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<h1>pcre2test man page</h1>

Return to the <a href="index.html">PCRE2 index page</a>.


This page is part of the PCRE2 HTML documentation. It was generated
automatically from the original man page. If there is any nonsense in it,
please consult the man page, in case the conversion went wrong.
 
<ul>
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
<li><a name="TOC2" href="#SEC2">PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a>
<li><a name="TOC3" href="#SEC3">INPUT ENCODING</a>
<li><a name="TOC4" href="#SEC4">COMMAND LINE OPTIONS</a>
<li><a name="TOC5" href="#SEC5">DESCRIPTION</a>
<li><a name="TOC6" href="#SEC6">COMMAND LINES</a>
<li><a name="TOC7" href="#SEC7">MODIFIER SYNTAX</a>
<li><a name="TOC8" href="#SEC8">PATTERN SYNTAX</a>
<li><a name="TOC9" href="#SEC9">SUBJECT LINE SYNTAX</a>
<li><a name="TOC10" href="#SEC10">PATTERN MODIFIERS</a>
<li><a name="TOC11" href="#SEC11">SUBJECT MODIFIERS</a>
<li><a name="TOC12" href="#SEC12">THE ALTERNATIVE MATCHING FUNCTION</a>
<li><a name="TOC13" href="#SEC13">DEFAULT OUTPUT FROM pcre2test</a>
<li><a name="TOC14" href="#SEC14">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
<li><a name="TOC15" href="#SEC15">RESTARTING AFTER A PARTIAL MATCH</a>
<li><a name="TOC16" href="#SEC16">CALLOUTS</a>
<li><a name="TOC17" href="#SEC17">NON-PRINTING CHARACTERS</a>
<li><a name="TOC18" href="#SEC18">SAVING AND RESTORING COMPILED PATTERNS</a>
<li><a name="TOC19" href="#SEC19">SEE ALSO</a>
<li><a name="TOC20" href="#SEC20">AUTHOR</a>
<li><a name="TOC21" href="#SEC21">REVISION</a>
</ul>
 <a name="SEC1" href="#TOC1">SYNOPSIS</a> 

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
<a href="pcre2pattern.html">pcre2pattern</a>
documentation. For details of the PCRE2 library function calls and their
options, see the
<a href="pcre2api.html">pcre2api</a>
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 function 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 libraries.

 <a name="SEC2" href="#TOC1">PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a> 

Different versions of the PCRE2 library can be built to support character
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 installed. 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 library functions. Results are converted back
to 8-bit code units for output.


In the rest of this document, the names of library functions and structures
are given in generic form, for example, pcre_compile(). The actual
names used in the libraries have a suffix _8, _16, or _32, as appropriate.
<a name="inputencoding"></a>
 <a name="SEC3" href="#TOC1">INPUT ENCODING</a> 

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 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, backslash escapes can be used. In addition,
when the utf modifier (see
<a href="#optionmodifiers">"Setting compilation options"</a>
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 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 character 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.

 <a name="SEC4" href="#TOC1">COMMAND LINE OPTIONS</a> 

-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 compiled.


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


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


-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 options 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:
<pre>
 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
</pre>
The following options output 1 for true or 0 for false, and set the exit code
to the same value:
<pre>
 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
</pre>
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 internal
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.


-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 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.


\fB-pattern\fB 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 output 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 output.


-version
Output the PCRE2 version number and then exit.

 <a name="SEC5" href="#TOC1">DESCRIPTION</a> 

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 pattern. 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 specification of perltest.sh, see the
comments near its beginning.


When the input is a terminal, pcre2test prompts for each line of input,
using "re&#62;" to prompt for regular expression patterns, and "data&#62;" to prompt
for subject lines. Command lines starting with # can be entered only in
response to the "re&#62;" 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 expected if there is
still input to be read.

 <a name="SEC6" href="#TOC1">COMMAND LINES</a> 

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:
<pre>
 #forbid_utf
</pre>
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 information, to avoid cluttering up test
output.
<pre>
 #load &#60;filename&#62;
</pre>
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"
<a href="#saverestore">below.</a>
<pre>
 #newline_default [&#60;newline-list&#62;]
</pre>
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 contain tests of various newline
conventions, but the majority of the tests expect a single linefeed to be
recognized as a newline by default. Without special action the tests would fail
when PCRE2 is compiled 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, ANYCRLF,
ANY, or NUL (in upper or lower case), for example:
<pre>
 #newline_default LF Any anyCRLF
</pre>
If the default newline is in the list, this command has no effect. Otherwise,
except when testing the POSIX API, a newline modifier that specifies the
first newline convention in the list (LF in the above example) 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 default
newline convention, though it is possible to set the newline convention 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.
<pre>
 #pattern &#60;modifier-list&#62;
</pre>
This command sets a default modifier list that applies to all subsequent
patterns. Modifiers on a pattern can change these settings.
<pre>
 #perltest
</pre>
The appearance of this line causes all subsequent modifier settings to be
checked for compatibility with the perltest.sh script, which is used to
confirm that Perl gives the same results as PCRE2. Also, apart from comment
lines, #pattern commands, and #subject commands that set or unset "mark", no
command lines are permitted, because they and many of the modifiers are
specific to pcre2test, and should not be used in test files that are also
processed by perltest.sh. The #perltest command helps detect tests
that are accidentally put in the wrong file.
<pre>
 #pop [&#60;modifiers&#62;]
 #popcopy [&#60;modifiers&#62;]
</pre>
These commands are used to manipulate the stack of compiled patterns, as
described in the section entitled "Saving and restoring compiled patterns"
<a href="#saverestore">below.</a>
<pre>
 #save &#60;filename&#62;
</pre>
This command is used to save a set of compiled patterns to a file, as described
in the section entitled "Saving and restoring compiled patterns"
<a href="#saverestore">below.</a>
<pre>
 #subject &#60;modifier-list&#62;
</pre>
This command sets a default modifier list that applies to all subsequent
subject lines. Modifiers on a subject line can change these settings.

 <a name="SEC7" href="#TOC1">MODIFIER SYNTAX</a> 

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 "anchored", and some of them must be
followed by an equals sign and a value, for example, "offset=12". Values cannot
contain comma characters, 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 letters, 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:
<pre>
 /abc/ig,newline=cr,jit=3
</pre>
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.

 <a name="SEC8" href="#TOC1">PATTERN SYNTAX</a> 

A pattern line must start with one of the following characters (common symbols,
excluding pattern meta-characters):
<pre>
 / ! " ' ` - = _ : ; , % & @ ~
</pre>
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 delimiter within the pattern
by escaping it with a backslash, for example
<pre>
 /abc\/def/
</pre>
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 followed by a
backslash, for example,
<pre>
 /abc/\
</pre>
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
<pre>
 /abc\/
</pre>
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 regular expression.


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

 <a name="SEC9" href="#TOC1">SUBJECT LINE SYNTAX</a> 

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
modifier was set for the pattern. The following provide a means of encoding
non-printing characters in a visible way:
<pre>
 \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 &#62; 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)
</pre>
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 hexadecimal
digits inside the braces; invalid values provoke error messages.


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:
<pre>
 \[&#60;characters&#62;]{&#60;count&#62;}
</pre>
This makes it possible to test long strings without having to provide them as
part of the file. For example:
<pre>
 \[abc]{4}
</pre>
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:
<pre>
 abc\=notbol,notempty
</pre>
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:
<pre>
 \= This is a comment.
 abc\= This is an invalid modifier list.
</pre>
A backslash followed by any other non-alphanumeric character just escapes 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 backslashes.
No replication is possible, and any subject modifiers must be set as defaults
by a #subject command.

 <a name="SEC10" href="#TOC1">PATTERN MODIFIERS</a> 

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.
<a name="optionmodifiers"></a>
 
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 abbreviations that are the same as
Perl options. 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 difference to the
way pcre2_compile() behaves. See
<a href="pcre2api.html">pcre2api</a>
for a description of the effects of these options.
<pre>
 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
 /x extended set PCRE2_EXTENDED
 /xx extended_more set PCRE2_EXTENDED_MORE
 firstline set PCRE2_FIRSTLINE
 literal set PCRE2_LITERAL
 match_line set PCRE2_EXTRA_MATCH_LINE
 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
</pre>
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.
<a name="controlmodifiers"></a>
 
Setting compilation controls
 

The following modifiers affect the compilation process or request information
about the pattern. There are single-letter abbreviations for some that are
heavily used in the test files.
<pre>
 bsr=[anycrlf|unicode] specify \R handling
 /B bincode show binary code without lengths
 callout_info show callout information
 convert=&#60;options&#62; 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[=&#60;number&#62;] use JIT
 jitfast use JIT fast path
 jitverify verify JIT use
 locale=&#60;name&#62; use this locale
 max_pattern_length=&#60;n&#62; set the maximum pattern length
 memory show memory used
 newline=&#60;type&#62; set newline type
 null_context compile with a NULL context
 parens_nest_limit=&#60;n&#62; 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=&#60;number&#62; test the stackguard feature
 subject_literal treat all subject lines as literal
 tables=[0|1|2] select internal tables
 use_length do not zero-terminate the pattern
 utf8_input treat input as UTF-8
</pre>
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 Unicode.


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 different internal
link sizes and different code unit widths. By using bincode, the same
regression tests can be used in different environments.


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:
<pre>
 re&#62; /(?i)(^a|^b)/m,info
 Capturing subpattern count = 1
 Compile options: multiline
 Overall options: caseless multiline
 First code unit at start or follows newline
 Subject length lower bound = 1

re&#62; /(?i)abc/info
 Capturing subpattern count = 0
 Compile options: &#60;none&#62;
 Overall options: caseless
 First code unit = 'a' (caseless)
 Last code unit = 'c' (caseless)
 Subject length lower bound = 3
</pre>
"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 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 information 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 interpreted as pairs
of hexadecimal digits. This feature is provided as a way of creating patterns
that contain binary zeros and other non-printing characters. White space is
permitted between pairs of digits. For example, this pattern contains three
characters:
<pre>
 /ab 32 59/hex
</pre>
Parts of such a pattern are taken literally if quoted. This pattern contains
nine characters, only two of which are specified in hexadecimal:
<pre>
 /ab "literal" 32/hex
</pre>
Either single or double quotes may be used. There is no way of including
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-terminated
strings but can be passed by length instead of being zero-terminated. 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 zeros.


If hex or use_length is used with the POSIX wrapper API (see
<a href="#posixwrapper">"Using the POSIX wrapper API"</a>
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
<a href="#inputencoding">"Input encoding"</a>
above.

 
Generating long repetitive patterns
 

Some tests use long patterns that are very repetitive. Instead of creating 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
<pre>
 \[&#60;characters&#62;]{&#60;count&#62;}
</pre>
are expanded before the pattern is passed to pcre2_compile(). For
example, \[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 recognized 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
<a href="pcre2jit.html">pcre2jit</a>
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"
<a href="#subjectmodifiers">below</a>
for details of how these options are specified for each match attempt.


JIT compilation is requested by the jit pattern modifier, which may
optionally 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:
<pre>
 1 compile JIT code for non-partial matching
 2 compile JIT code for soft partial matching
 4 compile JIT code for hard partial matching
</pre>
The possible values for the jit modifier are therefore:
<pre>
 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
</pre>
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 complete
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 automatically be
used when an appropriate type of match is run, except when incompatible
run-time options are specified. For more details, see the
<a href="pcre2jit.html">pcre2jit</a>
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 sanity
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
compilation 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:
<pre>
 /pattern/locale=fr_FR
</pre>
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_compile() 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
character 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 pattern is
subsequently passed to the JIT compiler, the size of the JIT compiled code is
also output. Here is an example:
<pre>
 re&#62; /a(b)c/jit,memory
 Memory allocation (code space): 21
 Memory allocation (JIT code): 1910

</PRE>

 
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 error.
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).
<a name="posixwrapper"></a>
 
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
<a href="pcre2posix.html">pcre2posix</a>
documentation. The following pattern modifiers set options for the
regcomp() function:
<pre>
 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 )
</pre>
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:
<pre>
 /abc/posix,regerror_buffsize=20
</pre>
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
below. 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
default, but if the use_length or hex modifiers are set, the
REG_PEND extension is used to pass it by length.

 
Testing the stack guard feature
 

The stackguard modifier is used to test the use of
pcre2_set_compile_recursion_guard(), a function that is provided to
enable stack availability to be checked during compilation (see the
<a href="pcre2api.html">pcre2api</a>
documentation 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, or 2. 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 tables as follows:
<pre>
 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
</pre>
In table 2, some characters whose codes are greater than 128 are identified as
letters, digits, spaces, etc. Setting alternate 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 subject line that is
processed with that pattern. These modifiers do not affect the compilation
process.
<pre>
 aftertext show text after match
 allaftertext show text after captures
 allcaptures show all captures
 allusedtext show all consulted text
 altglobal alternative global matching
 /g global global matching
 jitstack=&#60;n&#62; set size of JIT stack
 mark show mark values
 replace=&#60;string&#62; specify a replacement string
 startchar show starting character when relevant
 substitute_extended use PCRE2_SUBSTITUTE_EXTENDED
 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
</pre>
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 subject
lines that it matches are taken as literal strings, with no interpretation 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 patterns"
<a href="#saverestore">below.</a>
If pushcopy is used instead of push, a copy of the compiled
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 incompatible 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-separated list of
options, which set the equivalent option for the pcre2_pattern_convert()
function:
<pre>
 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
</pre>
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 pattern is
passed to pcre2_pattern_convert(). If the conversion is successful, 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 processing,
overriding the defaults, which are operating-system dependent.
<a name="subjectmodifiers"></a>
 <a name="SEC11" href="#TOC1">SUBJECT MODIFIERS</a> 

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
<a href="pcreapi.html">pcreapi</a>
for a description of their effects.
<pre>
 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
</pre>
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,
causing the POSIX wrapper API to be used, the only option-setting modifiers
that have any effect are notbol, notempty, and noteol,
causing REG_NOTBOL, 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 wrapper. It is
ignored (with a warning) if used for non-POSIX matching.
<pre>
 posix_startend=&#60;n&#62;[:&#60;m&#62;]
</pre>
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_STARTEND, see the
<a href="pcre2posix.html">pcre2posix</a>
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_startend to specify its length.

 
Setting match controls
 

The following modifiers affect the matching process or request additional
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.
<pre>
 aftertext show text after match
 allaftertext show text after captures
 allcaptures show all captures
 allusedtext show all consulted text (non-JIT only)
 altglobal alternative global matching
 callout_capture show captures at callout time
 callout_data=&#60;n&#62; set a value to pass via callouts
 callout_error=&#60;n&#62;[:&#60;m&#62;] control callout error
 callout_extra show extra callout information
 callout_fail=&#60;n&#62;[:&#60;m&#62;] control callout failure
 callout_no_where do not show position of a callout
 callout_none do not supply a callout function
 copy=&#60;number or name&#62; copy captured substring
 depth_limit=&#60;n&#62; set a depth limit
 dfa use pcre2_dfa_match()
 find_limits find match and depth limits
 get=&#60;number or name&#62; extract captured substring
 getall extract all captured substrings
 /g global global matching
 heap_limit=&#60;n&#62; set a limit on heap memory (Kbytes)
 jitstack=&#60;n&#62; set size of JIT stack
 mark show mark values
 match_limit=&#60;n&#62; set a match limit
 memory show heap memory usage
 null_context match with a NULL context
 offset=&#60;n&#62; set starting offset
 offset_limit=&#60;n&#62; set offset limit
 ovector=&#60;n&#62; set size of output vector
 recursion_limit=&#60;n&#62; obsolete synonym for depth_limit
 replace=&#60;string&#62; specify a replacement string
 startchar show startchar when relevant
 startoffset=&#60;n&#62; same as offset=&#60;n&#62;
 substitute_extedded use PCRE2_SUBSTITUTE_EXTENDED
 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
 zero_terminate pass the subject as zero-terminated
</pre>
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
modifiers 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 substrings as
well as the main matched substring. In each case the remainder 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. 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 lookbehind at the start of a match, or 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 output by '&#60;' or '&#62;' characters
underneath them. Here is an example:
<pre>
 re&#62; /(?&#60;=pqr)abc(?=xyz)/
 data&#62; 123pqrabcxyz456\=allusedtext
 0: pqrabcxyz
 &#60;&#60;&#60; &#62;&#62;&#62;
</pre>
This shows that the matched string is "abc", with the preceding and following
strings "pqr" and "xyz" having been consulted during the match (when processing
the assertions).


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 example:
<pre>
 re&#62; /abc\Kxyz/
 data&#62; abcxyz\=startchar
 0: abcxyz
 ^^^
</pre>
Unlike allusedtext, the startchar modifier can be used with JIT.
However, these two modifiers are mutually exclusive.

 
Showing the value of all capture groups
 

The allcaptures modifier requests that the values of all potential
captured 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 "&#60;unset&#62;". This modifier is not relevant for DFA matching (which
does no capturing); it is ignored, with a warning message, if present.

 
Testing callouts
 

A callout function is supplied when pcre2test calls the library matching
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"
<a href="#callouts">below.</a>

 
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 lookbehind
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 retried. This
imitates the way Perl handles such cases when using the /g modifier or
the split() function. Normally, the start offset is advanced by one
character, but if the newline convention recognizes CRLF as a newline, and the
current character is CR followed by LF, an advance of two characters occurs.

 
Testing substring extraction functions
 

The copy and get modifiers can be used to test the
pcre2_substring_copy_xxx() and pcre2_substring_get_xxx() functions.
They can be given more than once, and each can specify a group name or number,
for example:
<pre>
 abcd\=copy=1,copy=3,get=G1
</pre>
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 numbered
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. Note that replacement strings
cannot contain commas, because a comma signifies the end of a modifier. This is
not thought to be an issue in a test program.


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 provides 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():
<pre>
 global PCRE2_SUBSTITUTE_GLOBAL
 substitute_extended PCRE2_SUBSTITUTE_EXTENDED
 substitute_overflow_length PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
 substitute_unknown_unset PCRE2_SUBSTITUTE_UNKNOWN_UNSET
 substitute_unset_empty PCRE2_SUBSTITUTE_UNSET_EMPTY

</PRE>


After a successful substitution, the modified string is output, preceded by the
number of replacements. This may be zero if there were no matches. Here is a
simple example of a substitution test:
<pre>
 /abc/replace=xxx
 =abc=abc=
 1: =xxx=abc=
 =abc=abc=\=global
 2: =xxx=xxx=
</pre>
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 replacement string starting at the next
character. Here is an example that tests the edge case:
<pre>
 /abc/
 123abc123\=replace=[10]XYZ
 1: 123XYZ123
 123abc123\=replace=[9]XYZ
 Failed: error -47: no more memory
</pre>
The default action of pcre2_substitute() is to return
PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if the
PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the
substitute_overflow_length modifier), pcre2_substitute() continues
to go through the motions of matching and substituting, 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:
<pre>
 /abc/substitute_overflow_length
 123abc123\=replace=[9]XYZ
 Failed: error -47: no more memory: 10 code units are needed
</pre>
A replacement string is ignored with POSIX and DFA matching. Specifying partial
matching provokes an error return ("bad option value") from
pcre2_substitute().

 
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 appropriate 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 settings
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 function, 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
memory allocation and freeing calls that occur during a call to
pcre2_match() or pcre2_dfa_match(). These occur only when a match
requires 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 additional
output. No heap memory is allocated during matching with JIT, so in that case
the memory modifier never has any effect. 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.

 
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 modifier 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
appears, though of course it can also be used to set a default in a
#subject 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_create_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 function 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() or pcre2_jit_match(). If the null_context
modifier is set, however, NULL is passed. This is for testing that the matching
functions behave correctly in this case (they use default values). This
modifier cannot be used with the find_limits modifier or when testing the
substitution function.

 <a name="SEC12" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a> 

By default, pcre2test uses the standard PCRE2 matching function,
pcre2_match() to match each subject line. PCRE2 also supports an
alternative matching function, pcre2_dfa_match(), which operates in a
different way, and has some restrictions. The differences between the two
functions are described in the
<a href="pcre2matching.html">pcre2matching</a>
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 subject. If,
however, the dfa_shortest modifier is set, processing stops after the
first match is found. This is always the shortest possible match.

 <a name="SEC13" href="#TOC1">DEFAULT OUTPUT FROM pcre2test</a> 

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 substrings,
starting with number 0 for the string that matched the whole pattern.
Otherwise, it outputs "No match" when the return is PCRE2_ERROR_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.
<pre>
 $ pcre2test
 PCRE2 version 10.22 2016-07-29

re&#62; /^abc(\d+)/
 data&#62; abc123
 0: abc123
 1: 123
 data&#62; xyz
 No match
</pre>
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 "&#60;unset&#62;", as for the second data line.
<pre>
 re&#62; /(a)|(b)/
 data&#62; a
 0: a
 1: a
 data&#62; b
 0: b
 1: &#60;unset&#62;
 2: b
</pre>
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 definition 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:
<pre>
 re&#62; /cat/aftertext
 data&#62; cataract
 0: cat
 0+ aract
</pre>
If global matching is requested, the results of successive matching attempts
are output in sequence, like this:
<pre>
 re&#62; /\Bi(\w\w)/g
 data&#62; Mississippi
 0: iss
 1: ss
 0: iss
 1: ss
 0: ipp
 1: pp
</pre>
"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):
<pre>
 re&#62; /xyz/
 data&#62; xyz\=offset=4
 Error -24 (bad offset value)
</PRE>


Note that whereas patterns can be continued over several lines (a plain "&#62;"
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).

 <a name="SEC14" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a> 

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:
<pre>
 re&#62; /(tang|tangerine|tan)/
 data&#62; yellow tangerine\=dfa
 0: tangerine
 1: tang
 2: tan
</pre>
Using the normal matching function on this data finds only "tang". The
longest matching string is always given first (and numbered zero). After a
PCRE2_ERROR_PARTIAL return, the output is "Partial match:", followed 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:
<pre>
 re&#62; /(tang|tangerine|tan)/g
 data&#62; yellow tangerine and tangy sultana\=dfa
 0: tangerine
 1: tang
 2: tan
 0: tang
 1: tan
 0: tan
</pre>
The alternative matching function does not support substring capture, so the
modifiers that are concerned with captured substrings are not relevant.

 <a name="SEC15" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a> 

When the alternative matching function has given the PCRE2_ERROR_PARTIAL
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:
<pre>
 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
 data&#62; 23ja\=P,dfa
 Partial match: 23ja
 data&#62; n05\=dfa,dfa_restart
 0: n05
</pre>
For further information about partial matching, see the
<a href="pcre2partial.html">pcre2partial</a>
documentation.
<a name="callouts"></a>
 <a name="SEC16" href="#TOC1">CALLOUTS</a> 

If the pattern contains any callout requests, pcre2test's callout
function 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 arguments 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:
<pre>
 ---&#62;pqrabcdef
 0 ^ ^ \d
</pre>
This output indicates that callout number 0 occurred for a match attempt
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 positions are the same, or if
the current position precedes the start position, 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:
<pre>
 re&#62; /\d?[A-E]\*/auto_callout
 data&#62; E*
 ---&#62;E*
 +0 ^ \d?
 +3 ^ [A-E]
 +8 ^^ \*
 +10 ^ ^
 0: E*
</pre>
If a pattern contains (*MARK) items, an additional line is output whenever
a change of latest mark is passed to the callout function. For example:
<pre>
 re&#62; /a(*MARK:X)bc/auto_callout
 data&#62; abc
 ---&#62;abc
 +0 ^ a
 +1 ^^ (*MARK:X)
 +10 ^^ b
 Latest Mark: X
 +11 ^ ^ c
 +12 ^ ^
 0: abc
</pre>
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 "&#60;unset&#62;" 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 before the reflection of
the subject string, and the subject string is reflected for each callout. For
example:
<pre>
 re&#62; /^ab(?C'first')cd(?C"second")ef/
 data&#62; abcdefg
 Callout (7): 'first'
 ---&#62;abcdefg
 ^ ^ c
 Callout (20): "second"
 ---&#62;abcdefg
 ^ ^ e
 0: abcdef

</PRE>

 
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 callout (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:
<pre>
 re&#62; /(a+)b/auto_callout,no_start_optimize,no_auto_possess
 data&#62; aac\=callout_extra
 New match attempt
 ---&#62;aac
 +0 ^ (
 +1 ^ a+
 +3 ^ ^ )
 +4 ^ ^ b
 Backtrack
 ---&#62;aac
 +3 ^^ )
 +4 ^^ b
 Backtrack
 No other matching paths
 New match attempt
 ---&#62;aac
 +0 ^ (
 +1 ^ a+
 +3 ^^ )
 +4 ^^ b
 Backtrack
 No other matching paths
 New match attempt
 ---&#62;aac
 +0 ^ (
 +1 ^ a+
 Backtrack
 No other matching paths
 New match attempt
 ---&#62;aac
 +0 ^ (
 +1 ^ a+
 No match
</pre>
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 backtracks.


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 (causing matching to
backtrack) when a callout of that number is reached. If two numbers (&#60;n&#62;:&#60;m&#62;)
are given, 1 is returned when callout &#60;n&#62; is reached and there have been at
least &#60;m&#62; callouts. The callout_error modifier is similar, except that
PCRE2_ERROR_CALLOUT is returned, causing 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 number.
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
complicated regular expressions. For further information about callouts, see
the
<a href="pcre2callout.html">pcre2callout</a>
documentation.

 <a name="SEC17" href="#TOC1">NON-PRINTING CHARACTERS</a> 

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
isprint() function is used to distinguish printing and non-printing
characters.
<a name="saverestore"></a>
 <a name="SEC18" href="#TOC1">SAVING AND RESTORING COMPILED PATTERNS</a> 

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, converted to a stream of bytes. A single byte stream may
contain any number of compiled patterns, but they must all use the same
character tables. 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 serializing and de-serializing. They are described in the
<a href="pcre2serialize.html">pcre2serialize</a>
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
compiled, 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 immediate
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
<pre>
 #save &#60;filename&#62;
</pre>
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
<pre>
 #load &#60;filename&#62;
</pre>
reads the data in the file, and then arranges for it to be de-serialized, with
the resulting compiled patterns added to the pattern stack. The pattern on the
top of the stack can be retrieved by the #pop command, 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
<a href="#controlmodifiers">control modifiers</a>
that act after a pattern has been compiled. In particular, hex,
posix, posix_nosub, push, and pushcopy are not allowed,
nor are any
<a href="#optionmodifiers">option-setting modifiers.</a>
The JIT modifiers are, however permitted. Here is an example that saves and
reloads two patterns.
<pre>
 /abc/push
 /xyz/push
 #save tempfile
 #load tempfile
 #pop info
 xyz

#pop jit,bincode
 abc
</pre>
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.

 <a name="SEC19" href="#TOC1">SEE ALSO</a> 

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

 <a name="SEC20" href="#TOC1">AUTHOR</a> 

Philip Hazel
 
University Computing Service
 
Cambridge, England.
 

 <a name="SEC21" href="#TOC1">REVISION</a> 

Last updated: 21 July 2018
 
Copyright &copy; 1997-2018 University of Cambridge.
 

Return to the <a href="index.html">PCRE2 index page</a>.

MR SKB