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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.

       As the original fairly simple PCRE library evolved,  it	acquired  many
       different  features,  and  as  a	 result, the original pcretest program
       ended up	with a lot of options in a messy, arcane  syntax  for  testing
       all the features. The move to the new PCRE2 API provided	an opportunity
       to re-implement the test	program	as pcre2test, with a cleaner  modifier
       syntax.	Nevertheless,  there are still many obscure modifiers, some of
       which are specifically designed 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 li-
       braries.

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, pcre_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  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 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 characters	as hexadecimal pairs, which makes it possible  to  in-
       clude 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, backslash	escapes	can be
       used. In	addition, when the utf modifier	(see "Setting compilation  op-
       tions"  below)  is set, the pattern and any following subject lines are
       interpreted as UTF-8 strings and	translated to UTF-16 or	UTF-32 as  ap-
       propriate.

       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. This	is the
       only way	of passing such	code points in a pattern string.  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	only the 16-bit	library	has 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 only the 32-bit library has been built, this
		 is the	default. If the	32-bit library	has  not  been	built,
		 this option 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:
				0x15 or	0x25
				0 if used in an	ASCII 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

		 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 -LM 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 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, this does not	affect
       its interpretation. If the terminating delimiter	 is  immediately  fol-
       lowed by	a backslash, for example,

	 /abc/\

       then  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()   or
       pcre2_dfa_match(), leading and trailing white space is removed, and the
       line is scanned for backslash escapes, unless the subject_literal modi-
       fier was	set for	the pattern. The following provide a means of encoding
       non-printing characters in a visible way:

	 \a	    alarm (BEL,	\x07)
	 \b	    backspace (\x08)
	 \e	    escape (\x27)
	 \f	    form feed (\x0c)
	 \n	    newline (\x0a)
	 \r	    carriage return (\x0d)
	 \t	    tab	(\x09)
	 \v	    vertical tab (\x0b)
	 \nnn	    octal character (up	to 3 octal digits); always
		      a	byte unless > 255 in UTF-8 or 16-bit or	32-bit mode
	 \o{dd...}  octal character (any number	of octal digits}
	 \xhh	    hexadecimal	byte (up to 2 hex digits)
	 \x{hh...}  hexadecimal	character (any number of hex digits)

       The use of \x{hh...} is not dependent on	the use	of the utf modifier on
       the pattern. It is recognized always. There may be any number of	 hexa-
       decimal	digits	inside	the  braces; invalid values provoke error mes-
       sages.

       Note that \xhh specifies	one byte rather	than one  character  in	 UTF-8
       mode;  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, generating more than one byte if the value is
       greater than 127.  When testing the 8-bit library not  in  UTF-8	 mode,
       \x{hh} generates	one byte for values less than 256, and causes an error
       for greater values.

       In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
       possible	to construct invalid UTF-16 sequences for testing purposes.

       In  UTF-32  mode,  all  4- to 8-digit \x{...} values are	accepted. This
       makes it	possible to construct invalid  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.	For the	main options, there are	some single-letter ab-
       breviations that	are the	same as	Perl options. There  is	 special  han-
       dling  for  /x:	if  a second x is present, PCRE2_EXTENDED is converted
       into PCRE2_EXTENDED_MORE	as in Perl. A third appearance adds  PCRE2_EX-
       TENDED  as  well, though	this makes no difference to the	way pcre2_com-
       pile() behaves. See pcre2api for	a description of the effects of	 these
       options.

	     allow_empty_class	       set PCRE2_ALLOW_EMPTY_CLASS
	     allow_surrogate_escapes   set PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
	     alt_bsux		       set PCRE2_ALT_BSUX
	     alt_circumflex	       set PCRE2_ALT_CIRCUMFLEX
	     alt_verbnames	       set PCRE2_ALT_VERBNAMES
	     anchored		       set PCRE2_ANCHORED
	     auto_callout	       set PCRE2_AUTO_CALLOUT
	     bad_escape_is_literal     set PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
	 /i  caseless		       set PCRE2_CASELESS
	     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_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_dotstar_anchor	       set PCRE2_NO_DOTSTAR_ANCHOR
	     no_start_optimize	       set PCRE2_NO_START_OPTIMIZE
	     no_utf_check	       set PCRE2_NO_UTF_CHECK
	     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.

   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.

	     bsr=[anycrlf|unicode]     specify \R handling
	 /B  bincode		       show binary code	without	lengths
	     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
	     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_length=<n>    set the maximum pattern length
	     memory		       show memory used
	     newline=<type>	       set newline type
	     null_context	       compile with a NULL context
	     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
	     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 the	storage	frames
       used by pcre2_match() for handling backtracking.	The  size  depends  on
       the number of capturing parentheses in the pattern.

       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).

   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 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).

   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
	     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_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 pcreapi for a description	of their effects.

	     anchored		       set PCRE2_ANCHORED
	     endanchored	       set PCRE2_ENDANCHORED
	     dfa_restart	       set PCRE2_DFA_RESTART
	     dfa_shortest	       set PCRE2_DFA_SHORTEST
	     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.

	     aftertext			show text after	match
	     allaftertext		show text after	captures
	     allcaptures		show all captures
	     allvector			show the entire	ovector
	     allusedtext		show all consulted text	(non-JIT only)
	     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 match and depth limits
	     get=<number or name>	extract	captured substring
	     getall			extract	all captured substrings
	 /g  global			global matching
	     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
	     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_extedded	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	decribed 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.

       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
       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.

   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 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
       minimum	values	for  each  parameter that allows the match to complete
       without error. If JIT is	being used, only the match limit is relevant.

       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. A value of	zero disables the use of any heap memory; many
       simple  pattern	matches	can be done without using the heap, so zero is
       not an unreasonable setting.

   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(). These occur only when a  match  re-
       quires  a  bigger  vector than the default for remembering backtracking
       points (pcre2_match()) or for internal  workspace  (pcre2_dfa_match()).
       In  many	cases there will be no heap memory used	and therefore no addi-
       tional output. No heap memory is	allocated during matching with JIT, so
       in  that	 case the memory modifier never	has any	effect.	For this modi-
       fier 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.

   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  match  block  of
       exactly the right size for the pattern. (It is not possible to create a
       match block with	a zero-length ovector; there is	always	at  least  one
       pair of offsets.)

   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

       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 or substitute_callout modifiers.

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 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
       reload 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 analagous 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
       University Computing Service
       Cambridge, England.

REVISION

       Last updated: 14	September 2020
       Copyright (c) 1997-2020 University of Cambridge.

PCRE 10.36		       14 September 2020		  PCRE2TEST(1)

NAME | SYNOPSIS | PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES | INPUT ENCODING | COMMAND LINE OPTIONS | DESCRIPTION | COMMAND LINES | MODIFIER SYNTAX | PATTERN SYNTAX | SUBJECT LINE SYNTAX | PATTERN MODIFIERS | SUBJECT MODIFIERS | THE ALTERNATIVE MATCHING FUNCTION | DEFAULT OUTPUT FROM pcre2test | OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION | RESTARTING AFTER A PARTIAL MATCH | CALLOUTS | NON-PRINTING CHARACTERS | SAVING AND RESTORING COMPILED PATTERNS | SEE ALSO | AUTHOR | REVISION

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