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PCRETEST(1) PCRETEST(1)
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NAME
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pcretest - a program for testing Perl-compatible regular expressions.
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SYNOPSIS
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pcretest [options] [input file [output file]]
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pcretest was written as a test program for the PCRE regular expression
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library itself, but it can also be used for experimenting with regular
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expressions. This document describes the features of the test program;
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for details of the regular expressions themselves, see the pcrepattern
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documentation. For details of the PCRE library function calls and their
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options, see the pcreapi and pcre16 documentation. The input for
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pcretest is a sequence of regular expression patterns and strings to be
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matched, as described below. The output shows the result of each match.
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Options on the command line and the patterns control PCRE options and
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exactly what is output.
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PCRE's 8-BIT and 16-BIT LIBRARIES
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From release 8.30, two separate PCRE libraries can be built. The origi-
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nal one supports 8-bit character strings, whereas the newer 16-bit
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library supports character strings encoded in 16-bit units. The
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pcretest program can be used to test both libraries. However, it is
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itself still an 8-bit program, reading 8-bit input and writing 8-bit
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output. When testing the 16-bit library, the patterns and data strings
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are converted to 16-bit format before being passed to the PCRE library
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functions. Results are converted to 8-bit for output.
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References to functions and structures of the form pcre[16]_xx below
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mean "pcre_xx when using the 8-bit library or pcre16_xx when using the
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16-bit library".
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COMMAND LINE OPTIONS
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-16 If both the 8-bit and the 16-bit libraries have been built,
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this option causes the 16-bit library to be used. If only the
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16-bit library has been built, this is the default (so has no
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effect). If only the 8-bit library has been built, this
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option causes an error.
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-b Behave as if each pattern has the /B (show byte code) modi-
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fier; the internal form is output after compilation.
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-C Output the version number of the PCRE library, and all avail-
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able information about the optional features that are
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included, and then exit. All other options are ignored.
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-C option Output information about a specific build-time option, then
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exit. This functionality is intended for use in scripts such
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as RunTest. The following options output the value indicated:
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linksize the internal link size (2, 3, or 4)
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newline the default newline setting:
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CR, LF, CRLF, ANYCRLF, or ANY
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The following options output 1 for true or zero for false:
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jit just-in-time support is available
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pcre16 the 16-bit library was built
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pcre8 the 8-bit library was built
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ucp Unicode property support is available
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utf UTF-8 and/or UTF-16 support is available
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-d Behave as if each pattern has the /D (debug) modifier; the
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internal form and information about the compiled pattern is
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output after compilation; -d is equivalent to -b -i.
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-dfa Behave as if each data line contains the \D escape sequence;
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this causes the alternative matching function,
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pcre[16]_dfa_exec(), to be used instead of the standard
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pcre[16]_exec() function (more detail is given below).
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-help Output a brief summary these options and then exit.
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-i Behave as if each pattern has the /I modifier; information
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about the compiled pattern is given after compilation.
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-M Behave as if each data line contains the \M escape sequence;
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this causes PCRE to discover the minimum MATCH_LIMIT and
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MATCH_LIMIT_RECURSION settings by calling pcre[16]_exec()
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repeatedly with different limits.
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-m Output the size of each compiled pattern after it has been
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compiled. This is equivalent to adding /M to each regular
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expression. The size is given in bytes for both libraries.
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-o osize Set the number of elements in the output vector that is used
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when calling pcre[16]_exec() or pcre[16]_dfa_exec() to be
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osize. The default value is 45, which is enough for 14 cap-
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turing subexpressions for pcre[16]_exec() or 22 different
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matches for pcre[16]_dfa_exec(). The vector size can be
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changed for individual matching calls by including \O in the
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data line (see below).
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-p Behave as if each pattern has the /P modifier; the POSIX
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wrapper API is used to call PCRE. None of the other options
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has any effect when -p is set. This option can be used only
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with the 8-bit library.
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-q Do not output the version number of pcretest at the start of
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execution.
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-S size On Unix-like systems, set the size of the run-time stack to
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size megabytes.
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-s or -s+ Behave as if each pattern has the /S modifier; in other
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words, force each pattern to be studied. If -s+ is used, the
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PCRE_STUDY_JIT_COMPILE flag is passed to pcre[16]_study(),
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causing just-in-time optimization to be set up if it is
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available. If the /I or /D option is present on a pattern
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(requesting output about the compiled pattern), information
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about the result of studying is not included when studying is
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caused only by -s and neither -i nor -d is present on the
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command line. This behaviour means that the output from tests
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that are run with and without -s should be identical, except
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when options that output information about the actual running
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of a match are set.
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The -M, -t, and -tm options, which give information about
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resources used, are likely to produce different output with
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and without -s. Output may also differ if the /C option is
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present on an individual pattern. This uses callouts to trace
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the the matching process, and this may be different between
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studied and non-studied patterns. If the pattern contains
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(*MARK) items there may also be differences, for the same
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reason. The -s command line option can be overridden for spe-
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cific patterns that should never be studied (see the /S pat-
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tern modifier below).
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-t Run each compile, study, and match many times with a timer,
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and output resulting time per compile or match (in millisec-
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onds). Do not set -m with -t, because you will then get the
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size output a zillion times, and the timing will be dis-
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torted. You can control the number of iterations that are
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used for timing by following -t with a number (as a separate
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item on the command line). For example, "-t 1000" would iter-
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ate 1000 times. The default is to iterate 500000 times.
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-tm This is like -t except that it times only the matching phase,
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not the compile or study phases.
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DESCRIPTION
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If pcretest is given two filename arguments, it reads from the first
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and writes to the second. If it is given only one filename argument, it
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reads from that file and writes to stdout. Otherwise, it reads from
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stdin and writes to stdout, and prompts for each line of input, using
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"re>" to prompt for regular expressions, and "data>" to prompt for data
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lines.
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When pcretest is built, a configuration option can specify that it
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should be linked with the libreadline library. When this is done, if
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the input is from a terminal, it is read using the readline() function.
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This provides line-editing and history facilities. The output from the
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-help option states whether or not readline() will be used.
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The program handles any number of sets of input on a single input file.
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Each set starts with a regular expression, and continues with any num-
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ber of data lines to be matched against the pattern.
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Each data line is matched separately and independently. If you want to
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do multi-line matches, you have to use the \n escape sequence (or \r or
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\r\n, etc., depending on the newline setting) in a single line of input
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to encode the newline sequences. There is no limit on the length of
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data lines; the input buffer is automatically extended if it is too
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small.
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An empty line signals the end of the data lines, at which point a new
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regular expression is read. The regular expressions are given enclosed
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in any non-alphanumeric delimiters other than backslash, for example:
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/(a|bc)x+yz/
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White space before the initial delimiter is ignored. A regular expres-
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sion may be continued over several input lines, in which case the new-
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line characters are included within it. It is possible to include the
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delimiter within the pattern by escaping it, for example
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/abc\/def/
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If you do so, the escape and the delimiter form part of the pattern,
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but since delimiters are always non-alphanumeric, this does not affect
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its interpretation. If the terminating delimiter is immediately fol-
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lowed by a backslash, for example,
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/abc/\
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then a backslash is added to the end of the pattern. This is done to
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provide a way of testing the error condition that arises if a pattern
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finishes with a backslash, because
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/abc\/
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is interpreted as the first line of a pattern that starts with "abc/",
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causing pcretest to read the next line as a continuation of the regular
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expression.
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PATTERN MODIFIERS
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A pattern may be followed by any number of modifiers, which are mostly
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single characters. Following Perl usage, these are referred to below
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as, for example, "the /i modifier", even though the delimiter of the
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pattern need not always be a slash, and no slash is used when writing
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modifiers. White space may appear between the final pattern delimiter
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and the first modifier, and between the modifiers themselves.
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The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
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PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com-
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pile() is called. These four modifier letters have the same effect as
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they do in Perl. For example:
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/caseless/i
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The following table shows additional modifiers for setting PCRE com-
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pile-time options that do not correspond to anything in Perl:
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/8 PCRE_UTF8 ) when using the 8-bit
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/? PCRE_NO_UTF8_CHECK ) library
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/8 PCRE_UTF16 ) when using the 16-bit
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/? PCRE_NO_UTF16_CHECK ) library
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/A PCRE_ANCHORED
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/C PCRE_AUTO_CALLOUT
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/E PCRE_DOLLAR_ENDONLY
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/f PCRE_FIRSTLINE
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/J PCRE_DUPNAMES
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/N PCRE_NO_AUTO_CAPTURE
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/U PCRE_UNGREEDY
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/W PCRE_UCP
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/X PCRE_EXTRA
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/Y PCRE_NO_START_OPTIMIZE
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/<JS> PCRE_JAVASCRIPT_COMPAT
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/<cr> PCRE_NEWLINE_CR
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/<lf> PCRE_NEWLINE_LF
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/<crlf> PCRE_NEWLINE_CRLF
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/<anycrlf> PCRE_NEWLINE_ANYCRLF
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/<any> PCRE_NEWLINE_ANY
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/<bsr_anycrlf> PCRE_BSR_ANYCRLF
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/<bsr_unicode> PCRE_BSR_UNICODE
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The modifiers that are enclosed in angle brackets are literal strings
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as shown, including the angle brackets, but the letters within can be
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in either case. This example sets multiline matching with CRLF as the
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line ending sequence:
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/^abc/m<CRLF>
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As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
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all non-printing characters in output strings to be printed using the
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\x{hh...} notation. Otherwise, those less than 0x100 are output in hex
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without the curly brackets.
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Full details of the PCRE options are given in the pcreapi documenta-
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tion.
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Finding all matches in a string
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Searching for all possible matches within each subject string can be
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requested by the /g or /G modifier. After finding a match, PCRE is
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called again to search the remainder of the subject string. The differ-
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ence between /g and /G is that the former uses the startoffset argument
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to pcre[16]_exec() to start searching at a new point within the entire
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string (which is in effect what Perl does), whereas the latter passes
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over a shortened substring. This makes a difference to the matching
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process if the pattern begins with a lookbehind assertion (including \b
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or \B).
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If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
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string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
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PCRE_ANCHORED flags set in order to search for another, non-empty,
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match at the same point. If this second match fails, the start offset
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is advanced, and the normal match is retried. This imitates the way
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Perl handles such cases when using the /g modifier or the split() func-
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tion. Normally, the start offset is advanced by one character, but if
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the newline convention recognizes CRLF as a newline, and the current
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character is CR followed by LF, an advance of two is used.
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Other modifiers
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There are yet more modifiers for controlling the way pcretest operates.
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The /+ modifier requests that as well as outputting the substring that
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matched the entire pattern, pcretest should in addition output the
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remainder of the subject string. This is useful for tests where the
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subject contains multiple copies of the same substring. If the + modi-
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fier appears twice, the same action is taken for captured substrings.
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In each case the remainder is output on the following line with a plus
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character following the capture number. Note that this modifier must
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not immediately follow the /S modifier because /S+ has another meaning.
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The /= modifier requests that the values of all potential captured
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parentheses be output after a match. By default, only those up to the
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highest one actually used in the match are output (corresponding to the
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return code from pcre[16]_exec()). Values in the offsets vector corre-
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sponding to higher numbers should be set to -1, and these are output as
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"<unset>". This modifier gives a way of checking that this is happen-
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ing.
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The /B modifier is a debugging feature. It requests that pcretest out-
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put a representation of the compiled code after compilation. Normally
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this information contains length and offset values; however, if /Z is
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also present, this data is replaced by spaces. This is a special fea-
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ture for use in the automatic test scripts; it ensures that the same
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output is generated for different internal link sizes.
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The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
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that is, both the /B and the /I modifiers.
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The /F modifier causes pcretest to flip the byte order of the 2-byte
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and 4-byte fields in the compiled pattern. This facility is for testing
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the feature in PCRE that allows it to execute patterns that were com-
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piled on a host with a different endianness. This feature is not avail-
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able when the POSIX interface to PCRE is being used, that is, when the
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/P pattern modifier is specified. See also the section about saving and
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reloading compiled patterns below.
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The /I modifier requests that pcretest output information about the
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compiled pattern (whether it is anchored, has a fixed first character,
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and so on). It does this by calling pcre[16]_fullinfo() after compiling
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a pattern. If the pattern is studied, the results of that are also out-
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put.
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The /K modifier requests pcretest to show names from backtracking con-
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trol verbs that are returned from calls to pcre[16]_exec(). It causes
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pcretest to create a pcre[16]_extra block if one has not already been
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created by a call to pcre[16]_study(), and to set the PCRE_EXTRA_MARK
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flag and the mark field within it, every time that pcre[16]_exec() is
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called. If the variable that the mark field points to is non-NULL for a
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match, non-match, or partial match, pcretest prints the string to which
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it points. For a match, this is shown on a line by itself, tagged with
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"MK:". For a non-match it is added to the message.
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The /L modifier must be followed directly by the name of a locale, for
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example,
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/pattern/Lfr_FR
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For this reason, it must be the last modifier. The given locale is set,
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pcre[16]_maketables() is called to build a set of character tables for
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the locale, and this is then passed to pcre[16]_compile() when compil-
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ing the regular expression. Without an /L (or /T) modifier, NULL is
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passed as the tables pointer; that is, /L applies only to the expres-
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sion on which it appears.
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The /M modifier causes the size in bytes of the memory block used to
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hold the compiled pattern to be output. This does not include the size
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of the pcre[16] block; it is just the actual compiled data. If the pat-
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tern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
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the size of the JIT compiled code is also output.
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If the /S modifier appears once, it causes pcre[16]_study() to be
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called after the expression has been compiled, and the results used
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when the expression is matched. If /S appears twice, it suppresses
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studying, even if it was requested externally by the -s command line
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option. This makes it possible to specify that certain patterns are
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always studied, and others are never studied, independently of -s. This
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feature is used in the test files in a few cases where the output is
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different when the pattern is studied.
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If the /S modifier is immediately followed by a + character, the call
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to pcre[16]_study() is made with the PCRE_STUDY_JIT_COMPILE option,
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requesting just-in-time optimization support if it is available. Note
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that there is also a /+ modifier; it must not be given immediately
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after /S because this will be misinterpreted. If JIT studying is suc-
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cessful, it will automatically be used when pcre[16]_exec() is run,
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except when incompatible run-time options are specified. These include
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the partial matching options; a complete list is given in the pcrejit
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documentation. See also the \J escape sequence below for a way of set-
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ting the size of the JIT stack.
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The /T modifier must be followed by a single digit. It causes a spe-
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cific set of built-in character tables to be passed to pcre[16]_com-
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pile(). It is used in the standard PCRE tests to check behaviour with
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different character tables. The digit specifies the tables as follows:
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0 the default ASCII tables, as distributed in
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pcre_chartables.c.dist
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1 a set of tables defining ISO 8859 characters
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In table 1, some characters whose codes are greater than 128 are iden-
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tified as letters, digits, spaces, etc.
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Using the POSIX wrapper API
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The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
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rather than its native API. This supports only the 8-bit library. When
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/P is set, the following modifiers set options for the regcomp() func-
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tion:
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/i REG_ICASE
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/m REG_NEWLINE
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/N REG_NOSUB
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/s REG_DOTALL )
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/U REG_UNGREEDY ) These options are not part of
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/W REG_UCP ) the POSIX standard
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/8 REG_UTF8 )
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|
| 408 |
The /+ modifier works as described above. All other modifiers are
|
| 409 |
ignored.
|
| 410 |
|
| 411 |
|
| 412 |
DATA LINES
|
| 413 |
|
| 414 |
Before each data line is passed to pcre[16]_exec(), leading and trail-
|
| 415 |
ing white space is removed, and it is then scanned for \ escapes. Some
|
| 416 |
of these are pretty esoteric features, intended for checking out some
|
| 417 |
of the more complicated features of PCRE. If you are just testing
|
| 418 |
"ordinary" regular expressions, you probably don't need any of these.
|
| 419 |
The following escapes are recognized:
|
| 420 |
|
| 421 |
\a alarm (BEL, \x07)
|
| 422 |
\b backspace (\x08)
|
| 423 |
\e escape (\x27)
|
| 424 |
\f form feed (\x0c)
|
| 425 |
\n newline (\x0a)
|
| 426 |
\qdd set the PCRE_MATCH_LIMIT limit to dd
|
| 427 |
(any number of digits)
|
| 428 |
\r carriage return (\x0d)
|
| 429 |
\t tab (\x09)
|
| 430 |
\v vertical tab (\x0b)
|
| 431 |
\nnn octal character (up to 3 octal digits); always
|
| 432 |
a byte unless > 255 in UTF-8 or 16-bit mode
|
| 433 |
\xhh hexadecimal byte (up to 2 hex digits)
|
| 434 |
\x{hh...} hexadecimal character (any number of hex digits)
|
| 435 |
\A pass the PCRE_ANCHORED option to pcre[16]_exec()
|
| 436 |
or pcre[16]_dfa_exec()
|
| 437 |
\B pass the PCRE_NOTBOL option to pcre[16]_exec()
|
| 438 |
or pcre[16]_dfa_exec()
|
| 439 |
\Cdd call pcre[16]_copy_substring() for substring dd
|
| 440 |
after a successful match (number less than 32)
|
| 441 |
\Cname call pcre[16]_copy_named_substring() for substring
|
| 442 |
"name" after a successful match (name termin-
|
| 443 |
ated by next non alphanumeric character)
|
| 444 |
\C+ show the current captured substrings at callout
|
| 445 |
time
|
| 446 |
\C- do not supply a callout function
|
| 447 |
\C!n return 1 instead of 0 when callout number n is
|
| 448 |
reached
|
| 449 |
\C!n!m return 1 instead of 0 when callout number n is
|
| 450 |
reached for the nth time
|
| 451 |
\C*n pass the number n (may be negative) as callout
|
| 452 |
data; this is used as the callout return value
|
| 453 |
\D use the pcre[16]_dfa_exec() match function
|
| 454 |
\F only shortest match for pcre[16]_dfa_exec()
|
| 455 |
\Gdd call pcre[16]_get_substring() for substring dd
|
| 456 |
after a successful match (number less than 32)
|
| 457 |
\Gname call pcre[16]_get_named_substring() for substring
|
| 458 |
"name" after a successful match (name termin-
|
| 459 |
ated by next non-alphanumeric character)
|
| 460 |
\Jdd set up a JIT stack of dd kilobytes maximum (any
|
| 461 |
number of digits)
|
| 462 |
\L call pcre[16]_get_substringlist() after a
|
| 463 |
successful match
|
| 464 |
\M discover the minimum MATCH_LIMIT and
|
| 465 |
MATCH_LIMIT_RECURSION settings
|
| 466 |
\N pass the PCRE_NOTEMPTY option to pcre[16]_exec()
|
| 467 |
or pcre[16]_dfa_exec(); if used twice, pass the
|
| 468 |
PCRE_NOTEMPTY_ATSTART option
|
| 469 |
\Odd set the size of the output vector passed to
|
| 470 |
pcre[16]_exec() to dd (any number of digits)
|
| 471 |
\P pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec()
|
| 472 |
or pcre[16]_dfa_exec(); if used twice, pass the
|
| 473 |
PCRE_PARTIAL_HARD option
|
| 474 |
\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
|
| 475 |
(any number of digits)
|
| 476 |
\R pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec()
|
| 477 |
\S output details of memory get/free calls during matching
|
| 478 |
\Y pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec()
|
| 479 |
or pcre[16]_dfa_exec()
|
| 480 |
\Z pass the PCRE_NOTEOL option to pcre[16]_exec()
|
| 481 |
or pcre[16]_dfa_exec()
|
| 482 |
\? pass the PCRE_NO_UTF[8|16]_CHECK option to
|
| 483 |
pcre[16]_exec() or pcre[16]_dfa_exec()
|
| 484 |
\>dd start the match at offset dd (optional "-"; then
|
| 485 |
any number of digits); this sets the startoffset
|
| 486 |
argument for pcre[16]_exec() or pcre[16]_dfa_exec()
|
| 487 |
\<cr> pass the PCRE_NEWLINE_CR option to pcre[16]_exec()
|
| 488 |
or pcre[16]_dfa_exec()
|
| 489 |
\<lf> pass the PCRE_NEWLINE_LF option to pcre[16]_exec()
|
| 490 |
or pcre[16]_dfa_exec()
|
| 491 |
\<crlf> pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec()
|
| 492 |
or pcre[16]_dfa_exec()
|
| 493 |
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec()
|
| 494 |
or pcre[16]_dfa_exec()
|
| 495 |
\<any> pass the PCRE_NEWLINE_ANY option to pcre[16]_exec()
|
| 496 |
or pcre[16]_dfa_exec()
|
| 497 |
|
| 498 |
The use of \x{hh...} is not dependent on the use of the /8 modifier on
|
| 499 |
the pattern. It is recognized always. There may be any number of hexa-
|
| 500 |
decimal digits inside the braces; invalid values provoke error mes-
|
| 501 |
sages.
|
| 502 |
|
| 503 |
Note that \xhh specifies one byte in UTF-8 mode; this makes it possible
|
| 504 |
to construct invalid UTF-8 sequences for testing purposes. On the other
|
| 505 |
hand, \x{hh} is interpreted as a UTF-8 character in UTF-8 mode, gener-
|
| 506 |
ating more than one byte if the value is greater than 127. When testing
|
| 507 |
the 8-bit library not in UTF-8 mode, \x{hh} generates one byte for val-
|
| 508 |
ues less than 256, and causes an error for greater values.
|
| 509 |
|
| 510 |
In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
|
| 511 |
possible to construct invalid UTF-16 sequences for testing purposes.
|
| 512 |
|
| 513 |
The escapes that specify line ending sequences are literal strings,
|
| 514 |
exactly as shown. No more than one newline setting should be present in
|
| 515 |
any data line.
|
| 516 |
|
| 517 |
A backslash followed by anything else just escapes the anything else.
|
| 518 |
If the very last character is a backslash, it is ignored. This gives a
|
| 519 |
way of passing an empty line as data, since a real empty line termi-
|
| 520 |
nates the data input.
|
| 521 |
|
| 522 |
The \J escape provides a way of setting the maximum stack size that is
|
| 523 |
used by the just-in-time optimization code. It is ignored if JIT opti-
|
| 524 |
mization is not being used. Providing a stack that is larger than the
|
| 525 |
default 32K is necessary only for very complicated patterns.
|
| 526 |
|
| 527 |
If \M is present, pcretest calls pcre[16]_exec() several times, with
|
| 528 |
different values in the match_limit and match_limit_recursion fields of
|
| 529 |
the pcre[16]_extra data structure, until it finds the minimum numbers
|
| 530 |
for each parameter that allow pcre[16]_exec() to complete without
|
| 531 |
error. Because this is testing a specific feature of the normal inter-
|
| 532 |
pretive pcre[16]_exec() execution, the use of any JIT optimization that
|
| 533 |
might have been set up by the /S+ qualifier of -s+ option is disabled.
|
| 534 |
|
| 535 |
The match_limit number is a measure of the amount of backtracking that
|
| 536 |
takes place, and checking it out can be instructive. For most simple
|
| 537 |
matches, the number is quite small, but for patterns with very large
|
| 538 |
numbers of matching possibilities, it can become large very quickly
|
| 539 |
with increasing length of subject string. The match_limit_recursion
|
| 540 |
number is a measure of how much stack (or, if PCRE is compiled with
|
| 541 |
NO_RECURSE, how much heap) memory is needed to complete the match
|
| 542 |
attempt.
|
| 543 |
|
| 544 |
When \O is used, the value specified may be higher or lower than the
|
| 545 |
size set by the -O command line option (or defaulted to 45); \O applies
|
| 546 |
only to the call of pcre[16]_exec() for the line in which it appears.
|
| 547 |
|
| 548 |
If the /P modifier was present on the pattern, causing the POSIX wrap-
|
| 549 |
per API to be used, the only option-setting sequences that have any
|
| 550 |
effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
|
| 551 |
REG_NOTEOL, respectively, to be passed to regexec().
|
| 552 |
|
| 553 |
|
| 554 |
THE ALTERNATIVE MATCHING FUNCTION
|
| 555 |
|
| 556 |
By default, pcretest uses the standard PCRE matching function,
|
| 557 |
pcre[16]_exec() to match each data line. PCRE also supports an alterna-
|
| 558 |
tive matching function, pcre[16]_dfa_test(), which operates in a dif-
|
| 559 |
ferent way, and has some restrictions. The differences between the two
|
| 560 |
functions are described in the pcrematching documentation.
|
| 561 |
|
| 562 |
If a data line contains the \D escape sequence, or if the command line
|
| 563 |
contains the -dfa option, the alternative matching function is used.
|
| 564 |
This function finds all possible matches at a given point. If, however,
|
| 565 |
the \F escape sequence is present in the data line, it stops after the
|
| 566 |
first match is found. This is always the shortest possible match.
|
| 567 |
|
| 568 |
|
| 569 |
DEFAULT OUTPUT FROM PCRETEST
|
| 570 |
|
| 571 |
This section describes the output when the normal matching function,
|
| 572 |
pcre[16]_exec(), is being used.
|
| 573 |
|
| 574 |
When a match succeeds, pcretest outputs the list of captured substrings
|
| 575 |
that pcre[16]_exec() returns, starting with number 0 for the string
|
| 576 |
that matched the whole pattern. Otherwise, it outputs "No match" when
|
| 577 |
the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
|
| 578 |
partially matching substring when pcre[16]_exec() returns
|
| 579 |
PCRE_ERROR_PARTIAL. (Note that this is the entire substring that was
|
| 580 |
inspected during the partial match; it may include characters before
|
| 581 |
the actual match start if a lookbehind assertion, \K, \b, or \B was
|
| 582 |
involved.) For any other return, pcretest outputs the PCRE negative
|
| 583 |
error number and a short descriptive phrase. If the error is a failed
|
| 584 |
UTF string check, the offset of the start of the failing character and
|
| 585 |
the reason code are also output, provided that the size of the output
|
| 586 |
vector is at least two. Here is an example of an interactive pcretest
|
| 587 |
run.
|
| 588 |
|
| 589 |
$ pcretest
|
| 590 |
PCRE version 8.13 2011-04-30
|
| 591 |
|
| 592 |
re> /^abc(\d+)/
|
| 593 |
data> abc123
|
| 594 |
0: abc123
|
| 595 |
1: 123
|
| 596 |
data> xyz
|
| 597 |
No match
|
| 598 |
|
| 599 |
Unset capturing substrings that are not followed by one that is set are
|
| 600 |
not returned by pcre[16]_exec(), and are not shown by pcretest. In the
|
| 601 |
following example, there are two capturing substrings, but when the
|
| 602 |
first data line is matched, the second, unset substring is not shown.
|
| 603 |
An "internal" unset substring is shown as "<unset>", as for the second
|
| 604 |
data line.
|
| 605 |
|
| 606 |
re> /(a)|(b)/
|
| 607 |
data> a
|
| 608 |
0: a
|
| 609 |
1: a
|
| 610 |
data> b
|
| 611 |
0: b
|
| 612 |
1: <unset>
|
| 613 |
2: b
|
| 614 |
|
| 615 |
If the strings contain any non-printing characters, they are output as
|
| 616 |
\xhh escapes if the value is less than 256 and UTF mode is not set.
|
| 617 |
Otherwise they are output as \x{hh...} escapes. See below for the defi-
|
| 618 |
nition of non-printing characters. If the pattern has the /+ modifier,
|
| 619 |
the output for substring 0 is followed by the the rest of the subject
|
| 620 |
string, identified by "0+" like this:
|
| 621 |
|
| 622 |
re> /cat/+
|
| 623 |
data> cataract
|
| 624 |
0: cat
|
| 625 |
0+ aract
|
| 626 |
|
| 627 |
If the pattern has the /g or /G modifier, the results of successive
|
| 628 |
matching attempts are output in sequence, like this:
|
| 629 |
|
| 630 |
re> /\Bi(\w\w)/g
|
| 631 |
data> Mississippi
|
| 632 |
0: iss
|
| 633 |
1: ss
|
| 634 |
0: iss
|
| 635 |
1: ss
|
| 636 |
0: ipp
|
| 637 |
1: pp
|
| 638 |
|
| 639 |
"No match" is output only if the first match attempt fails. Here is an
|
| 640 |
example of a failure message (the offset 4 that is specified by \>4 is
|
| 641 |
past the end of the subject string):
|
| 642 |
|
| 643 |
re> /xyz/
|
| 644 |
data> xyz\>4
|
| 645 |
Error -24 (bad offset value)
|
| 646 |
|
| 647 |
If any of the sequences \C, \G, or \L are present in a data line that
|
| 648 |
is successfully matched, the substrings extracted by the convenience
|
| 649 |
functions are output with C, G, or L after the string number instead of
|
| 650 |
a colon. This is in addition to the normal full list. The string length
|
| 651 |
(that is, the return from the extraction function) is given in paren-
|
| 652 |
theses after each string for \C and \G.
|
| 653 |
|
| 654 |
Note that whereas patterns can be continued over several lines (a plain
|
| 655 |
">" prompt is used for continuations), data lines may not. However new-
|
| 656 |
lines can be included in data by means of the \n escape (or \r, \r\n,
|
| 657 |
etc., depending on the newline sequence setting).
|
| 658 |
|
| 659 |
|
| 660 |
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
|
| 661 |
|
| 662 |
When the alternative matching function, pcre[16]_dfa_exec(), is used
|
| 663 |
(by means of the \D escape sequence or the -dfa command line option),
|
| 664 |
the output consists of a list of all the matches that start at the
|
| 665 |
first point in the subject where there is at least one match. For exam-
|
| 666 |
ple:
|
| 667 |
|
| 668 |
re> /(tang|tangerine|tan)/
|
| 669 |
data> yellow tangerine\D
|
| 670 |
0: tangerine
|
| 671 |
1: tang
|
| 672 |
2: tan
|
| 673 |
|
| 674 |
(Using the normal matching function on this data finds only "tang".)
|
| 675 |
The longest matching string is always given first (and numbered zero).
|
| 676 |
After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
|
| 677 |
lowed by the partially matching substring. (Note that this is the
|
| 678 |
entire substring that was inspected during the partial match; it may
|
| 679 |
include characters before the actual match start if a lookbehind asser-
|
| 680 |
tion, \K, \b, or \B was involved.)
|
| 681 |
|
| 682 |
If /g is present on the pattern, the search for further matches resumes
|
| 683 |
at the end of the longest match. For example:
|
| 684 |
|
| 685 |
re> /(tang|tangerine|tan)/g
|
| 686 |
data> yellow tangerine and tangy sultana\D
|
| 687 |
0: tangerine
|
| 688 |
1: tang
|
| 689 |
2: tan
|
| 690 |
0: tang
|
| 691 |
1: tan
|
| 692 |
0: tan
|
| 693 |
|
| 694 |
Since the matching function does not support substring capture, the
|
| 695 |
escape sequences that are concerned with captured substrings are not
|
| 696 |
relevant.
|
| 697 |
|
| 698 |
|
| 699 |
RESTARTING AFTER A PARTIAL MATCH
|
| 700 |
|
| 701 |
When the alternative matching function has given the PCRE_ERROR_PARTIAL
|
| 702 |
return, indicating that the subject partially matched the pattern, you
|
| 703 |
can restart the match with additional subject data by means of the \R
|
| 704 |
escape sequence. For example:
|
| 705 |
|
| 706 |
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
|
| 707 |
data> 23ja\P\D
|
| 708 |
Partial match: 23ja
|
| 709 |
data> n05\R\D
|
| 710 |
0: n05
|
| 711 |
|
| 712 |
For further information about partial matching, see the pcrepartial
|
| 713 |
documentation.
|
| 714 |
|
| 715 |
|
| 716 |
CALLOUTS
|
| 717 |
|
| 718 |
If the pattern contains any callout requests, pcretest's callout func-
|
| 719 |
tion is called during matching. This works with both matching func-
|
| 720 |
tions. By default, the called function displays the callout number, the
|
| 721 |
start and current positions in the text at the callout time, and the
|
| 722 |
next pattern item to be tested. For example:
|
| 723 |
|
| 724 |
--->pqrabcdef
|
| 725 |
0 ^ ^ \d
|
| 726 |
|
| 727 |
This output indicates that callout number 0 occurred for a match
|
| 728 |
attempt starting at the fourth character of the subject string, when
|
| 729 |
the pointer was at the seventh character of the data, and when the next
|
| 730 |
pattern item was \d. Just one circumflex is output if the start and
|
| 731 |
current positions are the same.
|
| 732 |
|
| 733 |
Callouts numbered 255 are assumed to be automatic callouts, inserted as
|
| 734 |
a result of the /C pattern modifier. In this case, instead of showing
|
| 735 |
the callout number, the offset in the pattern, preceded by a plus, is
|
| 736 |
output. For example:
|
| 737 |
|
| 738 |
re> /\d?[A-E]\*/C
|
| 739 |
data> E*
|
| 740 |
--->E*
|
| 741 |
+0 ^ \d?
|
| 742 |
+3 ^ [A-E]
|
| 743 |
+8 ^^ \*
|
| 744 |
+10 ^ ^
|
| 745 |
0: E*
|
| 746 |
|
| 747 |
If a pattern contains (*MARK) items, an additional line is output when-
|
| 748 |
ever a change of latest mark is passed to the callout function. For
|
| 749 |
example:
|
| 750 |
|
| 751 |
re> /a(*MARK:X)bc/C
|
| 752 |
data> abc
|
| 753 |
--->abc
|
| 754 |
+0 ^ a
|
| 755 |
+1 ^^ (*MARK:X)
|
| 756 |
+10 ^^ b
|
| 757 |
Latest Mark: X
|
| 758 |
+11 ^ ^ c
|
| 759 |
+12 ^ ^
|
| 760 |
0: abc
|
| 761 |
|
| 762 |
The mark changes between matching "a" and "b", but stays the same for
|
| 763 |
the rest of the match, so nothing more is output. If, as a result of
|
| 764 |
backtracking, the mark reverts to being unset, the text "<unset>" is
|
| 765 |
output.
|
| 766 |
|
| 767 |
The callout function in pcretest returns zero (carry on matching) by
|
| 768 |
default, but you can use a \C item in a data line (as described above)
|
| 769 |
to change this and other parameters of the callout.
|
| 770 |
|
| 771 |
Inserting callouts can be helpful when using pcretest to check compli-
|
| 772 |
cated regular expressions. For further information about callouts, see
|
| 773 |
the pcrecallout documentation.
|
| 774 |
|
| 775 |
|
| 776 |
NON-PRINTING CHARACTERS
|
| 777 |
|
| 778 |
When pcretest is outputting text in the compiled version of a pattern,
|
| 779 |
bytes other than 32-126 are always treated as non-printing characters
|
| 780 |
are are therefore shown as hex escapes.
|
| 781 |
|
| 782 |
When pcretest is outputting text that is a matched part of a subject
|
| 783 |
string, it behaves in the same way, unless a different locale has been
|
| 784 |
set for the pattern (using the /L modifier). In this case, the
|
| 785 |
isprint() function to distinguish printing and non-printing characters.
|
| 786 |
|
| 787 |
|
| 788 |
SAVING AND RELOADING COMPILED PATTERNS
|
| 789 |
|
| 790 |
The facilities described in this section are not available when the
|
| 791 |
POSIX interface to PCRE is being used, that is, when the /P pattern
|
| 792 |
modifier is specified.
|
| 793 |
|
| 794 |
When the POSIX interface is not in use, you can cause pcretest to write
|
| 795 |
a compiled pattern to a file, by following the modifiers with > and a
|
| 796 |
file name. For example:
|
| 797 |
|
| 798 |
/pattern/im >/some/file
|
| 799 |
|
| 800 |
See the pcreprecompile documentation for a discussion about saving and
|
| 801 |
re-using compiled patterns. Note that if the pattern was successfully
|
| 802 |
studied with JIT optimization, the JIT data cannot be saved.
|
| 803 |
|
| 804 |
The data that is written is binary. The first eight bytes are the
|
| 805 |
length of the compiled pattern data followed by the length of the
|
| 806 |
optional study data, each written as four bytes in big-endian order
|
| 807 |
(most significant byte first). If there is no study data (either the
|
| 808 |
pattern was not studied, or studying did not return any data), the sec-
|
| 809 |
ond length is zero. The lengths are followed by an exact copy of the
|
| 810 |
compiled pattern. If there is additional study data, this (excluding
|
| 811 |
any JIT data) follows immediately after the compiled pattern. After
|
| 812 |
writing the file, pcretest expects to read a new pattern.
|
| 813 |
|
| 814 |
A saved pattern can be reloaded into pcretest by specifying < and a
|
| 815 |
file name instead of a pattern. The name of the file must not contain a
|
| 816 |
< character, as otherwise pcretest will interpret the line as a pattern
|
| 817 |
delimited by < characters. For example:
|
| 818 |
|
| 819 |
re> </some/file
|
| 820 |
Compiled pattern loaded from /some/file
|
| 821 |
No study data
|
| 822 |
|
| 823 |
If the pattern was previously studied with the JIT optimization, the
|
| 824 |
JIT information cannot be saved and restored, and so is lost. When the
|
| 825 |
pattern has been loaded, pcretest proceeds to read data lines in the
|
| 826 |
usual way.
|
| 827 |
|
| 828 |
You can copy a file written by pcretest to a different host and reload
|
| 829 |
it there, even if the new host has opposite endianness to the one on
|
| 830 |
which the pattern was compiled. For example, you can compile on an i86
|
| 831 |
machine and run on a SPARC machine. When a pattern is reloaded on a
|
| 832 |
host with different endianness, the confirmation message is changed to:
|
| 833 |
|
| 834 |
Compiled pattern (byte-inverted) loaded from /some/file
|
| 835 |
|
| 836 |
The test suite contains some saved pre-compiled patterns with different
|
| 837 |
endianness. These are reloaded using "<!" instead of just "<". This
|
| 838 |
suppresses the "(byte-inverted)" text so that the output is the same on
|
| 839 |
all hosts. It also forces debugging output once the pattern has been
|
| 840 |
reloaded.
|
| 841 |
|
| 842 |
File names for saving and reloading can be absolute or relative, but
|
| 843 |
note that the shell facility of expanding a file name that starts with
|
| 844 |
a tilde (~) is not available.
|
| 845 |
|
| 846 |
The ability to save and reload files in pcretest is intended for test-
|
| 847 |
ing and experimentation. It is not intended for production use because
|
| 848 |
only a single pattern can be written to a file. Furthermore, there is
|
| 849 |
no facility for supplying custom character tables for use with a
|
| 850 |
reloaded pattern. If the original pattern was compiled with custom
|
| 851 |
tables, an attempt to match a subject string using a reloaded pattern
|
| 852 |
is likely to cause pcretest to crash. Finally, if you attempt to load
|
| 853 |
a file that is not in the correct format, the result is undefined.
|
| 854 |
|
| 855 |
|
| 856 |
SEE ALSO
|
| 857 |
|
| 858 |
pcre(3), pcre16(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematch-
|
| 859 |
ing(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).
|
| 860 |
|
| 861 |
|
| 862 |
AUTHOR
|
| 863 |
|
| 864 |
Philip Hazel
|
| 865 |
University Computing Service
|
| 866 |
Cambridge CB2 3QH, England.
|
| 867 |
|
| 868 |
|
| 869 |
REVISION
|
| 870 |
|
| 871 |
Last updated: 13 January 2012
|
| 872 |
Copyright (c) 1997-2012 University of Cambridge.
|
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| 
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