Annotation of embedaddon/pcre/doc/pcretest.txt, revision 1.1
1.1 ! misho 1: PCRETEST(1) PCRETEST(1)
! 2:
! 3:
! 4: NAME
! 5: pcretest - a program for testing Perl-compatible regular expressions.
! 6:
! 7:
! 8: SYNOPSIS
! 9:
! 10: pcretest [options] [input file [output file]]
! 11:
! 12: pcretest was written as a test program for the PCRE regular expression
! 13: library itself, but it can also be used for experimenting with regular
! 14: expressions. This document describes the features of the test program;
! 15: for details of the regular expressions themselves, see the pcrepattern
! 16: documentation. For details of the PCRE library function calls and their
! 17: options, see the pcreapi documentation. The input for pcretest is a
! 18: sequence of regular expression patterns and strings to be matched, as
! 19: described below. The output shows the result of each match. Options on
! 20: the command line and the patterns control PCRE options and exactly what
! 21: is output.
! 22:
! 23:
! 24: COMMAND LINE OPTIONS
! 25:
! 26: -b Behave as if each pattern has the /B (show byte code) modi-
! 27: fier; the internal form is output after compilation.
! 28:
! 29: -C Output the version number of the PCRE library, and all avail-
! 30: able information about the optional features that are
! 31: included, and then exit.
! 32:
! 33: -d Behave as if each pattern has the /D (debug) modifier; the
! 34: internal form and information about the compiled pattern is
! 35: output after compilation; -d is equivalent to -b -i.
! 36:
! 37: -dfa Behave as if each data line contains the \D escape sequence;
! 38: this causes the alternative matching function,
! 39: pcre_dfa_exec(), to be used instead of the standard
! 40: pcre_exec() function (more detail is given below).
! 41:
! 42: -help Output a brief summary these options and then exit.
! 43:
! 44: -i Behave as if each pattern has the /I modifier; information
! 45: about the compiled pattern is given after compilation.
! 46:
! 47: -M Behave as if each data line contains the \M escape sequence;
! 48: this causes PCRE to discover the minimum MATCH_LIMIT and
! 49: MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
! 50: edly with different limits.
! 51:
! 52: -m Output the size of each compiled pattern after it has been
! 53: compiled. This is equivalent to adding /M to each regular
! 54: expression.
! 55:
! 56: -o osize Set the number of elements in the output vector that is used
! 57: when calling pcre_exec() or pcre_dfa_exec() to be osize. The
! 58: default value is 45, which is enough for 14 capturing subex-
! 59: pressions for pcre_exec() or 22 different matches for
! 60: pcre_dfa_exec(). The vector size can be changed for individ-
! 61: ual matching calls by including \O in the data line (see
! 62: below).
! 63:
! 64: -p Behave as if each pattern has the /P modifier; the POSIX
! 65: wrapper API is used to call PCRE. None of the other options
! 66: has any effect when -p is set.
! 67:
! 68: -q Do not output the version number of pcretest at the start of
! 69: execution.
! 70:
! 71: -S size On Unix-like systems, set the size of the run-time stack to
! 72: size megabytes.
! 73:
! 74: -s or -s+ Behave as if each pattern has the /S modifier; in other
! 75: words, force each pattern to be studied. If -s+ is used, the
! 76: PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(), caus-
! 77: ing just-in-time optimization to be set up if it is avail-
! 78: able. If the /I or /D option is present on a pattern
! 79: (requesting output about the compiled pattern), information
! 80: about the result of studying is not included when studying is
! 81: caused only by -s and neither -i nor -d is present on the
! 82: command line. This behaviour means that the output from tests
! 83: that are run with and without -s should be identical, except
! 84: when options that output information about the actual running
! 85: of a match are set. The -M, -t, and -tm options, which give
! 86: information about resources used, are likely to produce dif-
! 87: ferent output with and without -s. Output may also differ if
! 88: the /C option is present on an individual pattern. This uses
! 89: callouts to trace the the matching process, and this may be
! 90: different between studied and non-studied patterns. If the
! 91: pattern contains (*MARK) items there may also be differences,
! 92: for the same reason. The -s command line option can be over-
! 93: ridden for specific patterns that should never be studied
! 94: (see the /S pattern modifier below).
! 95:
! 96: -t Run each compile, study, and match many times with a timer,
! 97: and output resulting time per compile or match (in millisec-
! 98: onds). Do not set -m with -t, because you will then get the
! 99: size output a zillion times, and the timing will be dis-
! 100: torted. You can control the number of iterations that are
! 101: used for timing by following -t with a number (as a separate
! 102: item on the command line). For example, "-t 1000" would iter-
! 103: ate 1000 times. The default is to iterate 500000 times.
! 104:
! 105: -tm This is like -t except that it times only the matching phase,
! 106: not the compile or study phases.
! 107:
! 108:
! 109: DESCRIPTION
! 110:
! 111: If pcretest is given two filename arguments, it reads from the first
! 112: and writes to the second. If it is given only one filename argument, it
! 113: reads from that file and writes to stdout. Otherwise, it reads from
! 114: stdin and writes to stdout, and prompts for each line of input, using
! 115: "re>" to prompt for regular expressions, and "data>" to prompt for data
! 116: lines.
! 117:
! 118: When pcretest is built, a configuration option can specify that it
! 119: should be linked with the libreadline library. When this is done, if
! 120: the input is from a terminal, it is read using the readline() function.
! 121: This provides line-editing and history facilities. The output from the
! 122: -help option states whether or not readline() will be used.
! 123:
! 124: The program handles any number of sets of input on a single input file.
! 125: Each set starts with a regular expression, and continues with any num-
! 126: ber of data lines to be matched against the pattern.
! 127:
! 128: Each data line is matched separately and independently. If you want to
! 129: do multi-line matches, you have to use the \n escape sequence (or \r or
! 130: \r\n, etc., depending on the newline setting) in a single line of input
! 131: to encode the newline sequences. There is no limit on the length of
! 132: data lines; the input buffer is automatically extended if it is too
! 133: small.
! 134:
! 135: An empty line signals the end of the data lines, at which point a new
! 136: regular expression is read. The regular expressions are given enclosed
! 137: in any non-alphanumeric delimiters other than backslash, for example:
! 138:
! 139: /(a|bc)x+yz/
! 140:
! 141: White space before the initial delimiter is ignored. A regular expres-
! 142: sion may be continued over several input lines, in which case the new-
! 143: line characters are included within it. It is possible to include the
! 144: delimiter within the pattern by escaping it, for example
! 145:
! 146: /abc\/def/
! 147:
! 148: If you do so, the escape and the delimiter form part of the pattern,
! 149: but since delimiters are always non-alphanumeric, this does not affect
! 150: its interpretation. If the terminating delimiter is immediately fol-
! 151: lowed by a backslash, for example,
! 152:
! 153: /abc/\
! 154:
! 155: then a backslash is added to the end of the pattern. This is done to
! 156: provide a way of testing the error condition that arises if a pattern
! 157: finishes with a backslash, because
! 158:
! 159: /abc\/
! 160:
! 161: is interpreted as the first line of a pattern that starts with "abc/",
! 162: causing pcretest to read the next line as a continuation of the regular
! 163: expression.
! 164:
! 165:
! 166: PATTERN MODIFIERS
! 167:
! 168: A pattern may be followed by any number of modifiers, which are mostly
! 169: single characters. Following Perl usage, these are referred to below
! 170: as, for example, "the /i modifier", even though the delimiter of the
! 171: pattern need not always be a slash, and no slash is used when writing
! 172: modifiers. White space may appear between the final pattern delimiter
! 173: and the first modifier, and between the modifiers themselves.
! 174:
! 175: The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
! 176: PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
! 177: pile() is called. These four modifier letters have the same effect as
! 178: they do in Perl. For example:
! 179:
! 180: /caseless/i
! 181:
! 182: The following table shows additional modifiers for setting PCRE com-
! 183: pile-time options that do not correspond to anything in Perl:
! 184:
! 185: /8 PCRE_UTF8
! 186: /? PCRE_NO_UTF8_CHECK
! 187: /A PCRE_ANCHORED
! 188: /C PCRE_AUTO_CALLOUT
! 189: /E PCRE_DOLLAR_ENDONLY
! 190: /f PCRE_FIRSTLINE
! 191: /J PCRE_DUPNAMES
! 192: /N PCRE_NO_AUTO_CAPTURE
! 193: /U PCRE_UNGREEDY
! 194: /W PCRE_UCP
! 195: /X PCRE_EXTRA
! 196: /Y PCRE_NO_START_OPTIMIZE
! 197: /<JS> PCRE_JAVASCRIPT_COMPAT
! 198: /<cr> PCRE_NEWLINE_CR
! 199: /<lf> PCRE_NEWLINE_LF
! 200: /<crlf> PCRE_NEWLINE_CRLF
! 201: /<anycrlf> PCRE_NEWLINE_ANYCRLF
! 202: /<any> PCRE_NEWLINE_ANY
! 203: /<bsr_anycrlf> PCRE_BSR_ANYCRLF
! 204: /<bsr_unicode> PCRE_BSR_UNICODE
! 205:
! 206: The modifiers that are enclosed in angle brackets are literal strings
! 207: as shown, including the angle brackets, but the letters within can be
! 208: in either case. This example sets multiline matching with CRLF as the
! 209: line ending sequence:
! 210:
! 211: /^abc/m<CRLF>
! 212:
! 213: As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
! 214: any non-printing characters in output strings to be printed using the
! 215: \x{hh...} notation if they are valid UTF-8 sequences. Full details of
! 216: the PCRE options are given in the pcreapi documentation.
! 217:
! 218: Finding all matches in a string
! 219:
! 220: Searching for all possible matches within each subject string can be
! 221: requested by the /g or /G modifier. After finding a match, PCRE is
! 222: called again to search the remainder of the subject string. The differ-
! 223: ence between /g and /G is that the former uses the startoffset argument
! 224: to pcre_exec() to start searching at a new point within the entire
! 225: string (which is in effect what Perl does), whereas the latter passes
! 226: over a shortened substring. This makes a difference to the matching
! 227: process if the pattern begins with a lookbehind assertion (including \b
! 228: or \B).
! 229:
! 230: If any call to pcre_exec() in a /g or /G sequence matches an empty
! 231: string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
! 232: PCRE_ANCHORED flags set in order to search for another, non-empty,
! 233: match at the same point. If this second match fails, the start offset
! 234: is advanced, and the normal match is retried. This imitates the way
! 235: Perl handles such cases when using the /g modifier or the split() func-
! 236: tion. Normally, the start offset is advanced by one character, but if
! 237: the newline convention recognizes CRLF as a newline, and the current
! 238: character is CR followed by LF, an advance of two is used.
! 239:
! 240: Other modifiers
! 241:
! 242: There are yet more modifiers for controlling the way pcretest operates.
! 243:
! 244: The /+ modifier requests that as well as outputting the substring that
! 245: matched the entire pattern, pcretest should in addition output the
! 246: remainder of the subject string. This is useful for tests where the
! 247: subject contains multiple copies of the same substring. If the + modi-
! 248: fier appears twice, the same action is taken for captured substrings.
! 249: In each case the remainder is output on the following line with a plus
! 250: character following the capture number. Note that this modifier must
! 251: not immediately follow the /S modifier because /S+ has another meaning.
! 252:
! 253: The /= modifier requests that the values of all potential captured
! 254: parentheses be output after a match by pcre_exec(). By default, only
! 255: those up to the highest one actually used in the match are output (cor-
! 256: responding to the return code from pcre_exec()). Values in the offsets
! 257: vector corresponding to higher numbers should be set to -1, and these
! 258: are output as "<unset>". This modifier gives a way of checking that
! 259: this is happening.
! 260:
! 261: The /B modifier is a debugging feature. It requests that pcretest out-
! 262: put a representation of the compiled byte code after compilation. Nor-
! 263: mally this information contains length and offset values; however, if
! 264: /Z is also present, this data is replaced by spaces. This is a special
! 265: feature for use in the automatic test scripts; it ensures that the same
! 266: output is generated for different internal link sizes.
! 267:
! 268: The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
! 269: that is, both the /B and the /I modifiers.
! 270:
! 271: The /F modifier causes pcretest to flip the byte order of the fields in
! 272: the compiled pattern that contain 2-byte and 4-byte numbers. This
! 273: facility is for testing the feature in PCRE that allows it to execute
! 274: patterns that were compiled on a host with a different endianness. This
! 275: feature is not available when the POSIX interface to PCRE is being
! 276: used, that is, when the /P pattern modifier is specified. See also the
! 277: section about saving and reloading compiled patterns below.
! 278:
! 279: The /I modifier requests that pcretest output information about the
! 280: compiled pattern (whether it is anchored, has a fixed first character,
! 281: and so on). It does this by calling pcre_fullinfo() after compiling a
! 282: pattern. If the pattern is studied, the results of that are also out-
! 283: put.
! 284:
! 285: The /K modifier requests pcretest to show names from backtracking con-
! 286: trol verbs that are returned from calls to pcre_exec(). It causes
! 287: pcretest to create a pcre_extra block if one has not already been cre-
! 288: ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
! 289: the mark field within it, every time that pcre_exec() is called. If the
! 290: variable that the mark field points to is non-NULL for a match, non-
! 291: match, or partial match, pcretest prints the string to which it points.
! 292: For a match, this is shown on a line by itself, tagged with "MK:". For
! 293: a non-match it is added to the message.
! 294:
! 295: The /L modifier must be followed directly by the name of a locale, for
! 296: example,
! 297:
! 298: /pattern/Lfr_FR
! 299:
! 300: For this reason, it must be the last modifier. The given locale is set,
! 301: pcre_maketables() is called to build a set of character tables for the
! 302: locale, and this is then passed to pcre_compile() when compiling the
! 303: regular expression. Without an /L (or /T) modifier, NULL is passed as
! 304: the tables pointer; that is, /L applies only to the expression on which
! 305: it appears.
! 306:
! 307: The /M modifier causes the size of memory block used to hold the com-
! 308: piled pattern to be output. This does not include the size of the pcre
! 309: block; it is just the actual compiled data. If the pattern is success-
! 310: fully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
! 311: JIT compiled code is also output.
! 312:
! 313: If the /S modifier appears once, it causes pcre_study() to be called
! 314: after the expression has been compiled, and the results used when the
! 315: expression is matched. If /S appears twice, it suppresses studying,
! 316: even if it was requested externally by the -s command line option. This
! 317: makes it possible to specify that certain patterns are always studied,
! 318: and others are never studied, independently of -s. This feature is used
! 319: in the test files in a few cases where the output is different when the
! 320: pattern is studied.
! 321:
! 322: If the /S modifier is immediately followed by a + character, the call
! 323: to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option,
! 324: requesting just-in-time optimization support if it is available. Note
! 325: that there is also a /+ modifier; it must not be given immediately
! 326: after /S because this will be misinterpreted. If JIT studying is suc-
! 327: cessful, it will automatically be used when pcre_exec() is run, except
! 328: when incompatible run-time options are specified. These include the
! 329: partial matching options; a complete list is given in the pcrejit docu-
! 330: mentation. See also the \J escape sequence below for a way of setting
! 331: the size of the JIT stack.
! 332:
! 333: The /T modifier must be followed by a single digit. It causes a spe-
! 334: cific set of built-in character tables to be passed to pcre_compile().
! 335: It is used in the standard PCRE tests to check behaviour with different
! 336: character tables. The digit specifies the tables as follows:
! 337:
! 338: 0 the default ASCII tables, as distributed in
! 339: pcre_chartables.c.dist
! 340: 1 a set of tables defining ISO 8859 characters
! 341:
! 342: In table 1, some characters whose codes are greater than 128 are iden-
! 343: tified as letters, digits, spaces, etc.
! 344:
! 345: Using the POSIX wrapper API
! 346:
! 347: The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
! 348: rather than its native API. When /P is set, the following modifiers set
! 349: options for the regcomp() function:
! 350:
! 351: /i REG_ICASE
! 352: /m REG_NEWLINE
! 353: /N REG_NOSUB
! 354: /s REG_DOTALL )
! 355: /U REG_UNGREEDY ) These options are not part of
! 356: /W REG_UCP ) the POSIX standard
! 357: /8 REG_UTF8 )
! 358:
! 359: The /+ modifier works as described above. All other modifiers are
! 360: ignored.
! 361:
! 362:
! 363: DATA LINES
! 364:
! 365: Before each data line is passed to pcre_exec(), leading and trailing
! 366: white space is removed, and it is then scanned for \ escapes. Some of
! 367: these are pretty esoteric features, intended for checking out some of
! 368: the more complicated features of PCRE. If you are just testing "ordi-
! 369: nary" regular expressions, you probably don't need any of these. The
! 370: following escapes are recognized:
! 371:
! 372: \a alarm (BEL, \x07)
! 373: \b backspace (\x08)
! 374: \e escape (\x27)
! 375: \f form feed (\x0c)
! 376: \n newline (\x0a)
! 377: \qdd set the PCRE_MATCH_LIMIT limit to dd
! 378: (any number of digits)
! 379: \r carriage return (\x0d)
! 380: \t tab (\x09)
! 381: \v vertical tab (\x0b)
! 382: \nnn octal character (up to 3 octal digits)
! 383: always a byte unless > 255 in UTF-8 mode
! 384: \xhh hexadecimal byte (up to 2 hex digits)
! 385: \x{hh...} hexadecimal character, any number of digits
! 386: in UTF-8 mode
! 387: \A pass the PCRE_ANCHORED option to pcre_exec()
! 388: or pcre_dfa_exec()
! 389: \B pass the PCRE_NOTBOL option to pcre_exec()
! 390: or pcre_dfa_exec()
! 391: \Cdd call pcre_copy_substring() for substring dd
! 392: after a successful match (number less than 32)
! 393: \Cname call pcre_copy_named_substring() for substring
! 394: "name" after a successful match (name termin-
! 395: ated by next non alphanumeric character)
! 396: \C+ show the current captured substrings at callout
! 397: time
! 398: \C- do not supply a callout function
! 399: \C!n return 1 instead of 0 when callout number n is
! 400: reached
! 401: \C!n!m return 1 instead of 0 when callout number n is
! 402: reached for the nth time
! 403: \C*n pass the number n (may be negative) as callout
! 404: data; this is used as the callout return value
! 405: \D use the pcre_dfa_exec() match function
! 406: \F only shortest match for pcre_dfa_exec()
! 407: \Gdd call pcre_get_substring() for substring dd
! 408: after a successful match (number less than 32)
! 409: \Gname call pcre_get_named_substring() for substring
! 410: "name" after a successful match (name termin-
! 411: ated by next non-alphanumeric character)
! 412: \Jdd set up a JIT stack of dd kilobytes maximum (any
! 413: number of digits)
! 414: \L call pcre_get_substringlist() after a
! 415: successful match
! 416: \M discover the minimum MATCH_LIMIT and
! 417: MATCH_LIMIT_RECURSION settings
! 418: \N pass the PCRE_NOTEMPTY option to pcre_exec()
! 419: or pcre_dfa_exec(); if used twice, pass the
! 420: PCRE_NOTEMPTY_ATSTART option
! 421: \Odd set the size of the output vector passed to
! 422: pcre_exec() to dd (any number of digits)
! 423: \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
! 424: or pcre_dfa_exec(); if used twice, pass the
! 425: PCRE_PARTIAL_HARD option
! 426: \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
! 427: (any number of digits)
! 428: \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
! 429: \S output details of memory get/free calls during matching
! 430: \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
! 431: or pcre_dfa_exec()
! 432: \Z pass the PCRE_NOTEOL option to pcre_exec()
! 433: or pcre_dfa_exec()
! 434: \? pass the PCRE_NO_UTF8_CHECK option to
! 435: pcre_exec() or pcre_dfa_exec()
! 436: \>dd start the match at offset dd (optional "-"; then
! 437: any number of digits); this sets the startoffset
! 438: argument for pcre_exec() or pcre_dfa_exec()
! 439: \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
! 440: or pcre_dfa_exec()
! 441: \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
! 442: or pcre_dfa_exec()
! 443: \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
! 444: or pcre_dfa_exec()
! 445: \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
! 446: or pcre_dfa_exec()
! 447: \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
! 448: or pcre_dfa_exec()
! 449:
! 450: Note that \xhh always specifies one byte, even in UTF-8 mode; this
! 451: makes it possible to construct invalid UTF-8 sequences for testing pur-
! 452: poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
! 453: UTF-8 mode, generating more than one byte if the value is greater than
! 454: 127. When not in UTF-8 mode, it generates one byte for values less than
! 455: 256, and causes an error for greater values.
! 456:
! 457: The escapes that specify line ending sequences are literal strings,
! 458: exactly as shown. No more than one newline setting should be present in
! 459: any data line.
! 460:
! 461: A backslash followed by anything else just escapes the anything else.
! 462: If the very last character is a backslash, it is ignored. This gives a
! 463: way of passing an empty line as data, since a real empty line termi-
! 464: nates the data input.
! 465:
! 466: The \J escape provides a way of setting the maximum stack size that is
! 467: used by the just-in-time optimization code. It is ignored if JIT opti-
! 468: mization is not being used. Providing a stack that is larger than the
! 469: default 32K is necessary only for very complicated patterns.
! 470:
! 471: If \M is present, pcretest calls pcre_exec() several times, with dif-
! 472: ferent values in the match_limit and match_limit_recursion fields of
! 473: the pcre_extra data structure, until it finds the minimum numbers for
! 474: each parameter that allow pcre_exec() to complete without error.
! 475: Because this is testing a specific feature of the normal interpretive
! 476: pcre_exec() execution, the use of any JIT optimization that might have
! 477: been set up by the /S+ qualifier of -s+ option is disabled.
! 478:
! 479: The match_limit number is a measure of the amount of backtracking that
! 480: takes place, and checking it out can be instructive. For most simple
! 481: matches, the number is quite small, but for patterns with very large
! 482: numbers of matching possibilities, it can become large very quickly
! 483: with increasing length of subject string. The match_limit_recursion
! 484: number is a measure of how much stack (or, if PCRE is compiled with
! 485: NO_RECURSE, how much heap) memory is needed to complete the match
! 486: attempt.
! 487:
! 488: When \O is used, the value specified may be higher or lower than the
! 489: size set by the -O command line option (or defaulted to 45); \O applies
! 490: only to the call of pcre_exec() for the line in which it appears.
! 491:
! 492: If the /P modifier was present on the pattern, causing the POSIX wrap-
! 493: per API to be used, the only option-setting sequences that have any
! 494: effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
! 495: REG_NOTEOL, respectively, to be passed to regexec().
! 496:
! 497: The use of \x{hh...} to represent UTF-8 characters is not dependent on
! 498: the use of the /8 modifier on the pattern. It is recognized always.
! 499: There may be any number of hexadecimal digits inside the braces. The
! 500: result is from one to six bytes, encoded according to the original
! 501: UTF-8 rules of RFC 2279. This allows for values in the range 0 to
! 502: 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
! 503: or indeed valid UTF-8 characters according to the later rules in RFC
! 504: 3629.
! 505:
! 506:
! 507: THE ALTERNATIVE MATCHING FUNCTION
! 508:
! 509: By default, pcretest uses the standard PCRE matching function,
! 510: pcre_exec() to match each data line. From release 6.0, PCRE supports an
! 511: alternative matching function, pcre_dfa_test(), which operates in a
! 512: different way, and has some restrictions. The differences between the
! 513: two functions are described in the pcrematching documentation.
! 514:
! 515: If a data line contains the \D escape sequence, or if the command line
! 516: contains the -dfa option, the alternative matching function is called.
! 517: This function finds all possible matches at a given point. If, however,
! 518: the \F escape sequence is present in the data line, it stops after the
! 519: first match is found. This is always the shortest possible match.
! 520:
! 521:
! 522: DEFAULT OUTPUT FROM PCRETEST
! 523:
! 524: This section describes the output when the normal matching function,
! 525: pcre_exec(), is being used.
! 526:
! 527: When a match succeeds, pcretest outputs the list of captured substrings
! 528: that pcre_exec() returns, starting with number 0 for the string that
! 529: matched the whole pattern. Otherwise, it outputs "No match" when the
! 530: return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
! 531: tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
! 532: (Note that this is the entire substring that was inspected during the
! 533: partial match; it may include characters before the actual match start
! 534: if a lookbehind assertion, \K, \b, or \B was involved.) For any other
! 535: return, pcretest outputs the PCRE negative error number and a short
! 536: descriptive phrase. If the error is a failed UTF-8 string check, the
! 537: byte offset of the start of the failing character and the reason code
! 538: are also output, provided that the size of the output vector is at
! 539: least two. Here is an example of an interactive pcretest run.
! 540:
! 541: $ pcretest
! 542: PCRE version 8.13 2011-04-30
! 543:
! 544: re> /^abc(\d+)/
! 545: data> abc123
! 546: 0: abc123
! 547: 1: 123
! 548: data> xyz
! 549: No match
! 550:
! 551: Unset capturing substrings that are not followed by one that is set are
! 552: not returned by pcre_exec(), and are not shown by pcretest. In the fol-
! 553: lowing example, there are two capturing substrings, but when the first
! 554: data line is matched, the second, unset substring is not shown. An
! 555: "internal" unset substring is shown as "<unset>", as for the second
! 556: data line.
! 557:
! 558: re> /(a)|(b)/
! 559: data> a
! 560: 0: a
! 561: 1: a
! 562: data> b
! 563: 0: b
! 564: 1: <unset>
! 565: 2: b
! 566:
! 567: If the strings contain any non-printing characters, they are output as
! 568: \0x escapes, or as \x{...} escapes if the /8 modifier was present on
! 569: the pattern. See below for the definition of non-printing characters.
! 570: If the pattern has the /+ modifier, the output for substring 0 is fol-
! 571: lowed by the the rest of the subject string, identified by "0+" like
! 572: this:
! 573:
! 574: re> /cat/+
! 575: data> cataract
! 576: 0: cat
! 577: 0+ aract
! 578:
! 579: If the pattern has the /g or /G modifier, the results of successive
! 580: matching attempts are output in sequence, like this:
! 581:
! 582: re> /\Bi(\w\w)/g
! 583: data> Mississippi
! 584: 0: iss
! 585: 1: ss
! 586: 0: iss
! 587: 1: ss
! 588: 0: ipp
! 589: 1: pp
! 590:
! 591: "No match" is output only if the first match attempt fails. Here is an
! 592: example of a failure message (the offset 4 that is specified by \>4 is
! 593: past the end of the subject string):
! 594:
! 595: re> /xyz/
! 596: data> xyz\>4
! 597: Error -24 (bad offset value)
! 598:
! 599: If any of the sequences \C, \G, or \L are present in a data line that
! 600: is successfully matched, the substrings extracted by the convenience
! 601: functions are output with C, G, or L after the string number instead of
! 602: a colon. This is in addition to the normal full list. The string length
! 603: (that is, the return from the extraction function) is given in paren-
! 604: theses after each string for \C and \G.
! 605:
! 606: Note that whereas patterns can be continued over several lines (a plain
! 607: ">" prompt is used for continuations), data lines may not. However new-
! 608: lines can be included in data by means of the \n escape (or \r, \r\n,
! 609: etc., depending on the newline sequence setting).
! 610:
! 611:
! 612: OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
! 613:
! 614: When the alternative matching function, pcre_dfa_exec(), is used (by
! 615: means of the \D escape sequence or the -dfa command line option), the
! 616: output consists of a list of all the matches that start at the first
! 617: point in the subject where there is at least one match. For example:
! 618:
! 619: re> /(tang|tangerine|tan)/
! 620: data> yellow tangerine\D
! 621: 0: tangerine
! 622: 1: tang
! 623: 2: tan
! 624:
! 625: (Using the normal matching function on this data finds only "tang".)
! 626: The longest matching string is always given first (and numbered zero).
! 627: After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
! 628: lowed by the partially matching substring. (Note that this is the
! 629: entire substring that was inspected during the partial match; it may
! 630: include characters before the actual match start if a lookbehind asser-
! 631: tion, \K, \b, or \B was involved.)
! 632:
! 633: If /g is present on the pattern, the search for further matches resumes
! 634: at the end of the longest match. For example:
! 635:
! 636: re> /(tang|tangerine|tan)/g
! 637: data> yellow tangerine and tangy sultana\D
! 638: 0: tangerine
! 639: 1: tang
! 640: 2: tan
! 641: 0: tang
! 642: 1: tan
! 643: 0: tan
! 644:
! 645: Since the matching function does not support substring capture, the
! 646: escape sequences that are concerned with captured substrings are not
! 647: relevant.
! 648:
! 649:
! 650: RESTARTING AFTER A PARTIAL MATCH
! 651:
! 652: When the alternative matching function has given the PCRE_ERROR_PARTIAL
! 653: return, indicating that the subject partially matched the pattern, you
! 654: can restart the match with additional subject data by means of the \R
! 655: escape sequence. For example:
! 656:
! 657: re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
! 658: data> 23ja\P\D
! 659: Partial match: 23ja
! 660: data> n05\R\D
! 661: 0: n05
! 662:
! 663: For further information about partial matching, see the pcrepartial
! 664: documentation.
! 665:
! 666:
! 667: CALLOUTS
! 668:
! 669: If the pattern contains any callout requests, pcretest's callout func-
! 670: tion is called during matching. This works with both matching func-
! 671: tions. By default, the called function displays the callout number, the
! 672: start and current positions in the text at the callout time, and the
! 673: next pattern item to be tested. For example, the output
! 674:
! 675: --->pqrabcdef
! 676: 0 ^ ^ \d
! 677:
! 678: indicates that callout number 0 occurred for a match attempt starting
! 679: at the fourth character of the subject string, when the pointer was at
! 680: the seventh character of the data, and when the next pattern item was
! 681: \d. Just one circumflex is output if the start and current positions
! 682: are the same.
! 683:
! 684: Callouts numbered 255 are assumed to be automatic callouts, inserted as
! 685: a result of the /C pattern modifier. In this case, instead of showing
! 686: the callout number, the offset in the pattern, preceded by a plus, is
! 687: output. For example:
! 688:
! 689: re> /\d?[A-E]\*/C
! 690: data> E*
! 691: --->E*
! 692: +0 ^ \d?
! 693: +3 ^ [A-E]
! 694: +8 ^^ \*
! 695: +10 ^ ^
! 696: 0: E*
! 697:
! 698: If a pattern contains (*MARK) items, an additional line is output when-
! 699: ever a change of latest mark is passed to the callout function. For
! 700: example:
! 701:
! 702: re> /a(*MARK:X)bc/C
! 703: data> abc
! 704: --->abc
! 705: +0 ^ a
! 706: +1 ^^ (*MARK:X)
! 707: +10 ^^ b
! 708: Latest Mark: X
! 709: +11 ^ ^ c
! 710: +12 ^ ^
! 711: 0: abc
! 712:
! 713: The mark changes between matching "a" and "b", but stays the same for
! 714: the rest of the match, so nothing more is output. If, as a result of
! 715: backtracking, the mark reverts to being unset, the text "<unset>" is
! 716: output.
! 717:
! 718: The callout function in pcretest returns zero (carry on matching) by
! 719: default, but you can use a \C item in a data line (as described above)
! 720: to change this and other parameters of the callout.
! 721:
! 722: Inserting callouts can be helpful when using pcretest to check compli-
! 723: cated regular expressions. For further information about callouts, see
! 724: the pcrecallout documentation.
! 725:
! 726:
! 727: NON-PRINTING CHARACTERS
! 728:
! 729: When pcretest is outputting text in the compiled version of a pattern,
! 730: bytes other than 32-126 are always treated as non-printing characters
! 731: are are therefore shown as hex escapes.
! 732:
! 733: When pcretest is outputting text that is a matched part of a subject
! 734: string, it behaves in the same way, unless a different locale has been
! 735: set for the pattern (using the /L modifier). In this case, the
! 736: isprint() function to distinguish printing and non-printing characters.
! 737:
! 738:
! 739: SAVING AND RELOADING COMPILED PATTERNS
! 740:
! 741: The facilities described in this section are not available when the
! 742: POSIX interface to PCRE is being used, that is, when the /P pattern
! 743: modifier is specified.
! 744:
! 745: When the POSIX interface is not in use, you can cause pcretest to write
! 746: a compiled pattern to a file, by following the modifiers with > and a
! 747: file name. For example:
! 748:
! 749: /pattern/im >/some/file
! 750:
! 751: See the pcreprecompile documentation for a discussion about saving and
! 752: re-using compiled patterns. Note that if the pattern was successfully
! 753: studied with JIT optimization, the JIT data cannot be saved.
! 754:
! 755: The data that is written is binary. The first eight bytes are the
! 756: length of the compiled pattern data followed by the length of the
! 757: optional study data, each written as four bytes in big-endian order
! 758: (most significant byte first). If there is no study data (either the
! 759: pattern was not studied, or studying did not return any data), the sec-
! 760: ond length is zero. The lengths are followed by an exact copy of the
! 761: compiled pattern. If there is additional study data, this (excluding
! 762: any JIT data) follows immediately after the compiled pattern. After
! 763: writing the file, pcretest expects to read a new pattern.
! 764:
! 765: A saved pattern can be reloaded into pcretest by specifying < and a
! 766: file name instead of a pattern. The name of the file must not contain a
! 767: < character, as otherwise pcretest will interpret the line as a pattern
! 768: delimited by < characters. For example:
! 769:
! 770: re> </some/file
! 771: Compiled pattern loaded from /some/file
! 772: No study data
! 773:
! 774: If the pattern was previously studied with the JIT optimization, the
! 775: JIT information cannot be saved and restored, and so is lost. When the
! 776: pattern has been loaded, pcretest proceeds to read data lines in the
! 777: usual way.
! 778:
! 779: You can copy a file written by pcretest to a different host and reload
! 780: it there, even if the new host has opposite endianness to the one on
! 781: which the pattern was compiled. For example, you can compile on an i86
! 782: machine and run on a SPARC machine.
! 783:
! 784: File names for saving and reloading can be absolute or relative, but
! 785: note that the shell facility of expanding a file name that starts with
! 786: a tilde (~) is not available.
! 787:
! 788: The ability to save and reload files in pcretest is intended for test-
! 789: ing and experimentation. It is not intended for production use because
! 790: only a single pattern can be written to a file. Furthermore, there is
! 791: no facility for supplying custom character tables for use with a
! 792: reloaded pattern. If the original pattern was compiled with custom
! 793: tables, an attempt to match a subject string using a reloaded pattern
! 794: is likely to cause pcretest to crash. Finally, if you attempt to load
! 795: a file that is not in the correct format, the result is undefined.
! 796:
! 797:
! 798: SEE ALSO
! 799:
! 800: pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
! 801: tial(d), pcrepattern(3), pcreprecompile(3).
! 802:
! 803:
! 804: AUTHOR
! 805:
! 806: Philip Hazel
! 807: University Computing Service
! 808: Cambridge CB2 3QH, England.
! 809:
! 810:
! 811: REVISION
! 812:
! 813: Last updated: 02 December 2011
! 814: Copyright (c) 1997-2011 University of Cambridge.
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