PCRETEST(1)PCRETEST(1)NAMEpcretest - a program for testing Perl-compatible regular expressions.
SYNOPSISpcretest [options] [input file [output file]]
pcretest was written as a test program for the PCRE regular expression
library itself, 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 pcrepattern
documentation. For details of the PCRE library function calls and their
options, see the pcreapi , pcre16 and pcre32 documentation.
The input for pcretest is a sequence of regular expression patterns and
strings to be matched, as described below. The output shows the result
of each match. Options on the command line and the patterns control
PCRE options and exactly what is output.
As PCRE has evolved, it has acquired many different features, and as a
result, pcretest now has rather a lot of obscure options for testing
every possible feature. Some of these options are specifically designed
for use in conjunction with the test script and data files that are
distributed as part of PCRE, and are unlikely to be of use otherwise.
They are all documented here, but without much justification.
INPUT DATA FORMAT
Input to pcretest is processed line by line, either by calling the C
library's fgets() function, or via the libreadline library (see below).
In Unix-like environments, fgets() treats any bytes other than newline
as data characters. However, in some Windows environments character 26
(hex 1A) causes an immediate end of file, and no further data is read.
For maximum portability, therefore, it is safest to use only ASCII
characters in pcretest input files.
PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES
From release 8.30, two separate PCRE libraries can be built. The origi‐
nal one supports 8-bit character strings, whereas the newer 16-bit
library supports character strings encoded in 16-bit units. From
release 8.32, a third library can be built, supporting character
strings encoded in 32-bit units. The pcretest program can be used to
test all three libraries. However, it is itself still an 8-bit program,
reading 8-bit input and writing 8-bit output. When testing the 16-bit
or 32-bit library, the patterns and data strings are converted to 16-
or 32-bit format before being passed to the PCRE library functions.
Results are converted to 8-bit for output.
References to functions and structures of the form pcre[16|32]_xx below
mean "pcre_xx when using the 8-bit library, pcre16_xx when using the
16-bit library, or pcre32_xx when using the 32-bit library".
COMMAND LINE OPTIONS-8 If both the 8-bit library has been built, this option causes
the 8-bit library to be used (which is the default); if the
8-bit library has not been built, this option causes an
error.
-16 If both the 8-bit or the 32-bit, and the 16-bit libraries
have been built, this option causes the 16-bit library to be
used. If only the 16-bit library has been built, this is the
default (so has no effect). If only the 8-bit or the 32-bit
library has been built, this option causes an error.
-32 If both the 8-bit or the 16-bit, and the 32-bit libraries
have been built, this option causes the 32-bit library to be
used. If only the 32-bit library has been built, this is the
default (so has no effect). If only the 8-bit or the 16-bit
library has been built, this option causes an error.
-b Behave as if each pattern has the /B (show byte code) modi‐
fier; the internal form is output after compilation.
-C Output the version number of the PCRE library, and all avail‐
able information about the optional features that are
included, and then exit with zero exit code. All other
options are ignored.
-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, 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:
ebcdic compiled for an EBCDIC environment
jit just-in-time support is available
pcre16 the 16-bit library was built
pcre32 the 32-bit library was built
pcre8 the 8-bit library was built
ucp Unicode property support is available
utf UTF-8 and/or UTF-16 and/or UTF-32 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 /D (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 data line contains the \D escape sequence;
this causes the alternative matching function,
pcre[16|32]_dfa_exec(), to be used instead of the standard
pcre[16|32]_exec() function (more detail is given below).
-help Output a brief summary these options and then exit.
-i Behave as if each pattern has the /I modifier; information
about the compiled pattern is given after compilation.
-M Behave as if each data line contains the \M escape sequence;
this causes PCRE to discover the minimum MATCH_LIMIT and
MATCH_LIMIT_RECURSION settings by calling pcre[16|32]_exec()
repeatedly with different limits.
-m Output the size of each compiled pattern after it has been
compiled. This is equivalent to adding /M to each regular
expression. The size is given in bytes for both libraries.
-o osize Set the number of elements in the output vector that is used
when calling pcre[16|32]_exec() or pcre[16|32]_dfa_exec() to
be osize. The default value is 45, which is enough for 14
capturing subexpressions for pcre[16|32]_exec() or 22 differ‐
ent matches for pcre[16|32]_dfa_exec(). The vector size can
be changed for individual matching calls by including \O in
the data line (see below).
-p Behave as if each pattern has the /P modifier; the POSIX
wrapper API is used to call PCRE. None of the other options
has any effect when -p is set. This option can be used only
with the 8-bit library.
-q Do not output the version number of pcretest at the start of
execution.
-S size On Unix-like systems, set the size of the run-time stack to
size megabytes.
-s or -s+ Behave as if each pattern has the /S modifier; in other
words, force each pattern to be studied. If -s+ is used, all
the JIT compile options are passed to pcre[16|32]_study(),
causing just-in-time optimization to be set up if it is
available, for both full and partial matching. Specific JIT
compile options can be selected by following -s+ with a digit
in the range 1 to 7, which selects the JIT compile modes as
follows:
1 normal match only
2 soft partial match only
3 normal match and soft partial match
4 hard partial match only
6 soft and hard partial match
7 all three modes (default)
If -s++ is used instead of -s+ (with or without a following
digit), the text "(JIT)" is added to the first output line
after a match or no match when JIT-compiled code was actually
used.
Note that there are pattern options that can override -s,
either specifying no studying at all, or suppressing JIT com‐
pilation.
If the /I or /D option is present on a pattern (requesting
output about the compiled pattern), information about the
result of studying is not included when studying is caused
only by -s and neither -i nor -d is present on the command
line. This behaviour means that the output from tests that
are run with and without -s should be identical, except when
options that output information about the actual running of a
match are set.
The -M, -t, and -tm options, which give information about
resources used, are likely to produce different output with
and without -s. Output may also differ if the /C option is
present on an individual pattern. This uses callouts to trace
the the matching process, and this may be different between
studied and non-studied patterns. If the pattern contains
(*MARK) items there may also be differences, for the same
reason. The -s command line option can be overridden for spe‐
cific patterns that should never be studied (see the /S pat‐
tern modifier below).
-t Run each compile, study, and match many times with a timer,
and output resulting time per compile or match (in millisec‐
onds). Do not set -m with -t, because you will then get the
size output a zillion times, and the timing will be dis‐
torted. 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" would iter‐
ate 1000 times. The default is to iterate 500000 times.
-tm This is like -t except that it times only the matching phase,
not the compile or study phases.
DESCRIPTION
If pcretest is given two filename arguments, it reads from the first
and writes to the second. If it is given only one filename argument, it
reads from that file and writes to stdout. Otherwise, it reads from
stdin and writes to stdout, and prompts for each line of input, using
"re>" to prompt for regular expressions, and "data>" to prompt for data
lines.
When pcretest is built, a configuration option can specify that it
should be linked with the libreadline 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 sets of input on a single input file.
Each set starts with a regular expression, and continues with any num‐
ber of data lines to be matched against the pattern.
Each data 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
data lines; the input buffer is automatically extended if it is too
small.
An empty line signals the end of the data lines, at which point a new
regular expression is read. The regular expressions are given enclosed
in any non-alphanumeric delimiters other than backslash, for example:
/(a|bc)x+yz/
White space before the initial delimiter is ignored. A regular expres‐
sion may be continued over several input lines, in which case the new‐
line characters are included within it. It is possible to include the
delimiter within the pattern by escaping it, for example
/abc\/def/
If you do so, the escape and the delimiter form part of the pattern,
but since delimiters are always non-alphanumeric, this does not affect
its interpretation. If the terminating delimiter is immediately fol‐
lowed by a backslash, for example,
/abc/\
then a backslash is added to the end of the pattern. This is done to
provide a way of testing the error condition that arises if a pattern
finishes with a backslash, because
/abc\/
is interpreted as the first line of a pattern that starts with "abc/",
causing pcretest to read the next line as a continuation of the regular
expression.
PATTERN MODIFIERS
A pattern may be followed by any number of modifiers, which are mostly
single characters, though some of these can be qualified by further
characters. Following Perl usage, these are referred to below as, for
example, "the /i modifier", even though the delimiter of the pattern
need not always be a slash, and no slash is used when writing modi‐
fiers. White space may appear between the final pattern delimiter and
the first modifier, and between the modifiers themselves. For refer‐
ence, here is a complete list of modifiers. They fall into several
groups that are described in detail in the following sections.
/8 set UTF mode
/9 set PCRE_NEVER_UTF (locks out UTF mode)
/? disable UTF validity check
/+ show remainder of subject after match
/= show all captures (not just those that are set)
/A set PCRE_ANCHORED
/B show compiled code
/C set PCRE_AUTO_CALLOUT
/D same as /B plus /I
/E set PCRE_DOLLAR_ENDONLY
/F flip byte order in compiled pattern
/f set PCRE_FIRSTLINE
/G find all matches (shorten string)
/g find all matches (use startoffset)
/I show information about pattern
/i set PCRE_CASELESS
/J set PCRE_DUPNAMES
/K show backtracking control names
/L set locale
/M show compiled memory size
/m set PCRE_MULTILINE
/N set PCRE_NO_AUTO_CAPTURE
/P use the POSIX wrapper
/S study the pattern after compilation
/s set PCRE_DOTALL
/T select character tables
/U set PCRE_UNGREEDY
/W set PCRE_UCP
/X set PCRE_EXTRA
/x set PCRE_EXTENDED
/Y set PCRE_NO_START_OPTIMIZE
/Z don't show lengths in /B output
/<any> set PCRE_NEWLINE_ANY
/<anycrlf> set PCRE_NEWLINE_ANYCRLF
/<cr> set PCRE_NEWLINE_CR
/<crlf> set PCRE_NEWLINE_CRLF
/<lf> set PCRE_NEWLINE_LF
/<bsr_anycrlf> set PCRE_BSR_ANYCRLF
/<bsr_unicode> set PCRE_BSR_UNICODE
/<JS> set PCRE_JAVASCRIPT_COMPAT
Perl-compatible modifiers
The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
pcre[16|32]_compile() is called. These four modifier letters have the
same effect as they do in Perl. For example:
/caseless/i
Modifiers for other PCRE options
The following table shows additional modifiers for setting PCRE com‐
pile-time options that do not correspond to anything in Perl:
/8 PCRE_UTF8 ) when using the 8-bit
/? PCRE_NO_UTF8_CHECK ) library
/8 PCRE_UTF16 ) when using the 16-bit
/? PCRE_NO_UTF16_CHECK ) library
/8 PCRE_UTF32 ) when using the 32-bit
/? PCRE_NO_UTF32_CHECK ) library
/9 PCRE_NEVER_UTF
/A PCRE_ANCHORED
/C PCRE_AUTO_CALLOUT
/E PCRE_DOLLAR_ENDONLY
/f PCRE_FIRSTLINE
/J PCRE_DUPNAMES
/N PCRE_NO_AUTO_CAPTURE
/U PCRE_UNGREEDY
/W PCRE_UCP
/X PCRE_EXTRA
/Y PCRE_NO_START_OPTIMIZE
/<any> PCRE_NEWLINE_ANY
/<anycrlf> PCRE_NEWLINE_ANYCRLF
/<cr> PCRE_NEWLINE_CR
/<crlf> PCRE_NEWLINE_CRLF
/<lf> PCRE_NEWLINE_LF
/<bsr_anycrlf> PCRE_BSR_ANYCRLF
/<bsr_unicode> PCRE_BSR_UNICODE
/<JS> PCRE_JAVASCRIPT_COMPAT
The modifiers that are enclosed in angle brackets are literal strings
as shown, including the angle brackets, but the letters within can be
in either case. This example sets multiline matching with CRLF as the
line ending sequence:
/^abc/m<CRLF>
As well as turning on the PCRE_UTF8/16/32 option, the /8 modifier
causes all non-printing characters in output strings to be printed
using the \x{hh...} notation. Otherwise, those less than 0x100 are out‐
put in hex without the curly brackets.
Full details of the PCRE options are given in the pcreapi documenta‐
tion.
Finding all matches in a string
Searching for all possible matches within each subject string can be
requested by the /g or /G modifier. After finding a match, PCRE is
called again to search the remainder of the subject string. The differ‐
ence between /g and /G is that the former uses the startoffset argument
to pcre[16|32]_exec() to start searching at a new point within the
entire string (which is in effect what Perl does), whereas the latter
passes over a shortened substring. This makes a difference to the
matching process if the pattern begins with a lookbehind assertion
(including \b or \B).
If any call to pcre[16|32]_exec() in a /g or /G sequence matches an
empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
PCRE_ANCHORED flags set in order to search for another, non-empty,
match at the same point. If this second 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() func‐
tion. 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 is used.
Other modifiers
There are yet more modifiers for controlling the way pcretest operates.
The /+ modifier requests that as well as outputting the substring that
matched the entire pattern, pcretest 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. If the + modi‐
fier appears twice, the same action is taken for captured substrings.
In each case the remainder is output on the following line with a plus
character following the capture number. Note that this modifier must
not immediately follow the /S modifier because /S+ and /S++ have other
meanings.
The /= 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 pcre[16|32]_exec()). Values in the offsets vector cor‐
responding to higher numbers should be set to -1, and these are output
as "<unset>". This modifier gives a way of checking that this is hap‐
pening.
The /B modifier is a debugging feature. It requests that pcretest out‐
put a representation of the compiled code after compilation. Normally
this information contains length and offset values; however, if /Z is
also present, this data is replaced by spaces. This is a special fea‐
ture for use in the automatic test scripts; it ensures that the same
output is generated for different internal link sizes.
The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
that is, both the /B and the /I modifiers.
The /F modifier causes pcretest to flip the byte order of the 2-byte
and 4-byte fields in the compiled pattern. This facility is for testing
the feature in PCRE that allows it to execute patterns that were com‐
piled on a host with a different endianness. This feature is not avail‐
able when the POSIX interface to PCRE is being used, that is, when the
/P pattern modifier is specified. See also the section about saving and
reloading compiled patterns below.
The /I modifier requests that pcretest output information about the
compiled pattern (whether it is anchored, has a fixed first character,
and so on). It does this by calling pcre[16|32]_fullinfo() after com‐
piling a pattern. If the pattern is studied, the results of that are
also output.
The /K modifier requests pcretest to show names from backtracking con‐
trol verbs that are returned from calls to pcre[16|32]_exec(). It
causes pcretest to create a pcre[16|32]_extra block if one has not
already been created by a call to pcre[16|32]_study(), and to set the
PCRE_EXTRA_MARK flag and the mark field within it, every time that
pcre[16|32]_exec() is called. If the variable that the mark field
points to is non-NULL for a match, non-match, or partial match,
pcretest prints the string to which it points. For a match, this is
shown on a line by itself, tagged with "MK:". For a non-match it is
added to the message.
The /L modifier must be followed directly by the name of a locale, for
example,
/pattern/Lfr_FR
For this reason, it must be the last modifier. The given locale is set,
pcre[16|32]_maketables() is called to build a set of character tables
for the locale, and this is then passed to pcre[16|32]_compile() when
compiling the regular expression. Without an /L (or /T) modifier, NULL
is passed as the tables pointer; that is, /L applies only to the
expression on which it appears.
The /M modifier causes the size in bytes of the memory block used to
hold the compiled pattern to be output. This does not include the size
of the pcre[16|32] block; it is just the actual compiled data. If the
pattern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
the size of the JIT compiled code is also output.
The /S modifier causes pcre[16|32]_study() to be called after the
expression has been compiled, and the results used when the expression
is matched. There are a number of qualifying characters that may follow
/S. They may appear in any order.
If S is followed by an exclamation mark, pcre[16|32]_study() is called
with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
pcre_extra block, even when studying discovers no useful information.
If /S is followed by a second S character, it suppresses studying, even
if it was requested externally by the -s command line option. This
makes it possible to specify that certain patterns are always studied,
and others are never studied, independently of -s. This feature is used
in the test files in a few cases where the output is different when the
pattern is studied.
If the /S modifier is followed by a + character, the call to
pcre[16|32]_study() is made with all the JIT study options, requesting
just-in-time optimization support if it is available, for both normal
and partial matching. If you want to restrict the JIT compiling modes,
you can follow /S+ with a digit in the range 1 to 7:
1 normal match only
2 soft partial match only
3 normal match and soft partial match
4 hard partial match only
6 soft and hard partial match
7 all three modes (default)
If /S++ is used instead of /S+ (with or without a following digit), the
text "(JIT)" is added to the first output line after a match or no
match when JIT-compiled code was actually used.
Note that there is also an independent /+ modifier; it must not be
given immediately after /S or /S+ because this will be misinterpreted.
If JIT studying is successful, the compiled JIT code will automatically
be used when pcre[16|32]_exec() is run, except when incompatible run-
time options are specified. For more details, see the pcrejit documen‐
tation. See also the \J escape sequence below for a way of setting the
size of the JIT stack.
Finally, if /S is followed by a minus character, JIT compilation is
suppressed, even if it was requested externally by the -s command line
option. This makes it possible to specify that JIT is never to be used
for certain patterns.
The /T modifier must be followed by a single digit. It causes a spe‐
cific set of built-in character tables to be passed to pcre[16|32]_com‐
pile(). It is used in the standard PCRE tests to check behaviour with
different character tables. The digit specifies the tables as follows:
0 the default ASCII tables, as distributed in
pcre_chartables.c.dist
1 a set of tables defining ISO 8859 characters
In table 1, some characters whose codes are greater than 128 are iden‐
tified as letters, digits, spaces, etc.
Using the POSIX wrapper API
The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
rather than its native API. This supports only the 8-bit library. When
/P is set, the following modifiers set options for the regcomp() func‐
tion:
/i REG_ICASE
/m REG_NEWLINE
/N REG_NOSUB
/s REG_DOTALL )
/U REG_UNGREEDY ) These options are not part of
/W REG_UCP ) the POSIX standard
/8 REG_UTF8 )
The /+ modifier works as described above. All other modifiers are
ignored.
DATA LINES
Before each data line is passed to pcre[16|32]_exec(), leading and
trailing white space is removed, and it is then scanned for \ escapes.
Some of these are pretty esoteric features, intended for checking out
some of the more complicated features of PCRE. If you are just testing
"ordinary" regular expressions, you probably don't need any of these.
The following escapes are recognized:
\a alarm (BEL, \x07)
\b backspace (\x08)
\e escape (\x27)
\f form feed (\x0c)
\n newline (\x0a)
\qdd set the PCRE_MATCH_LIMIT limit to dd
(any number of digits)
\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
\xhh hexadecimal byte (up to 2 hex digits)
\x{hh...} hexadecimal character (any number of hex digits)
\A pass the PCRE_ANCHORED option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\B pass the PCRE_NOTBOL option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\Cdd call pcre[16|32]_copy_substring() for substring dd
after a successful match (number less than 32)
\Cname call pcre[16|32]_copy_named_substring() for substring
"name" after a successful match (name termin-
ated by next non alphanumeric character)
\C+ show the current captured substrings at callout
time
\C- do not supply a callout function
\C!n return 1 instead of 0 when callout number n is
reached
\C!n!m return 1 instead of 0 when callout number n is
reached for the nth time
\C*n pass the number n (may be negative) as callout
data; this is used as the callout return value
\D use the pcre[16|32]_dfa_exec() match function
\F only shortest match for pcre[16|32]_dfa_exec()
\Gdd call pcre[16|32]_get_substring() for substring dd
after a successful match (number less than 32)
\Gname call pcre[16|32]_get_named_substring() for substring
"name" after a successful match (name termin-
ated by next non-alphanumeric character)
\Jdd set up a JIT stack of dd kilobytes maximum (any
number of digits)
\L call pcre[16|32]_get_substringlist() after a
successful match
\M discover the minimum MATCH_LIMIT and
MATCH_LIMIT_RECURSION settings
\N pass the PCRE_NOTEMPTY option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec(); if used twice, pass the
PCRE_NOTEMPTY_ATSTART option
\Odd set the size of the output vector passed to
pcre[16|32]_exec() to dd (any number of digits)
\P pass the PCRE_PARTIAL_SOFT option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec(); if used twice, pass the
PCRE_PARTIAL_HARD option
\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
(any number of digits)
\R pass the PCRE_DFA_RESTART option to pcre[16|32]_dfa_exec()
\S output details of memory get/free calls during matching
\Y pass the PCRE_NO_START_OPTIMIZE option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\Z pass the PCRE_NOTEOL option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\? pass the PCRE_NO_UTF[8|16|32]_CHECK option to
pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
\>dd start the match at offset dd (optional "-"; then
any number of digits); this sets the startoffset
argument for pcre[16|32]_exec() or
pcre[16|32]_dfa_exec()
\<cr> pass the PCRE_NEWLINE_CR option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<lf> pass the PCRE_NEWLINE_LF option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<crlf> pass the PCRE_NEWLINE_CRLF option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<any> pass the PCRE_NEWLINE_ANY option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
The use of \x{hh...} is not dependent on the use of the /8 modifier on
the pattern. It is recognized always. There may be any number of hexa‐
decimal digits inside the braces; invalid values provoke error mes‐
sages.
Note that \xhh specifies one byte rather than one character in UTF-8
mode; this makes it possible to construct invalid UTF-8 sequences for
testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
character in UTF-8 mode, generating more than one byte if the value is
greater than 127. When testing the 8-bit library not in UTF-8 mode,
\x{hh} generates one byte for values less than 256, and causes an error
for greater values.
In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
possible to construct invalid UTF-16 sequences for testing purposes.
In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This
makes it possible to construct invalid UTF-32 sequences for testing
purposes.
The escapes that specify line ending sequences are literal strings,
exactly as shown. No more than one newline setting should be present in
any data line.
A backslash followed by anything else just escapes the anything else.
If the very last character is a backslash, it is ignored. This gives a
way of passing an empty line as data, since a real empty line termi‐
nates the data input.
The \J escape provides a way of setting the maximum stack size that is
used by the just-in-time optimization code. It is ignored if JIT opti‐
mization is not being used. Providing a stack that is larger than the
default 32K is necessary only for very complicated patterns.
If \M is present, pcretest calls pcre[16|32]_exec() several times, with
different values in the match_limit and match_limit_recursion fields of
the pcre[16|32]_extra data structure, until it finds the minimum num‐
bers for each parameter that allow pcre[16|32]_exec() to complete with‐
out error. Because this is testing a specific feature of the normal
interpretive pcre[16|32]_exec() execution, the use of any JIT optimiza‐
tion that might have been set up by the /S+ qualifier of -s+ option is
disabled.
The match_limit number is a measure of the amount of backtracking that
takes place, and checking it out 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. The match_limit_recursion
number is a measure of how much stack (or, if PCRE is compiled with
NO_RECURSE, how much heap) memory is needed to complete the match
attempt.
When \O is used, the value specified may be higher or lower than the
size set by the -O command line option (or defaulted to 45); \O applies
only to the call of pcre[16|32]_exec() for the line in which it
appears.
If the /P modifier was present on the pattern, causing the POSIX wrap‐
per API to be used, the only option-setting sequences that have any
effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
REG_NOTEOL, respectively, to be passed to regexec().
THE ALTERNATIVE MATCHING FUNCTION
By default, pcretest uses the standard PCRE matching function,
pcre[16|32]_exec() to match each data line. PCRE also supports an
alternative matching function, pcre[16|32]_dfa_test(), which operates
in a different way, and has some restrictions. The differences between
the two functions are described in the pcrematching documentation.
If a data line contains the \D escape sequence, or if the command line
contains the -dfa option, the alternative matching function is used.
This function finds all possible matches at a given point. If, however,
the \F escape sequence is present in the data line, it stops after the
first match is found. This is always the shortest possible match.
DEFAULT OUTPUT FROM PCRETEST
This section describes the output when the normal matching function,
pcre[16|32]_exec(), is being used.
When a match succeeds, pcretest outputs the list of captured substrings
that pcre[16|32]_exec() returns, starting with number 0 for the string
that matched the whole pattern. Otherwise, it outputs "No match" when
the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
partially matching substring when pcre[16|32]_exec() returns
PCRE_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, pcretest outputs the PCRE negative
error number and a short descriptive phrase. If the error is a failed
UTF string check, the offset of the start of the failing character and
the reason code are also output, provided that the size of the output
vector is at least two. Here is an example of an interactive pcretest
run.
$ pcretest
PCRE version 8.13 2011-04-30
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 returned by pcre[16|32]_exec(), and are not shown by pcretest. In
the following example, there are two capturing substrings, but when the
first data line is matched, the second, unset substring is not shown.
An "internal" unset substring is shown as "<unset>", as for the second
data line.
re> /(a)|(b)/
data> a
0: a
1: a
data> b
0: b
1: <unset>
2: b
If the strings contain any non-printing characters, they are output as
\xhh escapes if the value is less than 256 and UTF mode is not set.
Otherwise they are output as \x{hh...} escapes. See below for the defi‐
nition of non-printing characters. If the pattern has the /+ modifier,
the output for substring 0 is followed by the the rest of the subject
string, identified by "0+" like this:
re> /cat/+
data> cataract
0: cat
0+ aract
If the pattern has the /g or /G modifier, 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 \>4 is
past the end of the subject string):
re> /xyz/
data> xyz\>4
Error -24 (bad offset value)
If any of the sequences \C, \G, or \L are present in a data line that
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 paren‐
theses after each string for \C and \G.
Note that whereas patterns can be continued over several lines (a plain
">" prompt is used for continuations), data lines may not. However new‐
lines can be included in data by means of the \n escape (or \r, \r\n,
etc., depending on the newline sequence setting).
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
When the alternative matching function, pcre[16|32]_dfa_exec(), is used
(by means of the \D escape sequence or the -dfa command line option),
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 exam‐
ple:
re> /(tang|tangerine|tan)/
data> yellow tangerine\D
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 PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol‐
lowed by the partially matching substring. (Note that this is the
entire substring that was inspected during the partial match; it may
include characters before the actual match start if a lookbehind asser‐
tion, \K, \b, or \B was involved.)
If /g is present on the pattern, 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\D
0: tangerine
1: tang
2: tan
0: tang
1: tan
0: tan
Since the matching function does not support substring capture, the
escape sequences that are concerned with captured substrings are not
relevant.
RESTARTING AFTER A PARTIAL MATCH
When the alternative matching function has given the PCRE_ERROR_PARTIAL
return, indicating that the subject partially matched the pattern, you
can restart the match with additional subject data by means of the \R
escape sequence. For example:
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
data> 23ja\P\D
Partial match: 23ja
data> n05\R\D
0: n05
For further information about partial matching, see the pcrepartial
documentation.
CALLOUTS
If the pattern contains any callout requests, pcretest's callout func‐
tion is called during matching. This works with both matching func‐
tions. By default, the called function displays the callout number, the
start and current positions in the 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 of the data, and when the next
pattern item was \d. Just one circumflex is output if the start and
current positions are the same.
Callouts numbered 255 are assumed to be automatic callouts, inserted as
a result of the /C 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]\*/C
data> E*
--->E*
+0 ^ \d?
+3 ^ [A-E]
+8 ^^ \*
+10 ^ ^
0: E*
If a pattern contains (*MARK) items, an additional line is output when‐
ever a change of latest mark is passed to the callout function. For
example:
re> /a(*MARK:X)bc/C
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.
The callout function in pcretest returns zero (carry on matching) by
default, but you can use a \C item in a data line (as described above)
to change this and other parameters of the callout.
Inserting callouts can be helpful when using pcretest to check compli‐
cated regular expressions. For further information about callouts, see
the pcrecallout documentation.
NON-PRINTING CHARACTERS
When pcretest is outputting text in the compiled version of a pattern,
bytes other than 32-126 are always treated as non-printing characters
are are therefore shown as hex escapes.
When pcretest 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 /L modifier). In this case, the
isprint() function to distinguish printing and non-printing characters.
SAVING AND RELOADING COMPILED PATTERNS
The facilities described in this section are not available when the
POSIX interface to PCRE is being used, that is, when the /P pattern
modifier is specified.
When the POSIX interface is not in use, you can cause pcretest to write
a compiled pattern to a file, by following the modifiers with > and a
file name. For example:
/pattern/im >/some/file
See the pcreprecompile documentation for a discussion about saving and
re-using compiled patterns. Note that if the pattern was successfully
studied with JIT optimization, the JIT data cannot be saved.
The data that is written is binary. The first eight bytes are the
length of the compiled pattern data followed by the length of the
optional study data, each written as four bytes in big-endian order
(most significant byte first). If there is no study data (either the
pattern was not studied, or studying did not return any data), the sec‐
ond length is zero. The lengths are followed by an exact copy of the
compiled pattern. If there is additional study data, this (excluding
any JIT data) follows immediately after the compiled pattern. After
writing the file, pcretest expects to read a new pattern.
A saved pattern can be reloaded into pcretest by specifying < and a
file name instead of a pattern. The name of the file must not contain a
< character, as otherwise pcretest will interpret the line as a pattern
delimited by < characters. For example:
re> </some/file
Compiled pattern loaded from /some/file
No study data
If the pattern was previously studied with the JIT optimization, the
JIT information cannot be saved and restored, and so is lost. When the
pattern has been loaded, pcretest proceeds to read data lines in the
usual way.
You can copy a file written by pcretest to a different host and reload
it there, even if the new host has opposite endianness to the one on
which the pattern was compiled. For example, you can compile on an i86
machine and run on a SPARC machine. When a pattern is reloaded on a
host with different endianness, the confirmation message is changed to:
Compiled pattern (byte-inverted) loaded from /some/file
The test suite contains some saved pre-compiled patterns with different
endianness. These are reloaded using "<!" instead of just "<". This
suppresses the "(byte-inverted)" text so that the output is the same on
all hosts. It also forces debugging output once the pattern has been
reloaded.
File names for saving and reloading can be absolute or relative, but
note that the shell facility of expanding a file name that starts with
a tilde (~) is not available.
The ability to save and reload files in pcretest is intended for test‐
ing and experimentation. It is not intended for production use because
only a single pattern can be written to a file. Furthermore, there is
no facility for supplying custom character tables for use with a
reloaded pattern. If the original pattern was compiled with custom
tables, an attempt to match a subject string using a reloaded pattern
is likely to cause pcretest to crash. Finally, if you attempt to load
a file that is not in the correct format, the result is undefined.
SEE ALSOpcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3), pcrejit,
pcrematching(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).
AUTHOR
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
REVISION
Last updated: 26 April 2013
Copyright (c) 1997-2013 University of Cambridge.
PCRE 8.33 26 April 2013 PCRETEST(1)
