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

Change the way PCRE_PARTIAL_HARD handles \z, \Z, \b, \B, and $.   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 Behave as if each data line contains the \eM escape sequence; this causes 54 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by 55 calling \fBpcre_exec()\fP repeatedly with different limits. 56 .TP 10 57 \fB-m\fP 58 Output the size of each compiled pattern after it has been compiled. This is 59 equivalent to adding \fB/M\fP to each regular expression. For compatibility 60 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP. 61 .TP 10 62 \fB-o\fP \fIosize\fP 63 Set the number of elements in the output vector that is used when calling 64 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value 65 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or 66 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be 67 changed for individual matching calls by including \eO in the data line (see 68 below). 69 .TP 10 70 \fB-p\fP 71 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is 72 used to call PCRE. None of the other options has any effect when \fB-p\fP is 73 set. 74 .TP 10 75 \fB-q\fP 76 Do not output the version number of \fBpcretest\fP at the start of execution. 77 .TP 10 78 \fB-S\fP \fIsize\fP 79 On Unix-like systems, set the size of the runtime stack to \fIsize\fP 80 megabytes. 81 .TP 10 82 \fB-t\fP 83 Run each compile, study, and match many times with a timer, and output 84 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with 85 \fB-t\fP, because you will then get the size output a zillion times, and the 86 timing will be distorted. You can control the number of iterations that are 87 used for timing by following \fB-t\fP with a number (as a separate item on the 88 command line). For example, "-t 1000" would iterate 1000 times. The default is 89 to iterate 500000 times. 90 .TP 10 91 \fB-tm\fP 92 This is like \fB-t\fP except that it times only the matching phase, not the 93 compile or study phases. 94 . 95 . 96 .SH DESCRIPTION 97 .rs 98 .sp 99 If \fBpcretest\fP is given two filename arguments, it reads from the first and 100 writes to the second. If it is given only one filename argument, it reads from 101 that file and writes to stdout. Otherwise, it reads from stdin and writes to 102 stdout, and prompts for each line of input, using "re>" to prompt for regular 103 expressions, and "data>" to prompt for data lines. 104 .P 105 When \fBpcretest\fP is built, a configuration option can specify that it should 106 be linked with the \fBlibreadline\fP library. When this is done, if the input 107 is from a terminal, it is read using the \fBreadline()\fP function. This 108 provides line-editing and history facilities. The output from the \fB-help\fP 109 option states whether or not \fBreadline()\fP will be used. 110 .P 111 The program handles any number of sets of input on a single input file. Each 112 set starts with a regular expression, and continues with any number of data 113 lines to be matched against the pattern. 114 .P 115 Each data line is matched separately and independently. If you want to do 116 multi-line matches, you have to use the \en escape sequence (or \er or \er\en, 117 etc., depending on the newline setting) in a single line of input to encode the 118 newline sequences. There is no limit on the length of data lines; the input 119 buffer is automatically extended if it is too small. 120 .P 121 An empty line signals the end of the data lines, at which point a new regular 122 expression is read. The regular expressions are given enclosed in any 123 non-alphanumeric delimiters other than backslash, for example: 124 .sp 125 /(a|bc)x+yz/ 126 .sp 127 White space before the initial delimiter is ignored. A regular expression may 128 be continued over several input lines, in which case the newline characters are 129 included within it. It is possible to include the delimiter within the pattern 130 by escaping it, for example 131 .sp 132 /abc\e/def/ 133 .sp 134 If you do so, the escape and the delimiter form part of the pattern, but since 135 delimiters are always non-alphanumeric, this does not affect its interpretation. 136 If the terminating delimiter is immediately followed by a backslash, for 137 example, 138 .sp 139 /abc/\e 140 .sp 141 then a backslash is added to the end of the pattern. This is done to provide a 142 way of testing the error condition that arises if a pattern finishes with a 143 backslash, because 144 .sp 145 /abc\e/ 146 .sp 147 is interpreted as the first line of a pattern that starts with "abc/", causing 148 pcretest to read the next line as a continuation of the regular expression. 149 . 150 . 151 .SH "PATTERN MODIFIERS" 152 .rs 153 .sp 154 A pattern may be followed by any number of modifiers, which are mostly single 155 characters. Following Perl usage, these are referred to below as, for example, 156 "the \fB/i\fP modifier", even though the delimiter of the pattern need not 157 always be a slash, and no slash is used when writing modifiers. Whitespace may 158 appear between the final pattern delimiter and the first modifier, and between 159 the modifiers themselves. 160 .P 161 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS, 162 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when 163 \fBpcre_compile()\fP is called. These four modifier letters have the same 164 effect as they do in Perl. For example: 165 .sp 166 /caseless/i 167 .sp 168 The following table shows additional modifiers for setting PCRE compile-time 169 options that do not correspond to anything in Perl: 170 .sp 171 \fB/8\fP PCRE_UTF8 172 \fB/?\fP PCRE_NO_UTF8_CHECK 173 \fB/A\fP PCRE_ANCHORED 174 \fB/C\fP PCRE_AUTO_CALLOUT 175 \fB/E\fP PCRE_DOLLAR_ENDONLY 176 \fB/f\fP PCRE_FIRSTLINE 177 \fB/J\fP PCRE_DUPNAMES 178 \fB/N\fP PCRE_NO_AUTO_CAPTURE 179 \fB/U\fP PCRE_UNGREEDY 180 \fB/W\fP PCRE_UCP 181 \fB/X\fP PCRE_EXTRA 182 \fB/\fP PCRE_JAVASCRIPT_COMPAT 183 \fB/\fP PCRE_NEWLINE_CR 184 \fB/\fP PCRE_NEWLINE_LF 185 \fB/\fP PCRE_NEWLINE_CRLF 186 \fB/\fP PCRE_NEWLINE_ANYCRLF 187 \fB/\fP PCRE_NEWLINE_ANY 188 \fB/\fP PCRE_BSR_ANYCRLF 189 \fB/\fP PCRE_BSR_UNICODE 190 .sp 191 The modifiers that are enclosed in angle brackets are literal strings as shown, 192 including the angle brackets, but the letters can be in either case. This 193 example sets multiline matching with CRLF as the line ending sequence: 194 .sp 195 /^abc/m 196 .sp 197 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes 198 any non-printing characters in output strings to be printed using the 199 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE 200 options are given in the 201 .\" HREF 202 \fBpcreapi\fP 203 .\" 204 documentation. 205 . 206 . 207 .SS "Finding all matches in a string" 208 .rs 209 .sp 210 Searching for all possible matches within each subject string can be requested 211 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called 212 again to search the remainder of the subject string. The difference between 213 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to 214 \fBpcre_exec()\fP to start searching at a new point within the entire string 215 (which is in effect what Perl does), whereas the latter passes over a shortened 216 substring. This makes a difference to the matching process if the pattern 217 begins with a lookbehind assertion (including \eb or \eB). 218 .P 219 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an 220 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and 221 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the 222 same point. If this second match fails, the start offset is advanced by one 223 character, and the normal match is retried. This imitates the way Perl handles 224 such cases when using the \fB/g\fP modifier or the \fBsplit()\fP function. 225 . 226 . 227 .SS "Other modifiers" 228 .rs 229 .sp 230 There are yet more modifiers for controlling the way \fBpcretest\fP 231 operates. 232 .P 233 The \fB/+\fP modifier requests that as well as outputting the substring that 234 matched the entire pattern, pcretest should in addition output the remainder of 235 the subject string. This is useful for tests where the subject contains 236 multiple copies of the same substring. 237 .P 238 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP 239 output a representation of the compiled byte code after compilation. Normally 240 this information contains length and offset values; however, if \fB/Z\fP is 241 also present, this data is replaced by spaces. This is a special feature for 242 use in the automatic test scripts; it ensures that the same output is generated 243 for different internal link sizes. 244 .P 245 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to 246 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers. 247 .P 248 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the 249 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This 250 facility is for testing the feature in PCRE that allows it to execute patterns 251 that were compiled on a host with a different endianness. This feature is not 252 available when the POSIX interface to PCRE is being used, that is, when the 253 \fB/P\fP pattern modifier is specified. See also the section about saving and 254 reloading compiled patterns below. 255 .P 256 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the 257 compiled pattern (whether it is anchored, has a fixed first character, and 258 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a 259 pattern. If the pattern is studied, the results of that are also output. 260 .P 261 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking 262 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes 263 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been 264 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag 265 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is 266 called. If the variable that the \fBmark\fP field points to is non-NULL for a 267 match, non-match, or partial match, \fBpcretest\fP prints the string to which 268 it points. For a match, this is shown on a line by itself, tagged with "MK:". 269 For a non-match it is added to the message. 270 .P 271 The \fB/L\fP modifier must be followed directly by the name of a locale, for 272 example, 273 .sp 274 /pattern/Lfr_FR 275 .sp 276 For this reason, it must be the last modifier. The given locale is set, 277 \fBpcre_maketables()\fP is called to build a set of character tables for the 278 locale, and this is then passed to \fBpcre_compile()\fP when compiling the 279 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed 280 as the tables pointer; that is, \fB/L\fP applies only to the expression on 281 which it appears. 282 .P 283 The \fB/M\fP modifier causes the size of memory block used to hold the compiled 284 pattern to be output. 285 .P 286 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the 287 expression has been compiled, and the results used when the expression is 288 matched. 289 .P 290 The \fB/T\fP modifier must be followed by a single digit. It causes a specific 291 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is 292 used in the standard PCRE tests to check behaviour with different character 293 tables. The digit specifies the tables as follows: 294 .sp 295 0 the default ASCII tables, as distributed in 296 pcre_chartables.c.dist 297 1 a set of tables defining ISO 8859 characters 298 .sp 299 In table 1, some characters whose codes are greater than 128 are identified as 300 letters, digits, spaces, etc. 301 . 302 . 303 .SS "Using the POSIX wrapper API" 304 .rs 305 .sp 306 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper 307 API rather than its native API. When \fB/P\fP is set, the following modifiers 308 set options for the \fBregcomp()\fP function: 309 .sp 310 /i REG_ICASE 311 /m REG_NEWLINE 312 /N REG_NOSUB 313 /s REG_DOTALL ) 314 /U REG_UNGREEDY ) These options are not part of 315 /W REG_UCP ) the POSIX standard 316 /8 REG_UTF8 ) 317 .sp 318 The \fB/+\fP modifier works as described above. All other modifiers are 319 ignored. 320 . 321 . 322 .SH "DATA LINES" 323 .rs 324 .sp 325 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing 326 whitespace is removed, and it is then scanned for \e escapes. Some of these are 327 pretty esoteric features, intended for checking out some of the more 328 complicated features of PCRE. If you are just testing "ordinary" regular 329 expressions, you probably don't need any of these. The following escapes are 330 recognized: 331 .sp 332 \ea alarm (BEL, \ex07) 333 \eb backspace (\ex08) 334 \ee escape (\ex27) 335 \ef formfeed (\ex0c) 336 \en newline (\ex0a) 337 .\" JOIN 338 \eqdd set the PCRE_MATCH_LIMIT limit to dd 339 (any number of digits) 340 \er carriage return (\ex0d) 341 \et tab (\ex09) 342 \ev vertical tab (\ex0b) 343 \ennn octal character (up to 3 octal digits) 344 \exhh hexadecimal character (up to 2 hex digits) 345 .\" JOIN 346 \ex{hh...} hexadecimal character, any number of digits 347 in UTF-8 mode 348 .\" JOIN 349 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP 350 or \fBpcre_dfa_exec()\fP 351 .\" JOIN 352 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP 353 or \fBpcre_dfa_exec()\fP 354 .\" JOIN 355 \eCdd call pcre_copy_substring() for substring dd 356 after a successful match (number less than 32) 357 .\" JOIN 358 \eCname call pcre_copy_named_substring() for substring 359 "name" after a successful match (name termin- 360 ated by next non alphanumeric character) 361 .\" JOIN 362 \eC+ show the current captured substrings at callout 363 time 364 \eC- do not supply a callout function 365 .\" JOIN 366 \eC!n return 1 instead of 0 when callout number n is 367 reached 368 .\" JOIN 369 \eC!n!m return 1 instead of 0 when callout number n is 370 reached for the nth time 371 .\" JOIN 372 \eC*n pass the number n (may be negative) as callout 373 data; this is used as the callout return value 374 \eD use the \fBpcre_dfa_exec()\fP match function 375 \eF only shortest match for \fBpcre_dfa_exec()\fP 376 .\" JOIN 377 \eGdd call pcre_get_substring() for substring dd 378 after a successful match (number less than 32) 379 .\" JOIN 380 \eGname call pcre_get_named_substring() for substring 381 "name" after a successful match (name termin- 382 ated by next non-alphanumeric character) 383 .\" JOIN 384 \eL call pcre_get_substringlist() after a 385 successful match 386 .\" JOIN 387 \eM discover the minimum MATCH_LIMIT and 388 MATCH_LIMIT_RECURSION settings 389 .\" JOIN 390 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP 391 or \fBpcre_dfa_exec()\fP; if used twice, pass the 392 PCRE_NOTEMPTY_ATSTART option 393 .\" JOIN 394 \eOdd set the size of the output vector passed to 395 \fBpcre_exec()\fP to dd (any number of digits) 396 .\" JOIN 397 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP 398 or \fBpcre_dfa_exec()\fP; if used twice, pass the 399 PCRE_PARTIAL_HARD option 400 .\" JOIN 401 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd 402 (any number of digits) 403 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP 404 \eS output details of memory get/free calls during matching 405 .\" JOIN 406 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP 407 or \fBpcre_dfa_exec()\fP 408 .\" JOIN 409 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP 410 or \fBpcre_dfa_exec()\fP 411 .\" JOIN 412 \e? pass the PCRE_NO_UTF8_CHECK option to 413 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP 414 \e>dd start the match at offset dd (any number of digits); 415 .\" JOIN 416 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP 417 or \fBpcre_dfa_exec()\fP 418 .\" JOIN 419 \e pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP 420 or \fBpcre_dfa_exec()\fP 421 .\" JOIN 422 \e pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP 423 or \fBpcre_dfa_exec()\fP 424 .\" JOIN 425 \e pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP 426 or \fBpcre_dfa_exec()\fP 427 .\" JOIN 428 \e pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP 429 or \fBpcre_dfa_exec()\fP 430 .\" JOIN 431 \e pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP 432 or \fBpcre_dfa_exec()\fP 433 .sp 434 The escapes that specify line ending sequences are literal strings, exactly as 435 shown. No more than one newline setting should be present in any data line. 436 .P 437 A backslash followed by anything else just escapes the anything else. If 438 the very last character is a backslash, it is ignored. This gives a way of 439 passing an empty line as data, since a real empty line terminates the data 440 input. 441 .P 442 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with 443 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP 444 fields of the \fBpcre_extra\fP data structure, until it finds the minimum 445 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The 446 \fImatch_limit\fP number is a measure of the amount of backtracking that takes 447 place, and checking it out can be instructive. For most simple matches, the 448 number is quite small, but for patterns with very large numbers of matching 449 possibilities, it can become large very quickly with increasing length of 450 subject string. The \fImatch_limit_recursion\fP number is a measure of how much 451 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed 452 to complete the match attempt. 453 .P 454 When \eO is used, the value specified may be higher or lower than the size set 455 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to 456 the call of \fBpcre_exec()\fP for the line in which it appears. 457 .P 458 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper 459 API to be used, the only option-setting sequences that have any effect are \eB, 460 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively, 461 to be passed to \fBregexec()\fP. 462 .P 463 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use 464 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be 465 any number of hexadecimal digits inside the braces. The result is from one to 466 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This 467 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are 468 valid Unicode code points, or indeed valid UTF-8 characters according to the 469 later rules in RFC 3629. 470 . 471 . 472 .SH "THE ALTERNATIVE MATCHING FUNCTION" 473 .rs 474 .sp 475 By default, \fBpcretest\fP uses the standard PCRE matching function, 476 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an 477 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a 478 different way, and has some restrictions. The differences between the two 479 functions are described in the 480 .\" HREF 481 \fBpcrematching\fP 482 .\" 483 documentation. 484 .P 485 If a data line contains the \eD escape sequence, or if the command line 486 contains the \fB-dfa\fP option, the alternative matching function is called. 487 This function finds all possible matches at a given point. If, however, the \eF 488 escape sequence is present in the data line, it stops after the first match is 489 found. This is always the shortest possible match. 490 . 491 . 492 .SH "DEFAULT OUTPUT FROM PCRETEST" 493 .rs 494 .sp 495 This section describes the output when the normal matching function, 496 \fBpcre_exec()\fP, is being used. 497 .P 498 When a match succeeds, pcretest outputs the list of captured substrings that 499 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched 500 the whole pattern. Otherwise, it outputs "No match" when the return is 501 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching 502 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is 503 the entire substring that was inspected during the partial match; it may 504 include characters before the actual match start if a lookbehind assertion, 505 \eK, \eb, or \eB was involved.) For any other returns, it outputs the PCRE 506 negative error number. Here is an example of an interactive \fBpcretest\fP run. 507 .sp 508$ pcretest 509 PCRE version 7.0 30-Nov-2006 510 .sp 511 re> /^abc(\ed+)/ 512 data> abc123 513 0: abc123 514 1: 123 515 data> xyz 516 No match 517 .sp 518 Note that unset capturing substrings that are not followed by one that is set 519 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In 520 the following example, there are two capturing substrings, but when the first 521 data line is matched, the second, unset substring is not shown. An "internal" 522 unset substring is shown as "", as for the second data line. 523 .sp 524 re> /(a)|(b)/ 525 data> a 526 0: a 527 1: a 528 data> b 529 0: b 530 1: 531 2: b 532 .sp 533 If the strings contain any non-printing characters, they are output as \e0x 534 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the 535 pattern. See below for the definition of non-printing characters. If the 536 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by 537 the the rest of the subject string, identified by "0+" like this: 538 .sp 539 re> /cat/+ 540 data> cataract 541 0: cat 542 0+ aract 543 .sp 544 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive 545 matching attempts are output in sequence, like this: 546 .sp 547 re> /\eBi(\ew\ew)/g 548 data> Mississippi 549 0: iss 550 1: ss 551 0: iss 552 1: ss 553 0: ipp 554 1: pp 555 .sp 556 "No match" is output only if the first match attempt fails. 557 .P 558 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a 559 data line that is successfully matched, the substrings extracted by the 560 convenience functions are output with C, G, or L after the string number 561 instead of a colon. This is in addition to the normal full list. The string 562 length (that is, the return from the extraction function) is given in 563 parentheses after each string for \fB\eC\fP and \fB\eG\fP. 564 .P 565 Note that whereas patterns can be continued over several lines (a plain ">" 566 prompt is used for continuations), data lines may not. However newlines can be 567 included in data by means of the \en escape (or \er, \er\en, etc., depending on 568 the newline sequence setting). 569 . 570 . 571 . 572 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION" 573 .rs 574 .sp 575 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by 576 means of the \eD escape sequence or the \fB-dfa\fP command line option), the 577 output consists of a list of all the matches that start at the first point in 578 the subject where there is at least one match. For example: 579 .sp 580 re> /(tang|tangerine|tan)/ 581 data> yellow tangerine\eD 582 0: tangerine 583 1: tang 584 2: tan 585 .sp 586 (Using the normal matching function on this data finds only "tang".) The 587 longest matching string is always given first (and numbered zero). After a 588 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the 589 partially matching substring. (Note that this is the entire substring that was 590 inspected during the partial match; it may include characters before the actual 591 match start if a lookbehind assertion, \eK, \eb, or \eB was involved.) 592 .P 593 If \fB/g\fP is present on the pattern, the search for further matches resumes 594 at the end of the longest match. For example: 595 .sp 596 re> /(tang|tangerine|tan)/g 597 data> yellow tangerine and tangy sultana\eD 598 0: tangerine 599 1: tang 600 2: tan 601 0: tang 602 1: tan 603 0: tan 604 .sp 605 Since the matching function does not support substring capture, the escape 606 sequences that are concerned with captured substrings are not relevant. 607 . 608 . 609 .SH "RESTARTING AFTER A PARTIAL MATCH" 610 .rs 611 .sp 612 When the alternative matching function has given the PCRE_ERROR_PARTIAL return, 613 indicating that the subject partially matched the pattern, you can restart the 614 match with additional subject data by means of the \eR escape sequence. For 615 example: 616 .sp 617 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed\$/ 618 data> 23ja\eP\eD 619 Partial match: 23ja 620 data> n05\eR\eD 621 0: n05 622 .sp 623 For further information about partial matching, see the 624 .\" HREF 625 \fBpcrepartial\fP 626 .\" 627 documentation. 628 . 629 . 630 .SH CALLOUTS 631 .rs 632 .sp 633 If the pattern contains any callout requests, \fBpcretest\fP's callout function 634 is called during matching. This works with both matching functions. By default, 635 the called function displays the callout number, the start and current 636 positions in the text at the callout time, and the next pattern item to be 637 tested. For example, the output 638 .sp 639 --->pqrabcdef 640 0 ^ ^ \ed 641 .sp 642 indicates that callout number 0 occurred for a match attempt starting at the 643 fourth character of the subject string, when the pointer was at the seventh 644 character of the data, and when the next pattern item was \ed. Just one 645 circumflex is output if the start and current positions are the same. 646 .P 647 Callouts numbered 255 are assumed to be automatic callouts, inserted as a 648 result of the \fB/C\fP pattern modifier. In this case, instead of showing the 649 callout number, the offset in the pattern, preceded by a plus, is output. For 650 example: 651 .sp 652 re> /\ed?[A-E]\e*/C 653 data> E* 654 --->E* 655 +0 ^ \ed? 656 +3 ^ [A-E] 657 +8 ^^ \e* 658 +10 ^ ^ 659 0: E* 660 .sp 661 The callout function in \fBpcretest\fP returns zero (carry on matching) by 662 default, but you can use a \eC item in a data line (as described above) to 663 change this. 664 .P 665 Inserting callouts can be helpful when using \fBpcretest\fP to check 666 complicated regular expressions. For further information about callouts, see 667 the 668 .\" HREF 669 \fBpcrecallout\fP 670 .\" 671 documentation. 672 . 673 . 674 . 675 .SH "NON-PRINTING CHARACTERS" 676 .rs 677 .sp 678 When \fBpcretest\fP is outputting text in the compiled version of a pattern, 679 bytes other than 32-126 are always treated as non-printing characters are are 680 therefore shown as hex escapes. 681 .P 682 When \fBpcretest\fP is outputting text that is a matched part of a subject 683 string, it behaves in the same way, unless a different locale has been set for 684 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP 685 function to distinguish printing and non-printing characters. 686 . 687 . 688 . 689 .SH "SAVING AND RELOADING COMPILED PATTERNS" 690 .rs 691 .sp 692 The facilities described in this section are not available when the POSIX 693 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is 694 specified. 695 .P 696 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a 697 compiled pattern to a file, by following the modifiers with > and a file name. 698 For example: 699 .sp 700 /pattern/im >/some/file 701 .sp 702 See the 703 .\" HREF 704 \fBpcreprecompile\fP 705 .\" 706 documentation for a discussion about saving and re-using compiled patterns. 707 .P 708 The data that is written is binary. The first eight bytes are the length of the 709 compiled pattern data followed by the length of the optional study data, each 710 written as four bytes in big-endian order (most significant byte first). If 711 there is no study data (either the pattern was not studied, or studying did not 712 return any data), the second length is zero. The lengths are followed by an 713 exact copy of the compiled pattern. If there is additional study data, this 714 follows immediately after the compiled pattern. After writing the file, 715 \fBpcretest\fP expects to read a new pattern. 716 .P 717 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file 718 name instead of a pattern. The name of the file must not contain a < character, 719 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by < 720 characters. 721 For example: 722 .sp 723 re>