|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
PCRE2TEST(1) General Commands Manual PCRE2TEST(1)
pcre2test - a program for testing Perl-compatible regular
expressions.
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 documentation. For details of the PCRE2 library
function calls and their options, 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 function options, control how
the subject is processed, and what output is produced.
There are 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.
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,
pcre2_compile(). The actual names used in the libraries have a
suffix _8, _16, or _32, as appropriate.
Input to pcre2test is processed line by line, either by calling
the C library's fgets() function, or via the libreadline or
libedit library. In some Windows environments character 26 (hex
1A) causes an immediate end of file, and no further data is read,
so this character should be avoided unless you really want that
action.
The input is processed using C's string functions, so must not
contain binary zeros, even though in Unix-like environments,
fgets() treats any bytes other than newline as data characters.
An error is generated if a binary zero is encountered. By default
subject lines are processed for backslash escapes, which makes it
possible to include any data value in strings that are passed to
the library for matching. For patterns, there is a facility for
specifying some or all of the 8-bit input 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 "Setting compilation options" 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.
-8 If the 8-bit library has been built, this option causes it
to be used (this is the default). If the 8-bit library has
not been built, this option causes an error.
-16 If the 16-bit library has been built, this option causes
it to be used. If the 8-bit library has not been built,
this is the default. If the 16-bit library has not been
built, this option causes an error.
-32 If the 32-bit library has been built, this option causes
it to be used. If no other library has been built, this is
the default. If the 32-bit library has not been built,
this 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:
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
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.
-jitfast
Behave as if each pattern line has the jitfast modifier;
after successful compilation, each pattern is passed to
the just-in-time compiler, if available, and each subject
line is passed directly to the JIT matcher via its "fast
path".
-jitverify
Behave as if each pattern line has the jitverify modifier;
after successful compilation, each pattern is passed to
the just-in-time compiler, if available, and the use of
JIT for matching is verified.
-LM List modifiers: write a list of available pattern and
subject modifiers to the standard output, then exit with
zero exit code. All other options are ignored. If both -C
and any -Lx options are present, whichever is first is
recognized.
-LP List properties: write a list of recognized Unicode
properties to the standard output, then exit with zero
exit code. All other options are ignored. If both -C and
any -Lx options are present, whichever is first is
recognized.
-LS List scripts: write a list of recognized Unicode script
names to the standard output, then exit with zero exit
code. All other options are ignored. If both -C and any
-Lx options are present, whichever is first is recognized.
-pattern modifier-list
Behave as if each pattern line contains the given
modifiers.
-q Do not output the version number of pcre2test at the start
of execution.
-S size
On Unix-like systems, set the size of the run-time stack
to size mebibytes (units of 1024*1024 bytes).
-subject modifier-list
Behave as if each subject line contains the given
modifiers.
-t Run each compile and match many times with a timer, and
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.
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. 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 expected if there is still input to be read.
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 information, 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 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:
#newline_default LF Any anyCRLF
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.
#pattern <modifier-list>
This command sets a default modifier list that applies to all
subsequent patterns. Modifiers on a pattern can change these
settings.
#perltest
This line is used in test files that can also be processed by
perltest.sh to confirm that Perl gives the same results as PCRE2.
Subsequent tests are checked for the use of pcre2test features
that are incompatible 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 patterns" below.
#subject <modifier-list>
This command sets a default modifier list that applies to all
subsequent subject lines. Modifiers on a subject line can change
these settings.
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:
/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.
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 delimiter as a literal within the pattern
by escaping it with a backslash, for example
/abc\/def/
If you do this, the escape and the delimiter form part of the
pattern, but since the delimiters are all non-alphanumeric, the
inclusion of the backslash does not affect the pattern's
interpretation. Note, however, that this trick does not work
within \Q...\E literal bracketing because the backslash will
itself be interpreted as a literal. If the terminating delimiter
is immediately followed by a backslash, for example,
/abc/\
a backslash is added to the end of the pattern. This is done to
provide a way of testing the error condition that arises if a
pattern finishes with a backslash, because
/abc\/
is interpreted as the first line of a pattern that starts with
"abc/", causing pcre2test to read the next line as a continuation
of the regular expression.
A pattern can be followed by a modifier list (details below).
Before each subject line is passed to pcre2_match(),
pcre2_dfa_match(), or pcre2_jit_match(), leading and trailing
white space is removed, and the line is scanned for backslash
escapes, unless the subject_literal modifier was set for the
pattern. The following provide a means of 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 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:
\[<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
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.
There are several types of modifier that can appear in pattern
lines. Except where noted below, they may also be used in
#pattern commands. A pattern's modifier list can add to or
override default modifiers that were set by a previous #pattern
command.
Setting compilation options
The following modifiers set options for pcre2_compile(). Most of
them set bits in the options argument of that function, but those
whose names start with PCRE2_EXTRA are additional options that
are set in the compile context. Some of these options have
single-letter abbreviations. 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 pcre2api for a description of
the effects of these options.
allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
allow_lookaround_bsk set
PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK
allow_surrogate_escapes set
PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
alt_bsux set PCRE2_ALT_BSUX
alt_circumflex set PCRE2_ALT_CIRCUMFLEX
alt_verbnames set PCRE2_ALT_VERBNAMES
anchored set PCRE2_ANCHORED
/a ascii_all set all ASCII options
ascii_bsd set PCRE2_EXTRA_ASCII_BSD
ascii_bss set PCRE2_EXTRA_ASCII_BSS
ascii_bsw set PCRE2_EXTRA_ASCII_BSW
ascii_digit set PCRE2_EXTRA_ASCII_DIGIT
ascii_posix set PCRE2_EXTRA_ASCII_POSIX
auto_callout set PCRE2_AUTO_CALLOUT
bad_escape_is_literal set
PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
/i caseless set PCRE2_CASELESS
/r caseless_restrict set PCRE2_EXTRA_CASELESS_RESTRICT
dollar_endonly set PCRE2_DOLLAR_ENDONLY
/s dotall set PCRE2_DOTALL
dupnames set PCRE2_DUPNAMES
endanchored set PCRE2_ENDANCHORED
escaped_cr_is_lf set PCRE2_EXTRA_ESCAPED_CR_IS_LF
/x extended set PCRE2_EXTENDED
/xx extended_more set PCRE2_EXTENDED_MORE
extra_alt_bsux set PCRE2_EXTRA_ALT_BSUX
firstline set PCRE2_FIRSTLINE
literal set PCRE2_LITERAL
match_line set PCRE2_EXTRA_MATCH_LINE
match_invalid_utf set PCRE2_MATCH_INVALID_UTF
match_unset_backref set PCRE2_MATCH_UNSET_BACKREF
match_word set PCRE2_EXTRA_MATCH_WORD
/m multiline set PCRE2_MULTILINE
never_backslash_c set PCRE2_NEVER_BACKSLASH_C
never_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
information 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_compiled ) set maximum compiled pattern
_length=<n> ) length (bytes)
max_pattern_length=<n> set maximum pattern length (code
units)
max_varlookbehind=<n> set maximum variable lookbehind
length
memory show memory used
newline=<type> set newline type
null_context compile with a NULL context
null_pattern pass pattern as NULL
parens_nest_limit=<n> set maximum parentheses depth
posix use the POSIX API
posix_nosub use the POSIX API with REG_NOSUB
push push compiled pattern onto the
stack
pushcopy push a copy onto the stack
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 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:
re> /(?i)(^a|^b)/m,info
Capture group count = 1
Compile options: multiline
Overall options: caseless multiline
First code unit at start or follows newline
Subject length lower bound = 1
re> /(?i)abc/info
Capture group count = 0
Compile options: <none>
Overall options: caseless
First code unit = 'a' (caseless)
Last code unit = 'c' (caseless)
Subject length lower bound = 3
"Compile options" are those specified by modifiers; "overall
options" have added options that are taken or deduced from the
pattern. If both sets of options are the same, just a single
"options" line is output; if there are no options, the line is
omitted. "First code unit" is where any match must start; if
there is more than one they are listed as "starting code units".
"Last code unit" is the last literal code unit that must be
present in any match. This is not necessarily the last character.
These lines are omitted if no starting or ending code units are
recorded. The subject length line is omitted when
no_start_optimize is set because the minimum length is not
calculated when it can never be used.
The framesize modifier shows the size, in bytes, of each storage
frame used by pcre2_match() for handling backtracking. The size
depends on the number of capturing parentheses in the pattern. A
vector of these frames is used at matching time; its overall size
is shown when the heaframes_size subject modifier is set.
The callout_info modifier requests information about all the
callouts in the pattern. A list of them is output at the end of
any other 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).
Passing a NULL pattern
The null_pattern modifier is for testing the behaviour of
pcre2_compile() when the pattern argument is NULL. The length
value passed is the default PCRE2_ZERO_TERMINATED unless
use_length is set. Any length other than zero causes an error.
Specifying pattern characters in hexadecimal
The hex modifier specifies that the characters of the pattern,
except for substrings enclosed in single or double quotes, are to
be 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:
/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 hexadecimal:
/ab "literal" 32/hex
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
"Using the POSIX wrapper API" below), the REG_PEND extension is
used to pass the pattern's length.
Specifying a maximum for variable lookbehinds
Variable lookbehind assertions are supported only if, for each
one, there is a maximum length (in characters) that it can match.
There is a limit on this, whose default can be set at build time,
with an ultimate default of 255. The max_varlookbehind modifier
uses the pcre2_set_max_varlookbehind() function to change the
limit. Lookbehinds whose branches each match a fixed length are
limited to 65535 characters per branch.
Specifying wide characters in 16-bit and 32-bit modes
In 16-bit and 32-bit modes, all input is automatically treated as
UTF-8 and translated to UTF-16 or UTF-32 when the utf modifier is
set. For testing the 16-bit and 32-bit libraries in non-UTF mode,
the utf8_input modifier can be used. It is mutually exclusive
with utf. Input lines are interpreted as UTF-8 as a means of
specifying wide characters. More details are given in "Input
encoding" above.
Generating long repetitive patterns
Some tests use long patterns that are very repetitive. Instead of
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
\[<characters>]{<count>}
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 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 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:
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 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 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 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:
/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_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:
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 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).
Limiting the size of a compiled pattern
The max_pattern_compiled_length modifier sets a limit, in bytes,
to the amount of memory used by a compiled pattern. Breaching the
limit causes a compilation error. The default is the largest
number a PCRE2_SIZE variable can hold (essentially unlimited).
Using the POSIX wrapper API
The posix and posix_nosub modifiers cause pcre2test to call PCRE2
via the POSIX wrapper API rather than its native API. When
posix_nosub is used, the POSIX option REG_NOSUB is passed to
regcomp(). The POSIX wrapper supports only the 8-bit library.
Note that it does not imply POSIX matching semantics; for more
detail see the pcre2posix documentation. 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 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 pcre2api 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, 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 tables 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
identified as letters, digits, spaces, etc. Tables 3 can be used
only after a #loadtables command has loaded them from a binary
file. 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.
aftertext show text after match
allaftertext show text after captures
allcaptures show all captures
allvector show the entire ovector
allusedtext show all consulted text
altglobal alternative global matching
/g global global matching
heapframes_size show match data heapframes size
jitstack=<n> set size of JIT stack
mark show mark values
replace=<string> specify a replacement string
startchar show starting character when
relevant
substitute_callout use substitution callouts
substitute_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
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" below. 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:
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 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.
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
disable_recurseloop_check set
PCRE2_DISABLE_RECURSELOOP_CHECK
no_jit set PCRE2_NO_JIT
no_utf_check set PCRE2_NO_UTF_CHECK
notbol set PCRE2_NOTBOL
notempty set PCRE2_NOTEMPTY
notempty_atstart set PCRE2_NOTEMPTY_ATSTART
noteol set PCRE2_NOTEOL
partial_hard (or ph) set PCRE2_PARTIAL_HARD
partial_soft (or ps) set PCRE2_PARTIAL_SOFT
The partial matching modifiers are provided with abbreviations
because they appear frequently in tests.
If the posix or posix_nosub modifier was present on the pattern,
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.
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_STARTEND, 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_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, but can be
overridden by modifiers on the subject.
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 heap, match and depth
limits
find_limits_noheap find match and depth limits
get=<number or name> extract captured substring
getall extract all captured substrings
/g global global matching
heapframes_size show match data heapframes size
heap_limit=<n> set a limit on heap memory
(Kbytes)
jitstack=<n> set size of JIT stack
mark show mark values
match_limit=<n> set a match limit
memory show heap memory usage
null_context match with a NULL context
null_replacement substitute with NULL replacement
null_subject match with NULL subject
offset=<n> set starting offset
offset_limit=<n> set offset limit
ovector=<n> set size of output vector
recursion_limit=<n> obsolete synonym for depth_limit
replace=<string> specify a replacement string
startchar show startchar when relevant
startoffset=<n> same as offset=<n>
substitute_callout use substitution callouts
substitute_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 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, 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 lookbehind 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 output 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 consulted 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 example:
re> /abc\Kxyz/
data> abcxyz\=startchar
0: abcxyz
^^^
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 "<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,
whatever 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 after 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, "<unchanged>" 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
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" below. Testing callouts from
pcre2_substitute() is described separately in "Testing the
substitution function" below.
Finding all matches in a string
Searching for all possible matches within a subject can be
requested by the global or altglobal modifier. After finding a
match, the matching function is called again to search the
remainder of the subject. The difference between global and
altglobal is that the former uses the start_offset argument to
pcre2_match() or pcre2_dfa_match() to start searching at a new
point within the entire string (which is what Perl does), whereas
the latter passes over a shortened subject. This makes a
difference to the matching process if the pattern begins with a
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 capture group name or number, 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 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 (or after one
call of pcre2_match() in the case of PCRE2_SUBSTITUTE_MATCHED).
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.
Specifying a completely empty replacement string disables this
modifier. However, it is possible to specify an empty
replacement by providing a buffer length, as described below, for
an otherwise empty replacement.
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():
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,
preceded 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 replacement 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_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 (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
function is set up. The null_context modifier must not be set,
because the address of the callout function is passed in a match
context. When the callout function is called (after each
substitution), details of the input and output strings are
output. For example:
/abc/g,replace=<$0>,substitute_callout
abcdefabcpqr
1(1) Old 0 3 "abc" New 0 5 "<abc>"
2(1) Old 6 9 "abc" New 8 13 "<abc>"
2: <abc>def<abc>pqr
The first number on each callout line is the count of matches.
The parenthesized number is the number of pairs that are set in
the ovector (that is, one more than the number of capturing
groups that were set). Then are listed the offsets of the old
substring, its contents, and the same for the replacement.
By default, the substitution callout function returns zero, which
accepts the replacement and causes matching to continue if /g was
used. Two further modifiers can be used to test other return
values. If substitute_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, substitute_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 single 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
appropriate limits in the match context. These values are ignored
when the find_limits or find_limits_noheap modifier is specified.
Finding minimum limits
If the find_limits modifier is present on a subject line,
pcre2test calls the relevant matching function several times,
setting different values in the match context via
pcre2_set_heap_limit(), pcre2_set_match_limit(), or
pcre2_set_depth_limit() until it finds the smallest value for
each parameter that allows the match to complete without a "limit
exceeded" error. The match itself may succeed or fail. An
alternative modifier, find_limits_noheap, omits the heap limit.
This is used in the standard tests, because the minimum heap
limit varies between systems. If JIT is being used, only the
match limit is relevant, and the other two are automatically
omitted.
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.
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(). In the latter case, heap
memory is used only when a match requires more internal workspace
that the default allocation on the stack, so in many cases there
will be no output. No heap memory is allocated during matching
with JIT. For this modifier to work, the null_context modifier
must not be set on both the pattern and the subject, though it
can be set on one or the other.
Showing the heap frame overall vector size
The heapframes_size modifier is relevant for matches using
pcre2_match() without JIT. After a match has run (whether
successful or not) the size, in bytes, of the allocated heap
frames vector that is left attached to the match data block is
shown. If the matching action involved several calls to
pcre2_match() (for example, global matching or for timing) only
the final value is shown.
This modifier is ignored, with a warning, for POSIX or DFA
matching. JIT matching does not use the heap frames vector, so
the size is always zero, unless there was a previous non-JIT
match. Note that specifing a size of zero for the output vector
(see below) causes pcre2test to free its match data block (and
associated heap frames vector) and allocate a new one.
Setting a starting offset
The offset modifier sets an offset in the subject string at which
matching starts. Its value is a number of code units, not
characters.
Setting an offset limit
The offset_limit modifier sets a limit for unanchored matches. If
a match cannot be found starting at or before this offset in the
subject, a "no match" return is given. The data value is a number
of code units, not characters. When this modifier is used, the
use_offset_limit 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 new 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.)
The old match data block is freed.
Passing the subject as zero-terminated
By default, the subject string is passed to a native API matching
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, subject, or replacement
Normally, pcre2test passes a context block to pcre2_match(),
pcre2_dfa_match(), pcre2_jit_match() or pcre2_substitute(). If
the null_context modifier is set, however, NULL is passed. This
is for testing that the matching and substitution functions
behave correctly in this case (they use default values). This
modifier cannot be used with the find_limits, find_limits_noheap,
or substitute_callout modifiers.
Similarly, for testing purposes, if the null_subject or
null_replacement modifier is set, the subject or replacement
string pointers are passed as NULL, respectively, to the relevant
functions.
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 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 subject. If, however, the dfa_shortest modifier is set,
processing stops after the first match is found. This is always
the shortest possible match.
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.
$ 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 definition of non-printing characters. If the
aftertext modifier is set, the output for substring 0 is followed
by the rest of the subject string, identified by "0+" like this:
re> /cat/aftertext
data> cataract
0: cat
0+ aract
If global matching is requested, the results of successive
matching attempts 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).
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). 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:
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.
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:
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.
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:
--->pqrabcdef
0 ^ ^ \d
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:
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
whenever a change of latest mark is passed to the callout
function. For example:
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 before 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 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:
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 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 (<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, 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 pcre2callout documentation.
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.
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
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
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
#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-
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 control modifiers
that act after a pattern has been compiled. In particular, hex,
posix, posix_nosub, push, and pushcopy are not allowed, nor are
any option-setting modifiers. The JIT modifiers are, however
permitted. Here is an example that saves and reloads two
patterns.
/abc/push
/xyz/push
#save tempfile
#load tempfile
#pop info
xyz
#pop jit,bincode
abc
If jitverify is used with #pop, it does not automatically imply
jit, which is different behaviour from when it is used on a
pattern.
The #popcopy command is analogous to the pushcopy modifier in
that it makes current a copy of the topmost stack pattern,
leaving the original still on the stack.
pcre2(3), pcre2api(3), pcre2callout(3), pcre2jit,
pcre2matching(3), pcre2partial(d), pcre2pattern(3),
pcre2serialize(3).
Philip Hazel
Retired from University Computing Service
Cambridge, England.
Last updated: 24 April 2024
Copyright (c) 1997-2024 University of Cambridge.
This page is part of the PCRE (Perl Compatible Regular
Expressions) project. Information about the project can be found
at ⟨http://www.pcre.org/⟩. If you have a bug report for this
manual page, see
⟨http://bugs.exim.org/enter_bug.cgi?product=PCRE⟩. This page was
obtained from the tarball fetched from
⟨https://github.com/PhilipHazel/pcre2.git⟩ on 2024-06-14. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
PCRE 10.44 24 April 2024 PCRE2TEST(1)
|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|