660 lines
30 KiB
Plaintext
660 lines
30 KiB
Plaintext
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] [source] [destination]
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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 documentation.
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OPTIONS
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-b Behave as if each regex has the /B (show bytecode) modifier;
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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.
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-d Behave as if each regex 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_dfa_exec(), to be used instead of the standard
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pcre_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 regex 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_exec() repeat-
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edly 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. For compatibility with earlier versions of
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pcretest, -s is a synonym for -m.
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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_exec() or pcre_dfa_exec() to be osize. The
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default value is 45, which is enough for 14 capturing subex-
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pressions for pcre_exec() or 22 different matches for
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pcre_dfa_exec(). The vector size can be changed for individ-
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ual matching calls by including \O in the data line (see
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below).
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-p Behave as if each regex has the /P modifier; the POSIX wrap-
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per API is used to call PCRE. None of the other options has
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any effect when -p is set.
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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 runtime stack to
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size megabytes.
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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. Whitespace 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_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 options
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that do not correspond to anything in Perl:
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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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/X PCRE_EXTRA
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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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Those specifying line ending sequences are literal strings as shown,
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but the letters can be in either case. This example sets multiline
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matching with CRLF as the line ending sequence:
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/^abc/m<crlf>
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Details of the meanings of these PCRE options are given in the pcreapi
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documentation.
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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_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_exec() in a /g or /G sequence matches an empty
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string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
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flags set in order to search for another, non-empty, match at the same
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point. If this second match fails, the start offset is advanced by
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one, and the normal match is retried. This imitates the way Perl han-
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dles such cases when using the /g modifier or the split() function.
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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.
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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 byte code after compilation. Nor-
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mally this information contains length and offset values; however, if
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/Z is also present, this data is replaced by spaces. This is a special
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feature 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 /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_maketables() is called to build a set of character tables for the
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locale, and this is then passed to pcre_compile() when compiling the
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regular expression. Without an /L modifier, NULL is passed as the
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tables pointer; that is, /L applies only to the expression on which it
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appears.
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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_fullinfo() after compiling a
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pattern. If the pattern is studied, the results of that are also out-
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put.
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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 fields in
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the compiled pattern that contain 2-byte and 4-byte numbers. This
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facility is for testing the feature in PCRE that allows it to execute
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patterns that were compiled on a host with a different endianness. This
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feature is not available when the POSIX interface to PCRE is being
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used, that is, when the /P pattern modifier is specified. See also the
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section about saving and reloading compiled patterns below.
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The /S modifier causes pcre_study() to be called after the expression
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has been compiled, and the results used when the expression is matched.
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The /M modifier causes the size of memory block used to hold the com-
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piled pattern to be output.
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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. When this is done, all other modifiers
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except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
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and REG_NEWLINE is set if /m is present. The wrapper functions force
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PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
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The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
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set. This turns on support for UTF-8 character handling in PCRE, pro-
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vided that it was compiled with this support enabled. This modifier
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also causes any non-printing characters in output strings to be printed
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using the \x{hh...} notation if they are valid UTF-8 sequences.
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If the /? modifier is used with /8, it causes pcretest to call
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pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
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checking of the string for UTF-8 validity.
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DATA LINES
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Before each data line is passed to pcre_exec(), leading and trailing
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whitespace is removed, and it is then scanned for \ escapes. Some of
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these are pretty esoteric features, intended for checking out some of
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the more complicated features of PCRE. If you are just testing "ordi-
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nary" regular expressions, you probably don't need any of these. The
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following escapes are recognized:
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\a alarm (BEL, \x07)
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\b backspace (\x08)
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\e escape (\x27)
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\f formfeed (\x0c)
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\n newline (\x0a)
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\qdd set the PCRE_MATCH_LIMIT limit to dd
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(any number of digits)
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\r carriage return (\x0d)
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\t tab (\x09)
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\v vertical tab (\x0b)
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\nnn octal character (up to 3 octal digits)
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\xhh hexadecimal character (up to 2 hex digits)
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\x{hh...} hexadecimal character, any number of digits
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in UTF-8 mode
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\A pass the PCRE_ANCHORED option to pcre_exec()
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or pcre_dfa_exec()
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\B pass the PCRE_NOTBOL option to pcre_exec()
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or pcre_dfa_exec()
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\Cdd call pcre_copy_substring() for substring dd
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after a successful match (number less than 32)
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\Cname call pcre_copy_named_substring() for substring
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"name" after a successful match (name termin-
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ated by next non alphanumeric character)
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\C+ show the current captured substrings at callout
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time
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\C- do not supply a callout function
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\C!n return 1 instead of 0 when callout number n is
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reached
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\C!n!m return 1 instead of 0 when callout number n is
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reached for the nth time
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\C*n pass the number n (may be negative) as callout
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data; this is used as the callout return value
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\D use the pcre_dfa_exec() match function
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\F only shortest match for pcre_dfa_exec()
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\Gdd call pcre_get_substring() for substring dd
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after a successful match (number less than 32)
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\Gname call pcre_get_named_substring() for substring
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"name" after a successful match (name termin-
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ated by next non-alphanumeric character)
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\L call pcre_get_substringlist() after a
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successful match
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\M discover the minimum MATCH_LIMIT and
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MATCH_LIMIT_RECURSION settings
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\N pass the PCRE_NOTEMPTY option to pcre_exec()
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or pcre_dfa_exec()
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\Odd set the size of the output vector passed to
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pcre_exec() to dd (any number of digits)
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\P pass the PCRE_PARTIAL option to pcre_exec()
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or pcre_dfa_exec()
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\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
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(any number of digits)
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\R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
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\S output details of memory get/free calls during matching
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\Z pass the PCRE_NOTEOL option to pcre_exec()
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or pcre_dfa_exec()
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\? pass the PCRE_NO_UTF8_CHECK option to
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pcre_exec() or pcre_dfa_exec()
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\>dd start the match at offset dd (any number of digits);
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this sets the startoffset argument for pcre_exec()
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or pcre_dfa_exec()
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\<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
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or pcre_dfa_exec()
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\<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
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or pcre_dfa_exec()
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\<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
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or pcre_dfa_exec()
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\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
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or pcre_dfa_exec()
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\<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
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or pcre_dfa_exec()
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The escapes that specify line ending sequences are literal strings,
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exactly as shown. No more than one newline setting should be present in
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any data line.
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A backslash followed by anything else just escapes the anything else.
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If the very last character is a backslash, it is ignored. This gives a
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way of passing an empty line as data, since a real empty line termi-
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nates the data input.
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If \M is present, pcretest calls pcre_exec() several times, with dif-
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ferent values in the match_limit and match_limit_recursion fields of
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the pcre_extra data structure, until it finds the minimum numbers for
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each parameter that allow pcre_exec() to complete. The match_limit num-
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ber is a measure of the amount of backtracking that takes place, and
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checking it out can be instructive. For most simple matches, the number
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is quite small, but for patterns with very large numbers of matching
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possibilities, it can become large very quickly with increasing length
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of subject string. The match_limit_recursion number is a measure of how
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much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
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memory is needed to complete the match attempt.
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When \O is used, the value specified may be higher or lower than the
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size set by the -O command line option (or defaulted to 45); \O applies
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only to the call of pcre_exec() for the line in which it appears.
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If the /P modifier was present on the pattern, causing the POSIX wrap-
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per API to be used, the only option-setting sequences that have any
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effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
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to be passed to regexec().
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The use of \x{hh...} to represent UTF-8 characters is not dependent on
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the use of the /8 modifier on the pattern. It is recognized always.
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There may be any number of hexadecimal digits inside the braces. The
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result is from one to six bytes, encoded according to the original
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UTF-8 rules of RFC 2279. This allows for values in the range 0 to
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0x7FFFFFFF. Note that not all of those are valid Unicode code points,
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or indeed valid UTF-8 characters according to the later rules in RFC
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3629.
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THE ALTERNATIVE MATCHING FUNCTION
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By default, pcretest uses the standard PCRE matching function,
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pcre_exec() to match each data line. From release 6.0, PCRE supports an
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alternative matching function, pcre_dfa_test(), which operates in a
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different way, and has some restrictions. The differences between the
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two functions are described in the pcrematching documentation.
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If a data line contains the \D escape sequence, or if the command line
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contains the -dfa option, the alternative matching function is called.
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This function finds all possible matches at a given point. If, however,
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the \F escape sequence is present in the data line, it stops after the
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first match is found. This is always the shortest possible match.
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DEFAULT OUTPUT FROM PCRETEST
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This section describes the output when the normal matching function,
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pcre_exec(), is being used.
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When a match succeeds, pcretest outputs the list of captured substrings
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that pcre_exec() returns, starting with number 0 for the string that
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matched the whole pattern. Otherwise, it outputs "No match" or "Partial
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match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
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TIAL, respectively, and otherwise the PCRE negative error number. Here
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is an example of an interactive pcretest run.
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$ pcretest
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PCRE version 7.0 30-Nov-2006
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re> /^abc(\d+)/
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data> abc123
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0: abc123
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1: 123
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data> xyz
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No match
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Note that unset capturing substrings that are not followed by one that
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is set are not returned by pcre_exec(), and are not shown by pcretest.
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In the following example, there are two capturing substrings, but when
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the first data line is matched, the second, unset substring is not
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shown. An "internal" unset substring is shown as "<unset>", as for the
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second data line.
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re> /(a)|(b)/
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data> a
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0: a
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1: a
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data> b
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0: b
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1: <unset>
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2: b
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If the strings contain any non-printing characters, they are output as
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\0x escapes, or as \x{...} escapes if the /8 modifier was present on
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the pattern. See below for the definition of non-printing characters.
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If the pattern has the /+ modifier, the output for substring 0 is fol-
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lowed by the the rest of the subject string, identified by "0+" like
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this:
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re> /cat/+
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data> cataract
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0: cat
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0+ aract
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If the pattern has the /g or /G modifier, the results of successive
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matching attempts are output in sequence, like this:
|
|
|
|
re> /\Bi(\w\w)/g
|
|
data> Mississippi
|
|
0: iss
|
|
1: ss
|
|
0: iss
|
|
1: ss
|
|
0: ipp
|
|
1: pp
|
|
|
|
"No match" is output only if the first match attempt fails.
|
|
|
|
If any of the sequences \C, \G, or \L are present in a data line that
|
|
is successfully matched, the substrings extracted by the convenience
|
|
functions are output with C, G, or L after the string number instead of
|
|
a colon. This is in addition to the normal full list. The string length
|
|
(that is, the return from the extraction function) is given in paren-
|
|
theses after each string for \C and \G.
|
|
|
|
Note that whereas patterns can be continued over several lines (a plain
|
|
">" prompt is used for continuations), data lines may not. However new-
|
|
lines can be included in data by means of the \n escape (or \r, \r\n,
|
|
etc., depending on the newline sequence setting).
|
|
|
|
|
|
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
|
|
|
|
When the alternative matching function, pcre_dfa_exec(), is used (by
|
|
means of the \D escape sequence or the -dfa command line option), the
|
|
output consists of a list of all the matches that start at the first
|
|
point in the subject where there is at least one match. For example:
|
|
|
|
re> /(tang|tangerine|tan)/
|
|
data> yellow tangerine\D
|
|
0: tangerine
|
|
1: tang
|
|
2: tan
|
|
|
|
(Using the normal matching function on this data finds only "tang".)
|
|
The longest matching string is always given first (and numbered zero).
|
|
|
|
If /g is present on the pattern, the search for further matches resumes
|
|
at the end of the longest match. For example:
|
|
|
|
re> /(tang|tangerine|tan)/g
|
|
data> yellow tangerine and tangy sultana\D
|
|
0: tangerine
|
|
1: tang
|
|
2: tan
|
|
0: tang
|
|
1: tan
|
|
0: tan
|
|
|
|
Since the matching function does not support substring capture, the
|
|
escape sequences that are concerned with captured substrings are not
|
|
relevant.
|
|
|
|
|
|
RESTARTING AFTER A PARTIAL MATCH
|
|
|
|
When the alternative matching function has given the PCRE_ERROR_PARTIAL
|
|
return, indicating that the subject partially matched the pattern, you
|
|
can restart the match with additional subject data by means of the \R
|
|
escape sequence. For example:
|
|
|
|
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
|
|
data> 23ja\P\D
|
|
Partial match: 23ja
|
|
data> n05\R\D
|
|
0: n05
|
|
|
|
For further information about partial matching, see the pcrepartial
|
|
documentation.
|
|
|
|
|
|
CALLOUTS
|
|
|
|
If the pattern contains any callout requests, pcretest's callout func-
|
|
tion is called during matching. This works with both matching func-
|
|
tions. By default, the called function displays the callout number, the
|
|
start and current positions in the text at the callout time, and the
|
|
next pattern item to be tested. For example, the output
|
|
|
|
--->pqrabcdef
|
|
0 ^ ^ \d
|
|
|
|
indicates that callout number 0 occurred for a match attempt starting
|
|
at the fourth character of the subject string, when the pointer was at
|
|
the seventh character of the data, and when the next pattern item was
|
|
\d. Just one circumflex is output if the start and current positions
|
|
are the same.
|
|
|
|
Callouts numbered 255 are assumed to be automatic callouts, inserted as
|
|
a result of the /C pattern modifier. In this case, instead of showing
|
|
the callout number, the offset in the pattern, preceded by a plus, is
|
|
output. For example:
|
|
|
|
re> /\d?[A-E]\*/C
|
|
data> E*
|
|
--->E*
|
|
+0 ^ \d?
|
|
+3 ^ [A-E]
|
|
+8 ^^ \*
|
|
+10 ^ ^
|
|
0: E*
|
|
|
|
The callout function in pcretest returns zero (carry on matching) by
|
|
default, but you can use a \C item in a data line (as described above)
|
|
to change this.
|
|
|
|
Inserting callouts can be helpful when using pcretest to check compli-
|
|
cated regular expressions. For further information about callouts, see
|
|
the pcrecallout documentation.
|
|
|
|
|
|
NON-PRINTING CHARACTERS
|
|
|
|
When pcretest is outputting text in the compiled version of a pattern,
|
|
bytes other than 32-126 are always treated as non-printing characters
|
|
are are therefore shown as hex escapes.
|
|
|
|
When pcretest is outputting text that is a matched part of a subject
|
|
string, it behaves in the same way, unless a different locale has been
|
|
set for the pattern (using the /L modifier). In this case, the
|
|
isprint() function to distinguish printing and non-printing characters.
|
|
|
|
|
|
SAVING AND RELOADING COMPILED PATTERNS
|
|
|
|
The facilities described in this section are not available when the
|
|
POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
|
|
ifier is specified.
|
|
|
|
When the POSIX interface is not in use, you can cause pcretest to write
|
|
a compiled pattern to a file, by following the modifiers with > and a
|
|
file name. For example:
|
|
|
|
/pattern/im >/some/file
|
|
|
|
See the pcreprecompile documentation for a discussion about saving and
|
|
re-using compiled patterns.
|
|
|
|
The data that is written is binary. The first eight bytes are the
|
|
length of the compiled pattern data followed by the length of the
|
|
optional study data, each written as four bytes in big-endian order
|
|
(most significant byte first). If there is no study data (either the
|
|
pattern was not studied, or studying did not return any data), the sec-
|
|
ond length is zero. The lengths are followed by an exact copy of the
|
|
compiled pattern. If there is additional study data, this follows imme-
|
|
diately after the compiled pattern. After writing the file, pcretest
|
|
expects to read a new pattern.
|
|
|
|
A saved pattern can be reloaded into pcretest by specifing < and a file
|
|
name instead of a pattern. The name of the file must not contain a <
|
|
character, as otherwise pcretest will interpret the line as a pattern
|
|
delimited by < characters. For example:
|
|
|
|
re> </some/file
|
|
Compiled regex loaded from /some/file
|
|
No study data
|
|
|
|
When the pattern has been loaded, pcretest proceeds to read data lines
|
|
in the usual way.
|
|
|
|
You can copy a file written by pcretest to a different host and reload
|
|
it there, even if the new host has opposite endianness to the one on
|
|
which the pattern was compiled. For example, you can compile on an i86
|
|
machine and run on a SPARC machine.
|
|
|
|
File names for saving and reloading can be absolute or relative, but
|
|
note that the shell facility of expanding a file name that starts with
|
|
a tilde (~) is not available.
|
|
|
|
The ability to save and reload files in pcretest is intended for test-
|
|
ing and experimentation. It is not intended for production use because
|
|
only a single pattern can be written to a file. Furthermore, there is
|
|
no facility for supplying custom character tables for use with a
|
|
reloaded pattern. If the original pattern was compiled with custom
|
|
tables, an attempt to match a subject string using a reloaded pattern
|
|
is likely to cause pcretest to crash. Finally, if you attempt to load
|
|
a file that is not in the correct format, the result is undefined.
|
|
|
|
|
|
SEE ALSO
|
|
|
|
pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
|
|
pcrepattern(3), pcreprecompile(3).
|
|
|
|
|
|
AUTHOR
|
|
|
|
Philip Hazel
|
|
University Computing Service
|
|
Cambridge CB2 3QH, England.
|
|
|
|
|
|
REVISION
|
|
|
|
Last updated: 10 March 2009
|
|
Copyright (c) 1997-2009 University of Cambridge.
|