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PCRE2TEST(1)		    General Commands Manual		  PCRE2TEST(1)

NAME
       pcre2test - a program for testing Perl-compatible regular expressions.

SYNOPSIS

       pcre2test [options] [input file [output file]]

       pcre2test is a test program for the PCRE2 regular expression libraries,
       but  it	can  also  be used for experimenting with regular expressions.
       This document describes the features of the test	program;  for  details
       of  the regular expressions themselves, see the pcre2pattern documenta-
       tion. For details of the	PCRE2 library function	calls  and  their  op-
       tions, see the pcre2api documentation.

       The  input  for	pcre2test is a sequence	of regular expression patterns
       and subject strings to be matched. There	are  also  command  lines  for
       setting defaults	and controlling	some special actions. The output shows
       the  result  of	each  match attempt. Modifiers on external or internal
       command lines, the patterns, and	the subject lines specify PCRE2	 func-
       tion  options, control how the subject is processed, and	what output is
       produced.

       There are many obscure modifiers, some of which	are  specifically  de-
       signed  for use in conjunction with the test script and data files that
       are distributed as part of PCRE2.  All  the  modifiers  are  documented
       here, some without much justification, but many of them are unlikely to
       be of use except	when testing the libraries.

PCRE2's	8-BIT, 16-BIT AND 32-BIT LIBRARIES

       Different versions of the PCRE2 library can be built to support charac-
       ter  strings  that  are encoded in 8-bit, 16-bit, or 32-bit code	units.
       One, two, or all	three of these libraries  may  be  simultaneously  in-
       stalled.	 The  pcre2test	program	can be used to test all	the libraries.
       However,	its own	input and output are  always  in  8-bit	 format.  When
       testing	the  16-bit  or	32-bit libraries, patterns and subject strings
       are converted to	16-bit or 32-bit format	before being passed to the li-
       brary functions.	Results	are converted back to  8-bit  code  units  for
       output.

       In the rest of this document, the names of library functions and	struc-
       tures  are given	in generic form, for example, pcre2_compile(). The ac-
       tual names used in the libraries	have a suffix _8, _16, or _32, as  ap-
       propriate.

INPUT ENCODING

       Input  to  pcre2test is processed line by line, either by calling the C
       library's fgets() function, or via the libreadline or libedit  library.
       In  some	Windows	environments character 26 (hex 1A) causes an immediate
       end of file, and	no further data	is read, so this character  should  be
       avoided unless you really want that action.

       The  input is processed using C's string	functions, so must not contain
       binary zeros, even though in Unix-like environments, fgets() treats any
       bytes other than	newline	as data	characters. An error is	generated if a
       binary zero is encountered. By default subject lines are	processed  for
       backslash escapes, which	makes it possible to include any data value in
       strings	that  are  passed  to  the library for matching. For patterns,
       there is	a facility for specifying some or all of the 8-bit input char-
       acters as hexadecimal pairs, which makes	it possible to include	binary
       zeros.

   Input for the 16-bit	and 32-bit libraries

       When testing the	16-bit or 32-bit libraries, there is a need to be able
       to  generate character code points greater than 255 in the strings that
       are passed to the library. For subject lines and	some  patterns,	 back-
       slash  escapes  can  be	used.  In addition, when the utf modifier (see
       "Setting	compilation options" below) is set, the	pattern	and  any  fol-
       lowing subject lines are	interpreted as UTF-8 strings and translated to
       UTF-16 or UTF-32	as appropriate.

       For  non-UTF testing of wide characters,	the utf8_input modifier	can be
       used. This is mutually exclusive	with  utf,  and	 is  allowed  only  in
       16-bit  or  32-bit  mode.  It  causes the pattern and following subject
       lines to	be treated as UTF-8 according to the original definition  (RFC
       2279), which allows for character values	up to 0x7fffffff. Each charac-
       ter  is	placed	in one 16-bit or 32-bit	code unit (in the 16-bit case,
       values greater than 0xffff cause	an error to occur).

       UTF-8 (in its original definition) is not capable  of  encoding	values
       greater	than  0x7fffffff, but such values can be handled by the	32-bit
       library.	When testing this library in non-UTF mode with utf8_input set,
       if any character	is preceded by the byte	0xff (which is an invalid byte
       in UTF-8) 0x80000000 is added to	the  character's  value.  For  subject
       strings,	using an escape	sequence is preferable.

COMMAND	LINE OPTIONS

       -8	 If the	8-bit library has been built, this option causes it to
		 be  used  (this is the	default). If the 8-bit library has not
		 been built, this option causes	an error.

       -16	 If the	16-bit library has been	built, this option  causes  it
		 to  be	used. If the 8-bit library has not been	built, this is
		 the default. If the 16-bit library has	not been  built,  this
		 option	causes an error.

       -32	 If  the  32-bit library has been built, this option causes it
		 to be used. If	no other library has been built, this  is  the
		 default.  If  the 32-bit library has not been built, this op-
		 tion causes an	error.

       -ac	 Behave	as if each pattern has the auto_callout	modifier, that
		 is, insert automatic callouts into every pattern that is com-
		 piled.

       -AC	 As for	-ac, but in addition behave as if  each	 subject  line
		 has  the callout_extra	modifier, that is, show	additional in-
		 formation from	callouts.

       -b	 Behave	as if each pattern has the fullbincode	modifier;  the
		 full internal binary form of the pattern is output after com-
		 pilation.

       -C	 Output	 the  version  number  of  the	PCRE2 library, and all
		 available information about the optional  features  that  are
		 included,  and	 then  exit with zero exit code. All other op-
		 tions are ignored. If both -C and -LM are present,  whichever
		 is first is recognized.

       -C option Output	 information  about a specific build-time option, then
		 exit. This functionality is intended for use in scripts  such
		 as  RunTest.  The  following options output the value and set
		 the exit code as indicated:

		   ebcdic-nl  the code for LF (= NL) in	an EBCDIC environment:
				either 0x15 or 0x25
				0 if used in an	ASCII/Unicode environment
				exit code is always 0
		   linksize   the configured internal link size	(2, 3, or 4)
				exit code is set to the	link size
		   newline    the default newline setting:
				CR, LF,	CRLF, ANYCRLF, ANY, or NUL
				exit code is always 0
		   bsr	      the default setting for what \R matches:
				ANYCRLF	or ANY
				exit code is always 0

		 The following options output 1	for true or 0 for  false,  and
		 set the exit code to the same value:

		   backslash-C	\C is supported	(not locked out)
		   ebcdic	compiled for an	EBCDIC environment
		   jit		just-in-time support is	available
		   pcre2-16	the 16-bit library was built
		   pcre2-32	the 32-bit library was built
		   pcre2-8	the 8-bit library was built
		   unicode	Unicode	support	is available

		 Note that the availability of JIT support in the library does
		 not  guarantee	 that  it can actually be used because in some
		 environments it is unable to allocate executable memory.  The
		 option	 "jitusable"  gives  more detailed information.	It re-
		 turns one of the following values:

		   0  JIT is available and usable
		   1  JIT is available but cannot allocate executable memory
		   2  JIT is not available
		   3  Unexpected return	from test call to pcre2_jit_compile()

		 If an unknown option is given,	an error  message  is  output;
		 the exit code is 0.

       -d	 Behave	 as if each pattern has	the debug modifier; the	inter-
		 nal form and information about	the compiled pattern is	output
		 after compilation; -d is equivalent to	-b -i.

       -dfa	 Behave	as if each subject line	has the	dfa modifier; matching
		 is done using the pcre2_dfa_match() function instead  of  the
		 default pcre2_match().

       -error number[,number,...]
		 Call  pcre2_get_error_message() for each of the error numbers
		 in the	comma-separated	list, display the  resulting  messages
		 on  the  standard  output, then exit with zero	exit code. The
		 numbers may be	positive or negative. This  is	a  convenience
		 facility for PCRE2 maintainers.

       -help	 Output	a brief	summary	these options and then exit.

       -i	 Behave	 as if each pattern has	the info modifier; information
		 about the compiled pattern is given after compilation.

       -jit	 Behave	as if each pattern line	has the	 jit  modifier;	 after
		 successful  compilation,  each	pattern	is passed to the just-
		 in-time compiler, if available.

       -jitfast	 Behave	as if each pattern line	has the	jitfast	modifier;  af-
		 ter  successful  compilation,	each  pattern is passed	to the
		 just-in-time compiler,	if available, and each subject line is
		 passed	directly to the	JIT matcher via	its "fast path".

       -jitverify
		 Behave	as if each pattern line	has  the  jitverify  modifier;
		 after	successful  compilation, each pattern is passed	to the
		 just-in-time compiler,	if available, and the use of  JIT  for
		 matching is verified.

       -LM	 List modifiers: write a list of available pattern and subject
		 modifiers  to	the  standard output, then exit	with zero exit
		 code. All other options are ignored.  If both -C and any  -Lx
		 options are present, whichever	is first is recognized.

       -LP	 List  properties:  write a list of recognized Unicode proper-
		 ties to the standard output, then exit	with zero  exit	 code.
		 All other options are ignored.	If both	-C and any -Lx options
		 are present, whichever	is first is recognized.

       -LS	 List scripts: write a list of recognized Unicode script names
		 to  the  standard  output, then exit with zero	exit code. All
		 other options are ignored. If both -C and any -Lx options are
		 present, whichever is first is	recognized.

       -pattern	modifier-list
		 Behave	as if each pattern line	contains the given modifiers.

       -q	 Do not	output the version number of pcre2test at the start of
		 execution.

       -S size	 On Unix-like systems, set the size of the run-time  stack  to
		 size mebibytes	(units of 1024*1024 bytes).

       -subject	modifier-list
		 Behave	as if each subject line	contains the given modifiers.

       -t	 Run  each compile and match many times	with a timer, and out-
		 put the resulting times per compile or	 match.	 When  JIT  is
		 used,	separate  times	 are given for the initial compile and
		 the JIT compile. You can control  the	number	of  iterations
		 that  are used	for timing by following	-t with	a number (as a
		 separate item on the command line). For  example,  "-t	 1000"
		 iterates 1000 times. The default is to	iterate	500,000	times.

       -tm	 This is like -t except	that it	times only the matching	phase,
		 not the compile phase.

       -T -TM	 These	behave like -t and -tm,	but in addition, at the	end of
		 a run,	the total times	for all	compiles and matches are  out-
		 put.

       -version	 Output	the PCRE2 version number and then exit.

DESCRIPTION

       If  pcre2test  is given two filename arguments, it reads	from the first
       and writes to the second. If the	first name is "-", input is taken from
       the standard input. If pcre2test	is given only one argument,  it	 reads
       from that file and writes to stdout. Otherwise, it reads	from stdin and
       writes to stdout.

       When  pcre2test	is  built,  a configuration option can specify that it
       should be linked	with the libreadline or	libedit	library. When this  is
       done,  if the input is from a terminal, it is read using	the readline()
       function. This provides line-editing and	history	facilities. The	output
       from the	-help option states whether or not readline() will be used.

       The program handles any number of tests,	each of	which  consists	 of  a
       set  of input lines. Each set starts with a regular expression pattern,
       followed	by any number of subject lines to be matched against that pat-
       tern. In	between	sets of	test data, command lines that begin with # may
       appear. This file format, with some restrictions, can also be processed
       by the perltest.sh script that is distributed with PCRE2	as a means  of
       checking	that the behaviour of PCRE2 and	Perl is	the same. For a	speci-
       fication	 of perltest.sh, see the comments near its beginning. See also
       the #perltest command below.

       When the	input is a terminal, pcre2test prompts for each	line of	input,
       using "re>" to prompt for regular expression patterns, and  "data>"  to
       prompt  for subject lines. Command lines	starting with #	can be entered
       only in response	to the "re>" prompt.

       Each subject line is matched separately and independently. If you  want
       to do multi-line	matches, you have to use the \n	escape sequence	(or \r
       or  \r\n,  etc.,	 depending on the newline setting) in a	single line of
       input to	encode the newline sequences. There is no limit	on the	length
       of  subject  lines; the input buffer is automatically extended if it is
       too small. There	are replication	features that  makes  it  possible  to
       generate	 long  repetitive  pattern  or subject lines without having to
       supply them explicitly.

       An empty	line or	the end	of the file signals the	 end  of  the  subject
       lines  for  a test, at which point a new	pattern	or command line	is ex-
       pected if there is still	input to be read.

COMMAND	LINES

       In between sets of test data, a line that begins	with # is  interpreted
       as a command line. If the first character is followed by	white space or
       an  exclamation	mark,  the  line is treated as a comment, and ignored.
       Otherwise, the following	commands are recognized:

	 #forbid_utf

       Subsequent  patterns  automatically  have   the	 PCRE2_NEVER_UTF   and
       PCRE2_NEVER_UCP	options	 set, which locks out the use of the PCRE2_UTF
       and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start  of
       patterns.  This	command	 also  forces an error if a subsequent pattern
       contains	any occurrences	of \P, \p, or \X, which	 are  still  supported
       when  PCRE2_UTF	is not set, but	which require Unicode property support
       to be included in the library.

       This is a trigger guard that is used in test files to ensure  that  UTF
       or  Unicode property tests are not accidentally added to	files that are
       used when Unicode support is  not  included  in	the  library.  Setting
       PCRE2_NEVER_UTF	and  PCRE2_NEVER_UCP as	a default can also be obtained
       by the use of #pattern; the difference is that  #forbid_utf  cannot  be
       unset,  and the automatic options are not displayed in pattern informa-
       tion, to	avoid cluttering up test output.

	 #load <filename>

       This command is used to load a set of precompiled patterns from a file,
       as described in the section entitled  "Saving  and  restoring  compiled
       patterns" below.

	 #loadtables <filename>

       This  command is	used to	load a set of binary character tables that can
       be accessed by the tables=3 qualifier. Such tables can  be  created  by
       the pcre2_dftables program with the -b option.

	 #newline_default [<newline-list>]

       When  PCRE2  is	built,	a default newline convention can be specified.
       This determines which characters	and/or character pairs are  recognized
       as indicating a newline in a pattern or subject string. The default can
       be  overridden when a pattern is	compiled. The standard test files con-
       tain tests of various newline conventions,  but	the  majority  of  the
       tests  expect  a	 single	 linefeed to be	recognized as a	newline	by de-
       fault. Without special action the tests would fail when PCRE2  is  com-
       piled with either CR or CRLF as the default newline.

       The #newline_default command specifies a	list of	newline	types that are
       acceptable  as the default. The types must be one of CR,	LF, CRLF, ANY-
       CRLF, ANY, or NUL (in upper or lower case), for example:

	 #newline_default LF Any anyCRLF

       If the default newline is in the	list, this command has no effect. Oth-
       erwise, except when testing the POSIX  API,  a  newline	modifier  that
       specifies the first newline convention in the list (LF in the above ex-
       ample)  is  added  to  any pattern that does not	already	have a newline
       modifier. If the	newline	list is	empty, the feature is turned off. This
       command is present in a number of the standard test input files.

       When the	POSIX API is being tested there	is no way to override the  de-
       fault newline convention, though	it is possible to set the newline con-
       vention	from  within  the  pattern. A warning is given if the posix or
       posix_nosub modifier is used when #newline_default would	set a  default
       for the non-POSIX API.

	 #pattern <modifier-list>

       This  command  sets  a default modifier list that applies to all	subse-
       quent patterns. Modifiers on a pattern can change these settings.

	 #perltest

       This line is used in test files that can	also  be  processed  by	 perl-
       test.sh	to  confirm  that Perl gives the same results as PCRE2.	Subse-
       quent tests are checked for the use of pcre2test	features that are  in-
       compatible with the perltest.sh script.

       Patterns	 must  use  '/'	as their delimiter, and	only certain modifiers
       are supported. Comment lines, #pattern commands,	and #subject  commands
       that  set  or  unset "mark" are recognized and acted on.	The #perltest,
       #forbid_utf, and	#newline_default commands, which  are  needed  in  the
       relevant	pcre2test files, are silently ignored. All other command lines
       are  ignored,  but  give	a warning message. The #perltest command helps
       detect tests that are accidentally put in the wrong  file  or  use  the
       wrong  delimiter.  For  more  details of	the perltest.sh	script see the
       comments	it contains.

	 #pop [<modifiers>]
	 #popcopy [<modifiers>]

       These commands are used to manipulate the stack of  compiled  patterns,
       as  described  in  the  section entitled	"Saving	and restoring compiled
       patterns" below.

	 #save <filename>

       This command is used to save a set of compiled patterns to a  file,  as
       described  in  the section entitled "Saving and restoring compiled pat-
       terns" below.

	 #subject <modifier-list>

       This command sets a default modifier list that applies  to  all	subse-
       quent  subject lines. Modifiers on a subject line can change these set-
       tings.

MODIFIER SYNTAX

       Modifier	lists are used with both pattern and subject lines. Items in a
       list are	separated by commas followed by	optional white space. Trailing
       whitespace in a modifier	list is	ignored. Some modifiers	may  be	 given
       for  both patterns and subject lines, whereas others are	valid only for
       one or the other. Each modifier has  a  long  name,  for	 example  "an-
       chored",	 and  some  of	them  must be followed by an equals sign and a
       value, for example, "offset=12".	Values cannot  contain	comma  charac-
       ters,  but may contain spaces. Modifiers	that do	not take values	may be
       preceded	by a minus sign	to turn	off a previous setting.

       A few of	the more common	modifiers can also be specified	as single let-
       ters, for example "i" for "caseless". In	documentation,	following  the
       Perl convention,	these are written with a slash ("the /i	modifier") for
       clarity.	 Abbreviated  modifiers	 must all be concatenated in the first
       item of a modifier list.	If the first item is not recognized as a  long
       modifier	 name, it is interpreted as a sequence of these	abbreviations.
       For example:

	 /abc/ig,newline=cr,jit=3

       This is a pattern line whose modifier list starts with  two  one-letter
       modifiers  (/i  and  /g).  The lower-case abbreviated modifiers are the
       same as used in Perl.

PATTERN	SYNTAX

       A pattern line must start with one of the following characters  (common
       symbols,	excluding pattern meta-characters):

	 / ! " ' ` - = _ : ; , % & @ ~

       This  is	 interpreted  as the pattern's delimiter. A regular expression
       may be continued	over several input lines, in which  case  the  newline
       characters are included within it. It is	possible to include the	delim-
       iter  as	 a literal within the pattern by escaping it with a backslash,
       for example

	 /abc\/def/

       If you do this, the escape and the delimiter form part of the  pattern,
       but since the delimiters	are all	non-alphanumeric, the inclusion	of the
       backslash  does not affect the pattern's	interpretation.	Note, however,
       that this trick does not	work within \Q...\E literal bracketing because
       the backslash will itself be interpreted	as a literal. If the terminat-
       ing delimiter is	immediately followed by	a backslash, for example,

	 /abc/\

       a backslash is added to the end of the pattern. This is done to provide
       a way of	testing	the error condition that arises	if a pattern  finishes
       with a backslash, because

	 /abc\/

       is  interpreted as the first line of a pattern that starts with "abc/",
       causing pcre2test to read the next line as a continuation of the	 regu-
       lar expression.

       A pattern can be	followed by a modifier list (details below).

SUBJECT	LINE SYNTAX

       Before each subject line	is passed to pcre2_match(), pcre2_dfa_match(),
       or  pcre2_jit_match(), leading and trailing white space is removed, and
       the line	is scanned for backslash escapes, unless  the  subject_literal
       modifier	 was set for the pattern. The following	provide	a means	of en-
       coding non-printing characters in a visible way:

	 \a	     alarm (BEL, \x07)
	 \b	     backspace (\x08)
	 \e	     escape (\x27)
	 \f	     form feed (\x0c)
	 \n	     newline (\x0a)
	 \N{U+hh...} unicode character (any number of hex digits)
	 \r	     carriage return (\x0d)
	 \t	     tab (\x09)
	 \v	     vertical tab (\x0b)
	 \ddd	     octal number (up to 3 octal digits); represent a single
		       code point unless larger	than 255 with  the  8-bit  li-
       brary
	 \o{dd...}   octal number (any number of octal digits} representing a
		       character in UTF	mode or	a code point
	 \xhh	     hexadecimal byte (up to 2 hex digits)
	 \x{hh...}   hexadecimal number	(up to 8 hex digits) representing a
		       character in UTF	mode or	a code point

       Invoking	 \N{U+hh...}  or  \x{hh...} doesn't require the	use of the utf
       modifier	on the pattern.	It is always recognized. There may be any num-
       ber of hexadecimal digits inside	the braces; invalid values provoke er-
       ror messages but	when using \N{U+hh...} with some invalid unicode char-
       acters they will	be accepted with a warning instead.

       Note that even in UTF-8 mode, \xhh (and depending of how	 large,	 \ddd)
       describe	 one byte rather than one character; this makes	it possible to
       construct invalid UTF-8 sequences for testing purposes.	On  the	 other
       hand, \x{hh...} is interpreted as a UTF-8 character in UTF-8 mode, only
       generating  more	 than  one  byte  if the value is greater than 127. To
       avoid the ambiguity it is preferred to use \N{U+hh...} when  describing
       characters.  When  testing  the 8-bit library not in UTF-8 mode,	\x{hh}
       generates one byte for values that could	fit on it, and causes an error
       for greater values.

       When testing the	16-bit	library,  not  in  UTF-16  mode,  all  4-digit
       \x{hhhh}	 values	 are accepted. This makes it possible to construct in-
       valid UTF-16 sequences for testing purposes.

       When testing the	32-bit library,	not in UTF-32 mode, all	4  to  8-digit
       \x{...}	values	are  accepted. This makes it possible to construct in-
       valid UTF-32 sequences for testing purposes.

       There is	a special backslash sequence that specifies replication	of one
       or more characters:

	 \[<characters>]{<count>}

       This makes it possible to test long strings without having  to  provide
       them as part of the file. For example:

	 \[abc]{4}

       is  converted to	"abcabcabcabc".	This feature does not support nesting.
       To include a closing square bracket in the characters, code it as \x5D.

       A backslash followed by an equals sign marks the	 end  of  the  subject
       string and the start of a modifier list.	For example:

	 abc\=notbol,notempty

       If  the	subject	 string	is empty and \=	is followed by whitespace, the
       line is treated as a comment line, and is not used  for	matching.  For
       example:

	 \= This is a comment.
	 abc\= This is an invalid modifier list.

       A  backslash  followed by any other non-alphanumeric character just es-
       capes that character. A backslash followed by anything else  causes  an
       error.  However,	 if the	very last character in the line	is a backslash
       (and there is no	modifier list),	it is ignored. This  gives  a  way  of
       passing	an  empty line as data,	since a	real empty line	terminates the
       data input.

       If the subject_literal modifier is set for a pattern, all subject lines
       that follow are treated as literals, with no special treatment of back-
       slashes.	 No replication	is possible, and any subject modifiers must be
       set as defaults by a #subject command.

PATTERN	MODIFIERS

       There are several types of modifier that	can appear in  pattern	lines.
       Except where noted below, they may also be used in #pattern commands. A
       pattern's  modifier  list can add to or override	default	modifiers that
       were set	by a previous #pattern command.

   Setting compilation options

       The following modifiers set options for pcre2_compile().	Most  of  them
       set  bits  in  the  options  argument of	that function, but those whose
       names start with	PCRE2_EXTRA are	additional options that	are set	in the
       compile context.	 Some of these options	have  single-letter  abbrevia-
       tions.  There  is  special  handling  for /x: if	a second x is present,
       PCRE2_EXTENDED is converted into	 PCRE2_EXTENDED_MORE  as  in  Perl.  A
       third appearance	adds PCRE2_EXTENDED as well, though this makes no dif-
       ference to the way pcre2_compile() behaves. See pcre2api	for a descrip-
       tion of the effects of these options.

	     allow_empty_class	       set PCRE2_ALLOW_EMPTY_CLASS
	     allow_lookaround_bsk      set PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK
	     allow_surrogate_escapes   set PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
	     alt_bsux		       set PCRE2_ALT_BSUX
	     alt_circumflex	       set PCRE2_ALT_CIRCUMFLEX
	     alt_extended_class	       set PCRE2_ALT_EXTENDED_CLASS
	     alt_verbnames	       set PCRE2_ALT_VERBNAMES
	     anchored		       set PCRE2_ANCHORED
	 /a  ascii_all		       set all ASCII options
	     ascii_bsd		       set PCRE2_EXTRA_ASCII_BSD
	     ascii_bss		       set PCRE2_EXTRA_ASCII_BSS
	     ascii_bsw		       set PCRE2_EXTRA_ASCII_BSW
	     ascii_digit	       set PCRE2_EXTRA_ASCII_DIGIT
	     ascii_posix	       set PCRE2_EXTRA_ASCII_POSIX
	     auto_callout	       set PCRE2_AUTO_CALLOUT
	     bad_escape_is_literal     set PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
	 /i  caseless		       set PCRE2_CASELESS
	 /r  caseless_restrict	       set PCRE2_EXTRA_CASELESS_RESTRICT
	     dollar_endonly	       set PCRE2_DOLLAR_ENDONLY
	 /s  dotall		       set PCRE2_DOTALL
	     dupnames		       set PCRE2_DUPNAMES
	     endanchored	       set PCRE2_ENDANCHORED
	     escaped_cr_is_lf	       set PCRE2_EXTRA_ESCAPED_CR_IS_LF
	 /x  extended		       set PCRE2_EXTENDED
	 /xx extended_more	       set PCRE2_EXTENDED_MORE
	     extra_alt_bsux	       set PCRE2_EXTRA_ALT_BSUX
	     firstline		       set PCRE2_FIRSTLINE
	     literal		       set PCRE2_LITERAL
	     match_line		       set PCRE2_EXTRA_MATCH_LINE
	     match_invalid_utf	       set PCRE2_MATCH_INVALID_UTF
	     match_unset_backref       set PCRE2_MATCH_UNSET_BACKREF
	     match_word		       set PCRE2_EXTRA_MATCH_WORD
	 /m  multiline		       set PCRE2_MULTILINE
	     never_backslash_c	       set PCRE2_NEVER_BACKSLASH_C
	     never_callout	       set PCRE2_EXTRA_NEVER_CALLOUT
	     never_ucp		       set PCRE2_NEVER_UCP
	     never_utf		       set PCRE2_NEVER_UTF
	 /n  no_auto_capture	       set PCRE2_NO_AUTO_CAPTURE
	     no_auto_possess	       set PCRE2_NO_AUTO_POSSESS
	     no_bs0		       set PCRE2_EXTRA_NO_BS0
	     no_dotstar_anchor	       set PCRE2_NO_DOTSTAR_ANCHOR
	     no_start_optimize	       set PCRE2_NO_START_OPTIMIZE
	     no_utf_check	       set PCRE2_NO_UTF_CHECK
	     python_octal	       set PCRE2_EXTRA_PYTHON_OCTAL
	     turkish_casing	       set PCRE2_EXTRA_TURKISH_CASING
	     ucp		       set PCRE2_UCP
	     ungreedy		       set PCRE2_UNGREEDY
	     use_offset_limit	       set PCRE2_USE_OFFSET_LIMIT
	     utf		       set PCRE2_UTF

       As well as turning on the PCRE2_UTF option, the utf modifier causes all
       non-printing  characters	 in  output  strings  to  be printed using the
       \x{hh...} notation. Otherwise, those less than 0x100 are	output in  hex
       without	the  curly brackets. Setting utf in 16-bit or 32-bit mode also
       causes pattern and subject  strings  to	be  translated	to  UTF-16  or
       UTF-32, respectively, before being passed to library functions.

       The  following modifiers	enable or disable performance optimizations by
       calling pcre2_set_optimize() before invoking the	regex compiler.

	     optimization_full	    enable all optional	optimizations
	     optimization_none	    disable all	optional optimizations
	     auto_possess	    auto-possessify variable quantifiers
	     auto_possess_off	    don't auto-possessify variable quantifiers
	     dotstar_anchor	    anchor patterns starting with .*
	     dotstar_anchor_off	    don't anchor patterns starting with	.*
	     start_optimize	    enable pre-scan of subject string
	     start_optimize_off	    disable pre-scan of	subject	string

       See the pcre2_set_optimize documentation	for details on these optimiza-
       tions.

   Setting compilation controls

       The following modifiers affect the compilation process or  request  in-
       formation  about	the pattern. There are single-letter abbreviations for
       some that are heavily used in the test files.

	 /B  bincode		       show binary code	without	lengths
	     bsr=[anycrlf|unicode]     specify \R handling
	     callout_info	       show callout information
	     convert=<options>	       request foreign pattern conversion
	     convert_glob_escape=c     set glob	escape character
	     convert_glob_separator=c  set glob	separator character
	     convert_length	       set convert buffer length
	     debug		       same as info,fullbincode
	     expand		       expand repetition syntax	in pattern
	     framesize		       show matching frame size
	     fullbincode	       show binary code	with lengths
	 /I  info		       show info about compiled	pattern
	     hex		       unquoted	characters are hexadecimal
	     jit[=<number>]	       use JIT
	     jitfast		       use JIT fast path
	     jitverify		       verify JIT use
	     locale=<name>	       use this	locale
	     max_pattern_compiled      ) set maximum compiled pattern
			_length=<n>    )   length (bytes)
	     max_pattern_length=<n>    set maximum pattern length (code	units)
	     max_varlookbehind=<n>     set maximum variable lookbehind length
	     memory		       show memory used
	     newline=<type>	       set newline type
	     null_context	       compile with a NULL context
	     null_pattern	       pass pattern as NULL
	     parens_nest_limit=<n>     set maximum parentheses depth
	     posix		       use the POSIX API
	     posix_nosub	       use the POSIX API with REG_NOSUB
	     push		       push compiled pattern onto the stack
	     pushcopy		       push a copy onto	the stack
	     pushtablescopy	       push a copy with	tables onto the	stack
	     stackguard=<number>       test the	stackguard feature
	     subject_literal	       treat all subject lines as literal
	     tables=[0|1|2|3]	       select internal tables
	     use_length		       do not zero-terminate the pattern
	     utf8_input		       treat input as UTF-8

       The effects of these modifiers are described in the following sections.

   Newline and \R handling

       The bsr modifier	specifies what \R in a pattern should match. If	it  is
       set  to	"anycrlf",  \R	matches	 CR, LF, or CRLF only. If it is	set to
       "unicode", \R matches any Unicode newline sequence. The default can  be
       specified when PCRE2 is built; if it is not, the	default	is set to Uni-
       code.

       The  newline  modifier specifies	which characters are to	be interpreted
       as newlines, both in the	pattern	and in subject lines. The type must be
       one of CR, LF, CRLF, ANYCRLF, ANY, or NUL (in upper or lower case).

   Information about a pattern

       The debug modifier is a shorthand for info,fullbincode, requesting  all
       available information.

       The bincode modifier causes a representation of the compiled code to be
       output  after compilation. This information does	not contain length and
       offset values, which ensures that the same output is generated for dif-
       ferent internal link sizes and different	code  unit  widths.  By	 using
       bincode,	 the  same  regression tests can be used in different environ-
       ments.

       The fullbincode modifier, by contrast, does include length  and	offset
       values.	This is	used in	a few special tests that run only for specific
       code unit widths	and link sizes,	and is also useful for one-off tests.

       The info	modifier  requests  information	 about	the  compiled  pattern
       (whether	 it  is	anchored, has a	fixed first character, and so on). The
       information is obtained from the	 pcre2_pattern_info()  function.  Here
       are some	typical	examples:

	   re> /(?i)(^a|^b)/m,info
	 Capture group count = 1
	 Compile options: multiline
	 Overall options: caseless multiline
	 First code unit at start or follows newline
	 Subject length	lower bound = 1

	   re> /(?i)abc/info
	 Capture group count = 0
	 Compile options: <none>
	 Overall options: caseless
	 First code unit = 'a' (caseless)
	 Last code unit	= 'c' (caseless)
	 Subject length	lower bound = 3

       "Compile	 options"  are those specified by modifiers; "overall options"
       have added options that are taken or deduced from the pattern. If  both
       sets  of	 options are the same, just a single "options" line is output;
       if there	are no options,	the line is  omitted.  "First  code  unit"  is
       where  any  match must start; if	there is more than one they are	listed
       as "starting code units". "Last code unit" is  the  last	 literal  code
       unit  that  must	 be  present in	any match. This	is not necessarily the
       last character. These lines are omitted if no starting or  ending  code
       units   are   recorded.	 The  subject  length  line  is	 omitted  when
       no_start_optimize is set	because	the minimum length is  not  calculated
       when it can never be used.

       The  framesize modifier shows the size, in bytes, of each storage frame
       used by pcre2_match() for handling backtracking.	The  size  depends  on
       the  number  of capturing parentheses in	the pattern. A vector of these
       frames is used at matching time;	its overall size  is  shown  when  the
       heaframes_size subject modifier is set.

       The  callout_info  modifier requests information	about all the callouts
       in the pattern. A list of them is output	at the end of any other	infor-
       mation that is requested. For each callout, either its number or	string
       is given, followed by the item that follows it in the pattern.

   Passing a NULL context

       Normally, pcre2test passes a context block to pcre2_compile().  If  the
       null_context  modifier  is  set,	 however,  NULL	is passed. This	is for
       testing that pcre2_compile() behaves correctly in this  case  (it  uses
       default values).

   Passing a NULL pattern

       The  null_pattern  modifier  is for testing the behaviour of pcre2_com-
       pile() when the pattern argument	is NULL. The length  value  passed  is
       the default PCRE2_ZERO_TERMINATED unless	use_length is set.  Any	length
       other than zero causes an error.

   Specifying pattern characters in hexadecimal

       The  hex	 modifier specifies that the characters	of the pattern,	except
       for substrings enclosed in single or double quotes, are	to  be	inter-
       preted  as  pairs  of hexadecimal digits. This feature is provided as a
       way of creating patterns	that contain binary zeros and other non-print-
       ing characters. White space is permitted	between	pairs of  digits.  For
       example,	this pattern contains three characters:

	 /ab 32	59/hex

       Parts  of  such	a  pattern are taken literally if quoted. This pattern
       contains	nine characters, only two of which are specified in  hexadeci-
       mal:

	 /ab "literal" 32/hex

       Either  single or double	quotes may be used. There is no	way of includ-
       ing the delimiter within	a substring. The hex and expand	modifiers  are
       mutually	exclusive.

   Specifying the pattern's length

       By default, patterns are	passed to the compiling	functions as zero-ter-
       minated	strings	but can	be passed by length instead of being zero-ter-
       minated.	The use_length modifier	causes this to happen. Using a	length
       happens	automatically  (whether	 or not	use_length is set) when	hex is
       set, because patterns specified in hexadecimal may contain  binary  ze-
       ros.

       If hex or use_length is used with the POSIX wrapper API (see "Using the
       POSIX  wrapper  API" below), the	REG_PEND extension is used to pass the
       pattern's length.

   Specifying a	maximum	for variable lookbehinds

       Variable	lookbehind assertions are supported only  if,  for  each  one,
       there is	a maximum length (in characters) that it can match. There is a
       limit on	this, whose default can	be set at build	time, with an ultimate
       default	  of	255.   The   max_varlookbehind	 modifier   uses   the
       pcre2_set_max_varlookbehind() function to change	the limit. Lookbehinds
       whose branches each match a fixed length	are limited to	65535  charac-
       ters per	branch.

   Specifying wide characters in 16-bit	and 32-bit modes

       In 16-bit and 32-bit modes, all input is	automatically treated as UTF-8
       and  translated	to  UTF-16 or UTF-32 when the utf modifier is set. For
       testing the 16-bit and 32-bit libraries in non-UTF mode,	the utf8_input
       modifier	can be used. It	is mutually exclusive with  utf.  Input	 lines
       are interpreted as UTF-8	as a means of specifying wide characters. More
       details are given in "Input encoding" above.

   Generating long repetitive patterns

       Some  tests use long patterns that are very repetitive. Instead of cre-
       ating a very long input line for	such a pattern,	you can	use a  special
       repetition  feature,  similar  to  the  one described for subject lines
       above. If the expand modifier is	present	on a  pattern,	parts  of  the
       pattern that have the form

	 \[<characters>]{<count>}

       are expanded before the pattern is passed to pcre2_compile(). For exam-
       ple, \[AB]{6000}	is expanded to "ABAB..." 6000 times. This construction
       cannot  be  nested. An initial "\[" sequence is recognized only if "]{"
       followed	by decimal digits and "}" is found later in  the  pattern.  If
       not, the	characters remain in the pattern unaltered. The	expand and hex
       modifiers are mutually exclusive.

       If  part	 of an expanded	pattern	looks like an expansion, but is	really
       part of the actual pattern, unwanted expansion can be avoided by	giving
       two values in the quantifier. For example, \[AB]{6000,6000} is not rec-
       ognized as an expansion item.

       If the info modifier is set on an expanded pattern, the result  of  the
       expansion is included in	the information	that is	output.

   JIT compilation

       Just-in-time  (JIT)  compiling  is  a heavyweight optimization that can
       greatly speed up	pattern	matching. See the pcre2jit  documentation  for
       details.	 JIT  compiling	 happens, optionally, after a pattern has been
       successfully compiled into an internal form. The	JIT compiler  converts
       this to optimized machine code. It needs	to know	whether	the match-time
       options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
       because	different  code	 is generated for the different	cases. See the
       partial modifier	in "Subject Modifiers" below for details of how	 these
       options are specified for each match attempt.

       JIT compilation is requested by the jit pattern modifier, which may op-
       tionally	 be  followed by an equals sign	and a number in	the range 0 to
       7.  The three bits that make up the number specify which	of  the	 three
       JIT operating modes are to be compiled:

	 1  compile JIT	code for non-partial matching
	 2  compile JIT	code for soft partial matching
	 4  compile JIT	code for hard partial matching

       The possible values for the jit modifier	are therefore:

	 0  disable JIT
	 1  normal matching only
	 2  soft partial matching only
	 3  normal and soft partial matching
	 4  hard partial matching only
	 6  soft and hard partial matching only
	 7  all	three modes

       If  no  number  is  given,  7 is	assumed. The phrase "partial matching"
       means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT	or the
       PCRE2_PARTIAL_HARD option set. Note that	such a call may	return a  com-
       plete match; the	options	enable the possibility of a partial match, but
       do  not	require	it. Note also that if you request JIT compilation only
       for partial matching (for example, jit=2) but do	not  set  the  partial
       modifier	 on  a	subject	line, that match will not use JIT code because
       none was	compiled for non-partial matching.

       If JIT compilation is successful, the compiled JIT code will  automati-
       cally be	used when an appropriate type of match is run, except when in-
       compatible  run-time  options  are specified. For more details, see the
       pcre2jit	documentation. See also	the jitstack modifier below for	a  way
       of setting the size of the JIT stack.

       If  the	jitfast	 modifier is specified,	matching is done using the JIT
       "fast path" interface, pcre2_jit_match(), which skips some of the  san-
       ity  checks that	are done by pcre2_match(), and of course does not work
       when JIT	is not supported. If jitfast is	specified without  jit,	 jit=7
       is assumed.

       If  the jitverify modifier is specified,	information about the compiled
       pattern shows whether JIT compilation was or  was  not  successful.  If
       jitverify  is  specified	without	jit, jit=7 is assumed. If JIT compila-
       tion is successful when jitverify is set, the text "(JIT)" is added  to
       the first output	line after a match or non match	when JIT-compiled code
       was actually used in the	match.

   Setting a locale

       The locale modifier must	specify	the name of a locale, for example:

	 /pattern/locale=fr_FR

       The given locale	is set,	pcre2_maketables() is called to	build a	set of
       character  tables for the locale, and this is then passed to pcre2_com-
       pile() when compiling the regular expression. The same tables are  used
       when  matching the following subject lines. The locale modifier applies
       only to the pattern on which it appears,	but can	be given in a #pattern
       command if a default is needed. Setting a locale	and alternate  charac-
       ter tables are mutually exclusive.

   Showing pattern memory

       The memory modifier causes the size in bytes of the memory used to hold
       the  compiled  pattern  to be output. This does not include the size of
       the pcre2_code block; it	is just	the actual compiled data. If the  pat-
       tern  is	 subsequently  passed to the JIT compiler, the size of the JIT
       compiled	code is	also output. Here is an	example:

	   re> /a(b)c/jit,memory
	 Memory	allocation (code space): 21
	 Memory	allocation (JIT	code): 1910

   Limiting nested parentheses

       The parens_nest_limit modifier sets a limit  on	the  depth  of	nested
       parentheses  in a pattern. Breaching the	limit causes a compilation er-
       ror.  The default for the library is  set  when	PCRE2  is  built,  but
       pcre2test  sets	its  own default of 220, which is required for running
       the standard test suite.

   Limiting the	pattern	length

       The max_pattern_length modifier sets a limit, in	 code  units,  to  the
       length of pattern that pcre2_compile() will accept. Breaching the limit
       causes  a  compilation  error.  The  default  is	 the  largest number a
       PCRE2_SIZE variable can hold (essentially unlimited).

   Limiting the	size of	a compiled pattern

       The max_pattern_compiled_length modifier	sets a limit, in bytes,	to the
       amount of memory	used by	a compiled pattern. Breaching the limit	causes
       a compilation error. The	default	is the	largest	 number	 a  PCRE2_SIZE
       variable	can hold (essentially unlimited).

   Using the POSIX wrapper API

       The  posix  and posix_nosub modifiers cause pcre2test to	call PCRE2 via
       the POSIX wrapper API rather than its native API. When  posix_nosub  is
       used,  the  POSIX  option  REG_NOSUB  is	passed to regcomp(). The POSIX
       wrapper supports	only the 8-bit library.	Note that it  does  not	 imply
       POSIX matching semantics; for more detail see the pcre2posix documenta-
       tion.  The  following  pattern  modifiers set options for the regcomp()
       function:

	 caseless	    REG_ICASE
	 multiline	    REG_NEWLINE
	 dotall		    REG_DOTALL	   )
	 ungreedy	    REG_UNGREEDY   ) These options are not part	of
	 ucp		    REG_UCP	   )   the POSIX standard
	 utf		    REG_UTF8	   )

       The regerror_buffsize modifier specifies	a size for  the	 error	buffer
       that  is	 passed	to regerror() in the event of a	compilation error. For
       example:

	 /abc/posix,regerror_buffsize=20

       This provides a means of	testing	the behaviour of regerror()  when  the
       buffer  is  too	small  for the error message. If this modifier has not
       been set, a large buffer	is used.

       The aftertext and allaftertext subject modifiers	work as	described  be-
       low. All	other modifiers	are either ignored, with a warning message, or
       cause an	error.

       The  pattern  is	passed to regcomp() as a zero-terminated string	by de-
       fault, but if the use_length or hex modifiers are set, the REG_PEND ex-
       tension is used to pass it by length.

   Testing the stack guard feature

       The stackguard modifier is used	to  test  the  use  of	pcre2_set_com-
       pile_recursion_guard(),	a  function  that  is provided to enable stack
       availability to be checked during compilation (see the  pcre2api	 docu-
       mentation  for  details).  If  the  number specified by the modifier is
       greater than zero, pcre2_set_compile_recursion_guard() is called	to set
       up callback from	pcre2_compile()	to a local function. The  argument  it
       receives	 is  the current nesting parenthesis depth; if this is greater
       than the	value given by the modifier, non-zero is returned, causing the
       compilation to be aborted.

   Using alternative character tables

       The value specified for the tables modifier must	be one of  the	digits
       0, 1, 2,	or 3. It causes	a specific set of built-in character tables to
       be  passed to pcre2_compile(). This is used in the PCRE2	tests to check
       behaviour with different	character tables. The digit specifies the  ta-
       bles as follows:

	 0   do	not pass any special character tables
	 1   the default ASCII tables, as distributed in
	       pcre2_chartables.c.dist
	 2   a set of tables defining ISO 8859 characters
	 3   a set of tables loaded by the #loadtables command

       In tables 2, some characters whose codes	are greater than 128 are iden-
       tified as letters, digits, spaces, etc. Tables 3	can be used only after
       a  #loadtables  command has loaded them from a binary file. Setting al-
       ternate character tables	and a locale are mutually exclusive.

   Setting certain match controls

       The following modifiers are really subject modifiers, and are described
       under "Subject Modifiers" below.	However, they may  be  included	 in  a
       pattern's  modifier  list, in which case	they are applied to every sub-
       ject line that is processed with	that pattern. These modifiers  do  not
       affect the compilation process.

	     aftertext			 show text after match
	     allaftertext		 show text after captures
	     allcaptures		 show all captures
	     allvector			 show the entire ovector
	     allusedtext		 show all consulted text
	     altglobal			 alternative global matching
	 /g  global			 global	matching
	     heapframes_size		 show match data heapframes size
	     jitstack=<n>		 set size of JIT stack
	     mark			 show mark values
	     replace=<string>		 specify a replacement string
	     startchar			 show starting character when relevant
	     substitute_callout		 use substitution callouts
	     substitute_case_callout	 use substitution case callouts
	     substitute_extended	 use PCRE2_SUBSTITUTE_EXTENDED
	     substitute_literal		 use PCRE2_SUBSTITUTE_LITERAL
	     substitute_matched		 use PCRE2_SUBSTITUTE_MATCHED
	     substitute_overflow_length	 use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
	     substitute_replacement_only use PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
	     substitute_skip=<n>	 skip substitution <n>
	     substitute_stop=<n>	 skip substitution <n> and following
	     substitute_unknown_unset	 use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
	     substitute_unset_empty	 use PCRE2_SUBSTITUTE_UNSET_EMPTY

       These  modifiers	may not	appear in a #pattern command. If you want them
       as defaults, set	them in	a #subject command.

   Specifying literal subject lines

       If the subject_literal modifier is present on a pattern,	all  the  sub-
       ject lines that it matches are taken as literal strings,	with no	inter-
       pretation  of  backslashes. It is not possible to set subject modifiers
       on such lines, but any that are set as defaults by a  #subject  command
       are recognized.

   Saving a compiled pattern

       When  a	pattern	with the push modifier is successfully compiled, it is
       pushed onto a stack of compiled patterns,  and  pcre2test  expects  the
       next  line to contain a new pattern (or a command) instead of a subject
       line. This facility is used when	saving compiled	patterns to a file, as
       described in the	section	entitled "Saving and restoring	compiled  pat-
       terns"  below.  If pushcopy is used instead of push, a copy of the com-
       piled pattern is	stacked, leaving the original  as  current,  ready  to
       match  the  following  input  lines. This provides a way	of testing the
       pcre2_code_copy() function.  The	push and pushcopy  modifiers  are  in-
       compatible  with	compilation modifiers such as global that act at match
       time. Any that are specified are	ignored	(for the stacked copy),	with a
       warning message,	except for replace, which causes an error.  Note  that
       jitverify,  which  is allowed, does not carry through to	any subsequent
       matching	that uses a stacked pattern.

   Testing foreign pattern conversion

       The experimental	foreign	pattern	conversion functions in	PCRE2  can  be
       tested  by  setting the convert modifier. Its argument is a colon-sepa-
       rated list  of  options,	 which	set  the  equivalent  option  for  the
       pcre2_pattern_convert() function:

	 glob			 PCRE2_CONVERT_GLOB
	 glob_no_starstar	 PCRE2_CONVERT_GLOB_NO_STARSTAR
	 glob_no_wild_separator	 PCRE2_CONVERT_GLOB_NO_WILD_SEPARATOR
	 posix_basic		 PCRE2_CONVERT_POSIX_BASIC
	 posix_extended		 PCRE2_CONVERT_POSIX_EXTENDED
	 unset			 Unset all options

       The "unset" value is useful for turning off a default that has been set
       by a #pattern command. When one of these	options	is set,	the input pat-
       tern  is	 passed	 to pcre2_pattern_convert(). If	the conversion is suc-
       cessful,	the result is reflected	in  the	 output	 and  then  passed  to
       pcre2_compile().	The normal utf and no_utf_check	options, if set, cause
       the  PCRE2_CONVERT_UTF  and  PCRE2_CONVERT_NO_UTF_CHECK	options	 to be
       passed to pcre2_pattern_convert().

       By default, the conversion function is allowed to allocate a buffer for
       its output. However, if the convert_length modifier is set to  a	 value
       greater	than zero, pcre2test passes a buffer of	the given length. This
       makes it	possible to test the length check.

       The convert_glob_escape and  convert_glob_separator  modifiers  can  be
       used  to	 specify the escape and	separator characters for glob process-
       ing, overriding the defaults, which are operating-system	dependent.

SUBJECT	MODIFIERS

       The modifiers that can appear in	subject	lines and the #subject command
       are of two types.

   Setting match options

       The   following	 modifiers   set   options   for   pcre2_match()    or
       pcre2_dfa_match(). See pcre2api for a description of their effects.

	     anchored			set PCRE2_ANCHORED
	     copy_matched_subject	set PCRE2_COPY_MATCHED_SUBJECT
	     endanchored		set PCRE2_ENDANCHORED
	     dfa_restart		set PCRE2_DFA_RESTART
	     dfa_shortest		set PCRE2_DFA_SHORTEST
	     disable_recurseloop_check	set PCRE2_DISABLE_RECURSELOOP_CHECK
	     no_jit			set PCRE2_NO_JIT
	     no_utf_check		set PCRE2_NO_UTF_CHECK
	     notbol			set PCRE2_NOTBOL
	     notempty			set PCRE2_NOTEMPTY
	     notempty_atstart		set PCRE2_NOTEMPTY_ATSTART
	     noteol			set PCRE2_NOTEOL
	     partial_hard (or ph)	set PCRE2_PARTIAL_HARD
	     partial_soft (or ps)	set PCRE2_PARTIAL_SOFT

       The  partial matching modifiers are provided with abbreviations because
       they appear frequently in tests.

       If the posix or posix_nosub modifier was	present	on the pattern,	 caus-
       ing the POSIX wrapper API to be used, the only option-setting modifiers
       that have any effect are	notbol,	notempty, and noteol, causing REG_NOT-
       BOL,  REG_NOTEMPTY,  and	 REG_NOTEOL,  respectively,  to	 be  passed to
       regexec(). The other modifiers are ignored, with	a warning message.

       There is	one additional modifier	that can be used with the POSIX	 wrap-
       per. It is ignored (with	a warning) if used for non-POSIX matching.

	     posix_startend=<n>[:<m>]

       This  causes  the  subject  string  to be passed	to regexec() using the
       REG_STARTEND option, which uses offsets to specify which	 part  of  the
       string  is  searched.  If  only	one number is given, the end offset is
       passed as the end of the	subject	string.	For more detail	 of  REG_STAR-
       TEND,  see the pcre2posix documentation.	If the subject string contains
       binary zeros (coded as escapes such as \x{00}  because  pcre2test  does
       not support actual binary zeros in its input), you must use posix_star-
       tend to specify its length.

   Setting match controls

       The  following  modifiers  affect the matching process or request addi-
       tional information. Some	of them	may also be  specified	on  a  pattern
       line  (see  above), in which case they apply to every subject line that
       is matched against that pattern,	but can	be overridden by modifiers  on
       the subject.

	     aftertext			show text after	match
	     allaftertext		show text after	captures
	     allcaptures		show all captures
	     allusedtext		show all consulted text	(non-JIT only)
	     allvector			show the entire	ovector
	     altglobal			alternative global matching
	     callout_capture		show captures at callout time
	     callout_data=<n>		set a value to pass via	callouts
	     callout_error=<n>[:<m>]	control	callout	error
	     callout_extra		show extra callout information
	     callout_fail=<n>[:<m>]	control	callout	failure
	     callout_no_where		do not show position of	a callout
	     callout_none		do not supply a	callout	function
	     copy=<number or name>	copy captured substring
	     depth_limit=<n>		set a depth limit
	     dfa			use pcre2_dfa_match()
	     find_limits		find heap, match and depth limits
	     find_limits_noheap		find match and depth limits
	     get=<number or name>	extract	captured substring
	     getall			extract	all captured substrings
	 /g  global			global matching
	     heapframes_size		show match data	heapframes size
	     heap_limit=<n>		set a limit on heap memory (Kbytes)
	     jitstack=<n>		set size of JIT	stack
	     mark			show mark values
	     match_limit=<n>		set a match limit
	     memory			show heap memory usage
	     null_context		match with a NULL context
	     null_replacement		substitute with	NULL replacement
	     null_subject		match with NULL	subject
	     offset=<n>			set starting offset
	     offset_limit=<n>		set offset limit
	     ovector=<n>		set size of output vector
	     recursion_limit=<n>	obsolete synonym for depth_limit
	     replace=<string>		specify	a replacement string
	     startchar			show startchar when relevant
	     startoffset=<n>		same as	offset=<n>
	     substitute_callout		use substitution callouts
	     substitute_case_callout	use substitution case callouts
	     substitute_extended	use PCRE2_SUBSTITUTE_EXTENDED
	     substitute_literal		use PCRE2_SUBSTITUTE_LITERAL
	     substitute_matched		use PCRE2_SUBSTITUTE_MATCHED
	     substitute_overflow_length	use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
	     substitute_replacement_only use PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
	     substitute_skip=<n>	skip substitution number n
	     substitute_stop=<n>	skip substitution number n and greater
	     substitute_unknown_unset	use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
	     substitute_unset_empty	use PCRE2_SUBSTITUTE_UNSET_EMPTY
	     zero_terminate		pass the subject as zero-terminated

       The effects of these modifiers are described in the following sections.
       When  matching  via the POSIX wrapper API, the aftertext, allaftertext,
       and ovector subject modifiers work as described below. All other	 modi-
       fiers are either	ignored, with a	warning	message, or cause an error.

   Showing more	text

       The  aftertext modifier requests	that as	well as	outputting the part of
       the subject string that matched the entire pattern, pcre2test should in
       addition	output the remainder of	the subject string. This is useful for
       tests where the subject contains	multiple copies	of the same substring.
       The allaftertext	modifier requests the same action  for	captured  sub-
       strings as well as the main matched substring. In each case the remain-
       der is output on	the following line with	a plus character following the
       capture number.

       The  allusedtext	modifier requests that all the text that was consulted
       during a	successful pattern match by the	interpreter should  be	shown,
       for  both  full	and partial matches. This feature is not supported for
       JIT matching, and if requested with JIT it is ignored (with  a  warning
       message).  Setting this modifier	affects	the output if there is a look-
       behind at the start of a	match, or, for a complete match,  a  lookahead
       at the end, or if \K is used in the pattern. Characters that precede or
       follow  the start and end of the	actual match are indicated in the out-
       put by '<' or '>' characters underneath them.  Here is an example:

	   re> /(?<=pqr)abc(?=xyz)/
	 data> 123pqrabcxyz456\=allusedtext
	  0: pqrabcxyz
	     <<<   >>>
	 data> 123pqrabcxy\=ph,allusedtext
	 Partial match:	pqrabcxy
			<<<

       The first, complete match shows that the	matched	string is "abc",  with
       the  preceding  and  following strings "pqr" and	"xyz" having been con-
       sulted during the match (when processing	the assertions).  The  partial
       match can indicate only the preceding string.

       The  startchar  modifier	 requests  that	the starting character for the
       match be	indicated, if it is different to  the  start  of  the  matched
       string. The only	time when this occurs is when \K has been processed as
       part of the match. In this situation, the output	for the	matched	string
       is  displayed  from  the	 starting  character instead of	from the match
       point, with circumflex characters under the earlier characters. For ex-
       ample:

	   re> /abc\Kxyz/
	 data> abcxyz\=startchar
	  0: abcxyz
	     ^^^

       Unlike allusedtext, the startchar modifier can be used with JIT.	  How-
       ever, these two modifiers are mutually exclusive.

   Showing the value of	all capture groups

       The allcaptures modifier	requests that the values of all	potential cap-
       tured parentheses be output after a match. By default, only those up to
       the highest one actually	used in	the match are output (corresponding to
       the  return  code from pcre2_match()). Groups that did not take part in
       the match are output as "<unset>". This modifier	is  not	 relevant  for
       DFA  matching (which does no capturing) and does	not apply when replace
       is specified; it	is ignored, with a warning message, if present.

   Showing the entire ovector, for all outcomes

       The allvector modifier requests that the	entire ovector be shown, what-
       ever the	outcome	of the match. Compare allcaptures, which shows only up
       to the maximum number of	capture	groups for the pattern,	and then  only
       for  a successful complete non-DFA match. This modifier,	which acts af-
       ter any match result, and also for DFA matching,	provides  a  means  of
       checking	 that there are	no unexpected modifications to ovector fields.
       Before each match attempt, the ovector is filled	with a special	value,
       and  if	this  is  found	 in  both  elements of a capturing pair, "<un-
       changed>" is output. After a successful	match,	this  applies  to  all
       groups  after the maximum capture group for the pattern.	In other cases
       it applies to the entire	ovector. After a partial match,	the first  two
       elements	 are  the only ones that should	be set.	After a	DFA match, the
       amount of ovector that is used depends on the number  of	 matches  that
       were found.

   Testing pattern callouts

       A  callout function is supplied when pcre2test calls the	library	match-
       ing functions, unless callout_none is specified.	Its behaviour  can  be
       controlled  by  various	modifiers  listed above	whose names begin with
       callout_. Details are given in the section entitled  "Callouts"	below.
       Testing	callouts  from	pcre2_substitute()  is described separately in
       "Testing	the substitution function" below.

   Finding all matches in a string

       Searching for all possible matches within a subject can be requested by
       the global or altglobal modifier. After finding a match,	 the  matching
       function	 is  called  again to search the remainder of the subject. The
       difference between global and altglobal is that	the  former  uses  the
       start_offset  argument  to  pcre2_match() or pcre2_dfa_match() to start
       searching at a new point	within the entire string (which	is  what  Perl
       does), whereas the latter passes	over a shortened subject. This makes a
       difference to the matching process if the pattern begins	with a lookbe-
       hind assertion (including \b or \B).

       If  an  empty  string  is  matched,  the	 next  match  is done with the
       PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to	search
       for another, non-empty, match at	the same point in the subject. If this
       match fails, the	start offset is	advanced, and the normal match is  re-
       tried.  This imitates the way Perl handles such cases when using	the /g
       modifier	or the split() function. Normally, the	start  offset  is  ad-
       vanced  by one character, but if	the newline convention recognizes CRLF
       as a newline, and the current character is CR followed by  LF,  an  ad-
       vance of	two characters occurs.

   Testing substring extraction	functions

       The  copy  and  get  modifiers  can  be	used  to  test	the pcre2_sub-
       string_copy_xxx() and pcre2_substring_get_xxx() functions.  They	can be
       given more than once, and each can specify a capture group name or num-
       ber, for	example:

	  abcd\=copy=1,copy=3,get=G1

       If the #subject command is used to set default copy and/or  get	lists,
       these  can  be unset by specifying a negative number to cancel all num-
       bered groups and	an empty name to cancel	all named groups.

       The getall modifier tests  pcre2_substring_list_get(),  which  extracts
       all captured substrings.

       If  the	subject	line is	successfully matched, the substrings extracted
       by the convenience functions are	output with  C,	 G,  or	 L  after  the
       string  number  instead	of  a colon. This is in	addition to the	normal
       full list. The string length (that is, the return from  the  extraction
       function) is given in parentheses after each substring, followed	by the
       name when the extraction	was by name.

   Testing the substitution function

       If  the	replace	 modifier  is  set, the	pcre2_substitute() function is
       called instead of one of	the matching functions (or after one  call  of
       pcre2_match()  in  the case of PCRE2_SUBSTITUTE_MATCHED). Note that re-
       placement strings cannot	contain	commas,	because	a comma	signifies  the
       end  of	a  modifier. This is not thought to be an issue	in a test pro-
       gram.

       Specifying a completely empty replacement string	 disables  this	 modi-
       fier.   However,	it is possible to specify an empty replacement by pro-
       viding a	buffer length, as described below, for an otherwise empty  re-
       placement.

       Unlike  subject strings,	pcre2test does not process replacement strings
       for escape sequences. In	UTF mode, a replacement	string is  checked  to
       see  if it is a valid UTF-8 string. If so, it is	correctly converted to
       a UTF string of the appropriate code unit width.	If it is not  a	 valid
       UTF-8  string, the individual code units	are copied directly. This pro-
       vides a means of	passing	an invalid UTF-8 string	for testing purposes.

       The following modifiers set options (in additional to the normal	 match
       options)	for pcre2_substitute():

	 global			     PCRE2_SUBSTITUTE_GLOBAL
	 substitute_extended	     PCRE2_SUBSTITUTE_EXTENDED
	 substitute_literal	     PCRE2_SUBSTITUTE_LITERAL
	 substitute_matched	     PCRE2_SUBSTITUTE_MATCHED
	 substitute_overflow_length  PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
	 substitute_replacement_only PCRE2_SUBSTITUTE_REPLACEMENT_ONLY
	 substitute_unknown_unset    PCRE2_SUBSTITUTE_UNKNOWN_UNSET
	 substitute_unset_empty	     PCRE2_SUBSTITUTE_UNSET_EMPTY

       See the pcre2api	documentation for details of these options.

       After  a	 successful  substitution, the modified	string is output, pre-
       ceded by	the number of replacements. This may be	zero if	there were  no
       matches.	Here is	a simple example of a substitution test:

	 /abc/replace=xxx
	     =abc=abc=
	  1: =xxx=abc=
	     =abc=abc=\=global
	  2: =xxx=xxx=

       Subject	and replacement	strings	should be kept relatively short	(fewer
       than 256	characters) for	substitution tests, as fixed-size buffers  are
       used.  To  make it easy to test for buffer overflow, if the replacement
       string starts with a number in square brackets, that number  is	passed
       to  pcre2_substitute()  as  the size of the output buffer, with the re-
       placement string	starting at the	next character.	 Here  is  an  example
       that tests the edge case:

	 /abc/
	     123abc123\=replace=[10]XYZ
	  1: 123XYZ123
	     123abc123\=replace=[9]XYZ
	 Failed: error -47: no more memory

       The  default  action  of	 pcre2_substitute()  is	 to  return  PCRE2_ER-
       ROR_NOMEMORY when the output buffer  is	too  small.  However,  if  the
       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH	 option	 is  set (by using the substi-
       tute_overflow_length  modifier),	 pcre2_substitute()  continues	to  go
       through	the  motions  of  matching and substituting (but not doing any
       callouts), in order to compute the size of  buffer  that	 is  required.
       When  this  happens,  pcre2test shows the required buffer length	(which
       includes	space for the trailing zero) as	part of	the error message. For
       example:

	 /abc/substitute_overflow_length
	     123abc123\=replace=[9]XYZ
	 Failed: error -47: no more memory: 10 code units are needed

       A replacement string is ignored with POSIX and DFA matching. Specifying
       partial matching	provokes an error return  ("bad	 option	 value")  from
       pcre2_substitute().

   Testing substitute callouts

       If the substitute_callout modifier is set, a substitution callout func-
       tion  is	set up.	The null_context modifier must not be set, because the
       address of the callout function is passed in a match context. When  the
       callout	function  is  called (after each substitution),	details	of the
       input and output	strings	are output. For	example:

	 /abc/g,replace=<$0>,substitute_callout
	     abcdefabcpqr
	  1(1) Old 0 3 "abc" New 0 5 "<abc>"
	  2(1) Old 6 9 "abc" New 8 13 "<abc>"
	  2: <abc>def<abc>pqr

       The first number	on each	callout	line is	 the  count  of	 matches.  The
       parenthesized number is the number of pairs that	are set	in the ovector
       (that  is, one more than	the number of capturing	groups that were set).
       Then are	listed the offsets of the old substring, its contents, and the
       same for	the replacement.

       By default, the substitution callout function returns zero,  which  ac-
       cepts  the  replacement and causes matching to continue if /g was used.
       Two further modifiers can be used to test other return values. If  sub-
       stitute_skip  is	 set to	a value	greater	than zero the callout function
       returns +1 for the match	of that	number,	and similarly  substitute_stop
       returns	-1.  These cause the replacement to be rejected, and -1	causes
       no further matching to take place. If either of them are	 set,  substi-
       tute_callout is assumed.	For example:

	 /abc/g,replace=<$0>,substitute_skip=1
	     abcdefabcpqr
	  1(1) Old 0 3 "abc" New 0 5 "<abc> SKIPPED"
	  2(1) Old 6 9 "abc" New 6 11 "<abc>"
	  2: abcdef<abc>pqr
	     abcdefabcpqr\=substitute_stop=1
	  1(1) Old 0 3 "abc" New 0 5 "<abc> STOPPED"
	  1: abcdefabcpqr

       If both are set for the same number, stop takes precedence. Only	a sin-
       gle skip	or stop	is supported, which is sufficient for testing that the
       feature works.

   Testing substitute case callouts

       If  the	substitute_case_callout	 modifier  is set, a substitution case
       callout function	is set up. The callout function	 is  called  for  each
       substituted chunk which is to be	case-transformed.

       The callout function passed is a	fixed function with implementation for
       certain	behaviours:  inputs which shrink when case-transformed;	inputs
       which grow; inputs with distinct	upper/lower/titlecase forms. The char-
       acters which are	not special-cased for testing purposes are left	unmod-
       ified, as if they are caseless characters.

   Setting the JIT stack size

       The jitstack modifier provides a	way of setting the maximum stack  size
       that  is	 used  by the just-in-time optimization	code. It is ignored if
       JIT optimization	is not being used. The value is	a number of  kibibytes
       (units  of  1024	 bytes). Setting zero reverts to the default of	32KiB.
       Providing a stack that is larger	than the default is necessary only for
       very complicated	patterns. If jitstack is set  non-zero	on  a  subject
       line it overrides any value that	was set	on the pattern.

   Setting heap, match,	and depth limits

       The  heap_limit,	 match_limit, and depth_limit modifiers	set the	appro-
       priate limits in	the match context. These values	are ignored  when  the
       find_limits or find_limits_noheap modifier is specified.

   Finding minimum limits

       If  the	find_limits  modifier  is present on a subject line, pcre2test
       calls the relevant matching function several times,  setting  different
       values	 in    the    match    context	 via   pcre2_set_heap_limit(),
       pcre2_set_match_limit(),	or pcre2_set_depth_limit() until it finds  the
       smallest	 value	for  each  parameter that allows the match to complete
       without a "limit	exceeded" error. The match itself may succeed or fail.
       An alternative modifier,	find_limits_noheap, omits the heap limit. This
       is used in the standard tests, because the minimum  heap	 limit	varies
       between	systems.  If  JIT is being used, only the match	limit is rele-
       vant, and the other two are automatically omitted.

       When using this modifier, the pattern should not	contain	any limit set-
       tings such as (*LIMIT_MATCH=...)	 within	 it.  If  such	a  setting  is
       present and is lower than the minimum matching value, the minimum value
       cannot  be  found because pcre2_set_match_limit() etc. are only able to
       reduce the value	of an in-pattern limit;	they cannot increase it.

       For non-DFA matching, the minimum depth_limit number is	a  measure  of
       how much	nested backtracking happens (that is, how deeply the pattern's
       tree  is	 searched).  In	the case of DFA	matching, depth_limit controls
       the depth of recursive calls of the internal function that is used  for
       handling	pattern	recursion, lookaround assertions, and atomic groups.

       For non-DFA matching, the match_limit number is a measure of the	amount
       of backtracking that takes place, and learning the minimum value	can be
       instructive.  For  most	simple matches,	the number is quite small, but
       for patterns with very large numbers of matching	possibilities, it  can
       become  large very quickly with increasing length of subject string. In
       the case	of DFA matching, match_limit  controls	the  total  number  of
       calls, both recursive and non-recursive,	to the internal	matching func-
       tion, thus controlling the overall amount of computing resource that is
       used.

       For  both  kinds	 of  matching,	the  heap_limit	 number,  which	 is in
       kibibytes (units	of 1024	bytes),	limits the amount of heap memory  used
       for matching.

   Showing MARK	names

       The mark	modifier causes	the names from backtracking control verbs that
       are  returned from calls	to pcre2_match() to be displayed. If a mark is
       returned	for a match, non-match,	or partial match, pcre2test shows  it.
       For  a  match, it is on a line by itself, tagged	with "MK:". Otherwise,
       it is added to the non-match message.

   Showing memory usage

       The memory modifier causes pcre2test to log the sizes of	all heap  mem-
       ory   allocation	 and  freeing  calls  that  occur  during  a  call  to
       pcre2_match() or	pcre2_dfa_match(). In the latter case, heap memory  is
       used  only  when	 a match requires more internal	workspace that the de-
       fault allocation	on the stack, so in many cases there will be  no  out-
       put.  No	 heap  memory  is allocated during matching with JIT. For this
       modifier	to work, the null_context modifier must	not be set on both the
       pattern and the subject,	though it can be set on	one or the other.

   Showing the heap frame overall vector size

       The  heapframes_size   modifier	 is   relevant	 for   matches	 using
       pcre2_match() without JIT. After	a match	has run	(whether successful or
       not)  the  size,	 in bytes, of the allocated heap frames	vector that is
       left attached to	the match data block is	shown. If the matching	action
       involved	 several  calls	to pcre2_match() (for example, global matching
       or for timing) only the final value is shown.

       This modifier is	ignored, with a	warning, for POSIX  or	DFA  matching.
       JIT matching does not use the heap frames vector, so the	size is	always
       zero,  unless there was a previous non-JIT match. Note that specifing a
       size of zero for	the output vector (see below) causes pcre2test to free
       its match data block (and associated heap frames	vector)	and allocate a
       new one.

   Setting a starting offset

       The offset modifier sets	an offset  in  the  subject  string  at	 which
       matching	starts.	Its value is a number of code units, not characters.

   Setting an offset limit

       The  offset_limit  modifier  sets  a limit for unanchored matches. If a
       match cannot be found starting at or before this	offset in the subject,
       a "no match" return is given. The data value is a number	of code	units,
       not characters. When this modifier is used, the use_offset_limit	 modi-
       fier must have been set for the pattern;	if not,	an error is generated.

   Setting the size of the output vector

       The  ovector  modifier applies only to the subject line in which	it ap-
       pears, though of	course it can also be used to set a default in a #sub-
       ject command. It	specifies the number of	 pairs	of  offsets  that  are
       available for storing matching information. The default is 15.

       A  value	of zero	is useful when testing the POSIX API because it	causes
       regexec() to be called with a NULL capture vector. When not testing the
       POSIX API, a value of  zero  is	used  to  cause	 pcre2_match_data_cre-
       ate_from_pattern()  to  be called, in order to create a new match block
       of exactly the right size for the pattern. (It is not possible to  cre-
       ate  a match block with a zero-length ovector; there is always at least
       one pair	of offsets.) The old match data	block is freed.

   Passing the subject as zero-terminated

       By default, the subject string is passed	to a native API	matching func-
       tion with its correct length. In	order to test the facility for passing
       a zero-terminated string, the zero_terminate modifier is	 provided.  It
       causes  the length to be	passed as PCRE2_ZERO_TERMINATED. When matching
       via the POSIX interface,	this modifier is ignored, with a warning.

       When testing pcre2_substitute(),	this modifier also has the  effect  of
       passing the replacement string as zero-terminated.

   Passing a NULL context, subject, or replacement

       Normally,   pcre2test   passes	a   context  block  to	pcre2_match(),
       pcre2_dfa_match(), pcre2_jit_match()  or	 pcre2_substitute().   If  the
       null_context  modifier  is  set,	 however,  NULL	is passed. This	is for
       testing that the	matching and substitution functions  behave  correctly
       in  this	 case  (they use default values). This modifier	cannot be used
       with the	find_limits, find_limits_noheap, or  substitute_callout	 modi-
       fiers.

       Similarly,  for	testing	purposes, if the null_subject or null_replace-
       ment modifier is	set, the subject or replacement	 string	 pointers  are
       passed as NULL, respectively, to	the relevant functions.

THE ALTERNATIVE	MATCHING FUNCTION

       By  default,  pcre2test	uses  the  standard  PCRE2  matching function,
       pcre2_match() to	match each subject line. PCRE2 also supports an	alter-
       native matching function, pcre2_dfa_match(), which operates in  a  dif-
       ferent  way, and	has some restrictions. The differences between the two
       functions are described in the pcre2matching documentation.

       If the dfa modifier is set, the alternative matching function is	 used.
       This  function  finds all possible matches at a given point in the sub-
       ject. If, however, the dfa_shortest modifier is set,  processing	 stops
       after  the  first  match	is found. This is always the shortest possible
       match.

DEFAULT	OUTPUT FROM pcre2test

       This section describes the output when the  normal  matching  function,
       pcre2_match(), is being used.

       When  a	match  succeeds,  pcre2test  outputs the list of captured sub-
       strings,	starting with number 0 for the string that matched  the	 whole
       pattern.	 Otherwise, it outputs "No match" when the return is PCRE2_ER-
       ROR_NOMATCH,  or	 "Partial  match:"  followed by	the partially matching
       substring when the return is PCRE2_ERROR_PARTIAL. (Note	that  this  is
       the  entire  substring  that was	inspected during the partial match; it
       may include characters before the actual	match start  if	 a  lookbehind
       assertion, \K, \b, or \B	was involved.)

       For any other return, pcre2test outputs the PCRE2 negative error	number
       and  a  short  descriptive  phrase. If the error	is a failed UTF	string
       check, the code unit offset of the start	of the	failing	 character  is
       also output. Here is an example of an interactive pcre2test run.

	 $ pcre2test
	 PCRE2 version 10.22 2016-07-29

	   re> /^abc(\d+)/
	 data> abc123
	  0: abc123
	  1: 123
	 data> xyz
	 No match

       Unset capturing substrings that are not followed	by one that is set are
       not shown by pcre2test unless the allcaptures modifier is specified. In
       the following example, there are	two capturing substrings, but when the
       first  data  line is matched, the second, unset substring is not	shown.
       An "internal" unset substring is	shown as "<unset>", as for the	second
       data line.

	   re> /(a)|(b)/
	 data> a
	  0: a
	  1: a
	 data> b
	  0: b
	  1: <unset>
	  2: b

       If  the strings contain any non-printing	characters, they are output as
       \xhh escapes if the value is less than 256 and UTF  mode	 is  not  set.
       Otherwise they are output as \x{hh...} escapes. See below for the defi-
       nition  of  non-printing	 characters. If	the aftertext modifier is set,
       the output for substring	0 is followed  by  the	rest  of  the  subject
       string, identified by "0+" like this:

	   re> /cat/aftertext
	 data> cataract
	  0: cat
	  0+ aract

       If global matching is requested,	the results of successive matching at-
       tempts are output in sequence, like this:

	   re> /\Bi(\w\w)/g
	 data> Mississippi
	  0: iss
	  1: ss
	  0: iss
	  1: ss
	  0: ipp
	  1: pp

       "No  match" is output only if the first match attempt fails. Here is an
       example of a failure message (the offset	4 that	is  specified  by  the
       offset modifier is past the end of the subject string):

	   re> /xyz/
	 data> xyz\=offset=4
	 Error -24 (bad	offset value)

       Note that whereas patterns can be continued over	several	lines (a plain
       ">"  prompt  is used for	continuations),	subject	lines may not. However
       newlines	can be included	in a subject by	means of the \n	escape (or \r,
       \r\n, etc., depending on	the newline sequence setting).

OUTPUT FROM THE	ALTERNATIVE MATCHING FUNCTION

       When the	alternative matching function, pcre2_dfa_match(), is used, the
       output consists of a list of all	the matches that start	at  the	 first
       point in	the subject where there	is at least one	match. For example:

	   re> /(tang|tangerine|tan)/
	 data> yellow tangerine\=dfa
	  0: tangerine
	  1: tang
	  2: tan

       Using  the normal matching function on this data	finds only "tang". The
       longest matching	string is always given first (and numbered zero).  Af-
       ter  a PCRE2_ERROR_PARTIAL return, the output is	"Partial match:", fol-
       lowed by	the partially matching substring. Note that this is the	entire
       substring that was inspected during the partial match; it  may  include
       characters before the actual match start	if a lookbehind	assertion, \b,
       or \B was involved. (\K is not supported	for DFA	matching.)

       If global matching is requested,	the search for further matches resumes
       at the end of the longest match.	For example:

	   re> /(tang|tangerine|tan)/g
	 data> yellow tangerine	and tangy sultana\=dfa
	  0: tangerine
	  1: tang
	  2: tan
	  0: tang
	  1: tan
	  0: tan

       The  alternative	 matching function does	not support substring capture,
       so the modifiers	that are concerned with	captured  substrings  are  not
       relevant.

RESTARTING AFTER A PARTIAL MATCH

       When  the  alternative matching function	has given the PCRE2_ERROR_PAR-
       TIAL return, indicating that the	subject	partially matched the pattern,
       you can restart the match with additional subject data by means of  the
       dfa_restart modifier. For example:

	   re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
	 data> 23ja\=ps,dfa
	 Partial match:	23ja
	 data> n05\=dfa,dfa_restart
	  0: n05

       For  further  information  about	partial	matching, see the pcre2partial
       documentation.

CALLOUTS

       If the pattern contains any callout requests, pcre2test's callout func-
       tion is called during matching unless callout_none is  specified.  This
       works with both matching	functions, and with JIT, though	there are some
       differences  in behaviour. The output for callouts with numerical argu-
       ments and those with string arguments is	slightly different.

   Callouts with numerical arguments

       By default, the callout function	displays the callout number, the start
       and current positions in	the subject text at the	callout	time, and  the
       next pattern item to be tested. For example:

	 --->pqrabcdef
	   0	^  ^	 \d

       This  output  indicates	that callout number 0 occurred for a match at-
       tempt starting at the fourth character of the subject string, when  the
       pointer	was  at	 the seventh character,	and when the next pattern item
       was \d. Just one	circumflex is output if	the start  and	current	 posi-
       tions are the same, or if the current position precedes the start posi-
       tion, which can happen if the callout is	in a lookbehind	assertion.

       Callouts	numbered 255 are assumed to be automatic callouts, inserted as
       a result	of the auto_callout pattern modifier. In this case, instead of
       showing	the  callout  number, the offset in the	pattern, preceded by a
       plus, is	output.	For example:

	   re> /\d?[A-E]\*/auto_callout
	 data> E*
	 --->E*
	  +0 ^	    \d?
	  +3 ^	    [A-E]
	  +8 ^^	    \*
	 +10 ^ ^
	  0: E*

       If a pattern contains (*MARK) items, an additional line is output when-
       ever a change of	latest mark is passed to the callout function. For ex-
       ample:

	   re> /a(*MARK:X)bc/auto_callout
	 data> abc
	 --->abc
	  +0 ^	     a
	  +1 ^^	     (*MARK:X)
	 +10 ^^	     b
	 Latest	Mark: X
	 +11 ^ ^     c
	 +12 ^	^
	  0: abc

       The mark	changes	between	matching "a" and "b", but stays	the  same  for
       the  rest  of  the match, so nothing more is output. If,	as a result of
       backtracking, the mark reverts to being unset, the  text	 "<unset>"  is
       output.

   Callouts with string	arguments

       The output for a	callout	with a string argument is similar, except that
       instead	of outputting a	callout	number before the position indicators,
       the callout string and its offset in the	pattern	string are output  be-
       fore  the  reflection  of the subject string, and the subject string is
       reflected for each callout. For example:

	   re> /^ab(?C'first')cd(?C"second")ef/
	 data> abcdefg
	 Callout (7): 'first'
	 --->abcdefg
	     ^ ^	 c
	 Callout (20): "second"
	 --->abcdefg
	     ^	 ^	 e
	  0: abcdef

   Callout modifiers

       The callout function in pcre2test returns zero (carry on	 matching)  by
       default,	 but  you can use a callout_fail modifier in a subject line to
       change this and other parameters	of the callout (see below).

       If the callout_capture modifier is set, the current captured groups are
       output when a callout occurs. This is useful only for non-DFA matching,
       as pcre2_dfa_match() does not support capturing,	 so  no	 captures  are
       ever shown.

       The normal callout output, showing the callout number or	pattern	offset
       (as  described above) is	suppressed if the callout_no_where modifier is
       set.

       When using the interpretive  matching  function	pcre2_match()  without
       JIT,  setting  the callout_extra	modifier causes	additional output from
       pcre2test's callout function to be generated. For the first callout  in
       a  match	 attempt at a new starting position in the subject, "New match
       attempt"	is output. If there has	been a backtrack since the last	 call-
       out (or start of	matching if this is the	first callout),	"Backtrack" is
       output,	followed  by  "No other	matching paths"	if the backtrack ended
       the previous match attempt. For example:

	  re> /(a+)b/auto_callout,no_start_optimize,no_auto_possess
	 data> aac\=callout_extra
	 New match attempt
	 --->aac
	  +0 ^	     (
	  +1 ^	     a+
	  +3 ^ ^     )
	  +4 ^ ^     b
	 Backtrack
	 --->aac
	  +3 ^^	     )
	  +4 ^^	     b
	 Backtrack
	 No other matching paths
	 New match attempt
	 --->aac
	  +0  ^	     (
	  +1  ^	     a+
	  +3  ^^     )
	  +4  ^^     b
	 Backtrack
	 No other matching paths
	 New match attempt
	 --->aac
	  +0   ^     (
	  +1   ^     a+
	 Backtrack
	 No other matching paths
	 New match attempt
	 --->aac
	  +0	^    (
	  +1	^    a+
	 No match

       Notice that various optimizations must be turned	off if	you  want  all
       possible	 matching  paths  to  be  scanned. If no_start_optimize	is not
       used, there is an immediate "no match", without any  callouts,  because
       the  starting  optimization  fails to find "b" in the subject, which it
       knows must be present for any match. If no_auto_possess	is  not	 used,
       the  "a+"  item is turned into "a++", which reduces the number of back-
       tracks.

       The callout_extra modifier has no effect	if used	with the DFA  matching
       function, or with JIT.

   Return values from callouts

       The  default  return  from  the	callout	function is zero, which	allows
       matching	to continue. The callout_fail modifier can be given one	or two
       numbers.	If there is only one number, 1 is returned instead of 0	(caus-
       ing matching to backtrack) when a callout of that number	is reached. If
       two numbers (<n>:<m>) are given,	1 is  returned	when  callout  <n>  is
       reached	and  there  have been at least <m> callouts. The callout_error
       modifier	is similar, except that	PCRE2_ERROR_CALLOUT is returned, caus-
       ing the entire matching process to be aborted. If both these  modifiers
       are  set	 for  the same callout number, callout_error takes precedence.
       Note that callouts with string arguments	are always  given  the	number
       zero.

       The  callout_data  modifier can be given	an unsigned or a negative num-
       ber.  This is set as the	"user data" that is  passed  to	 the  matching
       function,  and  passed  back  when the callout function is invoked. Any
       value other than	zero is	used as	 a  return  from  pcre2test's  callout
       function.

       Inserting callouts can be helpful when using pcre2test to check compli-
       cated  regular expressions. For further information about callouts, see
       the pcre2callout	documentation.

NON-PRINTING CHARACTERS

       When pcre2test is outputting text in the	compiled version of a pattern,
       bytes other than	32-126 are always treated as  non-printing  characters
       and are therefore shown as hex escapes.

       When  pcre2test	is outputting text that	is a matched part of a subject
       string, it behaves in the same way, unless a different locale has  been
       set  for	the pattern (using the locale modifier). In this case, the is-
       print() function	is used	to distinguish printing	and non-printing char-
       acters.

SAVING AND RESTORING COMPILED PATTERNS

       It is possible to save compiled patterns	on disc	or elsewhere, and  re-
       load  them  later, subject to a number of restrictions. JIT data	cannot
       be saved. The host on which the patterns	are reloaded must  be  running
       the same	version	of PCRE2, with the same	code unit width, and must also
       have  the  same	endianness,  pointer width and PCRE2_SIZE type.	Before
       compiled	patterns can be	saved they must	be serialized, that  is,  con-
       verted  to a stream of bytes. A single byte stream may contain any num-
       ber of compiled patterns, but they must all use the same	character  ta-
       bles.  A	 single	copy of	the tables is included in the byte stream (its
       size is 1088 bytes).

       The functions whose names begin with pcre2_serialize_ are used for  se-
       rializing  and de-serializing. They are described in the	pcre2serialize
       documentation. In this section we describe the  features	 of  pcre2test
       that can	be used	to test	these functions.

       Note  that  "serialization" in PCRE2 does not convert compiled patterns
       to an abstract format like Java or .NET.	It  just  makes	 a  reloadable
       byte code stream.  Hence	the restrictions on reloading mentioned	above.

       In  pcre2test,  when  a pattern with push modifier is successfully com-
       piled, it is pushed onto	a stack	of compiled  patterns,	and  pcre2test
       expects	the next line to contain a new pattern (or command) instead of
       a subject line. By contrast, the	pushcopy modifier causes a copy	of the
       compiled	pattern	to be stacked, leaving the original available for  im-
       mediate	matching.  By using push and/or	pushcopy, a number of patterns
       can be compiled and retained. These  modifiers  are  incompatible  with
       posix, and control modifiers that act at	match time are ignored (with a
       message)	 for the stacked patterns. The jitverify modifier applies only
       at compile time.

       The command

	 #save <filename>

       causes all the stacked patterns to be serialized	and the	result written
       to the named file. Afterwards, all the stacked patterns are freed.  The
       command

	 #load <filename>

       reads  the  data	in the file, and then arranges for it to be de-serial-
       ized, with the resulting	compiled patterns added	to the pattern	stack.
       The  pattern  on	the top	of the stack can be retrieved by the #pop com-
       mand, which must	be followed by	lines  of  subjects  that  are	to  be
       matched	with  the pattern, terminated as usual by an empty line	or end
       of file.	This command may be followed by	 a  modifier  list  containing
       only  control  modifiers	that act after a pattern has been compiled. In
       particular, hex,	posix, posix_nosub, push, and  pushcopy	 are  not  al-
       lowed,  nor  are	 any option-setting modifiers.	The JIT	modifiers are,
       however permitted. Here is an example that saves	and reloads  two  pat-
       terns.

	 /abc/push
	 /xyz/push
	 #save tempfile
	 #load tempfile
	 #pop info
	 xyz

	 #pop jit,bincode
	 abc

       If  jitverify  is  used with #pop, it does not automatically imply jit,
       which is	different behaviour from when it is used on a pattern.

       The #popcopy command is analogous to the	pushcopy modifier in  that  it
       makes current a copy of the topmost stack pattern, leaving the original
       still on	the stack.

SEE ALSO

       pcre2(3),  pcre2api(3),	pcre2callout(3),  pcre2jit,  pcre2matching(3),
       pcre2partial(d),	pcre2pattern(3), pcre2serialize(3).

AUTHOR

       Philip Hazel
       Retired from University Computing Service
       Cambridge, England.

REVISION

       Last updated: 26	December 2024
       Copyright (c) 1997-2024 University of Cambridge.

PCRE2 10.45		       26 December 2024			  PCRE2TEST(1)

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