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PCRETEST(1) PCRETEST(1)
NAME
pcretest - a program for testing Perl-compatible regular expressions.
SYNOPSIS
pcretest [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 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.
COMMAND LINE OPTIONS
-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.
-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_dfa_exec(), to be used instead of the standard
pcre_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_exec() repeat-
edly 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.
-o osize Set the number of elements in the output vector that is used
when calling pcre_exec() or pcre_dfa_exec() to be osize. The
default value is 45, which is enough for 14 capturing subex-
pressions for pcre_exec() or 22 different matches for
pcre_dfa_exec(). The vector size can be changed for individ-
ual 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.
-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, the
PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(), caus-
ing just-in-time optimization to be set up if it is avail-
able. 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 dif-
ferent 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 over-
ridden for specific patterns that should never be studied
(see the /S pattern 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. 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
modifiers. White space may appear between the final pattern delimiter
and the first modifier, and between the modifiers themselves.
The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
pile() is called. These four modifier letters have the same effect as
they do in Perl. For example:
/caseless/i
The following table shows additional modifiers for setting PCRE com-
pile-time options that do not correspond to anything in Perl:
/8 PCRE_UTF8
/? PCRE_NO_UTF8_CHECK
/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
/<JS> PCRE_JAVASCRIPT_COMPAT
/<cr> PCRE_NEWLINE_CR
/<lf> PCRE_NEWLINE_LF
/<crlf> PCRE_NEWLINE_CRLF
/<anycrlf> PCRE_NEWLINE_ANYCRLF
/<any> PCRE_NEWLINE_ANY
/<bsr_anycrlf> PCRE_BSR_ANYCRLF
/<bsr_unicode> PCRE_BSR_UNICODE
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 option, the /8 modifier also causes
any non-printing characters in output strings to be printed using the
\x{hh...} notation if they are valid UTF-8 sequences. Full details of
the PCRE options are given in the pcreapi documentation.
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_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_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+ has another meaning.
The /= modifier requests that the values of all potential captured
parentheses be output after a match by pcre_exec(). By default, only
those up to the highest one actually used in the match are output (cor-
responding to the return code from pcre_exec()). Values in the offsets
vector corresponding to higher numbers should be set to -1, and these
are output as "<unset>". This modifier gives a way of checking that
this is happening.
The /B modifier is a debugging feature. It requests that pcretest out-
put a representation of the compiled byte code after compilation. Nor-
mally this information contains length and offset values; however, if
/Z is also present, this data is replaced by spaces. This is a special
feature 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 fields in
the compiled pattern that contain 2-byte and 4-byte numbers. This
facility is for testing the feature in PCRE that allows it to execute
patterns that were compiled on a host with a different endianness. This
feature is not available 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_fullinfo() after compiling a
pattern. If the pattern is studied, the results of that are also out-
put.
The /K modifier requests pcretest to show names from backtracking con-
trol verbs that are returned from calls to pcre_exec(). It causes
pcretest to create a pcre_extra block if one has not already been cre-
ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
the mark field within it, every time that pcre_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_maketables() is called to build a set of character tables for the
locale, and this is then passed to pcre_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 of memory block used to hold the com-
piled pattern to be output. This does not include the size of the pcre
block; it is just the actual compiled data. If the pattern is success-
fully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
JIT compiled code is also output.
If the /S modifier appears once, it causes pcre_study() to be called
after the expression has been compiled, and the results used when the
expression is matched. If /S appears twice, 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 immediately followed by a + character, the call
to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option,
requesting just-in-time optimization support if it is available. Note
that there is also a /+ modifier; it must not be given immediately
after /S because this will be misinterpreted. If JIT studying is suc-
cessful, it will automatically be used when pcre_exec() is run, except
when incompatible run-time options are specified. These include the
partial matching options; a complete list is given in the pcrejit docu-
mentation. See also the \J escape sequence below for a way of setting
the size of the JIT stack.
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_compile().
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. When /P is set, the following modifiers set
options for the regcomp() function:
/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_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 "ordi-
nary" 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 mode
\xhh hexadecimal byte (up to 2 hex digits)
\x{hh...} hexadecimal character, any number of digits
in UTF-8 mode
\A pass the PCRE_ANCHORED option to pcre_exec()
or pcre_dfa_exec()
\B pass the PCRE_NOTBOL option to pcre_exec()
or pcre_dfa_exec()
\Cdd call pcre_copy_substring() for substring dd
after a successful match (number less than 32)
\Cname call pcre_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_dfa_exec() match function
\F only shortest match for pcre_dfa_exec()
\Gdd call pcre_get_substring() for substring dd
after a successful match (number less than 32)
\Gname call pcre_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_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_exec()
or pcre_dfa_exec(); if used twice, pass the
PCRE_NOTEMPTY_ATSTART option
\Odd set the size of the output vector passed to
pcre_exec() to dd (any number of digits)
\P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
or pcre_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_dfa_exec()
\S output details of memory get/free calls during matching
\Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
or pcre_dfa_exec()
\Z pass the PCRE_NOTEOL option to pcre_exec()
or pcre_dfa_exec()
\? pass the PCRE_NO_UTF8_CHECK option to
pcre_exec() or pcre_dfa_exec()
\>dd start the match at offset dd (optional "-"; then
any number of digits); this sets the startoffset
argument for pcre_exec() or pcre_dfa_exec()
\<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
or pcre_dfa_exec()
\<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
or pcre_dfa_exec()
\<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
or pcre_dfa_exec()
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
or pcre_dfa_exec()
\<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
or pcre_dfa_exec()
Note that \xhh always specifies one byte, even in UTF-8 mode; this
makes it possible to construct invalid UTF-8 sequences for testing pur-
poses. 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 not in UTF-8 mode, it generates one byte for values less than
256, and causes an error for greater values.
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_exec() several times, with dif-
ferent values in the match_limit and match_limit_recursion fields of
the pcre_extra data structure, until it finds the minimum numbers for
each parameter that allow pcre_exec() to complete without error.
Because this is testing a specific feature of the normal interpretive
pcre_exec() execution, the use of any JIT optimization 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_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 use of \x{hh...} to represent UTF-8 characters is not dependent on
the use of the /8 modifier on the pattern. It is recognized always.
There may be any number of hexadecimal digits inside the braces. The
result is from one to six bytes, encoded according to the original
UTF-8 rules of RFC 2279. This allows for values in the range 0 to
0x7FFFFFFF. Note that not all of those are valid Unicode code points,
or indeed valid UTF-8 characters according to the later rules in RFC
3629.
THE ALTERNATIVE MATCHING FUNCTION
By default, pcretest uses the standard PCRE matching function,
pcre_exec() to match each data line. From release 6.0, PCRE supports an
alternative matching function, pcre_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 called.
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_exec(), is being used.
When a match succeeds, pcretest outputs the list of captured substrings
that pcre_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 par-
tially matching substring when pcre_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-8 string check, the
byte 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_exec(), and are not shown by pcretest. In the fol-
lowing 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
\0x escapes, or as \x{...} escapes if the /8 modifier was present on
the pattern. See below for the definition of non-printing characters.
If the pattern has the /+ modifier, the output for substring 0 is fol-
lowed 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_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 example:
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, the output
--->pqrabcdef
0 ^ ^ \d
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.
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 ALSO
pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
tial(d), pcrepattern(3), pcreprecompile(3).
AUTHOR
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
REVISION
Last updated: 02 December 2011
Copyright (c) 1997-2011 University of Cambridge.