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<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="Asciidoctor 2.0.26"><meta name="description" content="The `pcre2test` command for testing PCRE2"><title>pcre2test(1)</title><link rel="stylesheet" href="./css/document.css"><link rel="stylesheet" href="./css/standalone.css"><meta name="color-scheme" content="light dark"><meta name="theme-color" media="(prefers-color-scheme: light)" content="#0085cc"><meta name="theme-color" media="(prefers-color-scheme: dark)" content="#33b8ff"></head><body class="manpage toc2 toc-right offline-manual"><header class="offline-nav"><nav><a class="offline-index" href="./index.html">Index</a><a class="offline-home" href="https://www.pcre2.org/"><span aria-hidden="true">🌐︎</span> PCRE2 homepage</a></nav></header><main class="document-page"><header class="document-title"><h1>pcre2test(1)</h1><p class="document-meta">PCRE2 10.50-DEV manual; updated <time datetime="2026-08-22">22 Aug 2026</time></p></header><div class="document-layout"><nav id="toc" class="toc2" role="doc-toc"><h2 id="toc-title">Contents</h2><ol class="toc-list level-1"><li><a href="#_synopsis" title="Synopsis">Synopsis</a></li><li><a href="#_pcre2s_8_bit_16_bit_and_32_bit_libraries" title="PCRE2’s 8-bit, 16-bit and 32-bit libraries">PCRE2’s 8-bit, 16-bit and 32-bit libraries</a></li><li><a href="#_input_encoding" title="Input encoding">Input encoding</a><ol class="toc-list level-2"><li><a href="#_input_for_the_16_bit_and_32_bit_libraries" title="Input for the 16-bit and 32-bit libraries">Input for the 16-bit and 32-bit libraries</a></li></ol></li><li><a href="#_command_line_options" title="Command line options">Command line options</a></li><li><a href="#_description" title="Description">Description</a></li><li><a href="#_command_lines" title="Command lines">Command lines</a></li><li><a href="#_modifier_syntax" title="Modifier syntax">Modifier syntax</a></li><li><a href="#_pattern_syntax" title="Pattern syntax">Pattern syntax</a></li><li><a href="#_subject_line_syntax" title="Subject line syntax">Subject line syntax</a></li><li><a href="#_pattern_modifiers" title="Pattern modifiers">Pattern modifiers</a><ol class="toc-list level-2"><li><a href="#_setting_compilation_options" title="Setting compilation options">Setting compilation options</a></li><li><a href="#_setting_compilation_controls" title="Setting compilation controls">Setting compilation controls</a></li><li><a href="#_newline_and_r_handling" title="Newline and \R handling">Newline and \R handling</a></li><li><a href="#_information_about_a_pattern" title="Information about a pattern">Information about a pattern</a></li><li><a href="#_passing_a_null_context" title="Passing a NULL context">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> context</a></li><li><a href="#_passing_a_null_pattern" title="Passing a NULL pattern">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> pattern</a></li><li><a href="#_specifying_pattern_characters_in_hexadecimal" title="Specifying pattern characters in hexadecimal">Specifying pattern characters in hexadecimal</a></li><li><a href="#_specifying_the_patterns_length" title="Specifying the pattern’s length">Specifying the pattern’s length</a></li><li><a href="#_specifying_a_maximum_for_variable_lookbehinds" title="Specifying a maximum for variable lookbehinds">Specifying a maximum for variable lookbehinds</a></li><li><a href="#_specifying_wide_characters_in_16_bit_and_32_bit_modes" title="Specifying wide characters in 16-bit and 32-bit modes">Specifying wide characters in 16-bit and 32-bit modes</a></li><li><a href="#_generating_long_repetitive_patterns" title="Generating long repetitive patterns">Generating long repetitive patterns</a></li><li><a href="#_jit_compilation" title="JIT compilation">JIT compilation</a></li><li><a href="#_setting_a_locale" title="Setting a locale">Setting a locale</a></li><li><a href="#_showing_pattern_memory" title="Showing pattern memory">Showing pattern memory</a></li><li><a href="#_limiting_nested_parentheses" title="Limiting nested parentheses">Limiting nested parentheses</a></li><li><a href="#_limiting_the_pattern_length" title="Limiting the pattern length">Limiting the pattern length</a></li><li><a href="#_limiting_the_size_of_a_compiled_pattern" title="Limiting the size of a compiled pattern">Limiting the size of a compiled pattern</a></li><li><a href="#_using_the_posix_wrapper_api" title="Using the POSIX wrapper API">Using the POSIX wrapper API</a></li><li><a href="#_testing_the_stack_guard_feature" title="Testing the stack guard feature">Testing the stack guard feature</a></li><li><a href="#_using_alternative_character_tables" title="Using alternative character tables">Using alternative character tables</a></li><li><a href="#_setting_certain_match_controls" title="Setting certain match controls">Setting certain match controls</a></li><li><a href="#_specifying_literal_subject_lines" title="Specifying literal subject lines">Specifying literal subject lines</a></li><li><a href="#_saving_a_compiled_pattern" title="Saving a compiled pattern">Saving a compiled pattern</a></li><li><a href="#_testing_foreign_pattern_conversion" title="Testing foreign pattern conversion">Testing foreign pattern conversion</a></li></ol></li><li><a href="#_subject_modifiers" title="Subject modifiers">Subject modifiers</a><ol class="toc-list level-2"><li><a href="#_setting_match_options" title="Setting match options">Setting match options</a></li><li><a href="#_setting_match_controls" title="Setting match controls">Setting match controls</a></li><li><a href="#_showing_more_text" title="Showing more text">Showing more text</a></li><li><a href="#_showing_the_value_of_all_capture_groups" title="Showing the value of all capture groups">Showing the value of all capture groups</a></li><li><a href="#_showing_the_entire_ovector_for_all_outcomes" title="Showing the entire ovector, for all outcomes">Showing the entire ovector, for all outcomes</a></li><li><a href="#_testing_pattern_callouts" title="Testing pattern callouts">Testing pattern callouts</a></li><li><a href="#_finding_all_matches_in_a_string" title="Finding all matches in a string">Finding all matches in a string</a></li><li><a href="#_testing_substring_extraction_functions" title="Testing substring extraction functions">Testing substring extraction functions</a></li><li><a href="#_testing_the_substitution_function" title="Testing the substitution function">Testing the substitution function</a></li><li><a href="#_testing_substitute_callouts" title="Testing substitute callouts">Testing substitute callouts</a></li><li><a href="#_testing_substitute_case_callouts" title="Testing substitute case callouts">Testing substitute case callouts</a></li><li><a href="#_setting_the_jit_stack_size" title="Setting the JIT stack size">Setting the JIT stack size</a></li><li><a href="#_setting_heap_match_and_depth_limits" title="Setting heap, match, and depth limits">Setting heap, match, and depth limits</a></li><li><a href="#_finding_minimum_limits" title="Finding minimum limits">Finding minimum limits</a></li><li><a href="#_showing_mark_names" title="Showing MARK names">Showing MARK names</a></li><li><a href="#_showing_memory_usage" title="Showing memory usage">Showing memory usage</a></li><li><a href="#_showing_the_heap_frame_overall_vector_size" title="Showing the heap frame overall vector size">Showing the heap frame overall vector size</a></li><li><a href="#_setting_a_starting_offset" title="Setting a starting offset">Setting a starting offset</a></li><li><a href="#_setting_an_offset_limit" title="Setting an offset limit">Setting an offset limit</a></li><li><a href="#_setting_the_size_of_the_output_vector" title="Setting the size of the output vector">Setting the size of the output vector</a></li><li><a href="#_passing_the_subject_as_zero_terminated" title="Passing the subject as zero-terminated">Passing the subject as zero-terminated</a></li><li><a href="#_passing_a_null_context_subject_replacement_or_substitute_buffer" title="Passing a NULL context, subject, replacement, or substitute buffer">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> context, subject, replacement, or substitute buffer</a></li></ol></li><li><a href="#_the_alternative_matching_function" title="The alternative matching function">The alternative matching function</a></li><li><a href="#_default_output_from_pcre2test" title="Default output from pcre2test">Default output from pcre2test</a></li><li><a href="#_output_from_the_alternative_matching_function" title="Output from the alternative matching function">Output from the alternative matching function</a></li><li><a href="#_restarting_after_a_partial_match" title="Restarting after a partial match">Restarting after a partial match</a></li><li><a href="#callouts" title="Callouts">Callouts</a><ol class="toc-list level-2"><li><a href="#_callouts_with_numerical_arguments" title="Callouts with numerical arguments">Callouts with numerical arguments</a></li><li><a href="#_callouts_with_string_arguments" title="Callouts with string arguments">Callouts with string arguments</a></li><li><a href="#_callout_modifiers" title="Callout modifiers">Callout modifiers</a></li><li><a href="#_return_values_from_callouts" title="Return values from callouts">Return values from callouts</a></li></ol></li><li><a href="#_non_printing_characters" title="Non-printing characters">Non-printing characters</a></li><li><a href="#saving-restoring-patterns" title="Saving and restoring compiled patterns">Saving and restoring compiled patterns</a></li><li><a href="#_see_also" title="See also">See also</a></li></ol></nav><article class="prose" id="content"><section class="doc-section level-1"><h2 id="_synopsis">Synopsis</h2><div class="listing-block synopsis"><pre class="rouge highlight"><code data-lang="shell">pcre2test <span class="o">[</span>options] <span class="o">[</span>input file <span class="o">[</span>output file]]</code></pre></div>
<p><code>pcre2test</code> is a test program for the PCRE2 regular expression libraries,
but it can also be used for experimenting with regular expressions. This
document describes the features of the test program; for details of the regular
expressions themselves, see the
<a href="./pcre2pattern.html"><code>pcre2pattern</code></a>
documentation. For details of the PCRE2 library function calls and their
options, see the
<a href="./pcre2api.html"><code>pcre2api</code></a>
documentation.</p>
<p>The input for <code>pcre2test</code> is a sequence of regular expression patterns and
subject strings to be matched. There are also command lines for setting
defaults and controlling some special actions. The output shows the result of
each match attempt. Modifiers on external or internal command lines, the
patterns, and the subject lines specify PCRE2 function options, control how the
subject is processed, and what output is produced.</p>
<p>There are many obscure modifiers, some of which are specifically designed for
use in conjunction with the test script and data files that are distributed as
part of PCRE2. All the modifiers are documented here, some without much
justification, but many of them are unlikely to be of use except when testing
the libraries.</p></section>
<section class="doc-section level-1"><h2 id="_pcre2s_8_bit_16_bit_and_32_bit_libraries">PCRE2’s 8-bit, 16-bit and 32-bit libraries</h2><p>Different versions of the PCRE2 library can be built to support character
strings that are encoded in 8-bit, 16-bit, or 32-bit code units. One, two, or
all three of these libraries may be simultaneously installed. The
<code>pcre2test</code> program can be used to test all the libraries. However, its own
input and output are always in 8-bit format. When testing the 16-bit or 32-bit
libraries, patterns and subject strings are converted to 16-bit or 32-bit
format before being passed to the library functions. Results are converted back
to 8-bit code units for output.</p>
<p>In the rest of this document, the names of library functions and structures
are given in generic form, for example, <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. The actual
names used in the libraries have a suffix <code>_8</code>, <code>_16</code>, or <code>_32</code>, as appropriate.</p></section>
<section class="doc-section level-1"><h2 id="_input_encoding">Input encoding</h2><p>Input to <code>pcre2test</code> is processed line by line, either by calling the C
library’s <code class="c rouge" data-lang="c"><span class="nf">fgets</span><span class="p">()</span></code> function, or via the <code>libreadline</code> or <code>libedit</code>
library. In some Windows environments character 26 (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-1"><code class="character pcre2-api rouge"><span class="sc">0x1A</span></code><span class="character-card" id="pcre2-character-1" role="tooltip" aria-label="SUBSTITUTE (U+001A)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="SUBSTITUTE"></span><span class="character-codepoint" data-codepoint="U+001A"></span></span></span>) causes an immediate
end of file, and no further data is read, so this character should be avoided
unless you really want that action.</p>
<p>The input is processed using C’s string functions, so must not contain binary
zeros, even though in Unix-like environments, <code class="c rouge" data-lang="c"><span class="nf">fgets</span><span class="p">()</span></code> treats any bytes
other than newline as data characters. An error is generated if a binary zero
is encountered. By default subject lines are processed for backslash escapes,
which makes it possible to include any data value in strings that are passed to
the library for matching. For patterns, there is a facility for specifying some
or all of the 8-bit input characters as hexadecimal pairs, which makes it
possible to include binary zeros.</p>
<section class="doc-section level-2"><h3 id="_input_for_the_16_bit_and_32_bit_libraries">Input for the 16-bit and 32-bit libraries</h3><p>When testing the 16-bit or 32-bit libraries, there is a need to be able to
generate character code points greater than 255 in the strings that are passed
to the library. For subject lines and some patterns, backslash escapes can be
used. In addition, when the <code>utf</code> modifier (see
"Setting compilation options"
below) is set, the pattern and any following subject lines are interpreted as
UTF-8 strings and translated to UTF-16 or UTF-32 as appropriate.</p>
<p>For non-UTF testing of wide characters, the <code>utf8_input</code> modifier can be
used. This is mutually exclusive with <code>utf</code>, and is allowed only in 16-bit
or 32-bit mode. It causes the pattern and following subject lines to be treated
as UTF-8 according to the original definition (RFC 2279), which allows for
character values up to <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-2"><code class="character pcre2-api rouge"><span class="sc">0x7fffffff</span></code><span class="character-card" id="pcre2-character-2" role="tooltip" aria-label="Outside Unicode range (0x7fffffff)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="Outside Unicode range"></span><span class="character-codepoint" data-codepoint="0x7fffffff"></span></span></span>. Each character is placed in one 16-bit or
32-bit code unit (in the 16-bit case, values greater than <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-3"><code class="character pcre2-api rouge"><span class="sc">0xffff</span></code><span class="character-card" id="pcre2-character-3" role="tooltip" aria-label="<noncharacter-FFFF> (U+FFFF)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="<noncharacter-FFFF>"></span><span class="character-codepoint" data-codepoint="U+FFFF"></span></span></span> cause an error
to occur).</p>
<p>UTF-8 (in its original definition) is not capable of encoding values greater
than <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-4"><code class="character pcre2-api rouge"><span class="sc">0x7fffffff</span></code><span class="character-card" id="pcre2-character-4" role="tooltip" aria-label="Outside Unicode range (0x7fffffff)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="Outside Unicode range"></span><span class="character-codepoint" data-codepoint="0x7fffffff"></span></span></span>, but such values can be handled by the 32-bit library. When
testing this library in non-UTF mode with <code>utf8_input</code> set, if any
character is preceded by the byte <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-5"><code class="character pcre2-api rouge"><span class="sc">0xff</span></code><span class="character-card" id="pcre2-character-5" role="tooltip" aria-label="LATIN SMALL LETTER Y WITH DIAERESIS (U+00FF)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character="ÿ"></span><span class="character-name" data-character-name="LATIN SMALL LETTER Y WITH DIAERESIS"></span><span class="character-codepoint" data-codepoint="U+00FF"></span></span></span> (which is an invalid byte in UTF-8)
<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-6"><code class="character pcre2-api rouge"><span class="sc">0x80000000</span></code><span class="character-card" id="pcre2-character-6" role="tooltip" aria-label="Outside Unicode range (0x80000000)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="Outside Unicode range"></span><span class="character-codepoint" data-codepoint="0x80000000"></span></span></span> is added to the character’s value. For subject strings, using an
escape sequence is preferable.</p></section></section>
<section class="doc-section level-1"><h2 id="_command_line_options">Command line options</h2><dl class="options spaced" style="--tab-width: 12"><div class="dlist-item"><dt><span><code>-8</code></span></dt><dd>If the 8-bit library has been built, this option causes it to be used (this is
the default). If the 8-bit library has not been built, this option causes an
error.</dd></div><div class="dlist-item"><dt><span><code>-16</code></span></dt><dd>If the 16-bit library has been built, this option causes it to be used. If the
8-bit library has not been built, this is the default. If the 16-bit library
has not been built, this option causes an error.</dd></div><div class="dlist-item"><dt><span><code>-32</code></span></dt><dd>If the 32-bit library has been built, this option causes it to be used. If no
other library has been built, this is the default. If the 32-bit library has
not been built, this option causes an error.</dd></div><div class="dlist-item"><dt><span><code>-ac</code></span></dt><dd>Behave as if each pattern has the <code>auto_callout</code> modifier, that is, insert
automatic callouts into every pattern that is compiled.</dd></div><div class="dlist-item"><dt><span><code>-AC</code></span></dt><dd>As for <code>-ac</code>, but in addition behave as if each subject line has the
<code>callout_extra</code> modifier, that is, show additional information from
callouts.</dd></div><div class="dlist-item"><dt><span><code>-b</code></span></dt><dd>Behave as if each pattern has the <code>fullbincode</code> modifier; the full
internal binary form of the pattern is output after compilation.</dd></div><div class="dlist-item"><dt><span><code>-C</code></span></dt><dd>Output the version number of the PCRE2 library, and all available information
about the optional features that are included, and then exit with zero exit
code. All other options are ignored. If both -C and -LM are present, whichever
is first is recognized.</dd></div><div class="dlist-item"><dt><span><code>-C <em>option</em></code></span></dt><dd><p>Output information about a specific build-time option, then exit. This
functionality is intended for use in scripts such as <code>RunTest</code>. The
following options output the value and set the exit code as indicated:</p><div class="open-block"><div class="content"><dl class="compact" style="--tab-width: 6"><div class="dlist-item"><dt><span><code>linksize</code> </span></dt><dd>Output the configured internal link size (2, 3, or 4).
The exit code is set to the link size.</dd></div><div class="dlist-item"><dt><span><code>newline</code> </span></dt><dd>Output the default newline setting:
CR, LF, CRLF, ANYCRLF, ANY, or NUL.
The exit code is always 0.</dd></div><div class="dlist-item"><dt><span><code>bsr</code> </span></dt><dd>Output the default setting for what <code class="regex rouge"><span class="pcre2-semantic">\R</span></code> matches:
ANYCRLF or ANY. The exit code is always 0.</dd></div></dl></div></div>
<p>The following options output 1 for true or 0 for false, and set the exit code
to the same value:</p>
<div class="open-block"><div class="content"><dl class="compact" style="--tab-width: 8"><div class="dlist-item"><dt><span><code>backslash-C</code> </span></dt><dd><code class="regex rouge"><span class="pcre2-semantic">\C</span></code> is supported (not locked out)</dd></div><div class="dlist-item"><dt><span><code>ebcdic</code> </span></dt><dd>compiled for an EBCDIC environment</dd></div><div class="dlist-item"><dt><span><code>ebcdic-io</code> </span></dt><dd>if PCRE2 is compiled for EBCDIC, whether <code>pcre2test</code>'s input and
output is EBCDIC or ASCII</dd></div><div class="dlist-item"><dt><span><code>ebcdic-nl25</code> </span></dt><dd>if PCRE2 is compiled for EBCDIC, whether NL (= LF) is <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-7"><code class="character pcre2-api rouge"><span class="sc">0x25</span></code><span class="character-card" id="pcre2-character-7" role="tooltip" aria-label="PERCENT SIGN (U+0025)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character="%"></span><span class="character-name" data-character-name="PERCENT SIGN"></span><span class="character-codepoint" data-codepoint="U+0025"></span></span></span>
(otherwise it is <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-8"><code class="character pcre2-api rouge"><span class="sc">0x15</span></code><span class="character-card" id="pcre2-character-8" role="tooltip" aria-label="NEGATIVE ACKNOWLEDGE (U+0015)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="NEGATIVE ACKNOWLEDGE"></span><span class="character-codepoint" data-codepoint="U+0015"></span></span></span>, the default)</dd></div><div class="dlist-item"><dt><span><code>jit</code> </span></dt><dd>just-in-time support is available</dd></div><div class="dlist-item"><dt><span><code>pcre2-16</code> </span></dt><dd>the 16-bit library was built</dd></div><div class="dlist-item"><dt><span><code>pcre2-32</code> </span></dt><dd>the 32-bit library was built</dd></div><div class="dlist-item"><dt><span><code>pcre2-8</code> </span></dt><dd>the 8-bit library was built</dd></div><div class="dlist-item"><dt><span><code>unicode</code> </span></dt><dd>Unicode support is available</dd></div></dl></div></div>
<p>Note that the availability of JIT support in the library does not guarantee
that it can actually be used because in some environments it is unable to
allocate executable memory. The option "jitusable" gives more detailed
information. It returns one of the following values:</p>
<div class="open-block"><div class="content"><dl class="compact" style="--tab-width: 4"><div class="dlist-item"><dt><span>0</span></dt><dd>JIT is available and usable</dd></div><div class="dlist-item"><dt><span>1</span></dt><dd>JIT is available but cannot allocate executable memory</dd></div><div class="dlist-item"><dt><span>2</span></dt><dd>JIT is not available</dd></div><div class="dlist-item"><dt><span>3</span></dt><dd>Unexpected return from test call to <code class="function pcre2-api rouge"><span class="nf">pcre2_jit_compile()</span></code></dd></div></dl></div></div>
<p>If an unknown option is given, an error message is output; the exit code is 0.</p></dd></div><div class="dlist-item"><dt><span><code>--colo[u]r[=&lt;always,auto,never&gt;]</code></span></dt><dd>With <code>auto</code>, the output is coloured if the output is to a terminal. Force or
suppress output of ANSI colour escapes with <code>always</code> (or no specifier
provided) and <code>never</code> respectively. If no colour option is provided, the
default is <code>auto</code>, unless the NO_COLOR environment variable is defined and
non-empty.</dd></div><div class="dlist-item"><dt><span><code>-d</code></span></dt><dd>Behave as if each pattern has the <code>debug</code> modifier; the internal
form and information about the compiled pattern is output after compilation;
<code>-d</code> is equivalent to <code>-b -i</code>.</dd></div><div class="dlist-item"><dt><span><code>-dfa</code></span></dt><dd>Behave as if each subject line has the <code>dfa</code> modifier; matching is done
using the <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code> function instead of the default
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>.</dd></div><div class="dlist-item"><dt><span><code>-E</code></span></dt><dd>Run in "preprocess only" mode (similar to <code>gcc -E</code>). The <code>#if ... #endif</code>
commands are processed, and all other lines are printed verbatim.</dd></div><div class="dlist-item"><dt><span><code>-error <em>number</em>[,<em>number</em>,...]</code></span></dt><dd>Call <code class="function pcre2-api rouge"><span class="nf">pcre2_get_error_message()</span></code> for each of the error numbers in the
comma-separated list, display the resulting messages on the standard output,
then exit with zero exit code. The numbers may be positive or negative. This is
a convenience facility for PCRE2 maintainers.</dd></div><div class="dlist-item"><dt><span><code>-help</code></span></dt><dd>Output a brief summary these options and then exit.</dd></div><div class="dlist-item"><dt><span><code>-i</code></span></dt><dd>Behave as if each pattern has the <code>info</code> modifier; information about the
compiled pattern is given after compilation.</dd></div><div class="dlist-item"><dt><span><code>-jit</code></span></dt><dd>Behave as if each pattern line has the <code>jit</code> modifier; after successful
compilation, each pattern is passed to the just-in-time compiler, if available.</dd></div><div class="dlist-item"><dt><span><code>-jitfast</code></span></dt><dd>Behave as if each pattern line has the <code>jitfast</code> modifier; after
successful compilation, each pattern is passed to the just-in-time compiler, if
available, and each subject line is passed directly to the JIT matcher via its
"fast path".</dd></div><div class="dlist-item"><dt><span><code>-jitverify</code></span></dt><dd>Behave as if each pattern line has the <code>jitverify</code> modifier; after
successful compilation, each pattern is passed to the just-in-time compiler, if
available, and the use of JIT for matching is verified.</dd></div><div class="dlist-item"><dt><span><code>-LM</code></span></dt><dd>List modifiers: write a list of available pattern and subject modifiers to the
standard output, then exit with zero exit code. All other options are ignored.
If both -C and any -Lx options are present, whichever is first is recognized.</dd></div><div class="dlist-item"><dt><span><code>-LP</code></span></dt><dd>List properties: write a list of recognized Unicode properties to the standard
output, then exit with zero exit code. All other options are ignored. If both
-C and any -Lx options are present, whichever is first is recognized.</dd></div><div class="dlist-item"><dt><span><code>-LS</code></span></dt><dd>List scripts: write a list of recognized Unicode script names to the standard
output, then exit with zero exit code. All other options are ignored. If both
-C and any -Lx options are present, whichever is first is recognized.</dd></div><div class="dlist-item"><dt><span><code>-malloc</code></span></dt><dd>Exercise <code class="c rouge" data-lang="c"><span class="nf">malloc</span><span class="p">()</span></code> failures, by first counting the number of calls made to malloc
during pattern compilation and matching, then re-running the compilation and
matching that many times, exercising a failure of each malloc() call.</dd></div><div class="dlist-item"><dt><span><code>-pattern <em>modifier-list</em></code></span></dt><dd>Behave as if each pattern line contains the given modifiers.</dd></div><div class="dlist-item"><dt><span><code>-q</code></span></dt><dd>Do not output the version number of <code>pcre2test</code> at the start of execution.</dd></div><div class="dlist-item"><dt><span><code>-S <em>size</em></code></span></dt><dd>On Unix-like systems, set the size of the run-time stack to <em>size</em>
mebibytes (units of 1024*1024 bytes).</dd></div><div class="dlist-item"><dt><span><code>-subject <em>modifier-list</em></code></span></dt><dd>Behave as if each subject line contains the given modifiers.</dd></div><div class="dlist-item"><dt><span><code>-t</code></span></dt><dd>Run each compile and match many times with a timer, and output the resulting
times per compile or match. When JIT is used, separate times are given for the
initial compile and the JIT compile. You can control the number of iterations
that are used for timing by following <code>-t</code> with a number (as a separate
item on the command line). For example, "-t 1000" iterates 1000 times. The
default is to iterate 500,000 times.</dd></div><div class="dlist-item"><dt><span><code>-tm</code></span></dt><dd>This is like <code>-t</code> except that it times only the matching phase, not the
compile phase.</dd></div><div class="dlist-item"><dt><span><code>-T</code>, <code>-TM</code></span></dt><dd>These behave like <code>-t</code> and <code>-tm</code>, but in addition, at the end of a run,
the total times for all compiles and matches are output.</dd></div><div class="dlist-item"><dt><span><code>-unittest</code></span></dt><dd>Run a fixed set of additional tests of the PCRE2 API which are not driven by
the test input files, and then exit.</dd></div><div class="dlist-item"><dt><span><code>-version</code></span></dt><dd>Output the PCRE2 version number and then exit.</dd></div></dl></section>
<section class="doc-section level-1"><h2 id="_description">Description</h2><p>If <code>pcre2test</code> is given two filename arguments, it reads from the first and
writes to the second. If the first name is "-", input is taken from the
standard input. If <code>pcre2test</code> is given only one argument, it reads from
that file and writes to stdout. Otherwise, it reads from stdin and writes to
stdout.</p>
<p>When <code>pcre2test</code> is built, a configuration option can specify that it
should be linked with the <code>libreadline</code> or <code>libedit</code> library. When this
is done, if the input is from a terminal, it is read using the <code class="c rouge" data-lang="c"><span class="nf">readline</span><span class="p">()</span></code>
function. This provides line-editing and history facilities. The output from
the <code>-help</code> option states whether or not <code class="c rouge" data-lang="c"><span class="nf">readline</span><span class="p">()</span></code> will be used.</p>
<p>The program handles any number of tests, each of which consists of a set of
input lines. Each set starts with a regular expression pattern, followed by any
number of subject lines to be matched against that pattern. In between sets of
test data, command lines that begin with # may appear. This file format, with
some restrictions, can also be processed by the <code>PerlTest.sh</code> script that
is distributed with PCRE2 as a means of checking that the behaviour of PCRE2
and Perl is the same. For a specification of <code>PerlTest.sh</code>, see the
comments near its beginning. See also the #perltest command below.</p>
<p>When the input is a terminal, <code>pcre2test</code> prompts for each line of input,
using "re&gt;" to prompt for regular expression patterns, and "data&gt;" to prompt
for subject lines. Command lines starting with # can be entered only in
response to the "re&gt;" prompt.</p>
<p>Each subject line is matched separately and independently. If you want to do
multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
etc., depending on the newline setting) in a single line of input to encode the
newline sequences. There is no limit on the length of subject lines; the input
buffer is automatically extended if it is too small. There are replication
features that makes it possible to generate long repetitive pattern or subject
lines without having to supply them explicitly.</p>
<p>An empty line or the end of the file signals the end of the subject lines for a
test, at which point a new pattern or command line is expected if there is
still input to be read.</p></section>
<section class="doc-section level-1"><h2 id="_command_lines">Command lines</h2><p>In between sets of test data, a line that begins with # is interpreted as a
command line. If the first character is followed by white space or an
exclamation mark, the line is treated as a comment, and ignored. Otherwise, the
following commands are recognized:</p>
<div class="literal-block"><pre>#forbid_utf</pre></div>
<p>Subsequent patterns automatically have the <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UTF</span></code> and <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UCP</span></code>
options set, which locks out the use of the <code class="constant pcre2-api rouge"><span class="no">PCRE2_UTF</span></code> and <code class="constant pcre2-api rouge"><span class="no">PCRE2_UCP</span></code> options and
the use of (<code class="regex rouge"><span class="pcre2-semantic">*UTF</span></code>) and (<code class="regex rouge"><span class="pcre2-semantic">*UCP</span></code>) at the start of patterns. This command also forces
an error if a subsequent pattern contains any occurrences of <code class="regex rouge"><span class="pcre2-semantic">\P</span></code>, <code class="regex rouge"><span class="pcre2-semantic">\p</span></code>, or <code class="regex rouge"><span class="pcre2-semantic">\X</span></code>,
which are still supported when <code class="constant pcre2-api rouge"><span class="no">PCRE2_UTF</span></code> is not set, but which require Unicode
property support to be included in the library.</p>
<p>This is a trigger guard that is used in test files to ensure that UTF or
Unicode property tests are not accidentally added to files that are used when
Unicode support is not included in the library. Setting <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UTF</span></code> and
<code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UCP</span></code> as a default can also be obtained by the use of <code>#pattern</code>;
the difference is that <code>#forbid_utf</code> cannot be unset, and the automatic
options are not displayed in pattern information, to avoid cluttering up test
output.</p>
<div class="literal-block"><pre>#load &lt;filename&gt;</pre></div>
<p>This command is used to load a set of precompiled patterns from a file, as
described in the section <a href="#saving-restoring-patterns">Saving and restoring compiled patterns</a>
below.</p>
<div class="literal-block"><pre>#loadtables &lt;filename&gt;</pre></div>
<p>This command is used to load a set of binary character tables that can be
accessed by the <code>tables=3</code> qualifier. Such tables can be created by the
<code>pcre2_dftables</code> program with the -b option.</p>
<div class="literal-block"><pre>#newline_default [&lt;newline-list&gt;]</pre></div>
<p>When PCRE2 is built, a default newline convention can be specified. This
determines which characters and/or character pairs are recognized as indicating
a newline in a pattern or subject string. The default can be overridden when a
pattern is compiled. The standard test files contain tests of various newline
conventions, but the majority of the tests expect a single linefeed to be
recognized as a newline by default. Without special action the tests would fail
when PCRE2 is compiled with either CR or CRLF as the default newline.</p>
<p>The #newline_default command specifies a list of newline types that are
acceptable as the default. The types must be one of CR, LF, CRLF, ANYCRLF,
ANY, or NUL (in upper or lower case), for example:</p>
<div class="literal-block"><pre>#newline_default LF Any anyCRLF</pre></div>
<p>If the default newline is in the list, this command has no effect. Otherwise,
except when testing the POSIX API, a <code>newline</code> modifier that specifies the
first newline convention in the list (LF in the above example) is added to any
pattern that does not already have a <code>newline</code> modifier. If the newline
list is empty, the feature is turned off. This command is present in a number
of the standard test input files.</p>
<p>When the POSIX API is being tested there is no way to override the default
newline convention, though it is possible to set the newline convention from
within the pattern. A warning is given if the <code>posix</code> or <code>posix_nosub</code>
modifier is used when <code>#newline_default</code> would set a default for the
non-POSIX API.</p>
<div class="literal-block"><pre>#pattern &lt;modifier-list&gt;</pre></div>
<p>This command sets a default modifier list that applies to all subsequent
patterns. Modifiers on a pattern can change these settings.</p>
<div class="literal-block"><pre>#perltest</pre></div>
<p>This line is used in test files that can also be processed by <code>PerlTest.sh</code>
to confirm that Perl gives the same results as PCRE2. Subsequent tests are
checked for the use of <code>pcre2test</code> features that are incompatible with the
<code>PerlTest.sh</code> script.</p>
<p>Patterns must use '/' as their delimiter, and only certain modifiers are
supported. Comment lines, #pattern commands, and #subject commands that set or
unset "mark" are recognized and acted on. The #perltest, #forbid_utf, and
#newline_default commands, which are needed in the relevant pcre2test files,
are silently ignored. All other command lines are ignored, but give a warning
message. The <code>#perltest</code> command helps detect tests that are accidentally
put in the wrong file or use the wrong delimiter. For more details of the
<code>PerlTest.sh</code> script see the comments it contains.</p>
<div class="literal-block"><pre>#pop [&lt;modifiers&gt;]
#popcopy [&lt;modifiers&gt;]</pre></div>
<p>These commands are used to manipulate the stack of compiled patterns, as
described in the section <a href="#saving-restoring-patterns">Saving and restoring compiled patterns</a>
below.</p>
<div class="literal-block"><pre>#save &lt;filename&gt;</pre></div>
<p>This command is used to save a set of compiled patterns to a file, as described
in the section <a href="#saving-restoring-patterns">Saving and restoring compiled patterns</a>
below.</p>
<div class="literal-block"><pre>#subject &lt;modifier-list&gt;</pre></div>
<p>This command sets a default modifier list that applies to all subsequent
subject lines. Modifiers on a subject line can change these settings.</p>
<div class="literal-block"><pre>#if CONDITION
...
#endif</pre></div>
<p>If CONDITION is true, then the command is printed, and its contents are
processed as normal, including printing the commandlines to the output. If
CONDITION is false, then all lines between the "#if" and "#endif" are skipped
and not printed. The CONDITION can be any of the conditions which are tested by
the "-C" commandline option and which set pcre2test’s exit code to a boolean
value. The CONDITION may also be preceded by "!".</p></section>
<section class="doc-section level-1"><h2 id="_modifier_syntax">Modifier syntax</h2><p>Modifier lists are used with both pattern and subject lines. Items in a list
are separated by commas followed by optional white space. Trailing white space
in a modifier list is ignored. Some modifiers may be given for both patterns
and subject lines, whereas others are valid only for one or the other. Each
modifier has a long name, for example "anchored", and some of them must be
followed by an equals sign and a value, for example, "offset=12". Values cannot
contain comma characters, but may contain spaces. Modifiers that do not take
values may be preceded by a minus sign to turn off a previous setting.</p>
<p>A few of the more common modifiers can also be specified as single letters, for
example "i" for "caseless". In documentation, following the Perl convention,
these are written with a slash ("the /i modifier") for clarity. Abbreviated
modifiers must all be concatenated in the first item of a modifier list. If the
first item is not recognized as a long modifier name, it is interpreted as a
sequence of these abbreviations. For example:</p>
<div class="literal-block"><pre>/abc/ig,newline=cr,jit=3</pre></div>
<p>This is a pattern line whose modifier list starts with two one-letter modifiers
(/i and /g). The lower-case abbreviated modifiers are the same as used in Perl.</p></section>
<section class="doc-section level-1"><h2 id="_pattern_syntax">Pattern syntax</h2><p>A pattern line must start with one of the following characters (common symbols,
excluding pattern meta-characters):</p>
<div class="literal-block"><pre>/ ! " ' ` - = _ : ; , % &amp; @ ~</pre></div>
<p>This is interpreted as the pattern’s delimiter. A regular expression may be
continued over several input lines, in which case the newline characters are
included within it. It is possible to include the delimiter as a literal within
the pattern by escaping it with a backslash, for example</p>
<div class="literal-block"><pre>/abc\/def/</pre></div>
<p>If you do this, the escape and the delimiter form part of the pattern, but
since the delimiters are all non-alphanumeric, the inclusion of the backslash
does not affect the pattern’s interpretation. Note, however, that this trick
does not work within <code class="regex rouge"><span class="pcre2-semantic">\Q...\E</span></code> literal bracketing because the backslash will
itself be interpreted as a literal. If the terminating delimiter is immediately
followed by a backslash, for example,</p>
<div class="literal-block"><pre>/abc/\</pre></div>
<p>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</p>
<div class="literal-block"><pre>/abc\/</pre></div>
<p>is interpreted as the first line of a pattern that starts with "abc/", causing
pcre2test to read the next line as a continuation of the regular expression.</p>
<p>A pattern can be followed by a modifier list (details below).</p></section>
<section class="doc-section level-1"><h2 id="_subject_line_syntax">Subject line syntax</h2><p>Before each subject line is passed to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>,
<code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>, or <code class="function pcre2-api rouge"><span class="nf">pcre2_jit_match()</span></code>, leading and trailing white
space is removed, and the line is scanned for backslash escapes, unless the
<code>subject_literal</code> modifier was set for the pattern. The following provide a
means of encoding non-printing characters in a visible way:</p>
<dl class="compact" style="--tab-width: 10"><div class="dlist-item"><dt><span><code>\a</code> </span></dt><dd>alarm (BEL, <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-9"><code class="character pcre2-api rouge"><span class="sc">0x07</span></code><span class="character-card" id="pcre2-character-9" role="tooltip" aria-label="ALERT (U+0007)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="ALERT"></span><span class="character-codepoint" data-codepoint="U+0007"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\b</code> </span></dt><dd>backspace (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-10"><code class="character pcre2-api rouge"><span class="sc">0x08</span></code><span class="character-card" id="pcre2-character-10" role="tooltip" aria-label="BACKSPACE (U+0008)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="BACKSPACE"></span><span class="character-codepoint" data-codepoint="U+0008"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\e</code> </span></dt><dd>escape (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-11"><code class="character pcre2-api rouge"><span class="sc">0x27</span></code><span class="character-card" id="pcre2-character-11" role="tooltip" aria-label="APOSTROPHE (U+0027)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character="'"></span><span class="character-name" data-character-name="APOSTROPHE"></span><span class="character-codepoint" data-codepoint="U+0027"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\f</code> </span></dt><dd>form feed (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-12"><code class="character pcre2-api rouge"><span class="sc">0x0c</span></code><span class="character-card" id="pcre2-character-12" role="tooltip" aria-label="FORM FEED (U+000C)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="FORM FEED"></span><span class="character-codepoint" data-codepoint="U+000C"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\n</code> </span></dt><dd>newline (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-13"><code class="character pcre2-api rouge"><span class="sc">0x0a</span></code><span class="character-card" id="pcre2-character-13" role="tooltip" aria-label="LINE FEED (U+000A)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="LINE FEED"></span><span class="character-codepoint" data-codepoint="U+000A"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\N{U+<em>hh...</em>}</code> </span></dt><dd>unicode character (any number of hex digits)</dd></div><div class="dlist-item"><dt><span><code>\r</code> </span></dt><dd>carriage return (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-14"><code class="character pcre2-api rouge"><span class="sc">0x0d</span></code><span class="character-card" id="pcre2-character-14" role="tooltip" aria-label="CARRIAGE RETURN (U+000D)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="CARRIAGE RETURN"></span><span class="character-codepoint" data-codepoint="U+000D"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\t</code> </span></dt><dd>tab (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-15"><code class="character pcre2-api rouge"><span class="sc">0x09</span></code><span class="character-card" id="pcre2-character-15" role="tooltip" aria-label="CHARACTER TABULATION (U+0009)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="CHARACTER TABULATION"></span><span class="character-codepoint" data-codepoint="U+0009"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\v</code> </span></dt><dd>vertical tab (<span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-16"><code class="character pcre2-api rouge"><span class="sc">0x0b</span></code><span class="character-card" id="pcre2-character-16" role="tooltip" aria-label="LINE TABULATION (U+000B)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character=""></span><span class="character-name" data-character-name="LINE TABULATION"></span><span class="character-codepoint" data-codepoint="U+000B"></span></span></span>)</dd></div><div class="dlist-item"><dt><span><code>\<em>ddd</em></code> </span></dt><dd>octal number (up to 3 octal digits); represent a single
code point unless larger than 255 with the 8-bit library</dd></div><div class="dlist-item"><dt><span><code>\o{<em>dd...</em>}</code> </span></dt><dd>octal number (any number of octal digits) representing a
character in UTF mode or a code point</dd></div><div class="dlist-item"><dt><span><code>\x<em>hh</em></code> </span></dt><dd>hexadecimal byte (up to 2 hex digits)</dd></div><div class="dlist-item"><dt><span><code>\x{<em>hh...</em>}</code> </span></dt><dd>hexadecimal number (up to 8 hex digits) representing a
character in UTF mode or a code point</dd></div></dl>
<p>Invoking <code>\N{U+<em>hh...</em>}</code> or <code>\x{<em>hh...</em>}</code> doesn’t require the use of the <code>utf</code>
modifier on the pattern. It is always recognized. There may be any number of
hexadecimal digits inside the braces; invalid values provoke error messages
but when using <code>\N{U+<em>hh...</em>}</code> with some invalid unicode characters they will
be accepted with a warning instead.</p>
<p>Note that even in UTF-8 mode, <code>\x<em>hh</em></code> (and depending of how large, <code>\<em>ddd</em></code>)
describe one byte rather than one character; this makes it possible to
construct invalid UTF-8 sequences for testing purposes. On the other hand,
<code>\x{<em>hh...</em>}</code> is interpreted as a UTF-8 character in UTF-8 mode, only generating
more than one byte if the value is greater than 127. To avoid the ambiguity
it is preferred to use <code>\N{U+<em>hh</em>...}</code> when describing characters. When testing
the 8-bit library not in UTF-8 mode, <code>\x{<em>hh</em>}</code> generates one byte for values
that could fit on it, and causes an error for greater values.</p>
<p>When testing the 16-bit library, not in UTF-16 mode, all 4-digit <code>\x{<em>hhhh</em>}</code>
values are accepted. This makes it possible to construct invalid UTF-16
sequences for testing purposes.</p>
<p>When testing the 32-bit library, not in UTF-32 mode, all 4 to 8-digit <code>\x{...}</code>
values are accepted. This makes it possible to construct invalid UTF-32
sequences for testing purposes.</p>
<p>There is a special backslash sequence that specifies replication of one or more
characters:</p>
<div class="literal-block"><pre>\[&lt;characters&gt;]{&lt;count&gt;}</pre></div>
<p>This makes it possible to test long strings without having to provide them as
part of the file. For example:</p>
<div class="literal-block"><pre>\[abc]{4}</pre></div>
<p>is converted to "abcabcabcabc". This feature does not support nesting. To
include a closing square bracket in the characters, code it as \x5D.</p>
<p>A backslash followed by an equals sign marks the end of the subject string and
the start of a modifier list. For example:</p>
<div class="literal-block"><pre>abc\=notbol,notempty</pre></div>
<p>If the subject string is empty and \= is followed by white space, the line is
treated as a comment line, and is not used for matching. For example:</p>
<div class="literal-block"><pre>\= This is a comment.
abc\= This is an invalid modifier list.</pre></div>
<p>A backslash followed by any other non-alphanumeric character just escapes that
character. A backslash followed by anything else causes an error. However, if
the very last character in the line is a backslash (and there is no modifier
list), it is ignored. This gives a way of passing an empty line as data, since
a real empty line terminates the data input.</p>
<p>If the <code>subject_literal</code> modifier is set for a pattern, all subject lines
that follow are treated as literals, with no special treatment of backslashes.
No replication is possible, and any subject modifiers must be set as defaults
by a <code>#subject</code> command.</p></section>
<section class="doc-section level-1"><h2 id="_pattern_modifiers">Pattern modifiers</h2><p>There are several types of modifier that can appear in pattern lines. Except
where noted below, they may also be used in <code>#pattern</code> commands. A
pattern’s modifier list can add to or override default modifiers that were set
by a previous <code>#pattern</code> command.</p>
<section class="doc-section level-2"><h3 id="_setting_compilation_options">Setting compilation options</h3><p>The following modifiers set options for <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. Most of them set
bits in the options argument of that function, but those whose names start with
<code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA</span></code> are additional options that are set in the compile context.
Some of these options have single-letter abbreviations. There is special
handling for <code class="regex rouge"><span class="pcre2-semantic">/x</span></code>: if a second x is present, <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTENDED</span></code> is converted into
<code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTENDED_MORE</span></code> as in Perl. A third appearance adds <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTENDED</span></code> as well,
though this makes no difference to the way <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> behaves. See
<a href="./pcre2api.html"><code>pcre2api</code></a>
for a description of the effects of these options.</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>allow_empty_class</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ALLOW_EMPTY_CLASS</span></code></dd></div><div class="dlist-item"><dt><span><code>allow_lookaround_bsk</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK</span></code></dd></div><div class="dlist-item"><dt><span><code>allow_surrogate_escapes</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES</span></code></dd></div><div class="dlist-item"><dt><span><code>alt_bsux</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ALT_BSUX</span></code></dd></div><div class="dlist-item"><dt><span><code>alt_circumflex</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ALT_CIRCUMFLEX</span></code></dd></div><div class="dlist-item"><dt><span><code>alt_extended_class</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ALT_EXTENDED_CLASS</span></code></dd></div><div class="dlist-item"><dt><span><code>alt_verbnames</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ALT_VERBNAMES</span></code></dd></div><div class="dlist-item"><dt><span><code>anchored</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ANCHORED</span></code></dd></div><div class="dlist-item"><dt><span><code>/a ascii_all</code></span></dt><dd>set all ASCII options</dd></div><div class="dlist-item"><dt><span><code>ascii_bsd</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ASCII_BSD</span></code></dd></div><div class="dlist-item"><dt><span><code>ascii_bss</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ASCII_BSS</span></code></dd></div><div class="dlist-item"><dt><span><code>ascii_bsw</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ASCII_BSW</span></code></dd></div><div class="dlist-item"><dt><span><code>ascii_digit</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ASCII_DIGIT</span></code></dd></div><div class="dlist-item"><dt><span><code>ascii_posix</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ASCII_POSIX</span></code></dd></div><div class="dlist-item"><dt><span><code>auto_callout</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_AUTO_CALLOUT</span></code></dd></div><div class="dlist-item"><dt><span><code>bad_escape_is_literal</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL</span></code></dd></div><div class="dlist-item"><dt><span><code>/i caseless</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_CASELESS</span></code></dd></div><div class="dlist-item"><dt><span><code>/r caseless_restrict</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_CASELESS_RESTRICT</span></code></dd></div><div class="dlist-item"><dt><span><code>dollar_endonly</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DOLLAR_ENDONLY</span></code></dd></div><div class="dlist-item"><dt><span><code>/s dotall</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DOTALL</span></code></dd></div><div class="dlist-item"><dt><span><code>dupnames</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DUPNAMES</span></code></dd></div><div class="dlist-item"><dt><span><code>endanchored</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ENDANCHORED</span></code></dd></div><div class="dlist-item"><dt><span><code>escaped_cr_is_lf</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ESCAPED_CR_IS_LF</span></code></dd></div><div class="dlist-item"><dt><span><code>/x extended</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTENDED</span></code></dd></div><div class="dlist-item"><dt><span><code>/xx extended_more</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTENDED_MORE</span></code></dd></div><div class="dlist-item"><dt><span><code>extra_alt_bsux</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_ALT_BSUX</span></code></dd></div><div class="dlist-item"><dt><span><code>firstline</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_FIRSTLINE</span></code></dd></div><div class="dlist-item"><dt><span><code>literal</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_LITERAL</span></code></dd></div><div class="dlist-item"><dt><span><code>match_line</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_MATCH_LINE</span></code></dd></div><div class="dlist-item"><dt><span><code>match_invalid_utf</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_MATCH_INVALID_UTF</span></code></dd></div><div class="dlist-item"><dt><span><code>match_unset_backref</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_MATCH_UNSET_BACKREF</span></code></dd></div><div class="dlist-item"><dt><span><code>match_word</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_MATCH_WORD</span></code></dd></div><div class="dlist-item"><dt><span><code>/m multiline</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_MULTILINE</span></code></dd></div><div class="dlist-item"><dt><span><code>never_backslash_c</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_BACKSLASH_C</span></code></dd></div><div class="dlist-item"><dt><span><code>never_callout</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_NEVER_CALLOUT</span></code></dd></div><div class="dlist-item"><dt><span><code>never_ucp</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UCP</span></code></dd></div><div class="dlist-item"><dt><span><code>never_utf</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NEVER_UTF</span></code></dd></div><div class="dlist-item"><dt><span><code>/n no_auto_capture</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_AUTO_CAPTURE</span></code></dd></div><div class="dlist-item"><dt><span><code>no_auto_possess</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_AUTO_POSSESS</span></code></dd></div><div class="dlist-item"><dt><span><code>no_bs0</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_NO_BS0</span></code></dd></div><div class="dlist-item"><dt><span><code>no_dotstar_anchor</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_DOTSTAR_ANCHOR</span></code></dd></div><div class="dlist-item"><dt><span><code>no_start_optimize</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_START_OPTIMIZE</span></code></dd></div><div class="dlist-item"><dt><span><code>no_utf_check</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_UTF_CHECK</span></code></dd></div><div class="dlist-item"><dt><span><code>python_octal</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_PYTHON_OCTAL</span></code></dd></div><div class="dlist-item"><dt><span><code>turkish_casing</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_EXTRA_TURKISH_CASING</span></code></dd></div><div class="dlist-item"><dt><span><code>ucp</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_UCP</span></code></dd></div><div class="dlist-item"><dt><span><code>ungreedy</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_UNGREEDY</span></code></dd></div><div class="dlist-item"><dt><span><code>use_offset_limit</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_USE_OFFSET_LIMIT</span></code></dd></div><div class="dlist-item"><dt><span><code>utf</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_UTF</span></code></dd></div></dl>
<p>As well as turning on the <code class="constant pcre2-api rouge"><span class="no">PCRE2_UTF</span></code> option, the <code>utf</code> modifier causes all
non-printing characters in output strings to be printed using the <code class="regex rouge"><span class="pcre2-semantic">\x{<em>hh</em>...}</span></code>
notation. Otherwise, those less than <span class="character-info" title="" tabindex="0" aria-describedby="pcre2-character-17"><code class="character pcre2-api rouge"><span class="sc">0x100</span></code><span class="character-card" id="pcre2-character-17" role="tooltip" aria-label="LATIN CAPITAL LETTER A WITH MACRON (U+0100)" aria-hidden="true" data-pagefind-ignore=""><span class="character-glyph" data-character="Ā"></span><span class="character-name" data-character-name="LATIN CAPITAL LETTER A WITH MACRON"></span><span class="character-codepoint" data-codepoint="U+0100"></span></span></span> are output in hex without the curly
brackets. Setting <code>utf</code> in 16-bit or 32-bit mode also causes pattern and
subject strings to be translated to UTF-16 or UTF-32, respectively, before
being passed to library functions.</p>
<p>The following modifiers enable or disable performance optimizations by
calling <code class="function pcre2-api rouge"><span class="nf">pcre2_set_optimize()</span></code> before invoking the regex compiler.</p>
<dl class="options compact" style="--tab-width: 10"><div class="dlist-item"><dt><span><code>optimization_full</code></span></dt><dd>enable all optional optimizations</dd></div><div class="dlist-item"><dt><span><code>optimization_none</code></span></dt><dd>disable all optional optimizations</dd></div><div class="dlist-item"><dt><span><code>auto_possess</code></span></dt><dd>auto-possessify variable quantifiers</dd></div><div class="dlist-item"><dt><span><code>auto_possess_off</code></span></dt><dd>don’t auto-possessify variable quantifiers</dd></div><div class="dlist-item"><dt><span><code>dotstar_anchor</code></span></dt><dd>anchor patterns starting with <code class="regex rouge"><span class="pcre2-semantic">.*</span></code></dd></div><div class="dlist-item"><dt><span><code>dotstar_anchor_off</code></span></dt><dd>don’t anchor patterns starting with <code class="regex rouge"><span class="pcre2-semantic">.*</span></code></dd></div><div class="dlist-item"><dt><span><code>start_optimize</code></span></dt><dd>enable pre-scan of subject string</dd></div><div class="dlist-item"><dt><span><code>start_optimize_off</code></span></dt><dd>disable pre-scan of subject string</dd></div></dl>
<p>See the
<a href="./pcre2_set_optimize.html"><code>pcre2_set_optimize</code></a>
documentation for details on these optimizations.</p></section>
<section class="doc-section level-2"><h3 id="_setting_compilation_controls">Setting compilation controls</h3><p>The following modifiers affect the compilation process or request information
about the pattern. There are single-letter abbreviations for some that are
heavily used in the test files.</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>/B bincode</code></span></dt><dd>show binary code without lengths</dd></div><div class="dlist-item"><dt><span><code>bsr=[anycrlf|unicode]</code></span></dt><dd>specify \R handling</dd></div><div class="dlist-item"><dt><span><code>callout_info</code></span></dt><dd>show callout information</dd></div><div class="dlist-item"><dt><span><code>convert=&lt;options&gt;</code></span></dt><dd>request foreign pattern conversion</dd></div><div class="dlist-item"><dt><span><code>convert_glob_escape=c</code></span></dt><dd>set glob escape character</dd></div><div class="dlist-item"><dt><span><code>convert_glob_separator=c</code></span></dt><dd>set glob separator character</dd></div><div class="dlist-item"><dt><span><code>convert_length</code></span></dt><dd>set convert buffer length</dd></div><div class="dlist-item"><dt><span><code>debug</code></span></dt><dd>same as <code>info,fullbincode</code></dd></div><div class="dlist-item"><dt><span><code>expand</code></span></dt><dd>expand repetition syntax in pattern</dd></div><div class="dlist-item"><dt><span><code>framesize</code></span></dt><dd>show matching frame size</dd></div><div class="dlist-item"><dt><span><code>fullbincode</code></span></dt><dd>show binary code with lengths</dd></div><div class="dlist-item"><dt><span><code>/I info</code></span></dt><dd>show info about compiled pattern</dd></div><div class="dlist-item"><dt><span><code>hex</code></span></dt><dd>unquoted characters are hexadecimal</dd></div><div class="dlist-item"><dt><span><code>jit[=&lt;number&gt;]</code></span></dt><dd>use JIT</dd></div><div class="dlist-item"><dt><span><code>jitfast</code></span></dt><dd>use JIT fast path</dd></div><div class="dlist-item"><dt><span><code>jitverify</code></span></dt><dd>verify JIT use</dd></div><div class="dlist-item"><dt><span><code>locale=&lt;name&gt;</code></span></dt><dd>use this locale</dd></div><div class="dlist-item"><dt><span><code>max_pattern_compiled_length=&lt;n&gt;</code></span></dt><dd>set maximum compiled pattern length (bytes)</dd></div><div class="dlist-item"><dt><span><code>max_pattern_length=&lt;n&gt;</code></span></dt><dd>set maximum pattern length (code units)</dd></div><div class="dlist-item"><dt><span><code>max_varlookbehind=&lt;n&gt;</code></span></dt><dd>set maximum variable lookbehind length</dd></div><div class="dlist-item"><dt><span><code>memory</code></span></dt><dd>show memory used</dd></div><div class="dlist-item"><dt><span><code>newline=&lt;type&gt;</code></span></dt><dd>set newline type</dd></div><div class="dlist-item"><dt><span><code>null_context</code></span></dt><dd>compile with a NULL context</dd></div><div class="dlist-item"><dt><span><code>null_pattern</code></span></dt><dd>pass pattern as NULL</dd></div><div class="dlist-item"><dt><span><code>parens_nest_limit=&lt;n&gt;</code></span></dt><dd>set maximum parentheses depth</dd></div><div class="dlist-item"><dt><span><code>posix</code></span></dt><dd>use the POSIX API</dd></div><div class="dlist-item"><dt><span><code>posix_nosub</code></span></dt><dd>use the POSIX API with <code class="c rouge" data-lang="c"><span class="no">REG_NOSUB</span></code></dd></div><div class="dlist-item"><dt><span><code>push</code></span></dt><dd>push compiled pattern onto the stack</dd></div><div class="dlist-item"><dt><span><code>pushcopy</code></span></dt><dd>push a copy onto the stack</dd></div><div class="dlist-item"><dt><span><code>pushtablescopy</code></span></dt><dd>push a copy with tables onto the stack</dd></div><div class="dlist-item"><dt><span><code>stackguard=&lt;number&gt;</code></span></dt><dd>test the stackguard feature</dd></div><div class="dlist-item"><dt><span><code>subject_literal</code></span></dt><dd>treat all subject lines as literal</dd></div><div class="dlist-item"><dt><span><code>tables=[0|1|2|3]</code></span></dt><dd>select internal tables</dd></div><div class="dlist-item"><dt><span><code>use_length</code></span></dt><dd>do not zero-terminate the pattern</dd></div><div class="dlist-item"><dt><span><code>utf8_input</code></span></dt><dd>treat input as UTF-8</dd></div></dl>
<p>The effects of these modifiers are described in the following sections.</p></section>
<section class="doc-section level-2"><h3 id="_newline_and_r_handling">Newline and \R handling</h3><p>The <code>bsr</code> modifier specifies what <code class="regex rouge"><span class="pcre2-semantic">\R</span></code> in a pattern should match. If it is
set to "anycrlf", <code class="regex rouge"><span class="pcre2-semantic">\R</span></code> matches CR, LF, or CRLF only. If it is set to "unicode",
<code class="regex rouge"><span class="pcre2-semantic">\R</span></code> matches any Unicode newline sequence. The default can be specified when
PCRE2 is built; if it is not, the default is set to Unicode.</p>
<p>The <code>newline</code> modifier specifies which characters are to be interpreted as
newlines, both in the pattern and in subject lines. The type must be one of CR,
LF, CRLF, ANYCRLF, ANY, or NUL (in upper or lower case).</p></section>
<section class="doc-section level-2"><h3 id="_information_about_a_pattern">Information about a pattern</h3><p>The <code>debug</code> modifier is a shorthand for <code>info,fullbincode</code>, requesting
all available information.</p>
<p>The <code>bincode</code> modifier causes a representation of the compiled code to be
output after compilation. This information does not contain length and offset
values, which ensures that the same output is generated for different internal
link sizes and different code unit widths. By using <code>bincode</code>, the same
regression tests can be used in different environments.</p>
<p>The <code>fullbincode</code> modifier, by contrast, <em>does</em> include length and
offset values. This is used in a few special tests that run only for specific
code unit widths and link sizes, and is also useful for one-off tests.</p>
<p>The <code>info</code> modifier requests information about the compiled pattern
(whether it is anchored, has a fixed first character, and so on). The
information is obtained from the <code class="function pcre2-api rouge"><span class="nf">pcre2_pattern_info()</span></code> function. Here are
some typical examples:</p>
<div class="literal-block"><pre> re&gt; /(?i)(^a|^b)/m,info
Capture group count = 1
Compile options: multiline
Overall options: caseless multiline
First code unit at start or follows newline
Subject length lower bound = 1</pre></div>
<div class="literal-block"><pre> re&gt; /(?i)abc/info
Capture group count = 0
Compile options: &lt;none&gt;
Overall options: caseless
First code unit = 'a' (caseless)
Last code unit = 'c' (caseless)
Subject length lower bound = 3</pre></div>
<p>"Compile options" are those specified by modifiers; "overall options" have
added options that are taken or deduced from the pattern. If both sets of
options are the same, just a single "options" line is output; if there are no
options, the line is omitted. "First code unit" is where any match must start;
if there is more than one they are listed as "starting code units". "Last code
unit" is the last literal code unit that must be present in any match. This is
not necessarily the last character. These lines are omitted if no starting or
ending code units are recorded. The subject length line is omitted when
<code>no_start_optimize</code> is set because the minimum length is not calculated
when it can never be used.</p>
<p>The <code>framesize</code> modifier shows the size, in bytes, of each storage frame
used by <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> for handling backtracking. The size depends on the
number of capturing parentheses in the pattern. A vector of these frames is
used at matching time; its overall size is shown when the <code>heapframes_size</code>
subject modifier is set.</p>
<p>The <code>callout_info</code> modifier requests information about all the callouts in
the pattern. A list of them is output at the end of any other information that
is requested. For each callout, either its number or string is given, followed
by the item that follows it in the pattern.</p></section>
<section class="doc-section level-2"><h3 id="_passing_a_null_context">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> context</h3><p>Normally, <code>pcre2test</code> passes a context block to <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. If
the <code>null_context</code> modifier is set, however, <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> is passed. This is for
testing that <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> behaves correctly in this case (it uses
default values).</p></section>
<section class="doc-section level-2"><h3 id="_passing_a_null_pattern">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> pattern</h3><p>The <code>null_pattern</code> modifier is for testing the behaviour of
<code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> when the pattern argument is <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code>. The length value
passed is the default <code class="constant pcre2-api rouge"><span class="no">PCRE2_ZERO_TERMINATED</span></code> unless <code>use_length</code> is set.
Any length other than zero causes an error.</p></section>
<section class="doc-section level-2"><h3 id="_specifying_pattern_characters_in_hexadecimal">Specifying pattern characters in hexadecimal</h3><p>The <code>hex</code> modifier specifies that the characters of the pattern, except for
substrings enclosed in single or double quotes, are to be interpreted as pairs
of hexadecimal digits. This feature is provided as a way of creating patterns
that contain binary zeros and other non-printing characters. White space is
permitted between pairs of digits. For example, this pattern contains three
characters:</p>
<div class="literal-block"><pre>/ab 32 59/hex</pre></div>
<p>Parts of such a pattern are taken literally if quoted. This pattern contains
nine characters, only two of which are specified in hexadecimal:</p>
<div class="literal-block"><pre>/ab "literal" 32/hex</pre></div>
<p>Either single or double quotes may be used. There is no way of including
the delimiter within a substring. The <code>hex</code> and <code>expand</code> modifiers are
mutually exclusive.</p></section>
<section class="doc-section level-2"><h3 id="_specifying_the_patterns_length">Specifying the pattern’s length</h3><p>By default, patterns are passed to the compiling functions as zero-terminated
strings but can be passed by length instead of being zero-terminated. The
<code>use_length</code> modifier causes this to happen. Using a length happens
automatically (whether or not <code>use_length</code> is set) when <code>hex</code> is set,
because patterns specified in hexadecimal may contain binary zeros.</p>
<p>If <code>hex</code> or <code>use_length</code> is used with the POSIX wrapper API (see
"Using the POSIX wrapper API"
below), the REG_PEND extension is used to pass the pattern’s length.</p></section>
<section class="doc-section level-2"><h3 id="_specifying_a_maximum_for_variable_lookbehinds">Specifying a maximum for variable lookbehinds</h3><p>Variable lookbehind assertions are supported only if, for each one, there is a
maximum length (in characters) that it can match. There is a limit on this,
whose default can be set at build time, with an ultimate default of 255. The
<code>max_varlookbehind</code> modifier uses the <code class="function pcre2-api rouge"><span class="nf">pcre2_set_max_varlookbehind()</span></code>
function to change the limit. Lookbehinds whose branches each match a fixed
length are limited to 65,535 characters per branch.</p></section>
<section class="doc-section level-2"><h3 id="_specifying_wide_characters_in_16_bit_and_32_bit_modes">Specifying wide characters in 16-bit and 32-bit modes</h3><p>In 16-bit and 32-bit modes, all input is automatically treated as UTF-8 and
translated to UTF-16 or UTF-32 when the <code>utf</code> modifier is set. For testing
the 16-bit and 32-bit libraries in non-UTF mode, the <code>utf8_input</code> modifier
can be used. It is mutually exclusive with <code>utf</code>. Input lines are
interpreted as UTF-8 as a means of specifying wide characters. More details are
given in
"Input encoding"
above.</p></section>
<section class="doc-section level-2"><h3 id="_generating_long_repetitive_patterns">Generating long repetitive patterns</h3><p>Some tests use long patterns that are very repetitive. Instead of creating a
very long input line for such a pattern, you can use a special repetition
feature, similar to the one described for subject lines above. If the
<code>expand</code> modifier is present on a pattern, parts of the pattern that have
the form</p>
<div class="literal-block"><pre>\[&lt;characters&gt;]{&lt;count&gt;}</pre></div>
<p>are expanded before the pattern is passed to <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. For
example, \[AB]{6000} is expanded to "ABAB…​" 6000 times. This construction
cannot be nested. An initial "\[" sequence is recognized only if "]{" followed
by decimal digits and "}" is found later in the pattern. If not, the characters
remain in the pattern unaltered. The <code>expand</code> and <code>hex</code> modifiers are
mutually exclusive.</p>
<p>If part of an expanded pattern looks like an expansion, but is really part of
the actual pattern, unwanted expansion can be avoided by giving two values in
the quantifier. For example, \[AB]{6000,6000} is not recognized as an
expansion item.</p>
<p>If the <code>info</code> modifier is set on an expanded pattern, the result of the
expansion is included in the information that is output.</p></section>
<section class="doc-section level-2"><h3 id="_jit_compilation">JIT compilation</h3><p>Just-in-time (JIT) compiling is a heavyweight optimization that can greatly
speed up pattern matching. See the
<a href="./pcre2jit.html"><code>pcre2jit</code></a>
documentation for details. JIT compiling happens, optionally, after a pattern
has been successfully compiled into an internal form. The JIT compiler converts
this to optimized machine code. It needs to know whether the match-time options
<code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_HARD</span></code> and <code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_SOFT</span></code> are going to be used, because
different code is generated for the different cases. See the <code>partial</code>
modifier in "Subject Modifiers"
below
for details of how these options are specified for each match attempt.</p>
<p>JIT compilation is requested by the <code>jit</code> pattern modifier, which may
optionally be followed by an equals sign and a number in the range 0 to 7.
The three bits that make up the number specify which of the three JIT operating
modes are to be compiled:</p>
<dl class="compact" style="--tab-width: 4"><div class="dlist-item"><dt><span>1</span></dt><dd>compile JIT code for non-partial matching</dd></div><div class="dlist-item"><dt><span>2</span></dt><dd>compile JIT code for soft partial matching</dd></div><div class="dlist-item"><dt><span>4</span></dt><dd>compile JIT code for hard partial matching</dd></div></dl>
<p>The possible values for the <code>jit</code> modifier are therefore:</p>
<dl class="compact" style="--tab-width: 4"><div class="dlist-item"><dt><span>0</span></dt><dd>disable JIT</dd></div><div class="dlist-item"><dt><span>1</span></dt><dd>normal matching only</dd></div><div class="dlist-item"><dt><span>2</span></dt><dd>soft partial matching only</dd></div><div class="dlist-item"><dt><span>3</span></dt><dd>normal and soft partial matching</dd></div><div class="dlist-item"><dt><span>4</span></dt><dd>hard partial matching only</dd></div><div class="dlist-item"><dt><span>6</span></dt><dd>soft and hard partial matching only</dd></div><div class="dlist-item"><dt><span>7</span></dt><dd>all three modes</dd></div></dl>
<p>If no number is given, 7 is assumed. The phrase "partial matching" means a call
to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> with either the <code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_SOFT</span></code> or the
<code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_HARD</span></code> option set. Note that such a call may return a complete
match; the options enable the possibility of a partial match, but do not
require it. Note also that if you request JIT compilation only for partial
matching (for example, jit=2) but do not set the <code>partial</code> modifier on a
subject line, that match will not use JIT code because none was compiled for
non-partial matching.</p>
<p>If JIT compilation is successful, the compiled JIT code will automatically be
used when an appropriate type of match is run, except when incompatible
run-time options are specified. For more details, see the
<a href="./pcre2jit.html"><code>pcre2jit</code></a>
documentation. See also the <code>jitstack</code> modifier below for a way of
setting the size of the JIT stack.</p>
<p>If the <code>jitfast</code> modifier is specified, matching is done using the JIT
"fast path" interface, <code class="function pcre2-api rouge"><span class="nf">pcre2_jit_match()</span></code>, which skips some of the sanity
checks that are done by <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>, and of course does not work when
JIT is not supported. If <code>jitfast</code> is specified without <code>jit</code>, jit=7 is
assumed.</p>
<p>If the <code>jitverify</code> modifier is specified, information about the compiled
pattern shows whether JIT compilation was or was not successful. If
<code>jitverify</code> is specified without <code>jit</code>, jit=7 is assumed. If JIT
compilation is successful when <code>jitverify</code> is set, the text "(JIT)" is
added to the first output line after a match or non match when JIT-compiled
code was actually used in the match.</p></section>
<section class="doc-section level-2"><h3 id="_setting_a_locale">Setting a locale</h3><p>The <code>locale</code> modifier must specify the name of a locale, for example:</p>
<div class="literal-block"><pre>/pattern/locale=fr_FR</pre></div>
<p>The given locale is set, <code class="function pcre2-api rouge"><span class="nf">pcre2_maketables()</span></code> is called to build a set of
character tables for the locale, and this is then passed to
<code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> when compiling the regular expression. The same tables
are used when matching the following subject lines. The <code>locale</code> modifier
applies only to the pattern on which it appears, but can be given in a
<code>#pattern</code> command if a default is needed. Setting a locale and alternate
character tables are mutually exclusive.</p></section>
<section class="doc-section level-2"><h3 id="_showing_pattern_memory">Showing pattern memory</h3><p>The <code>memory</code> modifier causes the size in bytes of the memory used to hold
the compiled pattern to be output. This does not include the size of the
<code class="type pcre2-api rouge"><span class="kt">pcre2_code</span></code> block; it is just the actual compiled data. If the pattern is
subsequently passed to the JIT compiler, the size of the JIT compiled code is
also output. Here is an example:</p>
<div class="literal-block"><pre> re&gt; /a(b)c/jit,memory
Memory allocation (code space): 21
Memory allocation (JIT code): 1910</pre></div></section>
<section class="doc-section level-2"><h3 id="_limiting_nested_parentheses">Limiting nested parentheses</h3><p>The <code>parens_nest_limit</code> modifier sets a limit on the depth of nested
parentheses in a pattern. Breaching the limit causes a compilation error.
The default for the library is set when PCRE2 is built, but <code>pcre2test</code>
sets its own default of 220, which is required for running the standard test
suite.</p></section>
<section class="doc-section level-2"><h3 id="_limiting_the_pattern_length">Limiting the pattern length</h3><p>The <code>max_pattern_length</code> modifier sets a limit, in code units, to the
length of pattern that <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> will accept. Breaching the limit
causes a compilation error. The default is the largest number a <code class="type pcre2-api rouge"><span class="kt">PCRE2_SIZE</span></code>
variable can hold (essentially unlimited).</p></section>
<section class="doc-section level-2"><h3 id="_limiting_the_size_of_a_compiled_pattern">Limiting the size of a compiled pattern</h3><p>The <code>max_pattern_compiled_length</code> modifier sets a limit, in bytes, to the
amount of memory used by a compiled pattern. Breaching the limit causes a
compilation error. The default is the largest number a <code class="type pcre2-api rouge"><span class="kt">PCRE2_SIZE</span></code> variable can
hold (essentially unlimited).</p></section>
<section class="doc-section level-2"><h3 id="_using_the_posix_wrapper_api">Using the POSIX wrapper API</h3><p>The <code>posix</code> and <code>posix_nosub</code> modifiers cause <code>pcre2test</code> to call
PCRE2 via the POSIX wrapper API rather than its native API. When
<code>posix_nosub</code> is used, the POSIX option <code class="c rouge" data-lang="c"><span class="no">REG_NOSUB</span></code> is passed to
<code class="c rouge" data-lang="c"><span class="nf">regcomp</span><span class="p">()</span></code>. The POSIX wrapper supports only the 8-bit library. Note that
it does not imply POSIX matching semantics; for more detail see the
<a href="./pcre2posix.html"><code>pcre2posix</code></a>
documentation. The following pattern modifiers set options for the
<code class="c rouge" data-lang="c"><span class="nf">regcomp</span><span class="p">()</span></code> function:</p>
<dl class="compact" style="--tab-width: 6"><div class="dlist-item"><dt><span><code>caseless</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_ICASE</span></code></dd></div><div class="dlist-item"><dt><span><code>multiline</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_NEWLINE</span></code></dd></div><div class="dlist-item"><dt><span><code>dotall</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_DOTALL</span></code></dd></div><div class="dlist-item"><dt><span><code>ungreedy</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_UNGREEDY</span></code></dd></div><div class="dlist-item"><dt><span><code>ucp</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_UCP</span></code></dd></div><div class="dlist-item"><dt><span><code>utf</code> </span></dt><dd><code class="constant pcre2-api rouge"><span class="no">REG_UTF8</span></code></dd></div></dl>
<p>The four options <code class="constant pcre2-api rouge"><span class="no">REG_DOTALL</span></code>, <code class="constant pcre2-api rouge"><span class="no">REG_UNGREEDY</span></code>, <code class="constant pcre2-api rouge"><span class="no">REG_UCP</span></code>, and <code class="constant pcre2-api rouge"><span class="no">REG_UTF8</span></code> are not part of the
POSIX standard.</p>
<p>The <code>regerror_buffsize</code> modifier specifies a size for the error buffer that
is passed to <code class="c rouge" data-lang="c"><span class="nf">regerror</span><span class="p">()</span></code> in the event of a compilation error. For example:</p>
<div class="literal-block"><pre>/abc/posix,regerror_buffsize=20</pre></div>
<p>This provides a means of testing the behaviour of <code class="c rouge" data-lang="c"><span class="nf">regerror</span><span class="p">()</span></code> when the
buffer is too small for the error message. If this modifier has not been set, a
large buffer is used.</p>
<p>The <code>aftertext</code> and <code>allaftertext</code> subject modifiers work as described
below. All other modifiers are either ignored, with a warning message, or cause
an error.</p>
<p>The pattern is passed to <code class="c rouge" data-lang="c"><span class="nf">regcomp</span><span class="p">()</span></code> as a zero-terminated string by
default, but if the <code>use_length</code> or <code>hex</code> modifiers are set, the
<code class="c rouge" data-lang="c"><span class="no">REG_PEND</span></code> extension is used to pass it by length.</p></section>
<section class="doc-section level-2"><h3 id="_testing_the_stack_guard_feature">Testing the stack guard feature</h3><p>The <code>stackguard</code> modifier is used to test the use of
<code class="function pcre2-api rouge"><span class="nf">pcre2_set_compile_recursion_guard()</span></code>, a function that is provided to
enable stack availability to be checked during compilation (see the
<a href="./pcre2api.html"><code>pcre2api</code></a>
documentation for details). If the number specified by the modifier is greater
than zero, <code class="function pcre2-api rouge"><span class="nf">pcre2_set_compile_recursion_guard()</span></code> is called to set up
callback from <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code> to a local function. The argument it
receives is the current nesting parenthesis depth; if this is greater than the
value given by the modifier, non-zero is returned, causing the compilation to
be aborted.</p></section>
<section class="doc-section level-2"><h3 id="_using_alternative_character_tables">Using alternative character tables</h3><p>The value specified for the <code>tables</code> modifier must be one of the digits 0,
1, 2, or 3. It causes a specific set of built-in character tables to be passed
to <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. This is used in the PCRE2 tests to check behaviour
with different character tables. The digit specifies the tables as follows:</p>
<dl class="compact" style="--tab-width: 4"><div class="dlist-item"><dt><span>0</span></dt><dd>do not pass any special character tables</dd></div><div class="dlist-item"><dt><span>1</span></dt><dd>the default ASCII tables, as distributed in <code>pcre2_chartables.c.dist</code></dd></div><div class="dlist-item"><dt><span>2</span></dt><dd>a set of tables defining ISO 8859 characters</dd></div><div class="dlist-item"><dt><span>3</span></dt><dd>a set of tables loaded by the <code>#loadtables</code> command</dd></div></dl>
<p>In tables 2, some characters whose codes are greater than 128 are identified as
letters, digits, spaces, etc. Tables 3 can be used only after a
<code>#loadtables</code> command has loaded them from a binary file. Setting alternate
character tables and a locale are mutually exclusive.</p></section>
<section class="doc-section level-2"><h3 id="_setting_certain_match_controls">Setting certain match controls</h3><p>The following modifiers are really subject modifiers, and are described under
"Subject Modifiers" below. However, they may be included in a pattern’s
modifier list, in which case they are applied to every subject line that is
processed with that pattern. These modifiers do not affect the compilation
process.</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>aftertext</code></span></dt><dd>show text after match</dd></div><div class="dlist-item"><dt><span><code>allaftertext</code></span></dt><dd>show text after captures</dd></div><div class="dlist-item"><dt><span><code>allcaptures</code></span></dt><dd>show all captures</dd></div><div class="dlist-item"><dt><span><code>allvector</code></span></dt><dd>show the entire ovector</dd></div><div class="dlist-item"><dt><span><code>allusedtext</code></span></dt><dd>show all consulted text</dd></div><div class="dlist-item"><dt><span><code>altglobal</code></span></dt><dd>alternative global matching</dd></div><div class="dlist-item"><dt><span><code>/g global</code></span></dt><dd>global matching</dd></div><div class="dlist-item"><dt><span><code>heapframes_size</code></span></dt><dd>show match data heapframes size</dd></div><div class="dlist-item"><dt><span><code>jitstack=&lt;n&gt;</code></span></dt><dd>set size of JIT stack</dd></div><div class="dlist-item"><dt><span><code>mark</code></span></dt><dd>show mark values</dd></div><div class="dlist-item"><dt><span><code>null_substitute_match_data</code></span></dt><dd>substitute with NULL match data</dd></div><div class="dlist-item"><dt><span><code>replace=&lt;str&gt;</code></span></dt><dd>specify a replacement string</dd></div><div class="dlist-item"><dt><span><code>startchar</code></span></dt><dd>show starting character when relevant</dd></div><div class="dlist-item"><dt><span><code>substitute_callout</code></span></dt><dd>use substitution callouts</dd></div><div class="dlist-item"><dt><span><code>substitute_case_callout</code></span></dt><dd>use substitution case callouts</dd></div><div class="dlist-item"><dt><span><code>substitute_extended</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_EXTENDED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_literal</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_LITERAL</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_matched</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_MATCHED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_overflow_length</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_OVERFLOW_LENGTH</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_replacement_only</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_REPLACEMENT_ONLY</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_skip=&lt;n&gt;</code></span></dt><dd>skip substitution &lt;n&gt;</dd></div><div class="dlist-item"><dt><span><code>substitute_stop=&lt;n&gt;</code></span></dt><dd>skip substitution &lt;n&gt; and following</dd></div><div class="dlist-item"><dt><span><code>substitute_unknown_unset</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNKNOWN_UNSET</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_unset_empty</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNSET_EMPTY</span></code></dd></div></dl>
<p>These modifiers may not appear in a <code>#pattern</code> command. If you want them as
defaults, set them in a <code>#subject</code> command.</p></section>
<section class="doc-section level-2"><h3 id="_specifying_literal_subject_lines">Specifying literal subject lines</h3><p>If the <code>subject_literal</code> modifier is present on a pattern, all the subject
lines that it matches are taken as literal strings, with no interpretation of
backslashes. It is not possible to set subject modifiers on such lines, but any
that are set as defaults by a <code>#subject</code> command are recognized.</p></section>
<section class="doc-section level-2"><h3 id="_saving_a_compiled_pattern">Saving a compiled pattern</h3><p>When a pattern with the <code>push</code> modifier is successfully compiled, it is
pushed onto a stack of compiled patterns, and <code>pcre2test</code> expects the next
line to contain a new pattern (or a command) instead of a subject line. This
facility is used when saving compiled patterns to a file, as described in the
section <a href="#saving-restoring-patterns">Saving and restoring compiled patterns</a>
below.
If <code>pushcopy</code> is used instead of <code>push</code>, a copy of the compiled
pattern is stacked, leaving the original as current, ready to match the
following input lines. This provides a way of testing the
<code class="function pcre2-api rouge"><span class="nf">pcre2_code_copy()</span></code> function.
The <code>push</code> and <code>pushcopy</code> modifiers are incompatible with compilation
modifiers such as <code>global</code> that act at match time. Any that are specified
are ignored (for the stacked copy), with a warning message, except for
<code>replace</code>, which causes an error. Note that <code>jitverify</code>, which is
allowed, does not carry through to any subsequent matching that uses a stacked
pattern.</p></section>
<section class="doc-section level-2"><h3 id="_testing_foreign_pattern_conversion">Testing foreign pattern conversion</h3><p>The experimental foreign pattern conversion functions in PCRE2 can be tested by
setting the <code>convert</code> modifier. Its argument is a colon-separated list of
options, which set the equivalent option for the <code class="function pcre2-api rouge"><span class="nf">pcre2_pattern_convert()</span></code>
function:</p>
<dl class="options compact" style="--tab-width: 12"><div class="dlist-item"><dt><span><code>glob</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_GLOB</span></code></dd></div><div class="dlist-item"><dt><span><code>glob_no_starstar</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_GLOB_NO_STARSTAR</span></code></dd></div><div class="dlist-item"><dt><span><code>glob_no_wild_separator</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_GLOB_NO_WILD_SEPARATOR</span></code></dd></div><div class="dlist-item"><dt><span><code>posix_basic</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_POSIX_BASIC</span></code></dd></div><div class="dlist-item"><dt><span><code>posix_extended</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_POSIX_EXTENDED</span></code></dd></div><div class="dlist-item"><dt><span><code>unset</code></span></dt><dd>Unset all options</dd></div></dl>
<p>The "unset" value is useful for turning off a default that has been set by a
<code>#pattern</code> command. When one of these options is set, the input pattern is
passed to <code class="function pcre2-api rouge"><span class="nf">pcre2_pattern_convert()</span></code>. If the conversion is successful, the
result is reflected in the output and then passed to <code class="function pcre2-api rouge"><span class="nf">pcre2_compile()</span></code>. The
normal <code>utf</code> and <code>no_utf_check</code> options, if set, cause the
<code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_UTF</span></code> and <code class="constant pcre2-api rouge"><span class="no">PCRE2_CONVERT_NO_UTF_CHECK</span></code> options to be passed to
<code class="function pcre2-api rouge"><span class="nf">pcre2_pattern_convert()</span></code>.</p>
<p>By default, the conversion function is allowed to allocate a buffer for its
output. However, if the <code>convert_length</code> modifier is set to a value greater
than zero, <code>pcre2test</code> passes a buffer of the given length. This makes it
possible to test the length check.</p>
<p>The <code>convert_glob_escape</code> and <code>convert_glob_separator</code> modifiers can be
used to specify the escape and separator characters for glob processing,
overriding the defaults, which are operating-system dependent.</p></section></section>
<section class="doc-section level-1"><h2 id="_subject_modifiers">Subject modifiers</h2><p>The modifiers that can appear in subject lines and the <code>#subject</code>
command are of two types.</p>
<section class="doc-section level-2"><h3 id="_setting_match_options">Setting match options</h3><p>The following modifiers set options for <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> or
<code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>. See
<a href="./pcre2api.html"><code>pcre2api</code></a>
for a description of their effects.</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>anchored</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ANCHORED</span></code></dd></div><div class="dlist-item"><dt><span><code>copy_matched_subject</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_COPY_MATCHED_SUBJECT</span></code></dd></div><div class="dlist-item"><dt><span><code>endanchored</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_ENDANCHORED</span></code></dd></div><div class="dlist-item"><dt><span><code>dfa_restart</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DFA_RESTART</span></code></dd></div><div class="dlist-item"><dt><span><code>dfa_shortest</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DFA_SHORTEST</span></code></dd></div><div class="dlist-item"><dt><span><code>disable_recurseloop_check</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_DISABLE_RECURSELOOP_CHECK</span></code></dd></div><div class="dlist-item"><dt><span><code>no_jit</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_JIT</span></code></dd></div><div class="dlist-item"><dt><span><code>no_utf_check</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NO_UTF_CHECK</span></code></dd></div><div class="dlist-item"><dt><span><code>notbol</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NOTBOL</span></code></dd></div><div class="dlist-item"><dt><span><code>notempty</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NOTEMPTY</span></code></dd></div><div class="dlist-item"><dt><span><code>notempty_atstart</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NOTEMPTY_ATSTART</span></code></dd></div><div class="dlist-item"><dt><span><code>noteol</code></span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_NOTEOL</span></code></dd></div><div class="dlist-item"><dt><span><code>partial_hard</code> (or <code>ph</code>)</span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_HARD</span></code></dd></div><div class="dlist-item"><dt><span><code>partial_soft</code> (or <code>ps</code>)</span></dt><dd>set <code class="constant pcre2-api rouge"><span class="no">PCRE2_PARTIAL_SOFT</span></code></dd></div></dl>
<p>The partial matching modifiers are provided with abbreviations because they
appear frequently in tests.</p>
<p>If the <code>posix</code> or <code>posix_nosub</code> modifier was present on the pattern,
causing the POSIX wrapper API to be used, the only option-setting modifiers
that have any effect are <code>notbol</code>, <code>notempty</code>, and <code>noteol</code>,
causing <code class="c rouge" data-lang="c"><span class="no">REG_NOTBOL</span></code>, <code class="c rouge" data-lang="c"><span class="no">REG_NOTEMPTY</span></code>, and <code class="c rouge" data-lang="c"><span class="no">REG_NOTEOL</span></code>, respectively, to be passed to
<code class="c rouge" data-lang="c"><span class="nf">regexec</span><span class="p">()</span></code>. The other modifiers are ignored, with a warning message.</p>
<p>There is one additional modifier that can be used with the POSIX wrapper. It is
ignored (with a warning) if used for non-POSIX matching.</p>
<dl class="options compact" style="--tab-width: 4"><div class="dlist-item"><dt><span><code>posix_startend=&lt;n&gt;[:&lt;m&gt;]</code></span></dt><dd>This causes the subject string to be passed to <code class="c rouge" data-lang="c"><span class="nf">regexec</span><span class="p">()</span></code> using the
<code class="c rouge" data-lang="c"><span class="no">REG_STARTEND</span></code> option, which uses offsets to specify which part of the string is
searched. If only one number is given, the end offset is passed as the end of
the subject string. For more detail of <code class="c rouge" data-lang="c"><span class="no">REG_STARTEND</span></code>, see the
<a href="./pcre2posix.html"><code>pcre2posix</code></a>
documentation. If the subject string contains binary zeros (coded as escapes
such as \x{00} because <code>pcre2test</code> does not support actual binary zeros in
its input), you must use <code>posix_startend</code> to specify its length.</dd></div></dl></section>
<section class="doc-section level-2"><h3 id="_setting_match_controls">Setting match controls</h3><p>The following modifiers affect the matching process or request additional
information. Some of them may also be specified on a pattern line (see above),
in which case they apply to every subject line that is matched against that
pattern, but can be overridden by modifiers on the subject.</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>aftertext</code></span></dt><dd>show text after match</dd></div><div class="dlist-item"><dt><span><code>allaftertext</code></span></dt><dd>show text after captures</dd></div><div class="dlist-item"><dt><span><code>allcaptures</code></span></dt><dd>show all captures</dd></div><div class="dlist-item"><dt><span><code>allusedtext</code></span></dt><dd>show all consulted text (non-JIT only)</dd></div><div class="dlist-item"><dt><span><code>allvector</code></span></dt><dd>show the entire ovector</dd></div><div class="dlist-item"><dt><span><code>altglobal</code></span></dt><dd>alternative global matching</dd></div><div class="dlist-item"><dt><span><code>callout_capture</code></span></dt><dd>show captures at callout time</dd></div><div class="dlist-item"><dt><span><code>callout_data=&lt;n&gt;</code></span></dt><dd>set a value to pass via callouts</dd></div><div class="dlist-item"><dt><span><code>callout_error=&lt;n&gt;[:&lt;m&gt;]</code></span></dt><dd>control callout error</dd></div><div class="dlist-item"><dt><span><code>callout_extra</code></span></dt><dd>show extra callout information</dd></div><div class="dlist-item"><dt><span><code>callout_fail=&lt;n&gt;[:&lt;m&gt;]</code></span></dt><dd>control callout failure</dd></div><div class="dlist-item"><dt><span><code>callout_no_where</code></span></dt><dd>do not show position of a callout</dd></div><div class="dlist-item"><dt><span><code>callout_none</code></span></dt><dd>do not supply a callout function</dd></div><div class="dlist-item"><dt><span><code>copy=&lt;number or name&gt;</code></span></dt><dd>copy captured substring</dd></div><div class="dlist-item"><dt><span><code>depth_limit=&lt;n&gt;</code></span></dt><dd>set a depth limit</dd></div><div class="dlist-item"><dt><span><code>dfa</code></span></dt><dd>use <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code></dd></div><div class="dlist-item"><dt><span><code>find_limits</code></span></dt><dd>find heap, match and depth limits</dd></div><div class="dlist-item"><dt><span><code>find_limits_noheap</code></span></dt><dd>find match and depth limits</dd></div><div class="dlist-item"><dt><span><code>get=&lt;number or name&gt;</code></span></dt><dd>extract captured substring</dd></div><div class="dlist-item"><dt><span><code>getall</code></span></dt><dd>extract all captured substrings</dd></div><div class="dlist-item"><dt><span><code>/g global</code></span></dt><dd>global matching</dd></div><div class="dlist-item"><dt><span><code>heapframes_size</code></span></dt><dd>show match data heapframes size</dd></div><div class="dlist-item"><dt><span><code>heap_limit=&lt;n&gt;</code></span></dt><dd>set a limit on heap memory (Kbytes)</dd></div><div class="dlist-item"><dt><span><code>jitstack=&lt;n&gt;</code></span></dt><dd>set size of JIT stack</dd></div><div class="dlist-item"><dt><span><code>mark</code></span></dt><dd>show mark values</dd></div><div class="dlist-item"><dt><span><code>match_limit=&lt;n&gt;</code></span></dt><dd>set a match limit</dd></div><div class="dlist-item"><dt><span><code>memory</code></span></dt><dd>show heap memory usage</dd></div><div class="dlist-item"><dt><span><code>null_context</code></span></dt><dd>match with a NULL context</dd></div><div class="dlist-item"><dt><span><code>null_replacement</code></span></dt><dd>substitute with NULL replacement</dd></div><div class="dlist-item"><dt><span><code>null_subject</code></span></dt><dd>match with NULL subject</dd></div><div class="dlist-item"><dt><span><code>null_substitute_buffer</code></span></dt><dd>substitute with a NULL output buffer</dd></div><div class="dlist-item"><dt><span><code>null_substitute_match_data</code></span></dt><dd>substitute with NULL match data</dd></div><div class="dlist-item"><dt><span><code>offset=&lt;n&gt;</code></span></dt><dd>set starting offset</dd></div><div class="dlist-item"><dt><span><code>offset_limit=&lt;n&gt;</code></span></dt><dd>set offset limit</dd></div><div class="dlist-item"><dt><span><code>ovector=&lt;n&gt;</code></span></dt><dd>set size of output vector</dd></div><div class="dlist-item"><dt><span><code>recursion_limit=&lt;n&gt;</code></span></dt><dd>obsolete synonym for depth_limit</dd></div><div class="dlist-item"><dt><span><code>replace=&lt;str&gt;</code></span></dt><dd>specify a replacement string</dd></div><div class="dlist-item"><dt><span><code>startchar</code></span></dt><dd>show startchar when relevant</dd></div><div class="dlist-item"><dt><span><code>startoffset=&lt;n&gt;</code></span></dt><dd>same as offset=&lt;n&gt;</dd></div><div class="dlist-item"><dt><span><code>substitute_callout</code></span></dt><dd>use substitution callouts</dd></div><div class="dlist-item"><dt><span><code>substitute_case_callout</code></span></dt><dd>use substitution case callouts</dd></div><div class="dlist-item"><dt><span><code>substitute_extended</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_EXTENDED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_literal</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_LITERAL</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_matched</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_MATCHED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_overflow_length</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_OVERFLOW_LENGTH</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_replacement_only</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_REPLACEMENT_ONLY</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_skip=&lt;n&gt;</code></span></dt><dd>skip substitution number n</dd></div><div class="dlist-item"><dt><span><code>substitute_stop=&lt;n&gt;</code></span></dt><dd>skip substitution number n and greater</dd></div><div class="dlist-item"><dt><span><code>substitute_subject=&lt;str&gt;</code></span></dt><dd>specify a different subject for substitution</dd></div><div class="dlist-item"><dt><span><code>substitute_unknown_unset</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNKNOWN_UNSET</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_unset_empty</code></span></dt><dd>use <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNSET_EMPTY</span></code></dd></div><div class="dlist-item"><dt><span><code>zero_terminate</code></span></dt><dd>pass the subject as zero-terminated</dd></div></dl>
<p>The effects of these modifiers are described in the following sections. When
matching via the POSIX wrapper API, the <code>aftertext</code>, <code>allaftertext</code>,
and <code>ovector</code> subject modifiers work as described below. All other
modifiers are either ignored, with a warning message, or cause an error.</p></section>
<section class="doc-section level-2"><h3 id="_showing_more_text">Showing more text</h3><p>The <code>aftertext</code> modifier requests that as well as outputting the part of
the subject string that matched the entire pattern, <code>pcre2test</code> should in
addition output the remainder of the subject string. This is useful for tests
where the subject contains multiple copies of the same substring. The
<code>allaftertext</code> modifier requests the same action for captured substrings as
well as the main matched substring. In each case the remainder is output on the
following line with a plus character following the capture number.</p>
<p>The <code>allusedtext</code> modifier requests that all the text that was consulted
during a successful pattern match by the interpreter should be shown, for both
full and partial matches. This feature is not supported for JIT matching, and
if requested with JIT it is ignored (with a warning message). Setting this
modifier affects the output if there is a lookbehind at the start of a match,
or, for a complete match, a lookahead at the end, or if <code class="regex rouge"><span class="pcre2-semantic">\K</span></code> is used in the
pattern. Characters that precede or follow the start and end of the actual
match are indicated in the output by '&lt;' or '&gt;' characters underneath them.
Here is an example:</p>
<div class="literal-block"><pre> re&gt; /(?&lt;=pqr)abc(?=xyz)/
data&gt; 123pqrabcxyz456\=allusedtext
0: pqrabcxyz
&lt;&lt;&lt; &gt;&gt;&gt;
data&gt; 123pqrabcxy\=ph,allusedtext
Partial match: pqrabcxy
&lt;&lt;&lt;</pre></div>
<p>The first, complete match shows that the matched string is "abc", with the
preceding and following strings "pqr" and "xyz" having been consulted during
the match (when processing the assertions). The partial match can indicate only
the preceding string.</p>
<p>The <code>startchar</code> modifier requests that the starting character for the match
be indicated, if it is different to the start of the matched string. The only
time when this occurs is when <code class="regex rouge"><span class="pcre2-semantic">\K</span></code> has been processed as part of the match. In
this situation, the output for the matched string is displayed from the
starting character instead of from the match point, with circumflex characters
under the earlier characters. For example:</p>
<div class="literal-block"><pre> re&gt; /abc\Kxyz/
data&gt; abcxyz\=startchar
0: abcxyz
^^^</pre></div>
<p>Unlike <code>allusedtext</code>, the <code>startchar</code> modifier can be used with JIT.
However, these two modifiers are mutually exclusive.</p></section>
<section class="doc-section level-2"><h3 id="_showing_the_value_of_all_capture_groups">Showing the value of all capture groups</h3><p>The <code>allcaptures</code> 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 <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>). Groups that did not take part in the match
are output as "&lt;unset&gt;". This modifier is not relevant for DFA matching (which
does no capturing) and does not apply when <code>replace</code> is specified; it is
ignored, with a warning message, if present.</p></section>
<section class="doc-section level-2"><h3 id="_showing_the_entire_ovector_for_all_outcomes">Showing the entire ovector, for all outcomes</h3><p>The <code>allvector</code> modifier requests that the entire ovector be shown,
whatever the outcome of the match. Compare <code>allcaptures</code>, which shows only
up to the maximum number of capture groups for the pattern, and then only for a
successful complete non-DFA match. This modifier, which acts after any match
result, and also for DFA matching, provides a means of checking that there are
no unexpected modifications to ovector fields. Before each match attempt, the
ovector is filled with a special value, and if this is found in both elements
of a capturing pair, "&lt;unchanged&gt;" is output. After a successful match, this
applies to all groups after the maximum capture group for the pattern. In other
cases it applies to the entire ovector. After a partial match, the first two
elements are the only ones that should be set. After a DFA match, the amount of
ovector that is used depends on the number of matches that were found.</p></section>
<section class="doc-section level-2"><h3 id="_testing_pattern_callouts">Testing pattern callouts</h3><p>A callout function is supplied when <code>pcre2test</code> calls the library matching
functions, unless <code>callout_none</code> is specified. Its behaviour can be
controlled by various modifiers listed above whose names begin with
<code>callout_</code>. Details are given in the section <a href="#callouts">Callouts</a>
below.
Testing callouts from <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code> is described separately in
"Testing the substitution function"
below.</p></section>
<section class="doc-section level-2"><h3 id="_finding_all_matches_in_a_string">Finding all matches in a string</h3><p>Searching for all possible matches within a subject can be requested by the
<code>global</code> or <code>altglobal</code> modifier. After finding a match, the matching
function is called again to search the remainder of the subject. The difference
between <code>global</code> and <code>altglobal</code> is that the former uses the
<code class="parameter pcre2-api rouge"><span class="nv">start_offset</span></code> argument to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> or <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>
to start searching at a new point within the entire string (which is what Perl
does), whereas the latter passes over a shortened subject. This makes a
difference to the matching process if the pattern begins with a lookbehind
assertion (including <code class="regex rouge"><span class="pcre2-semantic">\b</span></code> or <code class="regex rouge"><span class="pcre2-semantic">\B</span></code>).</p>
<p>If an empty string is matched, the next match is done with the
<code class="constant pcre2-api rouge"><span class="no">PCRE2_NOTEMPTY_ATSTART</span></code> flag set, in order to search for another, non-empty,
match at the same point in the subject. This imitates the way Perl handles such
cases when using the <code class="regex rouge"><span class="pcre2-semantic">/g</span></code> modifier or the <code>split()</code> function.</p></section>
<section class="doc-section level-2"><h3 id="_testing_substring_extraction_functions">Testing substring extraction functions</h3><p>The <code>copy</code> and <code>get</code> modifiers can be used to test the
<code class="function pcre2-api rouge"><span class="nf">pcre2_substring_copy_xxx()</span></code> and <code class="function pcre2-api rouge"><span class="nf">pcre2_substring_get_xxx()</span></code> functions.
They can be given more than once, and each can specify a capture group name or
number, for example:</p>
<div class="literal-block"><pre> abcd\=copy=1,copy=3,get=G1</pre></div>
<p>If the <code>#subject</code> command is used to set default copy and/or get lists,
these can be unset by specifying a negative number to cancel all numbered
groups and an empty name to cancel all named groups.</p>
<p>The <code>getall</code> modifier tests <code class="function pcre2-api rouge"><span class="nf">pcre2_substring_list_get()</span></code>, which
extracts all captured substrings.</p>
<p>If the subject line is successfully matched, the substrings extracted by the
convenience functions are output with C, G, or L after the string number
instead of a colon. This is in addition to the normal full list. The string
length (that is, the return from the extraction function) is given in
parentheses after each substring, followed by the name when the extraction was
by name.</p></section>
<section class="doc-section level-2"><h3 id="_testing_the_substitution_function">Testing the substitution function</h3><p>If the <code>replace</code> modifier is set, the <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code> function is
called instead of one of the matching functions (or after one call of
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> in the case of <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_MATCHED</span></code>). Note that
replacement strings cannot contain commas, because a comma signifies the end of
a modifier. This is not thought to be an issue in a test program.</p>
<p>Specifying a completely empty replacement string disables this modifier.
However, it is possible to specify an empty replacement by providing a buffer
length, as described below, for an otherwise empty replacement.</p>
<p>Unlike subject strings, <code>pcre2test</code> does not process replacement strings
for escape sequences. In UTF mode, a replacement string is checked to see if it
is a valid UTF-8 string. If so, it is correctly converted to a UTF string of
the appropriate code unit width. If it is not a valid UTF-8 string, the
individual code units are copied directly. This provides a means of passing an
invalid UTF-8 string for testing purposes.</p>
<p>The following modifiers set options (in additional to the normal match options)
for <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code>:</p>
<dl class="options compact" style="--tab-width: 14"><div class="dlist-item"><dt><span><code>global</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_GLOBAL</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_extended</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_EXTENDED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_literal</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_LITERAL</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_matched</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_MATCHED</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_overflow_length</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_OVERFLOW_LENGTH</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_replacement_only</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_REPLACEMENT_ONLY</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_unknown_unset</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNKNOWN_UNSET</span></code></dd></div><div class="dlist-item"><dt><span><code>substitute_unset_empty</code></span></dt><dd><code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_UNSET_EMPTY</span></code></dd></div></dl>
<p>See the
<a href="./pcre2api.html"><code>pcre2api</code></a>
documentation for details of these options.</p>
<p>After a successful substitution, the modified string is output, preceded by the
number of replacements. This may be zero if there were no matches. Here is a
simple example of a substitution test:</p>
<div class="literal-block"><pre>/abc/replace=xxx
=abc=abc=
1: =xxx=abc=
=abc=abc=\=global
2: =xxx=xxx=</pre></div>
<p>Subject and replacement strings should be kept relatively short (fewer than 256
characters) for substitution tests, as fixed-size buffers are used. To make it
easy to test for buffer overflow, if the replacement string starts with a
number in square brackets, that number is passed to <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code> as
the size of the output buffer, with the replacement string starting at the next
character. Here is an example that tests the edge case:</p>
<div class="literal-block"><pre>/abc/
123abc123\=replace=[10]XYZ
1: 123XYZ123
123abc123\=replace=[9]XYZ
Failed: error -48: no more memory</pre></div>
<p>The default action of <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code> is to return
<code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_NOMEMORY</span></code> when the output buffer is too small. However, if the
<code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_OVERFLOW_LENGTH</span></code> option is set (by using the
<code>substitute_overflow_length</code> modifier), <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code> continues
to go through the motions of matching and substituting (but not doing any
callouts), in order to compute the size of buffer that is required. When this
happens, <code>pcre2test</code> shows the required buffer length (which includes space
for the trailing zero) as part of the error message. For example:</p>
<div class="literal-block"><pre>/abc/substitute_overflow_length
123abc123\=replace=[9]XYZ
Failed: error -48: no more memory: 10 code units are needed</pre></div>
<p>A replacement string is ignored with POSIX and DFA matching. Specifying partial
matching provokes an error return ("bad option value") from
<code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code>.</p>
<p>The <code>substitute_subject</code> modifier may be used to test the use of the PCRE2
API, in which a client calls <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> followed by <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code>
with <code class="constant pcre2-api rouge"><span class="no">PCRE2_SUBSTITUTE_MATCHED</span></code>, but the client performs an unexpected and
unsupported modification of the subject buffer in-place, in between the match
and substitution.</p></section>
<section class="doc-section level-2"><h3 id="_testing_substitute_callouts">Testing substitute callouts</h3><p>If the <code>substitute_callout</code> modifier is set, a substitution callout
function is set up. The <code>null_context</code> modifier must not be set, because
the address of the callout function is passed in a match context. When the
callout function is called (after each substitution), details of the input
and output strings are output. For example:</p>
<div class="literal-block"><pre>/abc/g,replace=&lt;$0&gt;,substitute_callout
abcdefabcpqr
1(1) Old 0 3 "abc" New 0 5 "&lt;abc&gt;"
2(1) Old 6 9 "abc" New 8 13 "&lt;abc&gt;"
2: &lt;abc&gt;def&lt;abc&gt;pqr</pre></div>
<p>The first number on each callout line is the count of matches. The
parenthesized number is the number of pairs that are set in the ovector (that
is, one more than the number of capturing groups that were set). Then are
listed the offsets of the old substring, its contents, and the same for the
replacement.</p>
<p>By default, the substitution callout function returns zero, which accepts the
replacement and causes matching to continue if /g was used. Two further
modifiers can be used to test other return values. If <code>substitute_skip</code> is
set to a value greater than zero the callout function returns <code class="c rouge" data-lang="c"><span class="o">+</span><span class="mi">1</span></code> for the match
of that number, and similarly <code>substitute_stop</code> returns -1. These cause the
replacement to be rejected, and -1 causes no further matching to take place. If
either of them are set, <code>substitute_callout</code> is assumed. For example:</p>
<div class="literal-block"><pre>/abc/g,replace=&lt;$0&gt;,substitute_skip=1
abcdefabcpqr
1(1) Old 0 3 "abc" New 0 5 "&lt;abc&gt; SKIPPED"
2(1) Old 6 9 "abc" New 6 11 "&lt;abc&gt;"
2: abcdef&lt;abc&gt;pqr
abcdefabcpqr\=substitute_stop=1
1(1) Old 0 3 "abc" New 0 5 "&lt;abc&gt; STOPPED"
1: abcdefabcpqr</pre></div>
<p>If both are set for the same number, stop takes precedence. Only a single skip
or stop is supported, which is sufficient for testing that the feature works.</p></section>
<section class="doc-section level-2"><h3 id="_testing_substitute_case_callouts">Testing substitute case callouts</h3><p>If the <code>substitute_case_callout</code> modifier is set, a substitution
case callout function is set up. The callout function is called for each
substituted chunk which is to be case-transformed.</p>
<p>The callout function passed is a fixed function with implementation for certain
behaviours: inputs which shrink when case-transformed; inputs which grow; inputs
with distinct upper/lower/titlecase forms. The characters which are not
special-cased for testing purposes are left unmodified, as if they are caseless
characters.</p></section>
<section class="doc-section level-2"><h3 id="_setting_the_jit_stack_size">Setting the JIT stack size</h3><p>The <code>jitstack</code> modifier provides a way of setting the maximum stack size
that is used by the just-in-time optimization code. It is ignored if JIT
optimization is not being used. The value is a number of kibibytes (units of
1024 bytes). Setting zero reverts to the default of 32KiB. Providing a stack
that is larger than the default is necessary only for very complicated
patterns. If <code>jitstack</code> is set non-zero on a subject line it overrides any
value that was set on the pattern.</p></section>
<section class="doc-section level-2"><h3 id="_setting_heap_match_and_depth_limits">Setting heap, match, and depth limits</h3><p>The <code>heap_limit</code>, <code>match_limit</code>, and <code>depth_limit</code> modifiers set
the appropriate limits in the match context. These values are ignored when the
<code>find_limits</code> or <code>find_limits_noheap</code> modifier is specified.</p></section>
<section class="doc-section level-2"><h3 id="_finding_minimum_limits">Finding minimum limits</h3><p>If the <code>find_limits</code> modifier is present on a subject line, <code>pcre2test</code>
calls the relevant matching function several times, setting different values in
the match context via <code class="function pcre2-api rouge"><span class="nf">pcre2_set_heap_limit()</span></code>,
<code class="function pcre2-api rouge"><span class="nf">pcre2_set_match_limit()</span></code>, or <code class="function pcre2-api rouge"><span class="nf">pcre2_set_depth_limit()</span></code> until it finds
the smallest value for each parameter that allows the match to complete without
a "limit exceeded" error. The match itself may succeed or fail. An alternative
modifier, <code>find_limits_noheap</code>, omits the heap limit. This is used in the
standard tests, because the minimum heap limit varies between systems. If JIT
is being used, only the match limit is relevant, and the other two are
automatically omitted.</p>
<p>When using this modifier, the pattern should not contain any limit settings
such as (<code class="regex rouge"><span class="pcre2-semantic">*LIMIT_MATCH=...</span></code>) within it. If such a setting is present and is
lower than the minimum matching value, the minimum value cannot be found
because <code class="function pcre2-api rouge"><span class="nf">pcre2_set_match_limit()</span></code> etc. are only able to reduce the value of
an in-pattern limit; they cannot increase it.</p>
<p>For non-DFA matching, the minimum <code>depth_limit</code> number is a measure of how
much nested backtracking happens (that is, how deeply the pattern’s tree is
In the case of DFA matching, <code>depth_limit</code> controls the depth of
recursive calls of the internal function that is used for handling pattern
recursion, lookaround assertions, and atomic groups.</p>
<p>For non-DFA matching, the <code>match_limit</code> number is a measure of the amount
of backtracking that takes place, and learning the minimum value can be
instructive. For most simple matches, the number is quite small, but for
patterns with very large numbers of matching possibilities, it can become large
very quickly with increasing length of subject string. In the case of DFA
matching, <code>match_limit</code> controls the total number of calls, both recursive
and non-recursive, to the internal matching function, thus controlling the
overall amount of computing resource that is used.</p>
<p>For both kinds of matching, the <code>heap_limit</code> number, which is in kibibytes
(units of 1024 bytes), limits the amount of heap memory used for matching.</p></section>
<section class="doc-section level-2"><h3 id="_showing_mark_names">Showing MARK names</h3><p>The <code>mark</code> modifier causes the names from backtracking control verbs that
are returned from calls to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> to be displayed. If a mark is
returned for a match, non-match, or partial match, <code>pcre2test</code> shows it.
For a match, it is on a line by itself, tagged with <code>MK:</code>. Otherwise, it
is added to the non-match message.</p></section>
<section class="doc-section level-2"><h3 id="_showing_memory_usage">Showing memory usage</h3><p>The <code>memory</code> modifier causes <code>pcre2test</code> to log the sizes of all heap
memory allocation and freeing calls that occur during a call to
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> or <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>. In the latter case, heap memory
is used only when a match requires more internal workspace that the default
allocation on the stack, so in many cases there will be no output. No heap
memory is allocated during matching with JIT. For this modifier to work, the
<code>null_context</code> modifier must not be set on both the pattern and the
subject, though it can be set on one or the other.</p></section>
<section class="doc-section level-2"><h3 id="_showing_the_heap_frame_overall_vector_size">Showing the heap frame overall vector size</h3><p>The <code>heapframes_size</code> modifier is relevant for matches using
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> without JIT. After a match has run (whether successful or
not) the size, in bytes, of the allocated heap frames vector that is left
attached to the match data block is shown. If the matching action involved
several calls to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> (for example, global matching or for
timing) only the final value is shown.</p>
<p>This modifier is ignored, with a warning, for POSIX or DFA matching. JIT
matching does not use the heap frames vector, so the size is always zero,
unless there was a previous non-JIT match. Note that specifing a size of zero
for the output vector (see below) causes <code>pcre2test</code> to free its match data
block (and associated heap frames vector) and allocate a new one.</p></section>
<section class="doc-section level-2"><h3 id="_setting_a_starting_offset">Setting a starting offset</h3><p>The <code>offset</code> modifier sets an offset in the subject string at which
matching starts. Its value is a number of code units, not characters.</p></section>
<section class="doc-section level-2"><h3 id="_setting_an_offset_limit">Setting an offset limit</h3><p>The <code>offset_limit</code> modifier sets a limit for unanchored matches. If a match
cannot be found starting at or before this offset in the subject, a "no match"
return is given. The data value is a number of code units, not characters. When
this modifier is used, the <code>use_offset_limit</code> modifier must have been set
for the pattern; if not, an error is generated.</p></section>
<section class="doc-section level-2"><h3 id="_setting_the_size_of_the_output_vector">Setting the size of the output vector</h3><p>The <code>ovector</code> modifier applies only to the subject line in which it
appears, though of course it can also be used to set a default in a
<code>#subject</code> command. It specifies the number of pairs of offsets that are
available for storing matching information. The default is 15.</p>
<p>A value of zero is useful when testing the POSIX API because it causes
<code class="c rouge" data-lang="c"><span class="nf">regexec</span><span class="p">()</span></code> to be called with a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> capture vector. When not testing the
POSIX API, a value of zero is used to cause
<code class="function pcre2-api rouge"><span class="nf">pcre2_match_data_create_from_pattern()</span></code> to be called, in order to create a
new match block of exactly the right size for the pattern. (It is not possible
to create a match block with a zero-length ovector; there is always at least
one pair of offsets.) The old match data block is freed.</p></section>
<section class="doc-section level-2"><h3 id="_passing_the_subject_as_zero_terminated">Passing the subject as zero-terminated</h3><p>By default, the subject string is passed to a native API matching function with
its correct length. In order to test the facility for passing a zero-terminated
string, the <code>zero_terminate</code> modifier is provided. It causes the length to
be passed as <code class="constant pcre2-api rouge"><span class="no">PCRE2_ZERO_TERMINATED</span></code>. When matching via the POSIX interface,
this modifier is ignored, with a warning.</p>
<p>When testing <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code>, this modifier also has the effect of
passing the replacement string as zero-terminated.</p></section>
<section class="doc-section level-2"><h3 id="_passing_a_null_context_subject_replacement_or_substitute_buffer">Passing a <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> context, subject, replacement, or substitute buffer</h3><p>Normally, <code>pcre2test</code> passes a context block to <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>,
<code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>, <code class="function pcre2-api rouge"><span class="nf">pcre2_jit_match()</span></code> or <code class="function pcre2-api rouge"><span class="nf">pcre2_substitute()</span></code>.
If the <code>null_context</code> modifier is set, however, <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code> is passed. This is for
testing that the matching and substitution functions behave correctly in this
case (they use default values). This modifier cannot be used with the
<code>find_limits</code>, <code>find_limits_noheap</code>, or <code>substitute_callout</code>
modifiers.</p>
<p>Similarly, for testing purposes, if the <code>null_subject</code>,
or <code>null_replacement</code>, or <code>null_substitute_buffer</code> modifiers are set, then the
subject, or replacement string, or substitute output buffer pointers are passed
as <code class="constant pcre2-api rouge"><span class="kc">NULL</span></code>, respectively, to the relevant functions. For <code>null_substitute_buffer</code>,
the paired argument for the passed-in buffer length is set by starting the
replacement string with "[NUM]" as described in "Testing the substitution
function" above.</p></section></section>
<section class="doc-section level-1"><h2 id="_the_alternative_matching_function">The alternative matching function</h2><p>By default, <code>pcre2test</code> uses the standard PCRE2 matching function,
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> to match each subject line. PCRE2 also supports an
alternative matching function, <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>, which operates in a
different way, and has some restrictions. The differences between the two
functions are described in the
<a href="./pcre2matching.html"><code>pcre2matching</code></a>
documentation.</p>
<p>If the <code>dfa</code> modifier is set, the alternative matching function is used.
This function finds all possible matches at a given point in the subject. If,
however, the <code>dfa_shortest</code> modifier is set, processing stops after the
first match is found. This is always the shortest possible match.</p></section>
<section class="doc-section level-1"><h2 id="_default_output_from_pcre2test">Default output from pcre2test</h2><p>This section describes the output when the normal matching function,
<code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code>, is being used.</p>
<p>When a match succeeds, <code>pcre2test</code> outputs the list of captured substrings,
starting with number 0 for the string that matched the whole pattern.
Otherwise, it outputs "No match" when the return is <code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_NOMATCH</span></code>, or
"Partial match:" followed by the partially matching substring when the
return is <code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_PARTIAL</span></code>. (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, <code class="regex rouge"><span class="pcre2-semantic">\K</span></code>, <code class="regex rouge"><span class="pcre2-semantic">\b</span></code>,
or <code class="regex rouge"><span class="pcre2-semantic">\B</span></code> was involved.)</p>
<p>For any other return, <code>pcre2test</code> outputs the PCRE2 negative error number
and a short descriptive phrase. If the error is a failed UTF string check, the
code unit offset of the start of the failing character is also output. Here is
an example of an interactive <code>pcre2test</code> run.</p>
<div class="literal-block"><pre>$ pcre2test
PCRE2 version 10.22 2016-07-29</pre></div>
<div class="literal-block"><pre> re&gt; /^abc(\d+)/
data&gt; abc123
0: abc123
1: 123
data&gt; xyz
No match</pre></div>
<p>Unset capturing substrings that are not followed by one that is set are not
shown by <code>pcre2test</code> unless the <code>allcaptures</code> modifier is specified. In
the following example, there are two capturing substrings, but when the first
data line is matched, the second, unset substring is not shown. An "internal"
unset substring is shown as "&lt;unset&gt;", as for the second data line.</p>
<div class="literal-block"><pre> re&gt; /(a)|(b)/
data&gt; a
0: a
1: a
data&gt; b
0: b
1: &lt;unset&gt;
2: b</pre></div>
<p>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 <code>\x{<em>hh</em>...}</code> escapes. See below for the definition of non-printing
characters. If the <code>aftertext</code> modifier is set, the output for substring 0
is followed by the rest of the subject string, identified by "0+" like this:</p>
<div class="literal-block"><pre> re&gt; /cat/aftertext
data&gt; cataract
0: cat
0+ aract</pre></div>
<p>If global matching is requested, the results of successive matching attempts
are output in sequence, like this:</p>
<div class="literal-block"><pre> re&gt; /\Bi(\w\w)/g
data&gt; Mississippi
0: iss
1: ss
0: iss
1: ss
0: ipp
1: pp</pre></div>
<p>"No match" is output only if the first match attempt fails. Here is an example
of a failure message (the offset 4 that is specified by the <code>offset</code>
modifier is past the end of the subject string):</p>
<div class="literal-block"><pre> re&gt; /xyz/
data&gt; xyz\=offset=4
Error -24 (bad offset value)</pre></div>
<p>Note that whereas patterns can be continued over several lines (a plain "&gt;"
prompt is used for continuations), subject lines may not. However newlines can
be included in a subject by means of the \n escape (or \r, \r\n, etc.,
depending on the newline sequence setting).</p></section>
<section class="doc-section level-1"><h2 id="_output_from_the_alternative_matching_function">Output from the alternative matching function</h2><p>When the alternative matching function, <code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code>, is used, the
output consists of a list of all the matches that start at the first point in
the subject where there is at least one match. For example:</p>
<div class="literal-block"><pre> re&gt; /(tang|tangerine|tan)/
data&gt; yellow tangerine\=dfa
0: tangerine
1: tang
2: tan</pre></div>
<p>Using the normal matching function on this data finds only "tang". The
longest matching string is always given first (and numbered zero). After a
<code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_PARTIAL</span></code> 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, <code class="regex rouge"><span class="pcre2-semantic">\b</span></code>, or <code class="regex rouge"><span class="pcre2-semantic">\B</span></code> was involved. (<code class="regex rouge"><span class="pcre2-semantic">\K</span></code> is not
supported for DFA matching.)</p>
<p>If global matching is requested, the search for further matches resumes
at the end of the longest match. For example:</p>
<div class="literal-block"><pre> re&gt; /(tang|tangerine|tan)/g
data&gt; yellow tangerine and tangy sultana\=dfa
0: tangerine
1: tang
2: tan
0: tang
1: tan
0: tan</pre></div>
<p>The alternative matching function does not support substring capture, so the
modifiers that are concerned with captured substrings are not relevant.</p></section>
<section class="doc-section level-1"><h2 id="_restarting_after_a_partial_match">Restarting after a partial match</h2><p>When the alternative matching function has given the <code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_PARTIAL</span></code>
return, indicating that the subject partially matched the pattern, you can
restart the match with additional subject data by means of the
<code>dfa_restart</code> modifier. For example:</p>
<div class="literal-block"><pre> re&gt; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
data&gt; 23ja\=ps,dfa
Partial match: 23ja
data&gt; n05\=dfa,dfa_restart
0: n05</pre></div>
<p>For further information about partial matching, see the
<a href="./pcre2partial.html"><code>pcre2partial</code></a>
documentation.</p></section>
<section class="doc-section level-1"><h2 id="callouts">Callouts</h2><p>If the pattern contains any callout requests, <code>pcre2test</code>'s callout
function is called during matching unless <code>callout_none</code> is specified. This
works with both matching functions, and with JIT, though there are some
differences in behaviour. The output for callouts with numerical arguments and
those with string arguments is slightly different.</p>
<section class="doc-section level-2"><h3 id="_callouts_with_numerical_arguments">Callouts with numerical arguments</h3><p>By default, the callout function displays the callout number, the start and
current positions in the subject text at the callout time, and the next pattern
item to be tested. For example:</p>
<div class="literal-block"><pre>---&gt;pqrabcdef
0 ^ ^ \d</pre></div>
<p>This output indicates that callout number 0 occurred for a match attempt
starting at the fourth character of the subject string, when the pointer was at
the seventh character, and when the next pattern item was <code class="regex rouge"><span class="pcre2-semantic">\d</span></code>. Just
one circumflex is output if the start and current positions are the same, or if
the current position precedes the start position, which can happen if the
callout is in a lookbehind assertion.</p>
<p>Callouts numbered 255 are assumed to be automatic callouts, inserted as a
result of the <code>auto_callout</code> pattern modifier. In this case, instead of
showing the callout number, the offset in the pattern, preceded by a plus, is
output. For example:</p>
<div class="literal-block"><pre> re&gt; /\d?[A-E]\*/auto_callout
data&gt; E*
---&gt;E*
+0 ^ \d?
+3 ^ [A-E]
+8 ^^ \*
+10 ^ ^
0: E*</pre></div>
<p>If a pattern contains <code class="regex rouge"><span class="pcre2-semantic">(*MARK)</span></code> items, an additional line is output whenever
a change of latest mark is passed to the callout function. For example:</p>
<div class="literal-block"><pre> re&gt; /a(*MARK:X)bc/auto_callout
data&gt; abc
---&gt;abc
+0 ^ a
+1 ^^ (*MARK:X)
+10 ^^ b
Latest Mark: X
+11 ^ ^ c
+12 ^ ^
0: abc</pre></div>
<p>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 "&lt;unset&gt;" is output.</p></section>
<section class="doc-section level-2"><h3 id="_callouts_with_string_arguments">Callouts with string arguments</h3><p>The output for a callout with a string argument is similar, except that instead
of outputting a callout number before the position indicators, the callout
string and its offset in the pattern string are output before the reflection of
the subject string, and the subject string is reflected for each callout. For
example:</p>
<div class="literal-block"><pre> re&gt; /^ab(?C’first')cd(?C"second")ef/
data&gt; abcdefg
Callout (7): 'first'
---&gt;abcdefg
^ ^ c
Callout (20): "second"
---&gt;abcdefg
^ ^ e
0: abcdef</pre></div></section>
<section class="doc-section level-2"><h3 id="_callout_modifiers">Callout modifiers</h3><p>The callout function in <code>pcre2test</code> returns zero (carry on matching) by
default, but you can use a <code>callout_fail</code> modifier in a subject line to
change this and other parameters of the callout (see below).</p>
<p>If the <code>callout_capture</code> modifier is set, the current captured groups are
output when a callout occurs. This is useful only for non-DFA matching, as
<code class="function pcre2-api rouge"><span class="nf">pcre2_dfa_match()</span></code> does not support capturing, so no captures are ever
shown.</p>
<p>The normal callout output, showing the callout number or pattern offset (as
described above) is suppressed if the <code>callout_no_where</code> modifier is set.</p>
<p>When using the interpretive matching function <code class="function pcre2-api rouge"><span class="nf">pcre2_match()</span></code> without JIT,
setting the <code>callout_extra</code> modifier causes additional output from
<code>pcre2test</code>'s callout function to be generated. For the first callout in a
match attempt at a new starting position in the subject, "New match attempt" is
output. If there has been a backtrack since the last callout (or start of
matching if this is the first callout), "Backtrack" is output, followed by "No
other matching paths" if the backtrack ended the previous match attempt. For
example:</p>
<div class="literal-block"><pre> re&gt; /(a+)b/auto_callout,no_start_optimize,no_auto_possess
data&gt; aac\=callout_extra
New match attempt
---&gt;aac
+0 ^ (
+1 ^ a+
+3 ^ ^ )
+4 ^ ^ b
Backtrack
---&gt;aac
+3 ^^ )
+4 ^^ b
Backtrack
No other matching paths
New match attempt
---&gt;aac
+0 ^ (
+1 ^ a+
+3 ^^ )
+4 ^^ b
Backtrack
No other matching paths
New match attempt
---&gt;aac
+0 ^ (
+1 ^ a+
Backtrack
No other matching paths
New match attempt
---&gt;aac
+0 ^ (
+1 ^ a+
No match</pre></div>
<p>Notice that various optimizations must be turned off if you want all possible
matching paths to be scanned. If <code>no_start_optimize</code> is not used, there is
an immediate "no match", without any callouts, because the starting
optimization fails to find "b" in the subject, which it knows must be present
for any match. If <code>no_auto_possess</code> is not used, the <code class="regex rouge"><span class="pcre2-semantic">a+</span></code> item is turned
into <code class="regex rouge"><span class="pcre2-semantic">a++</span></code>, which reduces the number of backtracks.</p>
<p>The <code>callout_extra</code> modifier has no effect if used with the DFA matching
function, or with JIT.</p></section>
<section class="doc-section level-2"><h3 id="_return_values_from_callouts">Return values from callouts</h3><p>The default return from the callout function is zero, which allows matching to
continue. The <code>callout_fail</code> modifier can be given one or two numbers. If
there is only one number, 1 is returned instead of 0 (causing matching to
backtrack) when a callout of that number is reached. If two numbers (&lt;n&gt;:&lt;m&gt;)
are given, 1 is returned when callout &lt;n&gt; is reached and there have been at
least &lt;m&gt; callouts. The <code>callout_error</code> modifier is similar, except that
<code class="constant pcre2-api rouge"><span class="no">PCRE2_ERROR_CALLOUT</span></code> is returned, causing the entire matching process to be
aborted. If both these modifiers are set for the same callout number,
<code>callout_error</code> takes precedence. Note that callouts with string arguments
are always given the number zero.</p>
<p>The <code>callout_data</code> modifier can be given an unsigned or a negative number.
This is set as the "user data" that is passed to the matching function, and
passed back when the callout function is invoked. Any value other than zero is
used as a return from <code>pcre2test</code>'s callout function.</p>
<p>Inserting callouts can be helpful when using <code>pcre2test</code> to check
complicated regular expressions. For further information about callouts, see
the
<a href="./pcre2callout.html"><code>pcre2callout</code></a>
documentation.</p></section></section>
<section class="doc-section level-1"><h2 id="_non_printing_characters">Non-printing characters</h2><p>When <code>pcre2test</code> is outputting text in the compiled version of a pattern,
bytes other than 32-126 are always treated as non-printing characters and are
therefore shown as hex escapes.</p>
<p>When <code>pcre2test</code> 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 <code>locale</code> modifier). In this case, the
<code class="c rouge" data-lang="c"><span class="nf">isprint</span><span class="p">()</span></code> function is used to distinguish printing and non-printing
characters.</p></section>
<section class="doc-section level-1"><h2 id="saving-restoring-patterns">Saving and restoring compiled patterns</h2><p>It is possible to save compiled patterns on disc or elsewhere, and reload them
later, subject to a number of restrictions. JIT data cannot be saved. The host
on which the patterns are reloaded must be running the same version of PCRE2,
with the same code unit width, and must also have the same endianness, pointer
width and <code class="type pcre2-api rouge"><span class="kt">PCRE2_SIZE</span></code> type. Before compiled patterns can be saved they must be
serialized, that is, converted to a stream of bytes. A single byte stream may
contain any number of compiled patterns, but they must all use the same
character tables. A single copy of the tables is included in the byte stream
(its size is 1,088 bytes).</p>
<p>The functions whose names begin with <code class="c rouge" data-lang="c"><span class="kt">pcre2_serialize_</span></code> are used
for serializing and de-serializing. They are described in the
<a href="./pcre2serialize.html"><code>pcre2serialize</code></a>
documentation. In this section we describe the features of <code>pcre2test</code> that
can be used to test these functions.</p>
<p>Note that "serialization" in PCRE2 does not convert compiled patterns to an
abstract format like Java or .NET. It just makes a reloadable byte code stream.
Hence the restrictions on reloading mentioned above.</p>
<p>In <code>pcre2test</code>, when a pattern with <code>push</code> modifier is successfully
compiled, it is pushed onto a stack of compiled patterns, and <code>pcre2test</code>
expects the next line to contain a new pattern (or command) instead of a
subject line. By contrast, the <code>pushcopy</code> modifier causes a copy of the
compiled pattern to be stacked, leaving the original available for immediate
matching. By using <code>push</code> and/or <code>pushcopy</code>, a number of patterns can
be compiled and retained. These modifiers are incompatible with <code>posix</code>,
and control modifiers that act at match time are ignored (with a message) for
the stacked patterns. The <code>jitverify</code> modifier applies only at compile
time.</p>
<p>The command</p>
<div class="literal-block"><pre>#save &lt;filename&gt;</pre></div>
<p>causes all the stacked patterns to be serialized and the result written to the
named file. Afterwards, all the stacked patterns are freed. The command</p>
<div class="literal-block"><pre>#load &lt;filename&gt;</pre></div>
<p>reads the data in the file, and then arranges for it to be de-serialized, with
the resulting compiled patterns added to the pattern stack. The pattern on the
top of the stack can be retrieved by the #pop command, which must be followed
by lines of subjects that are to be matched with the pattern, terminated as
usual by an empty line or end of file. This command may be followed by a
modifier list containing only
control modifiers
that act after a pattern has been compiled. In particular, <code>hex</code>,
<code>posix</code>, <code>posix_nosub</code>, <code>push</code>, and <code>pushcopy</code> are not allowed,
nor are any
option-setting modifiers.
The JIT modifiers are, however permitted. Here is an example that saves and
reloads two patterns.</p>
<div class="literal-block"><pre>/abc/push
/xyz/push
#save tempfile
#load tempfile
#pop info
xyz</pre></div>
<div class="literal-block"><pre>#pop jit,bincode
abc</pre></div>
<p>If <code>jitverify</code> is used with #pop, it does not automatically imply
<code>jit</code>, which is different behaviour from when it is used on a pattern.</p>
<p>The #popcopy command is analogous to the <code>pushcopy</code> modifier in that it
makes current a copy of the topmost stack pattern, leaving the original still
on the stack.</p></section>
<section class="doc-section level-1"><h2 id="_see_also">See also</h2><p><a href="./pcre2.html"><code>pcre2</code></a>, <a href="./pcre2api.html"><code>pcre2api</code></a>, <a href="./pcre2callout.html"><code>pcre2callout</code></a>,
<a href="./pcre2jit.html"><code>pcre2jit</code></a>, <a href="./pcre2matching.html"><code>pcre2matching</code></a>, <a href="./pcre2partial.html"><code>pcre2partial</code></a>,
<a href="./pcre2pattern.html"><code>pcre2pattern</code></a>, <a href="./pcre2serialize.html"><code>pcre2serialize</code></a>.</p>
<h2 id="_author" class="discrete">Author</h2>
<p>Philip Hazel<br>
Retired from University Computing Service<br>
Cambridge, England.</p>
<h2 id="_revision" class="discrete">Revision</h2>
<p>Last updated: 22 August 2026<br>
Copyright © 1997-2024 University of Cambridge.</p></section></article></div></main><footer class="offline-footer"></footer></body></html>