> /(tang|tangerine|tan)/g 523 data> yellow tangerine and tangy sultana\eD 524 0: tangerine 525 1: tang 526 2: tan 527 0: tang 528 1: tan 529 0: tan 530 .sp 531 Since the matching function does not support substring capture, the escape 532 sequences that are concerned with captured substrings are not relevant. 533 . 534 . 535 .SH "RESTARTING AFTER A PARTIAL MATCH" 536 .rs 537 .sp 538 When the alternative matching function has given the PCRE_ERROR_PARTIAL return, 539 indicating that the subject partially matched the pattern, you can restart the 540 match with additional subject data by means of the \eR escape sequence. For 541 example: 542 .sp 543 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/ 544 data> 23ja\eP\eD 545 Partial match: 23ja 546 data> n05\eR\eD 547 0: n05 548 .sp 549 For further information about partial matching, see the 550 .\" HREF 551 \fBpcrepartial\fP 552 .\" 553 documentation. 554 . 555 . 556 .SH CALLOUTS 557 .rs 558 .sp 559 If the pattern contains any callout requests, \fBpcretest\fP's callout function 560 is called during matching. This works with both matching functions. By default, 561 the called function displays the callout number, the start and current 562 positions in the text at the callout time, and the next pattern item to be 563 tested. For example, the output 564 .sp 565 --->pqrabcdef 566 0 ^ ^ \ed 567 .sp 568 indicates that callout number 0 occurred for a match attempt starting at the 569 fourth character of the subject string, when the pointer was at the seventh 570 character of the data, and when the next pattern item was \ed. Just one 571 circumflex is output if the start and current positions are the same. 572 .P 573 Callouts numbered 255 are assumed to be automatic callouts, inserted as a 574 result of the \fB/C\fP pattern modifier. In this case, instead of showing the 575 callout number, the offset in the pattern, preceded by a plus, is output. For 576 example: 577 .sp 578 re> /\ed?[A-E]\e*/C 579 data> E* 580 --->E* 581 +0 ^ \ed? 582 +3 ^ [A-E] 583 +8 ^^ \e* 584 +10 ^ ^ 585 0: E* 586 .sp 587 The callout function in \fBpcretest\fP returns zero (carry on matching) by 588 default, but you can use a \eC item in a data line (as described above) to 589 change this. 590 .P 591 Inserting callouts can be helpful when using \fBpcretest\fP to check 592 complicated regular expressions. For further information about callouts, see 593 the 594 .\" HREF 595 \fBpcrecallout\fP 596 .\" 597 documentation. 598 . 599 . 600 . 601 .SH "NON-PRINTING CHARACTERS" 602 .rs 603 .sp 604 When \fBpcretest\fP is outputting text in the compiled version of a pattern, 605 bytes other than 32-126 are always treated as non-printing characters are are 606 therefore shown as hex escapes. 607 .P 608 When \fBpcretest\fP is outputting text that is a matched part of a subject 609 string, it behaves in the same way, unless a different locale has been set for 610 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP 611 function to distinguish printing and non-printing characters. 612 . 613 . 614 . 615 .SH "SAVING AND RELOADING COMPILED PATTERNS" 616 .rs 617 .sp 618 The facilities described in this section are not available when the POSIX 619 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is 620 specified. 621 .P 622 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a 623 compiled pattern to a file, by following the modifiers with > and a file name. 624 For example: 625 .sp 626 /pattern/im >/some/file 627 .sp 628 See the 629 .\" HREF 630 \fBpcreprecompile\fP 631 .\" 632 documentation for a discussion about saving and re-using compiled patterns. 633 .P 634 The data that is written is binary. The first eight bytes are the length of the 635 compiled pattern data followed by the length of the optional study data, each 636 written as four bytes in big-endian order (most significant byte first). If 637 there is no study data (either the pattern was not studied, or studying did not 638 return any data), the second length is zero. The lengths are followed by an 639 exact copy of the compiled pattern. If there is additional study data, this 640 follows immediately after the compiled pattern. After writing the file, 641 \fBpcretest\fP expects to read a new pattern. 642 .P 643 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file 644 name instead of a pattern. The name of the file must not contain a < character, 645 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by < 646 characters. 647 For example: 648 .sp 649 re>

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