summaryrefslogtreecommitdiff
path: root/libs/Pcre16/docs/doc/html/pcretest.html
diff options
context:
space:
mode:
Diffstat (limited to 'libs/Pcre16/docs/doc/html/pcretest.html')
-rw-r--r--libs/Pcre16/docs/doc/html/pcretest.html1158
1 files changed, 1158 insertions, 0 deletions
diff --git a/libs/Pcre16/docs/doc/html/pcretest.html b/libs/Pcre16/docs/doc/html/pcretest.html
new file mode 100644
index 0000000000..839fabf189
--- /dev/null
+++ b/libs/Pcre16/docs/doc/html/pcretest.html
@@ -0,0 +1,1158 @@
+<html>
+<head>
+<title>pcretest specification</title>
+</head>
+<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
+<h1>pcretest man page</h1>
+<p>
+Return to the <a href="index.html">PCRE index page</a>.
+</p>
+<p>
+This page is part of the PCRE HTML documentation. It was generated automatically
+from the original man page. If there is any nonsense in it, please consult the
+man page, in case the conversion went wrong.
+<br>
+<ul>
+<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
+<li><a name="TOC2" href="#SEC2">INPUT DATA FORMAT</a>
+<li><a name="TOC3" href="#SEC3">PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a>
+<li><a name="TOC4" href="#SEC4">COMMAND LINE OPTIONS</a>
+<li><a name="TOC5" href="#SEC5">DESCRIPTION</a>
+<li><a name="TOC6" href="#SEC6">PATTERN MODIFIERS</a>
+<li><a name="TOC7" href="#SEC7">DATA LINES</a>
+<li><a name="TOC8" href="#SEC8">THE ALTERNATIVE MATCHING FUNCTION</a>
+<li><a name="TOC9" href="#SEC9">DEFAULT OUTPUT FROM PCRETEST</a>
+<li><a name="TOC10" href="#SEC10">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
+<li><a name="TOC11" href="#SEC11">RESTARTING AFTER A PARTIAL MATCH</a>
+<li><a name="TOC12" href="#SEC12">CALLOUTS</a>
+<li><a name="TOC13" href="#SEC13">NON-PRINTING CHARACTERS</a>
+<li><a name="TOC14" href="#SEC14">SAVING AND RELOADING COMPILED PATTERNS</a>
+<li><a name="TOC15" href="#SEC15">SEE ALSO</a>
+<li><a name="TOC16" href="#SEC16">AUTHOR</a>
+<li><a name="TOC17" href="#SEC17">REVISION</a>
+</ul>
+<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
+<P>
+<b>pcretest [options] [input file [output file]]</b>
+<br>
+<br>
+<b>pcretest</b> 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
+<a href="pcrepattern.html"><b>pcrepattern</b></a>
+documentation. For details of the PCRE library function calls and their
+options, see the
+<a href="pcreapi.html"><b>pcreapi</b></a>
+,
+<a href="pcre16.html"><b>pcre16</b></a>
+and
+<a href="pcre32.html"><b>pcre32</b></a>
+documentation.
+</P>
+<P>
+The input for <b>pcretest</b> 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.
+</P>
+<P>
+As PCRE has evolved, it has acquired many different features, and as a result,
+<b>pcretest</b> 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.
+</P>
+<br><a name="SEC2" href="#TOC1">INPUT DATA FORMAT</a><br>
+<P>
+Input to <b>pcretest</b> is processed line by line, either by calling the C
+library's <b>fgets()</b> function, or via the <b>libreadline</b> library (see
+below). In Unix-like environments, <b>fgets()</b> 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
+<b>pcretest</b> input files.
+</P>
+<br><a name="SEC3" href="#TOC1">PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><br>
+<P>
+From release 8.30, two separate PCRE libraries can be built. The original 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
+<b>pcretest</b> 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.
+</P>
+<P>
+References to functions and structures of the form <b>pcre[16|32]_xx</b> below
+mean "<b>pcre_xx</b> when using the 8-bit library, <b>pcre16_xx</b> when using
+the 16-bit library, or <b>pcre32_xx</b> when using the 32-bit library".
+</P>
+<br><a name="SEC4" href="#TOC1">COMMAND LINE OPTIONS</a><br>
+<P>
+<b>-8</b>
+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.
+</P>
+<P>
+<b>-16</b>
+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.
+</P>
+<P>
+<b>-32</b>
+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.
+</P>
+<P>
+<b>-b</b>
+Behave as if each pattern has the <b>/B</b> (show byte code) modifier; the
+internal form is output after compilation.
+</P>
+<P>
+<b>-C</b>
+Output the version number of the PCRE library, and all available information
+about the optional features that are included, and then exit with zero exit
+code. All other options are ignored.
+</P>
+<P>
+<b>-C</b> <i>option</i>
+Output information about a specific build-time option, then exit. This
+functionality is intended for use in scripts such as <b>RunTest</b>. The
+following options output the value and set the exit code as indicated:
+<pre>
+ ebcdic-nl the code for LF (= NL) in an EBCDIC environment:
+ 0x15 or 0x25
+ 0 if used in an ASCII environment
+ exit code is always 0
+ linksize the configured internal link size (2, 3, or 4)
+ exit code is set to the link size
+ newline the default newline setting:
+ CR, LF, CRLF, ANYCRLF, or ANY
+ exit code is always 0
+ bsr the default setting for what \R matches:
+ ANYCRLF or ANY
+ exit code is always 0
+</pre>
+The following options output 1 for true or 0 for false, and set the exit code
+to the same value:
+<pre>
+ 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
+</pre>
+If an unknown option is given, an error message is output; the exit code is 0.
+</P>
+<P>
+<b>-d</b>
+Behave as if each pattern has the <b>/D</b> (debug) modifier; the internal
+form and information about the compiled pattern is output after compilation;
+<b>-d</b> is equivalent to <b>-b -i</b>.
+</P>
+<P>
+<b>-dfa</b>
+Behave as if each data line contains the \D escape sequence; this causes the
+alternative matching function, <b>pcre[16|32]_dfa_exec()</b>, to be used instead
+of the standard <b>pcre[16|32]_exec()</b> function (more detail is given below).
+</P>
+<P>
+<b>-help</b>
+Output a brief summary these options and then exit.
+</P>
+<P>
+<b>-i</b>
+Behave as if each pattern has the <b>/I</b> modifier; information about the
+compiled pattern is given after compilation.
+</P>
+<P>
+<b>-M</b>
+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 <b>pcre[16|32]_exec()</b> repeatedly with different limits.
+</P>
+<P>
+<b>-m</b>
+Output the size of each compiled pattern after it has been compiled. This is
+equivalent to adding <b>/M</b> to each regular expression. The size is given in
+bytes for both libraries.
+</P>
+<P>
+<b>-O</b>
+Behave as if each pattern has the <b>/O</b> modifier, that is disable
+auto-possessification for all patterns.
+</P>
+<P>
+<b>-o</b> <i>osize</i>
+Set the number of elements in the output vector that is used when calling
+<b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> to be <i>osize</i>. The
+default value is 45, which is enough for 14 capturing subexpressions for
+<b>pcre[16|32]_exec()</b> or 22 different matches for
+<b>pcre[16|32]_dfa_exec()</b>.
+The vector size can be changed for individual matching calls by including \O
+in the data line (see below).
+</P>
+<P>
+<b>-p</b>
+Behave as if each pattern has the <b>/P</b> modifier; the POSIX wrapper API is
+used to call PCRE. None of the other options has any effect when <b>-p</b> is
+set. This option can be used only with the 8-bit library.
+</P>
+<P>
+<b>-q</b>
+Do not output the version number of <b>pcretest</b> at the start of execution.
+</P>
+<P>
+<b>-S</b> <i>size</i>
+On Unix-like systems, set the size of the run-time stack to <i>size</i>
+megabytes.
+</P>
+<P>
+<b>-s</b> or <b>-s+</b>
+Behave as if each pattern has the <b>/S</b> modifier; in other words, force each
+pattern to be studied. If <b>-s+</b> is used, all the JIT compile options are
+passed to <b>pcre[16|32]_study()</b>, 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 <b>-s+</b> with a digit in the range 1 to
+7, which selects the JIT compile modes as follows:
+<pre>
+ 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)
+</pre>
+If <b>-s++</b> is used instead of <b>-s+</b> (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.
+<br>
+<br>
+Note that there are pattern options that can override <b>-s</b>, either
+specifying no studying at all, or suppressing JIT compilation.
+<br>
+<br>
+If the <b>/I</b> or <b>/D</b> 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 <b>-s</b> and neither <b>-i</b> nor
+<b>-d</b> is present on the command line. This behaviour means that the output
+from tests that are run with and without <b>-s</b> should be identical, except
+when options that output information about the actual running of a match are
+set.
+<br>
+<br>
+The <b>-M</b>, <b>-t</b>, and <b>-tm</b> options, which give information about
+resources used, are likely to produce different output with and without
+<b>-s</b>. Output may also differ if the <b>/C</b> 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
+<b>-s</b> command line option can be overridden for specific patterns that
+should never be studied (see the <b>/S</b> pattern modifier below).
+</P>
+<P>
+<b>-t</b>
+Run each compile, study, and match many times with a timer, and output the
+resulting times per compile, study, or match (in milliseconds). Do not set
+<b>-m</b> with <b>-t</b>, because you will then get the size output a zillion
+times, and the timing will be distorted. You can control the number of
+iterations that are used for timing by following <b>-t</b> with a number (as a
+separate item on the command line). For example, "-t 1000" iterates 1000 times.
+The default is to iterate 500000 times.
+</P>
+<P>
+<b>-tm</b>
+This is like <b>-t</b> except that it times only the matching phase, not the
+compile or study phases.
+</P>
+<P>
+<b>-T</b> <b>-TM</b>
+These behave like <b>-t</b> and <b>-tm</b>, but in addition, at the end of a run,
+the total times for all compiles, studies, and matches are output.
+</P>
+<br><a name="SEC5" href="#TOC1">DESCRIPTION</a><br>
+<P>
+If <b>pcretest</b> 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&#62;" to prompt for regular
+expressions, and "data&#62;" to prompt for data lines.
+</P>
+<P>
+When <b>pcretest</b> is built, a configuration option can specify that it should
+be linked with the <b>libreadline</b> library. When this is done, if the input
+is from a terminal, it is read using the <b>readline()</b> function. This
+provides line-editing and history facilities. The output from the <b>-help</b>
+option states whether or not <b>readline()</b> will be used.
+</P>
+<P>
+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 number of data
+lines to be matched against that pattern.
+</P>
+<P>
+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.
+</P>
+<P>
+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:
+<pre>
+ /(a|bc)x+yz/
+</pre>
+White space before the initial delimiter is ignored. A regular expression may
+be continued over several input lines, in which case the newline characters are
+included within it. It is possible to include the delimiter within the pattern
+by escaping it, for example
+<pre>
+ /abc\/def/
+</pre>
+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 followed by a backslash, for
+example,
+<pre>
+ /abc/\
+</pre>
+then a backslash is added to the end of the pattern. This is done to provide a
+way of testing the error condition that arises if a pattern finishes with a
+backslash, because
+<pre>
+ /abc\/
+</pre>
+is interpreted as the first line of a pattern that starts with "abc/", causing
+pcretest to read the next line as a continuation of the regular expression.
+</P>
+<br><a name="SEC6" href="#TOC1">PATTERN MODIFIERS</a><br>
+<P>
+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
+<b>/i</b> 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. For reference, here is a complete list of modifiers. They
+fall into several groups that are described in detail in the following
+sections.
+<pre>
+ <b>/8</b> set UTF mode
+ <b>/9</b> set PCRE_NEVER_UTF (locks out UTF mode)
+ <b>/?</b> disable UTF validity check
+ <b>/+</b> show remainder of subject after match
+ <b>/=</b> show all captures (not just those that are set)
+
+ <b>/A</b> set PCRE_ANCHORED
+ <b>/B</b> show compiled code
+ <b>/C</b> set PCRE_AUTO_CALLOUT
+ <b>/D</b> same as <b>/B</b> plus <b>/I</b>
+ <b>/E</b> set PCRE_DOLLAR_ENDONLY
+ <b>/F</b> flip byte order in compiled pattern
+ <b>/f</b> set PCRE_FIRSTLINE
+ <b>/G</b> find all matches (shorten string)
+ <b>/g</b> find all matches (use startoffset)
+ <b>/I</b> show information about pattern
+ <b>/i</b> set PCRE_CASELESS
+ <b>/J</b> set PCRE_DUPNAMES
+ <b>/K</b> show backtracking control names
+ <b>/L</b> set locale
+ <b>/M</b> show compiled memory size
+ <b>/m</b> set PCRE_MULTILINE
+ <b>/N</b> set PCRE_NO_AUTO_CAPTURE
+ <b>/O</b> set PCRE_NO_AUTO_POSSESS
+ <b>/P</b> use the POSIX wrapper
+ <b>/Q</b> test external stack check function
+ <b>/S</b> study the pattern after compilation
+ <b>/s</b> set PCRE_DOTALL
+ <b>/T</b> select character tables
+ <b>/U</b> set PCRE_UNGREEDY
+ <b>/W</b> set PCRE_UCP
+ <b>/X</b> set PCRE_EXTRA
+ <b>/x</b> set PCRE_EXTENDED
+ <b>/Y</b> set PCRE_NO_START_OPTIMIZE
+ <b>/Z</b> don't show lengths in <b>/B</b> output
+
+ <b>/&#60;any&#62;</b> set PCRE_NEWLINE_ANY
+ <b>/&#60;anycrlf&#62;</b> set PCRE_NEWLINE_ANYCRLF
+ <b>/&#60;cr&#62;</b> set PCRE_NEWLINE_CR
+ <b>/&#60;crlf&#62;</b> set PCRE_NEWLINE_CRLF
+ <b>/&#60;lf&#62;</b> set PCRE_NEWLINE_LF
+ <b>/&#60;bsr_anycrlf&#62;</b> set PCRE_BSR_ANYCRLF
+ <b>/&#60;bsr_unicode&#62;</b> set PCRE_BSR_UNICODE
+ <b>/&#60;JS&#62;</b> set PCRE_JAVASCRIPT_COMPAT
+
+</PRE>
+</P>
+<br><b>
+Perl-compatible modifiers
+</b><br>
+<P>
+The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
+PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
+<b>pcre[16|32]_compile()</b> is called. These four modifier letters have the same
+effect as they do in Perl. For example:
+<pre>
+ /caseless/i
+
+</PRE>
+</P>
+<br><b>
+Modifiers for other PCRE options
+</b><br>
+<P>
+The following table shows additional modifiers for setting PCRE compile-time
+options that do not correspond to anything in Perl:
+<pre>
+ <b>/8</b> PCRE_UTF8 ) when using the 8-bit
+ <b>/?</b> PCRE_NO_UTF8_CHECK ) library
+
+ <b>/8</b> PCRE_UTF16 ) when using the 16-bit
+ <b>/?</b> PCRE_NO_UTF16_CHECK ) library
+
+ <b>/8</b> PCRE_UTF32 ) when using the 32-bit
+ <b>/?</b> PCRE_NO_UTF32_CHECK ) library
+
+ <b>/9</b> PCRE_NEVER_UTF
+ <b>/A</b> PCRE_ANCHORED
+ <b>/C</b> PCRE_AUTO_CALLOUT
+ <b>/E</b> PCRE_DOLLAR_ENDONLY
+ <b>/f</b> PCRE_FIRSTLINE
+ <b>/J</b> PCRE_DUPNAMES
+ <b>/N</b> PCRE_NO_AUTO_CAPTURE
+ <b>/O</b> PCRE_NO_AUTO_POSSESS
+ <b>/U</b> PCRE_UNGREEDY
+ <b>/W</b> PCRE_UCP
+ <b>/X</b> PCRE_EXTRA
+ <b>/Y</b> PCRE_NO_START_OPTIMIZE
+ <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
+ <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
+ <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
+ <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
+ <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
+ <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
+ <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
+ <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
+</pre>
+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:
+<pre>
+ /^abc/m&#60;CRLF&#62;
+</pre>
+As well as turning on the PCRE_UTF8/16/32 option, the <b>/8</b> 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.
+</P>
+<P>
+Full details of the PCRE options are given in the
+<a href="pcreapi.html"><b>pcreapi</b></a>
+documentation.
+</P>
+<br><b>
+Finding all matches in a string
+</b><br>
+<P>
+Searching for all possible matches within each subject string can be requested
+by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
+again to search the remainder of the subject string. The difference between
+<b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
+<b>pcre[16|32]_exec()</b> 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).
+</P>
+<P>
+If any call to <b>pcre[16|32]_exec()</b> in a <b>/g</b> or <b>/G</b> 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 <b>/g</b> modifier or the <b>split()</b> 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 is used.
+</P>
+<br><b>
+Other modifiers
+</b><br>
+<P>
+There are yet more modifiers for controlling the way <b>pcretest</b>
+operates.
+</P>
+<P>
+The <b>/+</b> modifier requests that as well as outputting the substring that
+matched the entire pattern, <b>pcretest</b> 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 <b>+</b> modifier 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.
+</P>
+<P>
+The <b>/=</b> 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 <b>pcre[16|32]_exec()</b>). Values in the offsets vector corresponding to
+higher numbers should be set to -1, and these are output as "&#60;unset&#62;". This
+modifier gives a way of checking that this is happening.
+</P>
+<P>
+The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
+output a representation of the compiled code after compilation. Normally this
+information contains length and offset values; however, if <b>/Z</b> 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.
+</P>
+<P>
+The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
+<b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
+</P>
+<P>
+The <b>/F</b> modifier causes <b>pcretest</b> 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 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 <b>/P</b> pattern modifier is
+specified. See also the section about saving and reloading compiled patterns
+below.
+</P>
+<P>
+The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
+compiled pattern (whether it is anchored, has a fixed first character, and
+so on). It does this by calling <b>pcre[16|32]_fullinfo()</b> after compiling a
+pattern. If the pattern is studied, the results of that are also output. In
+this output, the word "char" means a non-UTF character, that is, the value of a
+single data item (8-bit, 16-bit, or 32-bit, depending on the library that is
+being tested).
+</P>
+<P>
+The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
+control verbs that are returned from calls to <b>pcre[16|32]_exec()</b>. It causes
+<b>pcretest</b> to create a <b>pcre[16|32]_extra</b> block if one has not already
+been created by a call to <b>pcre[16|32]_study()</b>, and to set the
+PCRE_EXTRA_MARK flag and the <b>mark</b> field within it, every time that
+<b>pcre[16|32]_exec()</b> is called. If the variable that the <b>mark</b> field
+points to is non-NULL for a match, non-match, or partial match, <b>pcretest</b>
+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.
+</P>
+<P>
+The <b>/L</b> modifier must be followed directly by the name of a locale, for
+example,
+<pre>
+ /pattern/Lfr_FR
+</pre>
+For this reason, it must be the last modifier. The given locale is set,
+<b>pcre[16|32]_maketables()</b> is called to build a set of character tables for
+the locale, and this is then passed to <b>pcre[16|32]_compile()</b> when compiling
+the regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is
+passed as the tables pointer; that is, <b>/L</b> applies only to the expression
+on which it appears.
+</P>
+<P>
+The <b>/M</b> 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
+<b>pcre[16|32]</b> 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.
+</P>
+<P>
+The <b>/Q</b> modifier is used to test the use of <b>pcre_stack_guard</b>. It
+must be followed by '0' or '1', specifying the return code to be given from an
+external function that is passed to PCRE and used for stack checking during
+compilation (see the
+<a href="pcreapi.html"><b>pcreapi</b></a>
+documentation for details).
+</P>
+<P>
+The <b>/S</b> modifier causes <b>pcre[16|32]_study()</b> 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 <b>/S</b>.
+They may appear in any order.
+</P>
+<P>
+If <b>/S</b> is followed by an exclamation mark, <b>pcre[16|32]_study()</b> is
+called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
+<b>pcre_extra</b> block, even when studying discovers no useful information.
+</P>
+<P>
+If <b>/S</b> is followed by a second S character, it suppresses studying, even
+if it was requested externally by the <b>-s</b> command line option. This makes
+it possible to specify that certain patterns are always studied, and others are
+never studied, independently of <b>-s</b>. This feature is used in the test
+files in a few cases where the output is different when the pattern is studied.
+</P>
+<P>
+If the <b>/S</b> modifier is followed by a + character, the call to
+<b>pcre[16|32]_study()</b> 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 <b>/S+</b> with a digit in the range 1 to 7:
+<pre>
+ 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)
+</pre>
+If <b>/S++</b> is used instead of <b>/S+</b> (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.
+</P>
+<P>
+Note that there is also an independent <b>/+</b> modifier; it must not be given
+immediately after <b>/S</b> or <b>/S+</b> because this will be misinterpreted.
+</P>
+<P>
+If JIT studying is successful, the compiled JIT code will automatically be used
+when <b>pcre[16|32]_exec()</b> is run, except when incompatible run-time options
+are specified. For more details, see the
+<a href="pcrejit.html"><b>pcrejit</b></a>
+documentation. See also the <b>\J</b> escape sequence below for a way of
+setting the size of the JIT stack.
+</P>
+<P>
+Finally, if <b>/S</b> is followed by a minus character, JIT compilation is
+suppressed, even if it was requested externally by the <b>-s</b> command line
+option. This makes it possible to specify that JIT is never to be used for
+certain patterns.
+</P>
+<P>
+The <b>/T</b> modifier must be followed by a single digit. It causes a specific
+set of built-in character tables to be passed to <b>pcre[16|32]_compile()</b>. It
+is used in the standard PCRE tests to check behaviour with different character
+tables. The digit specifies the tables as follows:
+<pre>
+ 0 the default ASCII tables, as distributed in
+ pcre_chartables.c.dist
+ 1 a set of tables defining ISO 8859 characters
+</pre>
+In table 1, some characters whose codes are greater than 128 are identified as
+letters, digits, spaces, etc.
+</P>
+<br><b>
+Using the POSIX wrapper API
+</b><br>
+<P>
+The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
+API rather than its native API. This supports only the 8-bit library. When
+<b>/P</b> is set, the following modifiers set options for the <b>regcomp()</b>
+function:
+<pre>
+ /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 )
+</pre>
+The <b>/+</b> modifier works as described above. All other modifiers are
+ignored.
+</P>
+<br><b>
+Locking out certain modifiers
+</b><br>
+<P>
+PCRE can be compiled with or without support for certain features such as
+UTF-8/16/32 or Unicode properties. Accordingly, the standard tests are split up
+into a number of different files that are selected for running depending on
+which features are available. When updating the tests, it is all too easy to
+put a new test into the wrong file by mistake; for example, to put a test that
+requires UTF support into a file that is used when it is not available. To help
+detect such mistakes as early as possible, there is a facility for locking out
+specific modifiers. If an input line for <b>pcretest</b> starts with the string
+"&#60; forbid " the following sequence of characters is taken as a list of
+forbidden modifiers. For example, in the test files that must not use UTF or
+Unicode property support, this line appears:
+<pre>
+ &#60; forbid 8W
+</pre>
+This locks out the /8 and /W modifiers. An immediate error is given if they are
+subsequently encountered. If the character string contains &#60; but not &#62;, all the
+multi-character modifiers that begin with &#60; are locked out. Otherwise, such
+modifiers must be explicitly listed, for example:
+<pre>
+ &#60; forbid &#60;JS&#62;&#60;cr&#62;
+</pre>
+There must be a single space between &#60; and "forbid" for this feature to be
+recognised. If there is not, the line is interpreted either as a request to
+re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS"
+below) or, if there is a another &#60; character, as a pattern that uses &#60; as its
+delimiter.
+</P>
+<br><a name="SEC7" href="#TOC1">DATA LINES</a><br>
+<P>
+Before each data line is passed to <b>pcre[16|32]_exec()</b>, 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:
+<pre>
+ \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 &#62; 255 in UTF-8 or 16-bit or 32-bit mode
+ \o{dd...} octal character (any number of octal digits}
+ \xhh hexadecimal byte (up to 2 hex digits)
+ \x{hh...} hexadecimal character (any number of hex digits)
+ \A pass the PCRE_ANCHORED option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \B pass the PCRE_NOTBOL option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \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 <b>pcre[16|32]_dfa_exec()</b> match function
+ \F only shortest match for <b>pcre[16|32]_dfa_exec()</b>
+ \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 <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>; if used twice, pass the
+ PCRE_NOTEMPTY_ATSTART option
+ \Odd set the size of the output vector passed to <b>pcre[16|32]_exec()</b> to dd (any number of digits)
+ \P pass the PCRE_PARTIAL_SOFT option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>; 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 <b>pcre[16|32]_dfa_exec()</b>
+ \S output details of memory get/free calls during matching
+ \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \Z pass the PCRE_NOTEOL option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \? pass the PCRE_NO_UTF[8|16|32]_CHECK option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#62;dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i>
+ argument for <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+ \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
+</pre>
+The use of \x{hh...} is not dependent on the use of the <b>/8</b> modifier on
+the pattern. It is recognized always. There may be any number of hexadecimal
+digits inside the braces; invalid values provoke error messages.
+</P>
+<P>
+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.
+</P>
+<P>
+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.
+</P>
+<P>
+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.
+</P>
+<P>
+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.
+</P>
+<P>
+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 terminates the data
+input.
+</P>
+<P>
+The <b>\J</b> 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 optimization
+is not being used. Providing a stack that is larger than the default 32K is
+necessary only for very complicated patterns.
+</P>
+<P>
+If \M is present, <b>pcretest</b> calls <b>pcre[16|32]_exec()</b> several times,
+with different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
+fields of the <b>pcre[16|32]_extra</b> data structure, until it finds the minimum
+numbers for each parameter that allow <b>pcre[16|32]_exec()</b> to complete without
+error. Because this is testing a specific feature of the normal interpretive
+<b>pcre[16|32]_exec()</b> execution, the use of any JIT optimization that might
+have been set up by the <b>/S+</b> qualifier of <b>-s+</b> option is disabled.
+</P>
+<P>
+The <i>match_limit</i> 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 <i>match_limit_recursion</i> 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.
+</P>
+<P>
+When \O is used, the value specified may be higher or lower than the size set
+by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
+the call of <b>pcre[16|32]_exec()</b> for the line in which it appears.
+</P>
+<P>
+If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
+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 <b>regexec()</b>.
+</P>
+<br><a name="SEC8" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
+<P>
+By default, <b>pcretest</b> uses the standard PCRE matching function,
+<b>pcre[16|32]_exec()</b> to match each data line. PCRE also supports an
+alternative matching function, <b>pcre[16|32]_dfa_test()</b>, which operates in a
+different way, and has some restrictions. The differences between the two
+functions are described in the
+<a href="pcrematching.html"><b>pcrematching</b></a>
+documentation.
+</P>
+<P>
+If a data line contains the \D escape sequence, or if the command line
+contains the <b>-dfa</b> 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.
+</P>
+<br><a name="SEC9" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
+<P>
+This section describes the output when the normal matching function,
+<b>pcre[16|32]_exec()</b>, is being used.
+</P>
+<P>
+When a match succeeds, <b>pcretest</b> outputs the list of captured substrings
+that <b>pcre[16|32]_exec()</b> 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 <b>pcre[16|32]_exec()</b> 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, <b>pcretest</b> 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 <b>pcretest</b> run.
+<pre>
+ $ pcretest
+ PCRE version 8.13 2011-04-30
+
+ re&#62; /^abc(\d+)/
+ data&#62; abc123
+ 0: abc123
+ 1: 123
+ data&#62; xyz
+ No match
+</pre>
+Unset capturing substrings that are not followed by one that is set are not
+returned by <b>pcre[16|32]_exec()</b>, and are not shown by <b>pcretest</b>. In the
+following example, there are two capturing substrings, but when the first data
+line is matched, the second, unset substring is not shown. An "internal" unset
+substring is shown as "&#60;unset&#62;", as for the second data line.
+<pre>
+ re&#62; /(a)|(b)/
+ data&#62; a
+ 0: a
+ 1: a
+ data&#62; b
+ 0: b
+ 1: &#60;unset&#62;
+ 2: b
+</pre>
+If the strings contain any non-printing characters, they are output as \xhh
+escapes if the value is less than 256 and UTF mode is not set. Otherwise they
+are output as \x{hh...} escapes. See below for the definition of non-printing
+characters. If the pattern has the <b>/+</b> modifier, the output for substring
+0 is followed by the the rest of the subject string, identified by "0+" like
+this:
+<pre>
+ re&#62; /cat/+
+ data&#62; cataract
+ 0: cat
+ 0+ aract
+</pre>
+If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
+matching attempts are output in sequence, like this:
+<pre>
+ re&#62; /\Bi(\w\w)/g
+ data&#62; Mississippi
+ 0: iss
+ 1: ss
+ 0: iss
+ 1: ss
+ 0: ipp
+ 1: pp
+</pre>
+"No match" is output only if the first match attempt fails. Here is an example
+of a failure message (the offset 4 that is specified by \&#62;4 is past the end of
+the subject string):
+<pre>
+ re&#62; /xyz/
+ data&#62; xyz\&#62;4
+ Error -24 (bad offset value)
+</PRE>
+</P>
+<P>
+If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> 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
+parentheses after each string for <b>\C</b> and <b>\G</b>.
+</P>
+<P>
+Note that whereas patterns can be continued over several lines (a plain "&#62;"
+prompt is used for continuations), data lines may not. However newlines can be
+included in data by means of the \n escape (or \r, \r\n, etc., depending on
+the newline sequence setting).
+</P>
+<br><a name="SEC10" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
+<P>
+When the alternative matching function, <b>pcre[16|32]_dfa_exec()</b>, is used (by
+means of the \D escape sequence or the <b>-dfa</b> 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:
+<pre>
+ re&#62; /(tang|tangerine|tan)/
+ data&#62; yellow tangerine\D
+ 0: tangerine
+ 1: tang
+ 2: tan
+</pre>
+(Using the normal matching function on this data finds only "tang".) The
+longest matching string is always given first (and numbered zero). After a
+PCRE_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, \K, \b, or \B was involved.)
+</P>
+<P>
+If <b>/g</b> is present on the pattern, the search for further matches resumes
+at the end of the longest match. For example:
+<pre>
+ re&#62; /(tang|tangerine|tan)/g
+ data&#62; yellow tangerine and tangy sultana\D
+ 0: tangerine
+ 1: tang
+ 2: tan
+ 0: tang
+ 1: tan
+ 0: tan
+</pre>
+Since the matching function does not support substring capture, the escape
+sequences that are concerned with captured substrings are not relevant.
+</P>
+<br><a name="SEC11" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
+<P>
+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:
+<pre>
+ re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
+ data&#62; 23ja\P\D
+ Partial match: 23ja
+ data&#62; n05\R\D
+ 0: n05
+</pre>
+For further information about partial matching, see the
+<a href="pcrepartial.html"><b>pcrepartial</b></a>
+documentation.
+</P>
+<br><a name="SEC12" href="#TOC1">CALLOUTS</a><br>
+<P>
+If the pattern contains any callout requests, <b>pcretest</b>'s callout function
+is called during matching. This works with both matching functions. 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:
+<pre>
+ ---&#62;pqrabcdef
+ 0 ^ ^ \d
+</pre>
+This output indicates that callout number 0 occurred for a match attempt
+starting at the fourth character of the subject string, when the pointer was at
+the seventh character 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.
+</P>
+<P>
+Callouts numbered 255 are assumed to be automatic callouts, inserted as a
+result of the <b>/C</b> pattern modifier. In this case, instead of showing the
+callout number, the offset in the pattern, preceded by a plus, is output. For
+example:
+<pre>
+ re&#62; /\d?[A-E]\*/C
+ data&#62; E*
+ ---&#62;E*
+ +0 ^ \d?
+ +3 ^ [A-E]
+ +8 ^^ \*
+ +10 ^ ^
+ 0: E*
+</pre>
+If a pattern contains (*MARK) items, an additional line is output whenever
+a change of latest mark is passed to the callout function. For example:
+<pre>
+ re&#62; /a(*MARK:X)bc/C
+ data&#62; abc
+ ---&#62;abc
+ +0 ^ a
+ +1 ^^ (*MARK:X)
+ +10 ^^ b
+ Latest Mark: X
+ +11 ^ ^ c
+ +12 ^ ^
+ 0: abc
+</pre>
+The mark changes between matching "a" and "b", but stays the same for the rest
+of the match, so nothing more is output. If, as a result of backtracking, the
+mark reverts to being unset, the text "&#60;unset&#62;" is output.
+</P>
+<P>
+The callout function in <b>pcretest</b> 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.
+</P>
+<P>
+Inserting callouts can be helpful when using <b>pcretest</b> to check
+complicated regular expressions. For further information about callouts, see
+the
+<a href="pcrecallout.html"><b>pcrecallout</b></a>
+documentation.
+</P>
+<br><a name="SEC13" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
+<P>
+When <b>pcretest</b> 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.
+</P>
+<P>
+When <b>pcretest</b> 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 <b>/L</b> modifier). In this case, the <b>isprint()</b>
+function to distinguish printing and non-printing characters.
+</P>
+<br><a name="SEC14" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
+<P>
+The facilities described in this section are not available when the POSIX
+interface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
+specified.
+</P>
+<P>
+When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
+compiled pattern to a file, by following the modifiers with &#62; and a file name.
+For example:
+<pre>
+ /pattern/im &#62;/some/file
+</pre>
+See the
+<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
+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.
+</P>
+<P>
+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 second 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, <b>pcretest</b> expects to read a new pattern.
+</P>
+<P>
+A saved pattern can be reloaded into <b>pcretest</b> by specifying &#60; and a file
+name instead of a pattern. There must be no space between &#60; and the file name,
+which must not contain a &#60; character, as otherwise <b>pcretest</b> will
+interpret the line as a pattern delimited by &#60; characters. For example:
+<pre>
+ re&#62; &#60;/some/file
+ Compiled pattern loaded from /some/file
+ No study data
+</pre>
+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, <b>pcretest</b> proceeds to read data lines in the usual way.
+</P>
+<P>
+You can copy a file written by <b>pcretest</b> 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:
+<pre>
+ Compiled pattern (byte-inverted) loaded from /some/file
+</pre>
+The test suite contains some saved pre-compiled patterns with different
+endianness. These are reloaded using "&#60;!" instead of just "&#60;". 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.
+</P>
+<P>
+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.
+</P>
+<P>
+The ability to save and reload files in <b>pcretest</b> is intended for testing
+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 <b>pcretest</b> to crash.
+Finally, if you attempt to load a file that is not in the correct format, the
+result is undefined.
+</P>
+<br><a name="SEC15" href="#TOC1">SEE ALSO</a><br>
+<P>
+<b>pcre</b>(3), <b>pcre16</b>(3), <b>pcre32</b>(3), <b>pcreapi</b>(3),
+<b>pcrecallout</b>(3),
+<b>pcrejit</b>, <b>pcrematching</b>(3), <b>pcrepartial</b>(d),
+<b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
+</P>
+<br><a name="SEC16" href="#TOC1">AUTHOR</a><br>
+<P>
+Philip Hazel
+<br>
+University Computing Service
+<br>
+Cambridge CB2 3QH, England.
+<br>
+</P>
+<br><a name="SEC17" href="#TOC1">REVISION</a><br>
+<P>
+Last updated: 09 February 2014
+<br>
+Copyright &copy; 1997-2014 University of Cambridge.
+<br>
+<p>
+Return to the <a href="index.html">PCRE index page</a>.
+</p>